SERV1775 January 2004
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SERVICE TRAINING
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TECHNICAL PRESENTA PRESENTATION
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953C/963C TRACK LOADERS WITH TIER II ENGINES
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INTRODUCTION
Meeting Guide 775
953C/963C TRACK LOADERS WITH TIER TIER II ENGI ENGINE NES S - INTR INTROD ODUC UCTI TION ON SERV1775 AUDIENCE
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Level II–Service personnel who understand the principles of machine systems operation, diagnostic equipment, and procedures for testing and adjusting.
CONTENT
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This presentation provides update information on machine components and system operation of the power train hydraulic system and the implement hydraulic system, for the 953C and 963C Track Loaders with Tier II Engines. This presentation may be used for self paced and self directed training. OBJECTIVES
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After learning the information in this presentation, the technician will be able to:
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1. locate and identify the the new components on the 953C and 963C Tier Tier II Track Loaders; 2. explain explain the operation operation of the components components in the systems; systems; and 3. trace the the flow of of oil through through the the systems. systems.
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REFERENCES
"953C/963C/973C Track Loaders–Implement Hydraulic System" "'C" Series Track Loaders–Power Train'" STMG 735 "973C Track Loader–Introduction" "'C" Series Track Loaders–Power Train Calibration'" STMG 724 "963C Track Loader" 953C Track Loader Specalog 963C Track Loader Specalog
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Estimated Time: 3 Hours Illustrations: 74 Handouts: 17 Form: SERV1775 Date: 1/04 © 2004 Caterpil Caterpillar lar Inc.
SERV2695 SERV2694 SERV1735 SEVN4937 SERV1724 SERV1724 AEHQ5541 AEHQ5542
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TABLE OF CONTENTS CONTENTS INTRODUCTION ................................................... ....................................................... .....................................................................5 ..............5
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OPERATOR'S OPERATOR'S STA STATION.............................................................. ................................................9 SERVICE SERVICE COMPARTM COMPARTMENTS ENTS AND AREAS ....................................................... ...........................................................................23 ....................23 Engine ...................................................... ............................................................................................................. .............................................................................33 ......................33
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HYDRAULIC SYSTEMS..........................................................................................................40 963C Power Train Hystat Hydraulic Hydraulic System ................................................ .......................51 953C Power Train Hystat Hydraulic Hydraulic System ................................................ .......................67 963C Implement Hydraulic System .................................................... .....................................................................................83 .................................83
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ADVANCED ADVANCED OPTIONAL SYSTEMS.................................................... ...................................95 SIGNIFICANT MAINTENANCE CHANGES ..................................................... .........................................................................98 ....................98
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NEW TOOLING/SKILLS REQUIRED FOR SERVICE ....................................................... ..........................................................99 ...99 CONCLUSION.........................................................................................................................100
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HYDRAULIC SCHEMATIC COLOR CODE.........................................................................101 HANDOUTS.............................................................................................................................102
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NOTES
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953C/963C TRACK LOADERS WITH TIER II ENGINES INTRODUCTION
© 2004 Caterpillar Inc.
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INTRODUCTION
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Caterpillar is introducing updated 953C and 963C Track Loaders with a new electronically controlled engine. The updated 953C is powered by a Caterpillar 3126B, six-cylinder diesel engine, rated at 95 kW (129 hp) at 2000 rpm. The 953C Track Loader weighs 15 145 kg (33,389 lbs.). The updated 963C is powered by a Caterpillar 3126B, six-cylinder diesel engine, rated at 118 kW (158 hp) at 2000 rpm. The 963C weighs 19 589 kg (43,194 lb.) The updated machines retain the same nomenclature as the previous machines they are replacing. The work tools, buckets, ripper-scarifier, and GET are unchanged from the former models.
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The machines have an updated instrument panel to provide additional machine operating information to the operator. The machines retain the rear-mounted engine, box-section integral frame, electronically-controlled hydrostatic drive system, and the Z-bar loader linkage. It is designed for improved operator comfort, serviceability, operating costs, reliability, and durability.
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The 3126B engine provides more power than the 3116 engine it replaced. The 3126B engine has: Hydraulic-actuated Electronic Unit Injectors (HEUI), an air to air aftercooler (ATAAC), three valves per cylinder, and a turbocharger. The engine is controlled and monitored by an Advanced Diesel Engine Management – Electronic Control Module (ADEM III), which controls all major engine functions and regulates the HEUI. The new engine arrangement will meet all known emission requirements at the time of introduction, including US EPA Tier II and European Union Stage 2 regulations.
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The electronically controlled hydrostatic drive system automatically matches machine travel speed to the combined travel and implement loads on the machine enabling maximum travel speed up to the speed selected by the operator.
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The hydrostatic drive train also offers independent power and control of each track, with fast acceleration, infinitely variable speeds, and automatic, on-the-go, direction changes for each track. The operator can command smooth "power turns" or even counter-rotation of the tracks by simply pushing one of the steering pedals. The Caterpillar hydrostatic drive system manages itself, freeing the operator to concentrate on using the track loader's superb agility, speed, and maneuverability to do more productive work.
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The Z-bar linkage, which is unchanged from previous models, provides high breakout force for fast, easy loading, even from a "hard bank" of highly compacted material. The single, center-mounted tilt cylinder means fewer pivot points to maintain and a better view to the bucket corners, for high operator efficiency.
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Improvements have also been made to several systems to enhance customer value. NOTE: The "HYDRAULIC SCHEMATIC COLOR CODE" is located after the "CONCLUSION" of this presentation.
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The cab is designed for visibility, operator comfort, and convenience. The standard ROPS cab is sound suppressed, sealed, pressurized, air conditioned, and resiliently mounted to the frame. A fully adjustable air suspended seat, with side-to-side shock absorption, provides maximum operator comfort. Conveniently placed switches, gauges, information display, and controls improve operator comfort, awareness, and efficiency.
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The steel roof is now standard. The rugged steel roof resists bending and tearing, and can be easily repaired. The Caterpillar Monitoring System continuously monitors all important engine, implement hydraulic, and hydrostatic drive functions. The system permits fast troubleshooting, resulting in increased track loader availability and reduced downtime for repairs. The monitoring system is flashable using Caterpillar Electronic Technician (Cat ET).
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The cab improvements include:
- new dash with a flashable monitoring system - rocker switch parking brake control and rocker switch throttle control - new fuse panel
- improved sealing - improved defrost
- improved armrests
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The updated machines are now equipped with electronic engines featuring a new cooling system. The radiator grill swings out. Rated engine speed has been reduced to 2000 rpm from 2200 rpm. The 963C features remote oil filters and an under the hood muffler. The starter has been improved and the machines feature a brushless alternator. The undercarriage features larger track links and tough steel sprocket segments. A new optional attachment on the 953C and 963C is the Rotating Bushing Track (RBT).
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Due to the change in rated engine speed the implement pump size was increased to provide the same flow rate at 2000 rpm as the smaller pump did at 2200 rpm. The power train pumps remained the same. The gear ratios in the splitter box have changed to compensate for the change in engine rpm. Hystat Calibrations can be done through Caterpillar Electronic Technician (Cat ET). Maintenance intervals have been increased to 500 hours for the engine oil, engine oil filter, and fuel filters, reducing the cost and time required for engine maintenance. A number of other maintenance intervals have also been increased.
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OPERATOR'S STATION
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The 953C and 963C offers a premium quality seat as standard equipment. This seat, with cloth upholstery in cab-equipped machines (vinyl upholstery in open canopy machines), is ergonomically designed and fully adjustable for maximum operator comfort. The seat is suspended on a cushion of air and equipped with a special side-to-side "isolator" to support the operator and absorb vibrations. When the isolator in in the unlocked position the seat will function much like a shock absorber, dampening left to right seat motion. The isolator seat is equipped with an extra control (not shown) on the left side of the seat above the slide rail adjustment lever. Cushion side-bolsters on the seat help the wide safety belt keep the operator centered in the seat when working on side slopes and rough terrain. The backrest conforms to the operator's spinal curve and features adjustable recline angle and lumbar support. The removable headrest has vertical and tilt adjustments.
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The retractable seat belt is 75 mm (3 in) wide for comfortable restraint. The automatic retraction mechanism keeps the belt off the floor when not in use. The height of the armrests is easily adjusted. Total adjustability lets the operator customize the armrests to the most comfortable position. The right armrest is adjustable: up, down, forward, and backward.
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On the left console is the horn (1), engine speed selector switch (2), Work-Travel Mode (turtle/rabbit) switch (3), parking brake switch (4), and travel speed and direction control lever (5).
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The operator controls engine speed (rpm) by using an electronic engine speed selector switch which is a "rocker" switch located on the left console. The Engine ECM will always start the engine at low-idle. When the operator chooses to increase the engine rpm, the operator must press the upper (rpm increase) side of the switch. Pressing the rpm increase side of the switch once, for less than one second, will cause the engine rpm to go to high-idle. Pressing and holding the rpm increase side of the switch for longer than one second will increase the rpm (in increments of 200 rpm), at the rate of about 400 rpm per second. It will take 3 to 5 seconds for the operator to go from low-idle to highidle by holding the switch. The rpm decrease side of the switch works the same way when reducing the rpm of the engine. Any time the electronic engine speed selector switch is activated to change the rpm of the engine, the Electronic Message Display will automatically switch to the Digital Tachometer Mode for 15 seconds to show engine rpm.
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At customers’ requests, a Work-Travel Mode switch was added to the dashboard on the former models. On the current machines, this Work-Travel Mode switch is located on the operator’s left control console, within easy reach. The operator can change the turtle/rabbit command any time. Regardless of any change in the turtle/rabbit command, the Power Train Electronic Control Module (ECM) will not change the travel mode until the speed and direction control lever is returned to the NEUTRAL position.
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The operator can choose between two operating modes. 1. In Travel Mode (Rabbit), the Power Train ECM retains the standard speed features for machine operations.
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2. In Work Mode (Turtle), the Power Train ECM limits the maximum speed of the track loaders to 6.6 km/h, (4.1 mph), which is 67% of the machine’s maximum rated speed. The Work Mode offers the following advantages:
- When working in tight areas, choosing the Work Mode offers a lower overall speed range of the speed/direction lever allowing more precise control of the machine.
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- When in Work Mode, limiting the machine maximum speed reduces wear of undercarriage components, lowering the owning and operating costs of the machine.
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If the machine owner requests it, the dealer can reduce the top speed the machine will travel in either FORWARD or REVERSE while in the Travel (Rabbit) and Work (Turtle) Modes. If job conditions indicate a slower maximum speed would be desirable or the owner prefers to lower the top speed of reverse to reduce undercarriage wear, the Power Train ECM can be set to a lower maximum speed. Speed reductions programmed into the Power Train ECM reduce maximum speeds in both the Work Mode and the Travel Mode by the same percentages.
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The parking brake switch on the left console, is for the operator to use to apply the parking brakes after the machine is stopped. If this switch is moved to the "BRAKE-ON" position while the machine is moving, the Power Train ECM will quickly bring the machine to a controlled stop. If the switch is moved to the "BRAKE-OFF" position while the speed and direction control lever is in a forward or reverse position, the Power Train ECM will prevent the machine from moving until the speed and direction control lever is first moved to the zero speed position, and then moved to command a speed and direction.
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The travel speed and direction control lever (5) is connected to a position sensor that continuously signals the position of the lever to the Power Train ECM. The sensor detects three different lever positions: FORWARD, NEUTRAL, AND REVERSE. When the speed/direction lever is in the reverse direction side of the control, the back-up alarm will sound. The Power Train ECM uses the signal from the sensor to determine which steering solenoid valves to activate and how far to open them. The sensor changes its signal as the lever is moved farther from the brakes-on position into FORWARD on the "reverse V" or into REVERSE on the "reverse V" indicating the operator wants to travel at a faster speed in the chosen direction. Technicians can adjust the control sensitivity of the speed and direction control lever using Cat ET.
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When the engine is started, the ADEM III controller interfaces with the Power Train ECM to determine if the parking brake switch is in the "BRAKE-ON" position and the speed and direction control lever is in the "BRAKE-ON" position in the "reverse V" pattern. Either the parking brake switch or the speed and direction lever must be in the "BRAKE-ON" position for the ADEM III controller to start the engine. The speed and direction lever must be returned to the NEUTRAL position and then shifted again for the machine to move. The recommendation is to have both controls in the "BRAKE ON" position when starting.
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The fuse panel (1) along with the alternator breaker (2) have been relocated to the inside of the cab, behind the trim panel under the speed and direction control lever.
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The fuse panel cover has been removed.
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The dash and instrument panel provide all necessary functions and information within the operator’s normal line of sight. The Caterpillar Monitoring System constantly monitors all vital functions and alerts the operator to the nature and severity of any abnormalities. The monitoring system includes: - four gauges (1) - ten alert indicators (2)
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- Numeric Message Display (3) - action warning light (4)
- low fuel and low coolant warning (5) - action alarm horn (not shown)
- key start/stop switch (anti-theft feature is optional) (6) - switch for selecting the information to be shown on the Numeric Message Display (7) - parking brake-on warning light (8) - light switches (9)
- front - wiper/washer control (10) - rear - wiper/washer control (11)
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The four-gauge display includes engine coolant temperature (1), pump drive oil temperature (2), hydraulic tank oil temperature(3), and fuel level (4). The monitoring panel has ten alert indicators (5) and the Numeric Message Display (6). The ten alert indicators used are (left to right, top row first):
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- low fuel pressure from the transfer pump to the injection pump - case drain filter bypass - charge filter bypass
- pump drive oil temperature; indicates the pump drive oil temperature is too high. - charge pressure; indicates low hystat charge oil pressure - engine oil pressure; indicates low engine oil pressure - check engine; indicates a warning is being sent from the ADEM III engine control - electrical charging; indicates the alternator voltage is too high or too low - hydrostatic drive system warning; indicates the Power Train ECM is sending a problem signal to the Caterpillar Monitoring System - Air Inlet Heater (AIH); flashes when the air inlet heater is activated. The air inlet heater is standard and operates automatically if needed when the engine is started.
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The Numeric Message Display provides the operator or service technician with specific machine information. The operator mode switch (7) located on the dash panel, to the right of the monitoring lights, is for use by both the operator and service technician. Activating this switch will scroll the Numeric Message Display from the default mode (hour meter), engine rpm, override pressure, and odometer.
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The monitoring system performs a self-test to verify that the main display module is operating properly every time the key start switch is turned from the "OFF" to the "ON" position. The internal circuits and the indicators (gauges, action lamp, and action alarm) are automatically checked and the main warning light module performs an automatic self-test. The operator must observe the outputs to determine whether or not the modules and the outputs are operating properly. The Caterpillar Monitoring System returns to its normal mode of operation following the test. The tests are as follows: Main Cluster:
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- Each function monitored by the Numeric Message Display will turn on for approximately one second. The display will then return to default mode: hour meter. - All warning lights will flash for one second. Then the indicators will function according to the inputs. Gauge Cluster:
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- The pointers will move toward the straight up position within the first one-half second. - The pointers will move to the far left position within the next second. - The pointers will move to the far right position within the next one and one-half seconds. - The pointers will move to the actual monitor position based on the inputs within the next one-half second. Monitoring/Alarm Cluster:
- The action alarm horn will sound for approximately one second.
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- The action warning lamp will light for approximately three seconds.
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When in Service Mode, service codes from the MAC-14 Electronic Hydrostatic Control (EHC) or Power Train ECM will be shown on the monitoring system Numeric Message Display. The service code information is transferred via the Cat Data Link from the Power Train ECM to the main display module. The diagnostic information is shown when the main display module is in Service Mode. The Module Identifier (MID) indicates which electronic control module is sending the service code. Three service switches - service switch (1) - clear switch (2)
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- sensor/speed calibrate switch (3)
When a sensor fault is present, the corresponding warning for that sensor is also activated for the operator. For example, if the signal wire for the pump drive temperature sensor is shorted, then: a. the corresponding service code is stored in memory. b. the gauge for pump drive temperature is displayed in the warning range. c. the action lamp flashes. With the Service Mode switch, located below the operator’s right arm rest in the "Service" position, a service technician can troubleshoot the Caterpillar Monitoring System by using the Operator Mode switch on the instrument panel to view specific machine information.
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Service codes from the Power Train ECM and the Engine ECM will be displayed on the Numeric Message Display. The service code information is transferred via the Cat Data Link from the Power Train ECM and the Engine ECM to the main display module.
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The operator/service technician scrolling switch is on the right side of the instrument panel, above the key. Activating the switch, with the Service Mode switch tuned on, will scroll through any diagnostic/service fault codes and present the fault codes on the Numeric Message Display. Normally this switch would scroll through the hour meter, engine rpm, override pressure, and odometer for the operator.
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Service codes from all systems are shown whether a fault (service) code is currently present or occurred in the past. When the Numeric message displays "Service Code" text is on, the fault currently being shown is present in the machine. If the fault code is coming from the memory of the Caterpillar Monitoring System, not currently present, the "Service Code" is off. The Service Modes are as follows:
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Mode 1 (Harness Code Mode) shows the machine model on which the monitoring system is installed.
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Mode 2 lets the service technician scroll through each individual gauge. Mode 3 shows the diagnostic codes for existing or previous problem codes stored in the system. Three dashes (---) indicates no code or problem is present for that mode. If the warning light on the Caterpillar Monitoring System panel is on when a code is displayed, the fault is active. If the warning light on the Caterpillar Monitoring System panel is off when a code is displayed, the fault is in the system memory. After the fault has been repaired, the clear switch is used to remove the code from the system.
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Mode 4 is the "Tattletale Mode" which stores the "worst case" position of each gauge and the information displayed by the Numeric Message Display. In this mode, the Caterpillar Monitoring System will show the extreme value for each machine condition monitored. When in this mode, each gauge in the four-gauge cluster displays its highest or lowest recorded position, and highest numeric values will appear on the Numeric Message Display. The clear switch will reset the system. A fifth "Ghost" gauge for the engine oil pressure is stored in the Caterpillar Monitoring System memory. When the service technician scrolls through the Tattletale readings, the lowest engine oil pressure will be presented along with the other gauge readings.
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Mode 5 is the Calibration Mode, which has multiple submodes for calibrating various components in the hydrostatic drive system.
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The operator steers the track loader by depressing the left (1) or right (2) steering pedal. The center brake pedal (3) is used to decrease the speed of the machine, assist in reducing rollback, and hold the machine in position by causing the parking brakes to engage.
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The standard operator control for the two hydraulic circuits which operate the lift arms and bucket, is a single "joystick" lever (1) on the console to the operator’s right.
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- Forward and back movement lowers and raises the lift arms. - Left and right movement tilts the bucket back and dumps it. A second lever (2) is mounted to the right of the single lever control if the machine is equipped with an attachment implement hydraulic circuit. This lever and circuit is used to control and power the clamping feature of the multi-purpose bucket or to raise and lower the ripper. If both an MP bucket and a ripper are installed, a manual diverter valve, controlled by a push-pull cable and handle, is located just behind the second lever. The diverter valve will direct oil to either the MP bucket or the ripper.
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Below the control levers are the pilot valves. When a control lever is shifted, pilot oil is directed to shift the implement control spools. Pilot controls provide low lever efforts for the operator.
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Simultaneous lifting and dumping of the bucket is possible with either the single lever or two-lever configuration due to the design of the main control valve group. Simultaneous lift and dump makes it possible for the operator to begin dumping the bucket as it rises above the side of a truck for faster cycle times and increased productivity.
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The simultaneous lift and dump feature also lets the operator precisely dump material from the bucket as the bucket is being raised while the machine is spreading fill material to level and grade an area of ground for a smooth, finished surface.
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If the operator pulls the lift lever all the way to the rear (lift detent position), an electro-magnet holds the lever in this "detent position," and the lift arms go up. Power to the electro magnet is stopped when the lift arms rise to the preset height. The lift arms stop raising and the lever returns to the hold position.
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A two lever control is available as an attachment.
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Forward and back movement of the inboard lever (1) lowers and raises the lift arms. Forward and back movement of the middle lever (2) tilts the bucket back and dumps it. In the two-lever configuration, the track loader dump lever operates in the opposite direction of a wheel loader. Pull back on the bucket lever to dump. Push the lever forward to curl the bucket back.
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This outboard lever (3) and circuit is used to control and power the clamping feature of the multi-purpose bucket or to raise and lower the ripper. The push-pull lever (4) is used to manually operate the diverter valve.
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The Heating/Ventilation/Air Conditioning (HVAC) controls are on the far right of the operator's seat. One of the controls is for the fan (1) and the other (2) controls the temperature.
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Air conditioning is now standard on machines with cabs. A heater is standard on canopy-equipped machines. Both the air conditioner and the heater deliver filtered, pressurized, temperature-controlled air to the operator and/or windows. There are 10 louvered vents in the cab, with two on each door-post, for complete air circulation within the operator station. The cab pressurization filter offers the same filtering capacity as the previous machines. Access to the diagnostic connector (3) is obtained by opening the right side storage compartment. A 12 Volt outlet (4) and power inverter (5) are also located in this compartment.
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SERVICE COMPARTMENTS AND AREAS
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The updated 953C uses a 234 L (62 gal) corrosion-proof, non-metallic, fuel tank. This sturdy tank is nestled deep within the steel frame and loader tower structure of the 953C for maximum protection. The lockable fuel filler cap (arrow) is accessible from between the loader arms above the tank. The fuel tank water and sediment drain is located on the front of the machine behind an access door. The fuel tank has the same capacity of the previous 953C.
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The hydrostatic power train and the implement hydraulic system share a common hydraulic tank on the 953C. It is located between the loader towers, next to the fuel tank, in the front of the machine. The tank is sealed and pressurized to prevent contamination from dirt and dust and to provide a positive flow of oil to the implement and hydrostatic pumps. Implement hydraulic oil passes through a screen as it leaves the hydraulic tank, before going to the implement pump. Oil returning from the implement system flows through two drain filters on the front of the tank before it enters the tank.
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The operator or service technician should check the sight gauge on the hydraulic tank, daily, to confirm the quantity of oil in the system. When checking the hydraulic oil level sight gauge (1), the bucket must be flat on level ground and the ripper tips lowered to the ground. If additional oil is required, the fill cap (2), should be removed slowly because the hydraulic tank might be pressurized. The hydraulic oil temperature sensor transmits a signal to the monitoring system.
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The service interval for the hydraulic oil filter (3) is 1000 hours or 1 year and the hydraulic oil is 4000 hours or 2 years.
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The 963C hydraulic tank is located in the same location as the 953C. The sight gauge (1) on the 963C can be seen from ground level on the right side of the machine along with the fuel fill cap (2).
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The capacity of the updated 963C fuel tank is the same 315 L (83.2 gal) as the former 963C tank. The 963B tank held 19 L (5 gal) less fuel than the 963C tank. The fuel tank is located in the front of the machine between the loader towers and behind the hydraulic tank. The new fuel tank is made of 5 mm (0.20 in) thick steel plate rather than the 3 mm (0.12 in) plate used on the previous 963C. The fuel tank reinforcement straps are now on the inside. Welding procedures have been changed to eliminate stress points. The 963C has a manual pump for removing water and contaminates from the bottom of the tank.
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The engine radiator (1), air to air aftercooler (ATTAC) (2), and hydraulic oil cooler (3) are incorporated into a single cooling unit at the rear of the machines. By locating the cooling system in the rear of the loader, they are away from dust and debris stirred up by the bucket while the machine is working.
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The radiator uses a copper core cooler with seven rows of tubes and nine horizontal fins per inch. For the engine cooling system, Extended Life Coolant (ELC) is standard. The ELC should be changed every 6000 hours instead of 3000 hours for a traditional coolant. Coolant Extender should only be added every 3000 hours or 2 years. This dramatically decreases cooling system maintenance time and cost. The hydraulic oil cooler, located next to the engine radiator, is an aluminum, barplate core, oil-to-air cooler, with six horizontal fins per inch.
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The air to air aftercooler (ATAAC) is a single pass, steel, heat exchanger or cooling system for the air coming from the turbocharger, before it enters the intake manifold. The pre-cleaner bowl (4) for the engine air intake system is located directly behind the operator’s station. The bowl should be emptied when the dirt reaches the "full" mark.
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A manual, fuel priming pump (1) is located between the fuel tank and the combined water separator/primary fuel filter (2) behind access doors on the right side of the engine compartment. An electric fuel priming pump is available as an option. After passing through the water separator/primary filter, the fuel flows to the fuel transfer pump which pumps it through the secondary, high efficiency, fuel filter (3) before it flows to the cylinder head and the injectors. The dual fuel filter, water separator design, provides protection to the injection system against low-quality or contaminated fuel.
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The fuel supply shutoff valve (4) is located near the primary fuel filter/water separator on the right side of the machine. Also shown are the pump drive dipstick (5), pump drive fill tube (6), case drain filter (7) on the 963C, Product Link ECM (8), and disconnect switch (9).
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The hydraulic oil filters are located on the right side of the machine behind the forward access door. The 953C is equipped with two case drain filters (1 and 2). The 963C only has one (1) case drain filter. The hydraulic fluid for the hydrostatic drive system first passes through a screen when it leaves the tank before it goes to the charge pump (charge pumps on the 963C). From the charge pump, oil flows through a five micron charge oil filter (3) before going into the hydrostatic drive system and the pilot system for the implement controls. The oil is filtered again when it returns from the pump and motor case drains, before returning to the tank through the case drain filters (27 micron).
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If the oil is very cold or if the charge system filter is restricting the flow of oil due to contamination, a bypass valve contained within the charge oil filter housing will open, directing fluid back to the hydraulic tank. The bypass limits the maximum differential pressure across the filter. When the maximum differential is exceeded, the Power Train ECM will prevent the machine from moving until the differential pressure is below the bypass limit. The monitoring system provides input into the Power Train ECM as to the status of the bypass switch. This filter also has a bypass warning light on the dashboard. This light is deactivated for cold start since bypass is a normal operation for cold start. With cold oil the machine cannot move with the bypass open. A temperature sensor is used to communicate the transmission oil temperature to the monitoring system.
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Both machines use a MAC-14, Power Train ECM (1) to control the hydrostatic pumps and motors. The MAC-14, Power Train ECM is located on the right side of the machine behind the upper enclosure door on the left. The MAC-14 was used on the former 963C, but has been rotated 90 degrees to provide greater service access. The Power Train ECM system eliminates the mechanical linkages associated with the Hydrostatic Power Control Unit (HPCU) which was used on the 953/953B and 963/963B.
T K
The Power Train ECM receives input signals from the operator controls: the speed and direction lever, steering pedals, brake pedal, Work-Travel Mode switch, parking brake switch, or signals from the machine itself (pressures, engine rpm, travel motor speeds, and temperatures). With this information, the Power Train ECM makes calculations and directs output signals to the solenoid valves that control the hydrostatic drive. Speed sensors for the Tier II 963C machines are now on the the motors instead of the final drives. The Tier II 953C machine sensors are still on the final drives. The sensors are only required for calibrations.
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From the engine speed sensor, the Power Train ECM can sense the engine slowing due to increased load and will automatically upstroke the motors and destroke the pumps to maintain full power to the implement hydraulics while slowing the tracks, if necessary, to keep engine rpm from going too low. An additional ECM (2), mounted below the Power Train ECM, is used for the Machine Security System. This feature if added to the machine, prevents the engine from starting unless the appropriate key is used.
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The batteries (1), engine oil fill tube (2), engine oil dip stick (3), fuel pump (4), and air conditioning compressor (5) can be accessed through the right engine compartment at the rear of the machine.
T K
To ensure quick starting down to –18° C (0° F), the machines come standard with a 24-volt, 6 kW (8 hp) capacity starting motor and two 12-volt, 100 amp hour batteries wired in series. The standard battery has 750 amps of cold cranking capacity (CCA). As an option, the machines can be equipped with two, 172-amp hour, 950 CCA, batteries for starting the engine down to –32° C (–25° F). NOTE: This illustration is from a 953C. For the 963C one battery is located on each side of the machine.
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The primary and secondary air filter elements are located on the left side of the machine in the air cleaner housing (1). The filter element indicator (2) should be checked to determine if the elements require service. The engine oil filter (3) has been relocated on the 963C to a convenient location just inside an access door on the left side of the machine. This makes filter changes easier and decreases the risk of spilling oil when the filter is being changed.
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The turbocharger (4) uses exhaust gases to drive the impeller turbine which, in turn, drives an air compressor turbine to pack more air in the cylinders during each intake stroke. The Power Train ECM manifold (5) is to the left of the air cleaner housing. The functions of the Power Train ECM manifold are: control the displacement of the variable pumps and variable motors, engage or release the parking brakes, control pressure in the charge system, and supply control oil (charge oil) to all the solenoids. The fill tube (6) for the washer reservoir and the cab filter (7) are also located in this compartment. NOTE: Except for the engine oil filter, component locations are the same on the 953C.
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A 24 Volt, 70 amp alternator (1) is standard.
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The engine coolant tap (2) for S•O•S is located just above the alternator, which is used to take coolant samples for analysis. The engine oil filter (3) for the 953C is mounted to the engine block. The engine oil tap (4) for S•O•S is located just above the filter. The electric starter motor (not shown) and the starter relay are controlled by the Engine ECM. They are not wired directly to the key start switch. The Engine ECM prevents fuel being supplied to the engine for starting until sufficient oil pressure is present to prevent bearing wear due to operating without adequate lubrication.
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24
ENGINE
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The engine in the updated machines is a Cat 3126B, electronically controlled, six-cylinder, design that provides long, effective power strokes for high torque and efficient fuel combustion. The 3126B replaces the 3116 engine. Displacement of the 3126B is 7.2 L (442 in3), 9% more than the 6.6 L (403 in3), 3116 engine in the former machines. This engine is equipped with: Hydraulic-actuated Electronic Unit Injectors (HEUI), an air to air aftercooler (ATAAC), three valves per cylinder, and a turbocha rger. The engine is controlled and monitored by an Advanced Diesel Engine Management (ADEM III) - Electronic Control Module, which monitors all major engine functions and regulates the HEUI. These advanced electronics add value by improving power density through torque shaping, help to reduce emissions, and monitor and control engine systems.
O
The 3126B in the 953C is rated at 95 net kW (128 net hp) at 2000 rpm, but reaches a maximum of 96 kW (129 net hp) when lugged down into the "working range." The 3126B in the 963C is rated at 118 net kW (158 net hp) at 2000 rpm, but reaches a maximum of 119 net kW (159 net hp) when lugged down into the "working range." The engine provides power and acts as a working counterweight in the rear of the machine for optimum machine balance.
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Hydraulic-actuated Electronic Unit Injection is a unique and proven high-pressure, direct injection fuel system for diesel engines. The unit injectors combine the injector nozzle and high-pressure pump into one assembly for each cylinder, for excellent control of fuel delivery and injection timing under all loads and speeds. External high-pressure fuel lines are eliminated. This system provides very high injection pressure and short injection duration for fast response, low fuel consumption, and excellent emissions control.
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The ADEM III Engine ECM (arrow) for the engine is mounted behind the fuel filter/water separator.
T K
The fuel injection system responds to signals from the Engine ECM which electronically monitors operator and sensor inputs to provide engine control not possible with a mechanically operated fuel injection. Engine performance is optimized over the entire operating range. The Engine ECM continuously monitors: - engine oil pressure - engine oil temperature
- intake manifold temperature
O
- coolant temperature - fuel pressure - engine rpm
- operator selected rpm
The HEUI system is able to independently control: - injection pressure
- duration of the injection impulse - volume of fuel injected - timing of when the fuel is injected
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Precise control of the fuel injection process permits the HEUI system to control heat release during combustion in the power stroke for: - increased fuel economy (amount of fuel consumed per unit of power produced per hour) - reduced emission levels - improved torque rise - easier cold starting - reduced combustion noise
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The engine speed sensor (2) on the 963C can be seen from the right side of the machine through the front service compartment to the right of the ADEM III (1). The speed sensor is mounted in the flywheel housing.
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T K
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Cat ET must used used to access the machine machine ECMs. ECMs.
The ECM Selector Screen shows this particular machine is equipped with five ECMs. The monitoring system is "flashable" on the updated models.
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When the "3126B 963 TTL" ECM is selected, the technician can gain access to the the engine configuration screen. The technician has limited capabilities to change parameters with this particular engine.
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HYDRAULIC SYSTEMS
The hydraulic portion of 963C power train consists of the following major components: - two variable displacement, axial piston drive pumps with charge pumps - two variable displacement, link-type, piston motors
O
- synchronization manifold
- Power Train Train ECM manifold manifold
- charge filter
- case drain filter
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The 963C hydraulic implement system consists of: - a fixed displacement, vane-type pump - main control valve group - an optional third control valve with a main relief valve - pilot valve group - pressure reducing valve
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If no third valve is used, the main relief valve is located in the main control valve group. The pressure reducing valve is used to provide pilot oil to the pilot valves. The two systems share a common hydraulic tank.
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9 5 3 C POWER TRAIN AND IMPLEMENT HYDRAULIC SYSTEM COMPONENT IDENTIFICATION Ripper and Mult i-purpose Bucket Cylinders
Synchronization
Left Motor
Cylinder
Left Pump ECM Manifold Tank
Right Motor
Right Pump
P
Control Valve
Implement
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At t ach
Pump
S Lift
Tilt
Manifold
Cylinders
Main Control
Valve Group
Pilot Valve Group
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The 953C power train and implement hydraulic systems are similar. The 953C power train system has only one charge pump. An accumulator in the charge circuit has been added on the updated machines to help maintain the needed charge flow and pressure. The 953C implement control valves are located in the hydraulic tank. An accumulator is used to assist with lowering implements with a dead engine.
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The 953C is equipped with two case drain filters. The main relief valve is mounted to the implement pump.
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3 5
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The left (1) and right (2) hystat pumps, the vane-type implement pump (3), and the synchronization manifold (4) are located below the cab on both models. This illustration is from a 953C. Various pressure taps can be accessed with the cab floor plate removed. The pressure taps on the synchronization manifold are for left pump forward and reverse drive loop and right pump forward and reverse drive loop pressures. The synchronization solenoid valve (5) is used to connect both pump drive loops for straight travel in either FORWARD or REVERSE.
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The splitter box (6) contains the pump drive gears which transfer horsepower from the engine flywheel to the respective pump. The gear ratio to drive the hystat pumps was changed from a 1:1 ratio to a 1:1.1 ratio to compensate for the lower maximum full load engine speed. The engine speed changed from 2200 rpm to 2000 rpm. The main relief valve (7) is mounted on the top of the implement pump. The 953C uses a different implement pump than the 963C machines. The pumps, however, are the same as used on the former 953C and 963C machines.
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Each hystat pump has additional pressure taps mounted to them. Shown is the pump on a 963C.
T K
- The X1 or forward signal pressure from the pump control valve to the actuator tap (1) is shown above the other taps. - The X2 or reverse signal pressure from the pump control valve to the actuator tap (2) is shown below the other taps. - The case drain tap (3) is located between the other two taps. The pump control valve (4), to the left of the taps, is also mounted to the pump. The pump control valve directs signal oil to either side of the pump actuator to control stroking of the pump.
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10
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11
3 2
12
S 13
15
9
7
P 6
8 16
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The Power Train ECM manifold (1) contains the following components: - brake solenoid (2)
- left drive loop steering solenoids: forward (3), reverse (4) - right drive loop steering solenoids: forward (6), reverse (5)
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- transmission override solenoid (7) - override pressure sensor (8)
Not shown are: the left and right resolver, left signal pressure sensor, right signal pressure sensor, and charge relief valve which are also located in or near the Power Train ECM manifold. The override pressure sensor sends an analog signal to the converter (16). The converter changes the analog signal to a digital PWM signal. The PWM signal goes to the Power Train ECM.
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To make problem diagnosis faster and easier, quick-connect pressure fittings are part of the hydrostatic and implement hydraulic systems. Pressure taps shown are: - charge pressure (9) - brake control pressure (10) - left forward signal pressure (11) from the left forward steering solenoid - right forward signal pressure (12) from the right forward steering solenoid
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- left reverse signal pressure (13) from the left reverse steering solenoid
- right reverse signal pressure (14) from the right reverse steering solenoid The functions of the Power Train ECM manifold are to:
P
- control the displacement of the variable pumps and variable motors - engage or release the parking brakes
- control maximum charge pressure in the charge system
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- supply control oil (charge oil) to all the solenoids
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The remaining tap (15) is for checking the maximum implement supply pressure on a 963C.
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The pilot system tap (1) and pilot system accumulator (2) for the 953C are located below the cab on the right side of the machine.
T K
The pilot system accumulator is used to lower the implements with the engine off. The 963C is not equipped with a pilot accumulator. A resolver in the loader circuit is used to provide dead engine lowering capabilities.
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The tap (1) to check the implement hydraulic system is locate to the left of the Power Train ECM manifold.
T K
The 953C is equipped with an additional accumulator (2), which is used for the hystat hydraulic system. The accumulator is used to assist the single charge pump in maintaining charge system flow and pressure needs. The accumulator is located on the left side of the machine below the cab.
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The 963C motor speed sensor (1) senses how fast the motor is turning and communicates this to the Power Train ECM. The Power Train ECM will use this information to control the pumps and motors to control machine tracking. During calibrations the ECM matches the right side motor speed to the left side motor speed. The left side motor speed input is fixed at six points through the software.
T K
The minimum angle stop adjustment screw (2) is used to limit the minimum motor displacement angle to control the maximum speed. Screw (3) controls the stroking rate of the motor. The screw is used to set how much signal pressure is required to initiate shifting of the motor actuator.
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NOTE: The speed sensor for the 953C is still mounted in the final drive and senses the bullgear teeth as they pass.
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From the other side of the 963C drive motor, the flushing valve (1), the pressure override valve (3), and the maximum angle stop screw (2) can be found.
T K
During normal operation, the maximum angle stop screw is used to set the minimum machine speed. The pressure override valve, used only on the 963C, senses the drive loop pressure. When the pressure exceeds the valve setting, the valve opens and directs signal oil to the motor actuator to the tank, which causes the motor to move toward maximum angle, thereby, reducing machine speed and increasing torque to the drive sprockets. The flushing relief valve (4) is part of the flushing valve. When the machine is moving, the flushing relief valves maintain a minimum pressure in the low pressure side drive loop and charge circuit (internal drive loop leakage must not exceed flow output of charge pump).
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963C POWER TRAIN HYDRAULIC SYSTEM LEFT DRIVE LOOP Pressure Override Valve
Pressure Reducing Valve
Actu ator Piston
Drive Motor Group
Synchronization Valve
Parking Brake
Charge Filter
Motor Control Valve
Left Drive Motor Group
Flushing Relief Valve
Flushing Shuttle Valve
O Charge Pump
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P
Left Drive Pump Group
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Synchronization Manifold
S
Left Pump Actu ator
Left Pump Control Valve
38
963C Power Train Hystat Hydraulic System
The left drive pump and drive motor make up the left drive loop. The right drive loop consists of the right drive pump and drive motor. When the machine is not turning, the synchronization valve ensures that the drive pressures are equal in the left and right drive loops to allow for straight travel. The power train ECM will de-energize the valve in underspeed conditions.
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The left drive pump contains makeup and line relief valves, a pump control valve, an actuator, and a charge pump. The charge pumps supply oil to the drive loops and the Power Train ECM manifold. The charge pumps provide oil for the following functions: steering valve operation, pump actuator displacement, parking brake operation, and flushing and cooling flow for the drive pumps and motors. The charge pumps also supply the pilot oil to the implement hydraulic system. The line reliefs control the maximum drive loop pressures, while the makeup valves allow charge oil to replenish the low pressure drive loops.
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The pump control valve directs oil from the charge pump to shift the pump actuator. The pump actuator strokes the pump to increase flow for machine movement. The left drive motor contains the flushing shuttle valve, flushing relief valve, actuator piston, motor control valve, pressure reducing valve, and a pressure override valve.
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The flushing shuttle valve allows a continuous flow of oil from the low pressure side of the drive loop to enter the motor case when the machine is moving. This purge flow removes contaminants that enter the drive loops or the contaminants that are created within the drive loops. The purge flow also removes hot oil that can be generated in the drive loop. When the machine is moving, the flushing relief valves maintain a minimum pressure in the low pressure side drive loop and charge circuit (internal drive loop leakage must not exceed flow output of charge pump).
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The motor actuator piston is controlled by the motor control valve and pressure override valve. The signal oil from the steering solenoid valves is directed to the motor control valve to cause the motor to destroke for faster machine speed. The pressure override valve will destroke the motor hydraulically when its setting is overcome.
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The pressure reducing valve is used to prevent pressure spikes to the motor actuator. The right drive loop features similar components except for not having the synchronization manifold and solenoid valve mounted to it.
T K
The two drive loops share a common charge filter.
The synchronization manifold is used to keep the left and the right drive pressures equal when the machine is not turning. When the machine is traveling in straight line, the Power Train ECM will energize the synchronization valve to connect the left and right drive loops. When the drive loops are connected the flow and the pressure between the two drive loops equalize to provide straight travel.
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The synchronization valve is energized by the Power Train ECM without any input from the operator. The synchronization valve is de-energized when a steering pedal is depressed or when underspeed conditions occur. De-energizing the synchronization valve blocks flow between the left and right drive loops. NOTE: The update 963C power train hydraulic system is very similar to the previous 963C system. Some of the line routings have changed. These changes are shown throughout the following 963C power train schematics.
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The Power Train ECM manifold receives electrical signals from the Power Train ECM. Electrical signals are used to control the following solenoid valves: - parking brake control valve - transmission override valve
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- left forward steering valve - left reverse steering valve
- right forward steering valve - right reverse steering valve
The Power Train ECM uses the transmission override solenoid valve to put the machine in NEUTRAL if certain electrical faults exist. The proportional solenoid valve is used as an on/off valve. When the solenoid is de-energized the flow of oil is blocked. This causes the pumps to destroke to NEUTRAL.
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The parking brake solenoid valve engages the brakes. The brakes are spring applied and hydraulically released. When the operator places the speed/direction control lever in the PARK position, the Power Train ECM de-energizes the parking brake solenoid valve which relieves the hydraulic pressure and the brakes are engaged. When the machine is NOT in the PARK position, the Power Train ECM energizes the solenoid valve which directs the charge pressure oil to the brakes to release the brakes. The Power Train ECM uses a +battery signal to activate the parking brake solenoid.
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The parking brake switch on the console or the center foot pedal can also de-energize the parking brake solenoid valve to engage the brakes.
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The four steering solenoid valves and the transmission override solenoid valve are proportional. The Power Train ECM uses the proportional steering solenoid valves to control the speed and the direction of the machine. The Power Train ECM directs a pulse width modulated (PWM) signal to the appropriate steering solenoid valves. This PWM signal is based on the information from the following: - speed/direction control lever - left pedal - right pedal - center pedal
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The PWM signal varies the hydraulic signal output of the solenoid valve. The amount of signal oil controls the swashplate angle of the pumps and motors.
T K
The following sensors provide feedback to the Power Train ECM: - override pressure sensor
- pressure sensor for the signal to the right drive motor - pressure sensor for the signal to the left drive motor The PWM sensors for the signal pressure to the motors direct input signals to the Power Train ECM that indicate the output pressure of the steering valves. The Power Train ECM uses this input in order to determine if a steering valve is sticking.
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The override pressure sensor senses the charge system pressure and sends an analog signal to a converter. The converter changes the analog signal to a PWM signal which is sent to the Power Train ECM. The Power Train ECM uses the information for the override pressure in order to determine if the brake pressure and the lubrication pressure are correct. If the pressure is not correct and the machine is not in PARK, the Power Train ECM will inform the operator by turning on a monitoring system alert indicator. The right signal resolver and the left signal resolver sense the FORWARD and REVERSE signal pressures from the steering valves. The signal resolvers send the higher pressure to the respective drive motors. These signal pressures are sent to the motor control valves in order to control the output of the drive motors. The charge relief valve limits the pressure that is sent from the charge pumps.
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963C POWER TRAIN HYDRAULIC SYSTEM PRESSURE FITTING LOCATIONS Charge Pressure
"M" Port
Left Forward
Left Reverse
Right Reverse
Right Forward
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Charge Pressure
Reverse Signal Pressure
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Forward Signal Pressure
"M" Port
Forward Act uato r Pressure
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Parking Brake Pressure Reverse Signal Pressure
Reverse Act uato r Pressure
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The test ports shown above are used when testing the 963C hystat hydraulic system. The "M" port is used to check the pressure to the motor actuator.
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963C POWER TRAIN HYDRAULIC SYSTEM PARK Pressure Override Valve
Synchronization Valve
Brake Charge Relief Valve
Charge Filter
Left Steering Valves REV
Act uat or
Motor Cont rol Valve
Flushing Valve
U FWD
FWD
Charge Pump
Act uat or
Motor
P
Pump Control Valve
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Case Drain Filter
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Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
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When the engine is started with the speed/direction control lever in PARK, the charge pumps draw tank oil from the hydraulic tank (not shown). The charge pumps direct the charge pressure oil to the charge filter. A bypass valve inside the housing opens if the pressure differential becomes too high. Cold charge oil that has bypassed the charge filter is directed to a check valve by the bypass valve.
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This check valve helps the charge system maintain adequate lubrication pressure until the system oil is warm enough to flow through the charge filter. If the pressure differential across the filter exceeds the specification, the oil flow from the charge pumps is also directed to the hydraulic tank. The monitoring system provides input into the Power Train ECM as to the status of the bypass switch. With cold oil the machine cannot move with the bypass open. A temperature sensor is used to communicate the transmission oil temperature to the monitoring system. As the oil temperature increases to normal operating temperatures, the filter bypass valve closes. Now if the bypass valve opens the monitoring system will signal the Power Train ECM the open status of the bypass valve. The Power Train ECM will stop the machine.
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After the charge oil flows through the charge filter, the oil is directed to four areas: - the low pressure side of both drive loops through makeup and line relief valves and the pump control valves in the drive pumps - charge relief valve on the Power Train ECM manifold - transmission override valve and brake control valve - the implement circuit to provide pilot oil
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The drive loops constantly lose oil through leakage in the drive pumps and in the drive motors. Also, the drive loops lose oil through the flushing valves when the machine is moving. The supply of charge pressure oil replenishes the low pressure sides of both drive loops through the makeup and line relief valves. The flushing oil directs contaminants and hot oil out of the drive pumps and drive motors to the case drain filter.
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The override pressure sensor provides information on the override pressure to the Power Train ECM. If the override pressure drops below the level that is required in order to keep the brakes from engaging during travel, a warning is issued to the Caterpillar Monitoring System if the machine is traveling.
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The synchronization valve is energized when the speed/direction control lever is in the PARK position. Energizing the synchronization valve allows the left drive loop and the right drive loop to be connected in order to equalize the flow and the pressure between the two drive loops to provide straight travel.
T K
The drive pumps are at zero swashplate angle and the port plates in the drive motors are at the maximum angle when the speed/direction control lever is in the PARK position. When the speed/direction control lever is in the PARK position, the flushing valves are in the center position, blocking oil in the drive loops from flowing to the flushing relief valves. An orifice in each pump allows some flushing of the charge oil.
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When the speed/direction control lever is in the PARK position, the transmission override valve is DE-ENERGIZED by the power train ECM in order to put the machine in NEUTRAL, which blocks charge oil to the steering valves. When the speed/direction control lever is in the PARK position, the steering valves are also in the DE-ENERGIZED position. In this position, the steering valves drain oil from both ends of pump control valves in the drive pumps. The pump control valve moves to the center position to drain oil from both sides of the pump actuator. Springs in the pump actuator move the pump swashplate to zero angle. Also, the steering valves drain oil from motor control valves in the drive motors to keep the port plates in the drive motors at maximum angle.
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9 6 3 C POWER TRAIN HYDRAULIC SYSTEM BRAKES RELEASED Pressure Override Valve
Synchronization Valve
Brake Charge Relief Valve
Charge Filter
Left Steering Valves REV
Ac t uat or
Motor Contr ol Valve
Flushing Valve
U FWD
FWD
Charge Pump
Ac t uat or
Motor
P
Pump Control Valve
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Case Drain Filter
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Transmission Override Valve
Brake Contr ol Valve
Right Steering Valves
REV
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When the brakes are disengaged, the Power Train ECM processes the information from the sensor on the speed/direction control lever. The Power Train ECM sends a signal to the brake control valve. When the brake control valve is energized, charge oil is directed to the brakes to release the brakes.
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9 6 3 C POWER TRAIN HYDRAULIC SYSTEM MAXIMUM FORWARD Pressure Override Valve
Synchronization Valve Brake Charge Relief Valve
Charge Filter
Left Steering Valves Act uat or
Motor Control Valve
REV
Flushing Valve
U FWD
FWD
Charge Pump
Act uat or
Motor
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Pump Contr ol Valve
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Case Drain Filter
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Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
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When the operator shifts the speed/direction control lever to the maximum FORWARD position, the Power Train ECM processes the information from the sensor on the speed/direction control lever. The Power Train ECM sends an electrical signal to the transmission override valve. The ECM also directs PWM signals to the steering valves. The energized transmission override valve supplies charge oil to the steering valves.
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As the steering valves are energized, each valve directs signal oil to the drive pumps. The signal oil to the drive pumps causes the swashplates to move. When the signal pressure increases, the pump control valves shift. When the pump control valves shift, charge oil is directed to one side of the pump actuator. The actuator shifts and moves the pump swashplate. Pump flow increases. The signal oil is also directed to drive motors through the signal resolvers. When the pressure increases enough to shift the motor control valves, drive loop oil is directed to the motor actuators and pressure override valves. The actuators shift and move the port plates toward minimum angle.
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The pressure in the FORWARD drive loop is proportional to the drawbar pull. The pressure is limited by the line relief function of the makeup and line relief valves. When the speed/direction control lever is in the maximum FORWARD position, the Power Train ECM sends PWM signals to the right forward steering valve and left forward steering valve.
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The steering valves direct signal oil to the drive pumps in order to stroke the pumps. Also, the steering valves direct signal oil to the drive motors in order to destroke the motors. The swashplates in the drive pumps rotate and the pump flow pressurizes the FORWARD side of the drive loops.
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The motor flushing shuttle valves shift to direct charge oil into an orifice and to the flushing relief valves. When the machine is moving, the flushing relief valves maintain a minimum pressure in the low pressure side drive loop and charge circuit (internal leakage must not exceed flow output of charge pump). Maintaining the charge pressure is required to fully release the brakes and to fully shift the pumps and motors.
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To maintain the correct tracking of the machine, the Power Train ECM energizes the synchronization valve. This connects the left and the right drive loops in order to provide straight travel. The synchronization valve is opened in the FORWARD and REVERSE directions.
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To reach full FORWARD, the signal oil from the steering valves moves the actuators in the drive pumps. The drive pumps will upstroke to the maximum swashplate angle. This generates approximately 33% of the maximum machine speed. The drive motors receive the same signal oil from the steering valves. The motors will begin to destroke once the maximum swashplate angle is reached in the respective drive pumps. Machine speed will continue to increase until the machine reaches the maximum speed of approximately 9.5 km/h (5.9 mph). The underspeed feature is automatically utilized when the load on the drawbar causes the engine to lug. The underspeed feature overrides the input of the speed/direction control lever. The underspeed feature will change the speed setting of the machine in order to keep the engine speed at the designated rpm by reducing the current to the steering valves, which reduces the signal pressure to the drive pumps and motors. The drive motors will upstroke first and then drive pumps will destroke. The engine speed is maintained regardless of the changing loads. There is no adjustment for the designated engine speed under load.
O
This engine speed is determined by the programmed software in the Power Train ECM. The implement circuit has priority over the transmission to use engine horsepower. When the engine lugs, the Power Train ECM uses the underspeed feature to reduce speed of the tracks by reducing the electrical signal to the steering valves. This will reduce the load on the engine. When the engine has returned to normal operating speed, the full electrical signal will return to the steering valves.
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When the engine lugs heavily due to high loads, the synchronization valve is de-energized by the Power Train ECM. The valve closes and blocks the flow between the drive loops in order to prevent the engine from stalling. The ECM monitors the loading of the engine with the magnetic engine speed sensor that is mounted on the engine flywheel housing. The magnetic engine speed sensor generates a signal that varies in proportion to the engine speed.
S
When drive loop pressure exceeds the motor pressure override valve spring setting due to high loads, the valve shifts and drains oil to the large end of actuator to the tank. Pressure working on the other end of the actuator will cause the actuator to shift to upstroke the motor.
O
T K
O
P
U
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9 6 3 C POWER TRAIN HYDRAULIC SYSTEM RIGHT TURN FORWARD Pressure Override Valve
Synchronization Valve
Brake Charge Relief Valve
Charge Filter
Left Steering Valves REV
Act uat or
Motor Control Valve
Flushing Valve
U FWD
FWD
Act uat or
Charge Pump
Motor
P
Pump Control Valve
O
Case Drain Filter
T K
REV
S
Transmission Override Valve
Brake Control Valve
Right Steering Valves
44
To make a right turn when the machine is traveling in FORWARD, the right steering pedal is partially depressed which causes the synchronization valve to be de-energized. The synchronization valve is DE-ENERGIZED at the initial depression of the steering pedal in order to separate the drive loops. If the valve is not DE-ENERGIZED at the initial depression of the steering pedal, small steering turns at the initial depression of the steering pedal are not possible.
O
As the steering pedal is depressed, the PWM signal from the rotary sensor on the pedal is directed to the Power Train ECM. The Power Train ECM sends a reduced PWM signal to right FORWARD steering valve. The right FORWARD steering valve reduces the signal oil to the right drive pump control valve and to the right drive motor control valve. The control valves shift according to the amount of signal reduction. The motor control shifts first.
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As the motor control valve shifts, pressure on the head end of the actuator is reduced. The actuator starts to move to the left which increases the angle of the port plate in the drive motor as the operator depresses the right steering pedal. When the right steering pedal is depressed enough in order to slow the right track to 33% of the maximum speed, the angle of the port plate in the right drive motor reaches the maximum angle.
S
Then, as the right steering pedal is depressed further, the pump control valve moves to reduce pressure at the pump actuator. The swashplate for the right drive pump starts to move toward zero angle.
U
Due to the left drive pump being upstroked and the motor being destroked, the left track maintains speed,while the right track slows down . The machine makes a right turn. Operation for a left turn is similar for the left drive loop.
P
NOTE: If the initial steering response occurs at a position besides the initial depression of the steering pedal, the steering pedal may need to be calibrated.
O
T K
O
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9 6 3 C POWER TRAIN HYDRAULIC SYSTEM RIGHT SPOT TURN Pressure Override Valve
Synchronization Valve
Brake Charge Relief Valve
Charge Filter
Left Steering Valves REV
Act uat or
Motor Contr ol Valve
Flushing Valve
U FWD
FWD
Charge Pump
Act uat or
Motor
P
Pump Control Valve
O
Case Drain Filter
T K
S
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
45
If the operator depresses the right steering pedal completely, the Power Train ECM will stop the PWM signal to the right forward steering valve. Then, the Power Train ECM sends a PWM signal to the right reverse steering valve. The right reverse steering valve directs signal oil to the right drive pump and drive motor. The signal oil shifts the pump control valve, which directs charge oil to the other side of the pump actuator. The swashplates shifts overcenter to direct oil flow to the REVERSE side of the drive loop.
O
The right drive motor rotates in the REVERSE direction while the left drive motor continues to rotate in the FORWARD direction. The synchronization valve is DE-ENERGIZED at the initial depression of the steering pedal in order to separate the drive loops. If the valve is not DE-ENERGIZED at the initial depression of the steering pedal, steering turns are erratic. NOTE: If the initial steering response occurs at a position besides the initial depression of the steering pedal, the steering pedal may need to be calibrated.
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9 6 3 C POWER TRAIN HYDRAULIC SYSTEM CENTER PEDAL PARTIAL DEPRESSED Pressure Override Valve
Synchronization Valve
Brake
Left Steering Valves REV
Act uat or
Motor Control Valve
U FWD
FWD
Act uat or
Motor
P
Pump Control Valve
O
Case Drain Filter
T K
S
Transmission Override Valve
Brake Contr ol Valve
Right Steering Valves
REV
46
When the operator partially depresses the center pedal, the Power Train ECM reduces the PWM signal to the energized steering valves to reduce signal oil to the control valves on the pump and motors. The motor control valve shifts first to drain oil to the motor actuator to the tank. The pump control valve then shifts to drain oil to the pump actuator to the tank. At maximum speed, partial depression of the center pedal will cause the motor control valves to shift the motor actuators causing the port plates in the drive motors to move toward the maximum angle. When the center pedal is depressed enough in order to lower the machine speed to 33% of maximum speed, the port plates in the drive motors reach the maximum angle. Further depression of the center pedal will move the pump control valves to shift the pump actuators to move the pump swashplates toward the minimum angle.
O
The machine starts to slow down. The further the center pedal is depressed, the more the machine slows down.
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963C POWER TRAIN HYDRAULIC SYSTEM CENTER PEDAL FULLY DEPRESSED Pressure Override Valve
Synchronization Valve
Brake
Left Steering Valves REV
Act uat or
Motor Contr ol Valve
U FWD
FWD
Act uat or
Motor
P
Pump Contr ol Valve
O
Case Drain Filter
T K
S
Transmission Override Valve
Brake Cont rol Valve
Right Steering Valves
REV
47
When the operator fully depresses the center pedal while moving in a direction, the Power Train ECM minimizes the PWM signal to the energized steering valves to reduce the signal oil to the the pumps and the motors. When the center pedal is fully depressed, the motor control valves shift to drain oil to the motor actuators. The actuators shift and move the port plates in drive motors to the maximum angle. Due to the loss of signal oil, the pump control valves and actuators shift to move the swashplates toward the minimum angle. The pumps stay slightly stroked to maintain pressure in the respective drive loop. The machine abruptly stops because of the dynamic braking of the power train hydraulic system. The brake valve is also DE-ENERGIZED blocking charge oil to the parking brakes. The parking brakes engage and the motors stop.
O
There may be a slight growling from the power train hydraulic system when the brakes are fully applied. The flow from the drive pumps is the source of the growling. The center pedal should be depressed when the operator is working on a slope in order to prevent the machine from rolling down the slope. While the center pedal is depressed, the operator may move the speed/direction control lever in order to demand travel. When the operator slowly releases the center pedal, the operator has precise control of the machine.
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953C POWER TRAIN HYDRAULIC SYSTEM LEFT DRIVE LOOP / ENGINE OFF Synchronization Manifold Motor Control Valve
Left Drive Motor
Charge Pump
Charge Filter
Parking Brakes
Act uato r Flushing Piston Relief Valve
Flushing Shuttle Valve
Synchronization Valve
Drive Pump
O
P
Makeup and Line Relief Valves
T K
U Control Piston
S
Pump Control Pilot Valve Spool
48
953C Power Train Hystat Hydraulic System
The left drive pump and drive motor make up the left drive loop. The right drive loop consists of the right drive pump and drive motor. When the machine is not turning, the synchronization valve ensures that the drive pressures are equal in the left drive loop and in the right drive loop.
O
The left drive pump contains makeup and line relief valves, a pilot spool, a pump control valve, an actuator, and a charge pump. The charge pump supplies oil to the drive loops and the Power Train ECM manifold. The charge oil provides oil for the following functions: steering valve operation, pump and motor displacements, parking brake operation, and flushing and cooling flow for the drive pumps and motors. The charge pumps also supply the pilot oil to the implement hydraulic system. The line reliefs control the maximum drive loop pressures while the makeup valves allow charge oil to replenish the low pressure drive loops.
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The pilot spool shifts the pump control valve to direct charge pressure oil to shift the pump actuator. The pump actuator strokes the pump to increase flow for machine movement. The left drive motor contains the flushing shuttle valve, flushing relief valve, actuator piston, and motor control valve. A pressure override valve is not used on the 953C motors.
S
The flushing shuttle valve allows a continuous flow of oil from the low pressure side of the drive loop to enter the motor case when the machine is moving. This purge flow removes contaminants that enter the drive loops or the contaminants that are created within the drive loops. The purge flow also removes hot oil that can be generated in the drive loop. When the machine is moving, the flushing relief valves maintain a minimum pressure in the low pressure side drive loop and charge circuit (internal leakage must not exceed flow output of charge pump). Maintaining the charge pressure is required to fully release the brakes and to fully shift the pumps and motors.
P
U
The motor actuator piston is controlled by the motor control valve. The signal oil from the steering solenoid valves is directed to the control valve to cause the motor to destroke for faster machine speed.
O
The right drive loop features similar components except for not having the synchronization manifold mounted to it and no charge pump. The two drive loops share a common charge filter.
T K
The synchronization manifold is used in order to keep the left drive pressure and the right drive pressure equal when the machine is not turning. When the machine is traveling in straight line the Power Train ECM will energize the synchronization valve to connect the left drive loop and the right drive loop. When the drive loops are connected the flow and the pressure between the two drive loops equalize. This provides straight travel.
O
The synchronization valve is energized by the Power Train ECM without any input from the operator. The synchronization valve is de-energized when a steering pedal is depressed or when underspeed conditions occur. De-energizing the synchronization valve blocks flow between the left drive loop and the right drive loop. NOTE: The updated 953C power train hydraulic system is very similar to the previous 953C system. Some of the line routings have changed along with the addition of a accumulator in the charge circuit. These changes are shown throughout the following 963C power train schematics.
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9 5 3 C POWER TRAIN HYDRAULIC SYSTEM PRESSURE FITTING LOCATIONS Left Forward Drive Pressure
Upstroke Act uator Pressure
Left Reverse Drive Pressure
Right Reverse Drive Pressure
Right Forward Drive Pressure
Charge Pressure
Case Drain
Reverse
Forward
Upstroke Act uator Pressure
Destroke Act uator Pressure
Case Drain
T K
O
P
Reverse Signal Pressure
U Forward Signal Pressure
S Brake Pressure
49
The test ports shown above are used when testing the 953C hystat hydraulic system.
O
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953C POWER TRAIN HYDRAULIC SYSTEM PARK
Synchronization Valve
Accumu lator Motor Control Valve
Charge Filter Actuato r Brake
Charge Pump
S
Charge Relief Valve Left Steering Valves
Left Drive Loop
REV
Flushing Valve
U
FWD Actuat or Drive Motor
FWD
Pump Control Valve
Right Drive Loop Motor
T K
O
P
Pilot Spool
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
Case Drain Filters
50
When the engine is started with the speed/direction control lever in PARK, the charge pump draws tank oil from the the hydraulic tank (not shown). The charge pumps direct the charge charge pressure oil to the charge filter. filter. A bypass valve inside the housing opens ope ns if the pressure differential becomes too high. high. Cold charge oil that has bypassed the charge filter is is directed to a check valve by the bypass valve.
O
This check valve helps the charge system maintain adequate lubrication pressure until the system oil is warm enough to flow through charge filter. filter. If the pressure differential across the the filter exceeds the specification, the oil flow from the charge pump is also directed to the hydraulic tank. The monitoring system provides input into the Power Train ECM as to the status of the bypass switch. With cold oil the machine cannot move with the bypass open. A temperature sensor is used to communicate the transmission oil temperature to the monitoring system. As the oil temperature increases to normal operating temperatures, the filter bypass valve closes. Now if the bypass valve opens the monitoring monitoring system will signal signal the Power Train Train ECM the open status of the bypass valve. The Power Train Train ECM will stop the machine. machine.
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After the charge oil flows through the filter, the oil is directed to five areas: - the low pressure side of both drive loops through makeup and line relief valves and the pump control valves in the drive pumps - the accumulator and charge relief valve on the Power Train ECM manifold - transmission override valve and brake control valve - the implement circuit to provide pilot oil - the travel motor control valves
U
S
The accumulator stores and provides a supply of oil to maintain the charge system flow and pressure.
P
The drive loops constantly lose oil through leakage in the drive pumps and in the drive motors. Also, the drive loops lose oil oil through the flushing valves when the machine is is moving. The supply of charge pressure oil replenishes the low pressure sides of both drive loops through the makeup and line relief valves. The flushing oil directs contaminants and hot oil out of the drive pumps and drive motors to the case drain filter.
O
The override pressure sensor provides information on the override pressure to the Power Train ECM. If the override pressure drops below the level that is required required in order to keep the brakes from engaging during travel, a warning is issued to the Caterpillar Monitoring System.
T K
The synchronization valve is energized when the speed/direction control lever is in the PARK position. Energizing the synchronization valve va lve allows the left drive loop and a nd the right drive loop to be connected in order to equalize the flow and the pressure between the two drive loops to provide straight travel. The drive pumps are at zero swashplate angle and the port plates in the drive motors are at the maximum angle when the speed/direction control lever is is in the PARK PARK position. When the speed/direction control lever is in the PARK position, the flushing valves are in the center position blocking drive loop oil from the flushing relief valves.
O
When the speed/direction control lever is in the PARK position, the transmission override valve is DE-ENERGIZED by the power train train ECM in order to put the machine in NEUTRAL. The DE-ENERGIZED position blocks oil from the charge pump to the steering valves. When the speed/direction control lever is in the PARK position, the steering valves are also in the DE-ENERGIZED position. In this position, the steering steering valves drain oil from both ends of pilot valves in the drive pumps. The pump control valve moves to the center position to drain oil from both sides of the pump actuator. actuator. Springs in the pump actuator move the pump swashplate to zero angle. Also, the steering valves drain oil from control valves in the drive motors to keep the port plates in the drive motors at maximum angle.
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9 5 3 C POWER TRAIN HYDRAULIC SYSTEM BRAKES RELEASED
Synchronization Valve
Accum ulato r Motor Control Control Valve
Charge Filter
Actuat or Brake
Charge Pump
S
Charge Relief Valve Left Steering Valves
Left Drive Loop
REV
Flushing Valve
U
FWD Actuat or Drive Motor
FWD
Pump Control Valve
Right Drive Loop Motor
T K
O
P
Pilot Spool
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
Case Drain Filters
51
When the brakes are disengaged, the Power Train ECM processes the information from the sensor on the speed/direction control lever. lever. The Power Train Train ECM sends a signal to the brake control valve. When the brake control valve is energized, energized, charge oil is directed to the brakes to release the brakes.
O
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9 5 3 C POWER TRAIN HYDRAULIC SYSTEM MAXIMUM FORWARD
Motor Control Valve
Synchronization Valve
Actuat or Brake
S
Charge Relief Valve
Left Drive Loop
REV
Flushing Valve
Left Steering Valves
U
FWD Actuat or Drive Motor
Pump Control Valve
Right Drive Loop Motor
T K
O
P
Pilot Spool
FWD
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
52
When the operator shifts the speed/direction control lever to the maximum FORWARD position, the Power Train ECM processes the information from the sensor on the speed/direction control lever. The Power Train ECM sends an electrical signal to the transmission override valve. The ECM also directs PWM signals to the steering valves. The energized transmission override valve supplies charge oil to the steering valves.
O
As the steering valves are energized, each valve directs signal oil to the drive pumps. The signal oil to the drive pumps causes the swashplates to move. When the signal pressure increases enough, the pilot spools move to shift the pump control valves. When the pump control valves shift, charge oil is directed to one side of the pump actuator. The actuator shifts and moves the pump swashplate. Pump flow increases. The signal oil is also directed to drive motors through the signal resolvers. When the pressure increases enough to shift the motor control valves, charge oil is directed to the motor actuators. The actuators shift and move the port plates toward minimum angle.
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The pressure in the FORWARD drive loop is proportional to the drawbar pull. The pressure is limited by line relief function of the makeup and line relief valves. When the speed/direction control lever is in the maximum FORWARD position, the Power Train ECM sends PWM signals to the right forward steering valve and left forward steering valve.
S
The steering valves direct signal oil to the drive pumps in order to stroke the pumps. Also, the steering valves direct signal oil to the drive motors in order to destroke the motors. The swashplates in the drive pumps rotate and the pump flow pressurizes the FORWARD side of the drive loops.
U
The motor flushing shuttle valves shift to direct charge oil into an orifice and to the flushing relief valves. When the machine is moving, the flushing relief valves maintain a minimum pressure in the low pressure side drive loop and charge circuit (internal drive loop leakage must not exceed flow output of charge pump). The flushing relief valves maintain back pressure against the orifices before the oil flows to case drain.
P
To maintain the correct tracking of the machine, the Power Train ECM energizes the synchronization valve. This connects the left and the right drive loops in order to provide straight travel. The synchronization valve is opened in the FORWARD direction and in the REVERSE directions.
T K
O
To reach full FORWARD, the signal oil from the steering valves moves the actuators in the drive pumps. The drive pumps will upstroke to the maximum swashplate angle to generate approximately 33% of the maximum machine speed. The drive motors receive the same signal oil from the steering valves. The motors will begin to destroke once the maximum swashplate angle is reached in the respective drive pumps. Machine speed will continue to increase until the machine reaches the maximum speed of approximately 9.7 km/h (6.0 mph). The underspeed feature is automatically utilized when the load on the drawbar causes the engine to lug. The underspeed feature overrides the input of the speed/direction control lever. The underspeed feature will change the speed setting of the machine in order to keep the engine speed at the designated rpm by reducing the current to the steering valves, which reduces the signal pressure to the drive pumps and motors. The drive motors will upstroke first and then the drive pumps will destroke. The engine speed is maintained regardless of the changing loads. There is no adjustment for the designated engine speed under load.
O
This engine speed is determined by the programmed software in the Power Train ECM. The implement circuit has priority over the transmission to using engine horsepower. When the engine lugs, the Power Train ECM uses the underspeed feature to reduce speed of the tracks by reducing the electrical signal to the steering valves. This will reduce the load on the engine. When the engine has returned to normal operating speed, the full electrical signal will return to the steering valves.
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When the engine lugs heavily due to high loads, the synchronization valve is DE-ENERGIZED by the Power Train ECM. The valve closes and blocks the flow between the drive loops in order to maintain engine power. The ECM monitors the loading of the engine with the magnetic engine speed sensor that is mounted on the engine flywheel housing. The magnetic engine speed sensor generates a signal that varies in proportion to the engine speed.
O
T K
O
P
U
S
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9 5 3 C POWER TRAIN HYDRAULIC SYSTEM RIGHT TURN FORWARD
Motor Control Valve
Actuat or Brake
Left Drive Loop
REV
Flushing Valve
Left Steering Valves
U
FWD Actuat or Drive Motor
Pump Control Valve
Right Drive Loop Motor
T K
O
P
Pilot Spool
FWD
S
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
53
To make a right turn when the machine is traveling in FORWARD, the right steering pedal is partially depressed which causes the synchronization valve to be de-energized. The synchronization valve is DE-ENERGIZED at the initial depression of the steering pedal in order to separate the drive loops. If the valve is not DE-ENERGIZED at the initial depression of the steering pedal, small steering turns at the initial depression of the steering pedal are not possible.
O
As the motor control valve shifts, pressure on the one end of the actuator is reduced. The actuator starts to move to increase the angle of the port plate in the drive motor as the operator depresses the right steering pedal. When the right steering pedal is depressed enough in order to slow the right track to 33% of the maximum speed, the angle of the port plate in the right drive motor reaches the maximum angle. Then, as the right steering pedal is depressed further, the pump pilot spool and pump control valve moves to reduce pressure at the pump actuator. The swashplate for the right drive pump starts to move toward zero angle.
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Due to the left drive pump being upstroked and the left motor being destroked, the left track maintains speed, while the right track slows down . The machine makes a right turn. Operation for a left turn is similar for the left drive loop.
S
NOTE: If the initial steering response occurs at a position beside the initial depression of the steering pedal, the steering pedal may need to be calibrated.
O
T K
O
P
U
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9 5 3 C POWER TRAIN HYDRAULIC SYSTEM RIGHT SPOT TURN Forward
Motor Control Valve
Act uat or Brake
Left Drive Loop
REV
Flushing Valve
Left Steering Valves
U
FWD Act uat or Drive Motor
FWD
Pump Contr ol Valve
Right Drive Loop Motor
Reverse
T K
O
P
Pilot Spool
S
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
54
If the operator depresses the right steering pedal completely, the Power Train ECM will stop the PWM signal to the right forward steering valve. Then, the Power Train ECM sends a PWM signal to the right reverse steering valve. The right reverse steering valve directs signal oil to the right drive pump and drive motor. The signal oil shifts the pilot valve, which moves the pump control valve and directs charge oil to the other side of the pump actuator. The swashplates shifts overcenter to direct oil flow to the REVERSE side of the drive loop.
O
The right drive motor rotates in the REVERSE direction while the left drive motor continues to rotate in the FORWARD direction. The synchronization valve is DE-ENERGIZED at the initial depression of the steering pedal in order to separate the drive loops. If the valve is not DE-ENERGIZED at the initial depression of the steering pedal, steering turns are erratic. NOTE: If the initial steering response occurs at a position beside the initial depression of the steering pedal, the steering pedal may need to be calibrated.
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9 5 3 C POWER TRAIN HYDRAULIC SYSTEM CENTER PEDAL PARTIALLY DEPRESSED
Motor Control Valve
Act uat or Brake
S
Charge Relief Valve
Left Drive Loop
REV
Flushing Valve
Left Steering Valves
U
FWD Act uat or Drive Motor
Pump Control Valve
Right Drive Loop Motor
T K
O
P
Pilot Spool
FWD
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
55
When the operator partially depresses the center pedal, the Power Train ECM reduces the PWM signal to the energized steering valves to reduce signal oil to the pilot spool on the pump and the control valve on the motors. The pilot spool on the pump shifts the pump control valve. When the control valves shift, charge oil is directed to the pump and the motor actuators to cause them to shift. The motor control valve shifts first.
O
At maximum speed, partial depression of the center pedal will cause the motor control valves to shift the motor actuators causing the port plates in the drive motors to move toward the maximum angle. When the center pedal is depressed enough in order to lower the machine speed to 33% of maximum speed, the port plates in the drive motors reach the maximum angle. Further depression of the center pedal will move the pump pilot valves and pump control valves to shift the pump actuators to move the pump swashplates toward the minimum angle. The machine starts to slow down. The further the center pedal is depressed, the more the machine slows down.
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953C POWER TRAIN HYDRAULIC SYSTEM CENTER PEDAL FULLY DEPRESSED
Motor Control Valve
Actuat or Brake
Left Drive Loop
REV
Left Steering Valves
U
FWD Actuat or Drive Motor
Pump Control Valve
Right Drive Loop Motor
T K
O
P
Pilot Spool
FWD
S
Transmission Override Valve
Brake Control Valve
Right Steering Valves
REV
56
When the operator fully depresses the center pedal while moving in a direction, the Power Train ECM minimizes the PWM signal to the energized steering valves to reduce the signal oil to the the pumps and the motors. When the center pedal is fully depressed, the motor control valves shift to drain oil to the motor actuators. The actuators shift and move the port plates in drive motors to the maximum angle. Due to the loss of signal oil, the pilot spools, pump control valves, and actuators shift to move the swashplates toward the minimum angle. The machine abruptly stops because of the dynamic braking of the power train hydraulic system. The pumps stay slightly stroked to maintain pressure in the respective drive loop. The brake valve is also DE-ENERGIZED blocking charge oil to the parking brakes. The parking brakes engage and the motors stop.
O
There may be a slight growling from the power train hydraulic system when the brakes are fully applied. The flow from the drive pumps is the source of the growling. The center pedal should be depressed when the operator is working on a slope in order to prevent the machine from rolling down the slope. While the center pedal is depressed, the operator may move the speed/direction control lever in order to demand travel. When the operator slowly releases the center pedal, the operator has precise control of the machine.
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T K
O
P
U
S
57
When the "Hydrostatic Transmission" ECM is selected from the ECM Selector Screen using Cat ET, the technician can gain access to the power train Configuration Screen. The technician has some limited capabilities to change parameters for the Power Train ECM. Highlight the parameter and then use the "Change" button on the lower left to change the parameter. The parameter for "Parking Brake Lockout Status" can be used for performing a hystat stall test or for servicing the machine. The steering sensitivity can be adjusted using the "Steering Response Rate Setting" parameter.
O
The Calibration Reset feature resets the track speed and pedal lever calibrations. This feature should be used whenever one of the electro-hydraulic components that require calibrations are replaced. The feature may also be used when certain fault codes are present or when the technician wants to return the system to known good values. This feature resets the component values back to the default settings. The component then needs to be calibrated. Refer to the Calibration Procedures. All three parameters can be adjusted or done using the monitor. Refer to the Service Manual for more information on this Configuration Screen.
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T K
O
P
U
S
58
When Calibrations is selected in Cat ET for the hystat transmission the screen shown above appears. The technician can select to one or more of the four calibrations available to calibrate the steering and brake pedal or the transmission lever.
O
The technician can also use the toggle switch shown earlier in the right console to perform the same calibrations.
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963C IMPLEMENT HYDRAULIC SYSTEM HOLD Multi-purpose Cylinders
Ripper Cylinders
Tilt Cylinder
Lift Cylinders
Diverter Valve
From Charge Filter Bypass and Charge Relief Valve Main Relief Valve
Shuttle Valve
From Brake Valve
Att ach Control Valve
Pressure Reducing Valve
S
Vented Makeup Valve
Tilt Control Valve
Implement Pump
From Charge Pumps To Charge Pumps
P
Pilot Valve Group
From Case Drain Tank
T K
O
U
Lift Control Valve
Float Valve
Vacuum Breaker
59
963C Implement Hydraulic System
The hydraulic system controls the operation of the bucket and the ripper. The hydraulic system can be different from one machine to the next machine according to the optional equipment that is on the machine. The basic hydraulic system consists of the following components: hydraulic tank and filter, hydraulic pump, main control valve group (lift and tilt), third control valve, main relief valve, diverter valve (if equipped), hydraulic cylinders, pressure reducing valve, pilot valve group, and hydraulic oil cooler.
O
The pressure reducing valve is used to provide pilot oil for the pilot valve group. Charge oil from the power train charge pump is used as the supply source for the pilot oil. The valve also works with the shuttle valve and uses lift cylinder oil to create pilot oil to lower the implements when the engine is not running. NOTE: The following illustrations should be used to supplement the materials found in Technical Instruction Module "953C/963C/973C Track Loaders–Implement Hydraulic System" (SERV2695). The previous training package did not provide cut-away illustrations for the pilot valves or the implement control valves.
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PILOT CONTROL VALVE - JOYSTICK HOLD
SHIFT Act uat or
Rod Detent Coil
Plunger
Ret ainer Ret urn To Tank Passage
Spring Chamber
Stem
Pilot Supply Passage
Hole Internal Passage
From Cont rol Valve
From Cont rol Valve
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From Control Valve
S
To Control Valve
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The 963C and 953C use the same pilot valves. Some machines may be equipped with a joystick-type pilot valve for lift and tilt functions. In HOLD, springs hold the plungers and stems up. Pilot supply oil is blocked by the stems. The pilot lines from the control valve are open to the tank through the internal passage and the cross-drilled hole in each stem and the spring chamber.
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Some of the circuits may use detent coils to hold the lever for certain functions such as FLOAT or for the bucket kickouts. When the lever is shifted, the actuator and rod contacts the plunger and pushes it down against the springs and retainer. As the retainer moves down, the springs move the stem down. Depending on how far the actuator is shifted determines how far the stem moves.
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As the stem moves down, it will close off the cross-drilled hole and the internal passage from the spring chamber. The passage to the control valve is no longer open to the tank. Pilot oil enters the cross-drilled hole and internal passage and flows to the control valve to shift the control spool. The greater the pilot oil flow to the control spool the greater the control spool travel.
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As pressure increases in the pilot line to the control valve, the pressure works on the stem to move the stem up to a balance position against the springs to maintain the pilot pressure in the pilot line. This will maintain the position of the control spool in the control valve.
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When the key start switch is in the ON position, the detent coils are energized.
If the operator shifts the lever further the plate above the rod contacts the detent coil. The actuator and plate are then held by the detent coil until the operator moves the lever out of detent or power to the detent is stopped.
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Power may be stopped by "kickout" switches mounted on the cylinders or loader linkage.
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PILOT CONTROL VALVE - LEVER Ac t uat or
HOLD
SHIFT
Detent
Plunger
Ret urn t o Tank Passage
Spring Chamber
Stem
Hole
Pilot Supply Passage
From Control Valve
Internal Passage
From Control Valve
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P
U From Control Valve
S
Ret ainer
To Control Valve
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The 963C and 953C use the same pilot valves. Some machines may be equipped with a joystick for lift and tilt functions as discussed, while other machines use separate levers for each function. The third function, if equipped, uses the lever-type pilot valve. In HOLD, springs hold the plungers and stems up. Pilot supply oil is blocked by the stems. The pilot lines from the control valve are open to the tank through the internal passage and cross-drilled hole in each stem and the spring chamber.
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Some of the circuits may use detent coils to hold the lever for certain functions such as FLOAT or for the bucket kickouts. When the joystick is shifted, the actuator contacts the plunger and pushes it down against the springs and retainer. As the retainer moves down, the springs move the stem down. Depending on how far the actuator is shifted determines how far the stem moves.
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As the stem moves down, it will close off the cross-drilled hole and the internal passage from the spring chamber. The passage to the control valve is no longer open to the tank. Pilot oil enters the cross-drilled hole and internal passage and flows to the control valve to shift the control spool. The greater the pilot oil flow to the control spool the greater the control spool travel.
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As pressure increases in the pilot line to the control valve, the pressure works on the stem to move the stem up to a balance position against the springs to maintain the pilot pressure in the pilot line. This will maintain the position of the control spool in the control valve.
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When the key start switch is in the ON position, the detent coils are energized.
If the operator shifts the joystick further the actuator contacts the detent coil. The actuator is then held by the detent coil until the operator moves the joystick out of detent or power to the detent is stopped.
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Power may be stopped by "kickout" switches mounted on the cylinders or loader linkage.
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9 6 3 C MAIN CONTROL VALVE GROUP TILT HOLD / LIFT HOLD Load Check Valve
Head End
Rod End
To Pilot Valves
S Supply
Makeup Valve
Tilt Spool
Lift Spool
Float Vent Valve
Rod End
O Head End
From Float Valve
T K
P
U
To Pilot Valves
Load Check Valve
Tank
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The two open-center control spools in the main control valve group provide the tilt and lift functions for the machine. The tilt circuit has flow priority over the lift circuit The tilt spool has three positions: TILT BACK, HOLD, and DUMP. If the tilt valve spool is in the HOLD position, the oil will flow around the tilt valve spool to the lift valve spool. The lift valve spool also has three positions: RAISE, HOLD, and LOWER. When the lift is shifted to full lower the float vent valve opens to provide FLOAT.
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Movement of the lift valve spool and the tilt valve spool is controlled by pressurized pilot oil from the pilot valves. Centering springs keep the spools in the HOLD position when the pilot valves (not shown) are in HOLD. With tilt valve spool in the HOLD position, pump oil is sent from the supply passage, around the tilt spool to the lift valve spool. When the lift spool is in the HOLD position, the oil flows around the lift valve spool to the tank passage. With the spools in hold the passages to the cylinders are blocked.
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963C MAIN CONTROL VALVE GROUP TILT BACK / LIFT HOLD Rod End
Head End
Load Check Valve
S Supply
Makeup Valve
From Pilot Valve
To Pilot Valves
Tilt Spool
Lift Spool Float Vent Valve
Head End
Rod End From Float Valve
T K
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Tank
P
U
To Pilot Valve
Load Check Valve
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When the tilt control lever is moved to the TILT BACK position, pilot oil is sent to the pilot chamber on the right end of the tilt spool to shift the spool to the left. Supply oil is blocked from going to the lift spool and the rod end of the tilt cylinder is open to the tank around both spools. Pressure increases in the supply passage and unseats the tilt load check valve. Supply oil is then directed to the head end of the tilt cylinder. Return oil from the rod end flows to the tank. The bucket tilts back.
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As the oil from the rod end of the tilt cylinder bypasses the tilt spool and the lift spool, the Tilt Back Operation and the Raise Operation are prevented from occurring at the same time. When tilt valve spool is in the full TILT BACK position, no pressure oil flows to the lift valve spool. The lift circuit is inoperable.
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9 6 3 C MAIN CONTROL VALVE GROUP TILT HOLD / LIFT RAISE Rod End
To Pilot Valve
Head End
Load Check Valve
Tilt Spool
From Pilot Valve
S Supply
Makeup Valve
Lift Spool
Float Vent Valve From Float Valve
Rod End
O Head End
T K
P
U
To Pilot Valves
Load Check Valve
Tank
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When the lift control lever is moved to the RAISE position, pilot oil from the pilot valve shifts the lift spool to the right. Oil from the main pump is directed from the inlet supply passage around the tilt spool to the lift spool. Supply oil is blocked from going to the tank and the rod end of the lift cylinders are open to the tank around the lift spool. Pressure increases in the supply passage and unseats the lift load check valve. Supply oil is then directed to the head end of the lift cylinders. Return oil from the rod ends flows to the tank causing the lift arms to raise.
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9 6 3 C MAIN CONTROL VALVE GROUP TILT BACK / LIFT RAISE Rod End
Head End Load Check Valve
To Pilot Valve
From Pilot Valve
Tilt Spool
From Pilot Valve
S Supply
Makeup Valve
Lift Spool
Float Vent Valve
O Head End
Rod From Float End Valve
T K
Tank
P
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To Pilot Valve
Load Check Valve
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If the full TILT BACK is activated while the lift spool has been shifted, there is no supply oil available to operate the lift circuit. The lift load check valve seats and the lift cylinders stop moving. The tilt circuit has flow priority over the lift circuit. If the tilt spool is partially shifted for TILT BACK, there will be some supply oil available for the lift to RAISE. The lift cylinder speed will be dramatically reduced.
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In typical truck loading operations, the operator will shift the lift pilot valve lever into the raise detent position and then operate the tilt pilot lever to maximize the bucket load while loading. When the bucket breaks free of the pile, the operator releases the tilt pilot lever and the raise circuit keeps moving until the bucket reaches the "lift kickout." When this occurs, power is cut to the detent coil in the pilot valve and the load is ready to be dumped into a truck.
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When tilt DUMP and lift RAISE are required at the same time, return oil from the head end of the tilt cylinder is directed to the lift spool to provide supply oil for the lift circuit.
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9 6 3 C MAIN CONTROL VALVE GROUP TILT HOLD / LIFT FLOAT Load Check Valve
Head End
Rod End
S Supply
Makeup Valve
To Pilot Valve
To Pilot Valves
Tilt Spool
Lift Spool
Float Vent Valve To Float Valve
Rod End
O Head End
T K
P
U
From Pilot Valve
Load Check Valve
Tank
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When the lift control lever is moved to the FLOAT position, the lift spool is moved to the left by pilot oil. At the same time, the solenoid on the float valve (not shown) is energized to open the vent passage below the float vent valve to the tank. The vent valve opens due to the pressure differential. Oil flow opens the vent valve. With the vent valve open the rod end of the lift cylinders is open to the tank. The head end of the lift cylinders are also open to tank around the lift spool.
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Supply oil from the pump unseats the lift load check valve and also flows around the lift spool and the float vent valve to the tank. This action keeps the oil in the cylinders slightly pressurized to create some down pressure on the bucket to improve backdragging.
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963C ATTACHMENT CONTROL VALVE Load Check Valve
At t achm ent Spool
HOLD
To Pilot Valve
Head End
Rod End
To Tilt Valve
From Pilot Valve
Head End
U
Load Check Valve
At t achm ent Spool
SHIFT
Supply
Rod End
T K
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P
Supply
S
To Pilot Valve
To Pilot Valve
To Tilt Valve
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If the 963C is equipped with an attachment circuit to use with a ripper or multi-purpose bucket, the circuit has flow priority over the tilt and lift circuits. Operation of the attachment valve is the same as the tilt circuit except for not having a makeup valve.
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When the attachment spool is shifted fully, as shown, no supply oil is available to the tilt and lift circuits. If the attachment spool is partially shifted, some supply oil is available for the tilt and lift circuits. The tilt and lift cylinder speeds will be dramatically reduced. When the attachment valve is shifted to the left (not as shown) return oil from the rod end is available as supply oil for the tilt and lift circuits.
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ADVANCED OPTIONAL SYSTEMS
The updated 953C and 963C can be equipped with the optional Machine Security System. When the anti-theft feature is installed, a microchip is imbedded in the rubber grip of the key. This microchip responds to a signal sent from an antenna around the start/stop switch (key slot). Only if the key has the appropriate, pre-programmed microchip can the engine be started.
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The wrong microchip or no microchip will not allow electrical power to be sent to the main power relay or the starter relay, preventing the engine from being started. The wrong microchip will also disable the ADEM III electronic governor, shutting off fuel to the engine so that simply bypassing the starter relay will not start the engine. When the "MSS" ECM is selected from the ECM Status Summary Screen using Cat ET, the technician can gain access to the Machine Security System configuration screen. Highlight the parameter and then use the "Change" button on the lower left to change the parameter. Refer to the Service Manual for more information on this configuration screen and the Machine Security System.
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The 953C and 963C can be equipped with the optional Product Link System. When the "Product Link" ECM is selected from the ECM Status Summary Screen using Cat ET, the technician can gain access to the the the Product Link System configuration screen. Highlight the parameter and then use the "Change" button on the lower left to change the parameter.
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Scroll down on the screen to access the remaining parameters. Refer to the Service Manual for more information on these configuration screens and the Product Link System.
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72
SIGNIFICANT MAINTENANCE CHANGES
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A new optional attachment on the 953C and 963C is the Rotating Bushing Track (RBT). This option is a sealed and lubricated system which includes four track seals per joint, non-restrained rotating bushings, longer track pins, redesigned track links with wider pin bosses and bushing straps, and taller rails. It has a unique pin retention system. The rotating bushing virtually eliminates relative motion between the bushing and sprocket teeth. The minimal bushing wear that does occur is evenly distributed around the bushing. Therefore, no bushing turn is required and sprocket wear is dramatically reduced. RBT significantly increases bushing and sprocket life in abrasive soil conditions.
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The standard equipment track links on the 963C are the newest generation of Extended Wear Life (EWL) track. These new links include even more wear material for even longer track life than the original EWL track. Each 963C link has a center strut to help carry the machine load. A two-piece, split master-link allows easy track chain removal and installation should it be necessary to break the track chain. Disassembly of this link is significantly faster and easier than removing a pressed-in track pin, reducing service time and cost for the customer. Tough Steel™ sprocket segments are a new addition to the machines. Five Tough Steel segments are bolted onto each final drive sprocket hub. These segments can be removed or replaced without breaking the track. Each segment has five teeth. When the track chain travels over the sprocket, it is driven by every second sprocket tooth so two complete revolutions of the final drive are necessary for each tooth to contact a bushing once. The result is long, even, wear of the sprocket teeth.
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NEW TOOLING/SKILLS REQUIRED FOR SERVICE
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Due to the high pressures that may be reached when testing the hystat drive loops the pressure taps (arrow) are larger than what are used on lower pressure circuits. To test the hystat system the following parts and tooling are suggested: 4 - 187-3546 quick couplers
2 - 177-7865 high pressure hoses 2 - 8T0861 pressure gauges
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2 - 171-1879 adapters 2 - 187-3547 nipples
When assembled, two of the test ports can be checks at the same time. Double the quantities above to test all four ports.
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74
CONCLUSION
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This concludes the presentation on the updated 953C and 953C Track Loaders with Tier II engines. This presentation supports the service manual and previous released training materials. When used in conjunction with the service manual, the information in this package should permit the technician to do a thorough job of analyzing a problem in these systems. For service repairs, adjustments, and maintenance, always refer to the Owner and Operator Manual, Service Manuals, and other related service publications.
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HYDRAULIC SCHEMATIC COLOR CODE Black - Mechanical connection. Seal
Red - High pressure oi l
Dark Gray - Cutaway section
Red/White Stripes - 1st pressure reduction
Light Gray - Surface color
Red Crosshatch - 2nd reduction in pressure
White - Atm os pher e or Air (no pressure)
Pink - 3rd reduction in pressure
Purple - Pneumatic pressure
Red/Pink Stripes - Secondary source oi l pressure
Yellow - Moving or activated components
Orange - Pilot, signal, or Torque Converter oil
Cat Yellow - (restricted usage) Identification of components within a moving group
Orange/White Stripes Reduced pilot, signal, or TC oi l pressure
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Orange Crosshatch - 2nd reduction in pilot, signal, or TC oi l pressure.
Brown - Lubricating oi l Green - Tank, sump, or return oi l
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Green/White Stripes Scavenge Oil or Hydraulic Void
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Blue - Trapped oi l
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HYDRAULIC SCHEMATIC COLOR CODES
The colors on the hydraulic schematics and cross-sectional views shown throughout this presentation denote specific meanings. This illustration identifies the meaning of each color.
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ILLUSTRATION LIST 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45.
963C model view 95C model view Similarities and Differences Chart Seat Left console Fuse panel Dash and instrument panel Instrument display Service switches Steering and brake pedals Joystick controls Lever controls Right console and compartment 953C fuel tank 953C hydraulic tank 963C hydraulic tank Radiator and ATTAC Right side engine compartment Case drain filters Power Train ECM Batteries Left side below cab Left side engine compartment 3126B engine Engine ECM Engine speed sensor Cat ET ECM summary screen Engine configuration screen 963C hydraulic block diagram 953C hydraulic block diagram Hystat pumps Hystat taps on pump ECM manifold Implement pilot accumulator 953C hystat accumulator and implement tap 963C hystat motor with speed sensor 963C hystat motor with flushing valve 963C Left Drive Loop Power Train ECM Manifold 963C Pressure Fitting Locations 963C Power Train Hydraulic System PARK 963C Power Train Hydraulic System BRAKES RELEASED 963C Power Train Hydraulic System MAXIMUM FORWARD 963C Power Train Hydraulic System RIGHT TURN FORWARD 963C Power Train Hydraulic System -
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46. 47. 48. 49. 50. 51. 52. 53. 54. 55.
RIGHT SPOT TURN 963C Power Train Hydraulic System CENTER PEDAL PARTIAL DEPRESSED 963C Power Train Hydraulic System CENTER PEDAL FULLY DEPRESSED 953C Left Drive Loop 953C Pressure Tap Locations 953C Power Train Hydraulic System PARK 953C Power Train Hydraulic System BRAKES RELEASED 953C Power Train Hydraulic System MAXIMUM FORWARD 953C Power Train Hydraulic System RIGHT TURN FORWARD 953C Power Train Hydraulic System RIGHT SPOT TURN 953C Power Train Hydraulic System CENTER PEDAL PARTIAL DEPRESSED 953C Power Train Hydraulic System CENTER PEDAL FULLY DEPRESSED Hystat Configuration Screen in Cat ET Hystat Calibrations 963C Implement Hydraulic System Pilot Control Valve - Joystick Pilot Control Valve - Lever 963C Main Control Valve Group - TILT HOLD/LIFT HOLD 963C Main Control Valve Group - TILT BACK/LIFT HOLD 963C Main Control Valve Group - TILT HOLD/LIFT RAISE 963C Main Control Valve Group - TILT BACK/LIFT RAISE 963C Main Control Valve Group - TILT DUMP/LIFT RAISE 963C Main Control Valve Group - TILT HOLD/LIFT FLOAT 963C Attachment Control Valve Machine Security System Screen Product Link Screen Product Link Screen (continued) Undercarriage Pressure taps 953C model view
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57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74.
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E D O l C i o e R r u s O s e r p L h g O i H C d e C R I T A M E H l C a e S S . n o C t I i e L c n U n o A l c a i R c n a D h c Y M e H k -
n o i t c u d e r e r u s s e r p t s 1 s e p i r t S e t i h W / d e R
n o i t c e s y a w a t u C y a r G k r a D
O c a l B
e r u s s e r p n i n o i t c u d e r d n 2 h c t a h s s o r C d e R
e r u s s e r p n i n o i t c u d e r d r 3 k n i P
e r u s s e r p l i o e c r u o s y r a d n o c e S s e p i r t S k n i P / d e R
T K r o l o c e c a f r u S y a r G t h g i L
) e r r o u s e r s e e r h p p o s n o ( r m i t A A e t i h W
Handout No. 1
l i o r e t r e v n o C e u q r o T r o l , a n g i s t , o l i P e g n a r O
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e r u s s e r p c i t a m u e n P e l p r u P
s t n e n o p m o c d e t a v i t c a r o g n i v o M w o l l e Y
e r u s s e r p l i o C T r - o , s l a e n p g i r i t S s , e t o t i l h i p W d / e e c g u n d a r e O R
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n i n o i t . c e u r d u e r s s d e n r p 2 l - i h o c C t a T h r s o s l , o r a C n g e i g s n t , a o r l i O p
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s t n e n o p p u m o r ) o c g e f g o g n a i s n v u i o o l i d t a m o e t i c a g c f i n n i r i t i t t n h s e t a i i e c r d ( I w r b u w L o l l n e Y w t o r a B C
l i o d e p p a r T e u l B
l i o n r u t e r r o , p m u s , k n a T n e e r G
S d i o V c i l u - a r s d e y p H i r r t o S l i e t i O h e g W / n n e e v e r a c G S
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Handout No. 2
Machine Walk-around Checklist Directions: Use this sheet when performing a machine orientation lab exercise.
Place a check in the blank if the fluid level is acceptable. 953C
963C
Engine oil level Hydraulic system oil level Cooling system fluid level Pump drive (splitter box) fluid level Fuel level Place a check in the blank if acceptable or after task was performed. 953C
963C
Drain water separator Check seat belt
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Check air filter indicator and pre-cleaner
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Place a check in the blank after locating each of the following controls. 953C
963C
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Left steering pedal
Right Steering Pedal Service brake pedal
Parking brake lever
Transmission control lever Loader lift and tilt Attachment lever
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Diverter valve lever (if equipped)
Place a check in the left blank after locating each of the following identification plates. Fill in the right blank with number requested. 953C
Machine Serial Number
953C
Engine Serial Number
963C
Machine Serial Number
963C
Engine Serial Number
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Handout No. 3
Machine Walk-around Checklist (continued) Directions: Use this sheet when performing a machine orientation lab exercise.
Place a check in the blank after locating and reading the following warnings label on the machine. 953C
963C
Before operating Use of ether Accumulators Before roading Loader arm brace ROPS Use of Jumpers
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Handout No. 4
Electrical/Electronic Reference Handout - Cab Switches: Governor control switch: sends operator inputs about the desired engine rpm to the ADEM III Electronic Engine control, which communicates with the MAC-14 to control the hydrostatic drive system.
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Speed/direction control lever: brake-on switch is activated when the speed/direction lever is in the "BRAKE-ON" position, venting pressure to the brake release actuator piston.
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Parking brake switch : on the left console for the operator to apply or disengage the parking brakes. Disconnect switch: disconnects the batteries from the entire machine electrical system. Rear wiper switch: activates the rear wiper.
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Front wiper switch: activates the front wiper. It has an intermittent wiper feature. A/C blower switch: is a seven position switch for selecting one of three blower speeds; three speeds for A/C, one position off, three speeds for heating.
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Forward horn switch: activates the forward horn.
Key start switch: starts the 3126B engine by signaling the ADEM III engine controller and supplies power for all electrical components. This switch is also used to stop the engine.
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MSS Anti-theft key start switch: available as an attachment. Numeric Message Display switch: allows the operator to scroll through different information on the 963C monitoring system Numeric Message display (hour meter, engine rpm, override pressure, odometer). Lamp switch: turns on the instrument panel lights and the outside lights.
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Service switch: is one of three Service Mode switches located below the right armrest. The switch is used for accessing on-board fault codes and service information history, and for calibrating various machine functions. Clear switch: one of the three Service Mode switches, is used to clear fault codes. Sensor/speed calibrate switch: the third Service Mode switch and is used for calibrations. Case drain filter bypass switch: illuminates the monitoring system warning light if hydraulic oil is bypassing the case drain filter. Charge filter bypass switch: illuminates the monitoring system warning light if hydraulic oil is bypassing the charge filter.
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Handout No. 5
Electrical/Electronic Reference Handout - Inputs Sensors: Hydraulic oil temperature sensor: is used to measure the temperature of the oil in the hydraulic tank. This information is available on one of the gauges of the 963C monitoring system, and activates one of the monitoring system warning lights.
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Override pressure sensor: sends the Override pressure data from the drive loops to the Power Train ECM and activates a warning indicator on the monitoring system.
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Engine speed sensor: provides the engine rpm data to the Power Train ECM and the ADEM III Engine control. Left/right pilot pressure sensors: senses pressure in the left and right resolvers to detect a stuck solenoid.
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Left/right travel motor rpm sensors : located on the travel motors, provide the track speed to the Power Train ECM. Left/right steering pedal sensors: provide the positions of the steering pedals to the Power Train ECM, which controls the power train accordingly.
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Brake pedal sensor: provides the position of the center brake pedal to the Power Train ECM, which controls the hydrostatic drive system and brake solenoid accordingly.
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Speed/direction lever sensor: provides the position of the speed/direction lever (reverse V-pattern) to the Power Train ECM, which controls the power train accordingly. Coolant level sensor: sends a signal to the monitoring system, which controls a light on the instrument panel to indicate if the engine coolant level is adequate before the engine is started. Senders:
Fuel level sender: provides fuel quantity information to the monitoring system gauge and one of the indicator lights.
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Pump drive (splitter box) oil temperature sender: provides the temperature of the pump drive oil to one of the gauges of the monitoring system, and one of the indicator lights. Engine oil pressure sender: provides information to one of the monitoring system warning lights and to the ADEM III engine control. The monitoring system stores and "Tattletales" engine oil pressure as if it were a gauge. Engine coolant temperature sender: provides the temperature of the coolant in the engine to the ADEM III, the monitoring system and the gauge on the instrument panel. Hydraulic oil temperature sender: provides the temperature of the hydraulic oil to the monitoring system and to the gauge on the instrument panel.
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Handout No. 6
Engine Air Inlet and Exhaust System Component Identification Directions: Use this worksheet during the visual presentation to take notes on the location and function of the components. During the lab exercise, place a check in the blank as each component is identified on the machine. If letters or numbers are used for component identification enter it in the blank instead. After locating the components use the Parts Manual or SIS and record the part name and number as time allows
1. Manifold (boost) pressure sensor Location: Function: Parts Manual Name 2. Air inlet temperature sensor Location: Function: Parts Manual Name 3. Air filter indicator Location: Function: Parts Manual Name 4. Pre-cleaner Location: Function: Parts Manual Name 5. Exhaust Manifold Location:
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Function:
Parts Manual Name
6. Turbocharger
Location:
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Part No.
Part No.
Function:
Parts Manual Name
Part No.
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Handout No. 7
7. Air to air aftercooler Location: Function: Parts Manual Name 8. Air inlet heater (AIH) Location: Function: Parts Manual Name
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Handout No. 8
Engine Fuel System Component Identification Directions: Use this worksheet during the visual presentation to take notes on the location and function of the components. During the lab exercise, place a check in the blank as each component is identified on the machine. If letters or numbers are used for component identification enter it in the blank instead. After locating the components use the Parts Manual or SIS and record the part name and number as time allows
1. Priming pump Location: Function: Parts Manual Name 2. Primary fuel filter/water separator Location: Function: Parts Manual Name 3. Secondary fuel filter Location: Function: Parts Manual Name
T K
4. Fuel shutoff lever (if equipped) Location: Function: Parts Manual Name
5. Injectors
O
Location:
Function:
Parts Manual Name
6. HEUI pump
U
S
Part No.
O
P
Part No.
Part No.
Part No.
Part No.
Location:
Function:
Parts Manual Name
Part No.
STMG 775 1/04
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Handout No. 9
7. Engine ECM Location: Function: Parts Manual Name
8. Ether start solenoid Location: Function: Parts Manual Name
U
Part No.
9. Speed timing sensor Location: Function: Parts Manual Name
O
S
Part No.
T K
O
P
Part No.
STMG 775 1/04
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Handout No. 10
Engine Lubrication System Component Identification Directions: Use this worksheet during the visual presentation to take notes on the location and function of the components. During the lab exercise, place a check in the blank as each component is identified on the machine. If letters or numbers are used for component identification enter it in the blank instead. After locating the components use the Parts Manual or SIS and record the part name and number as time allows
1. Oil pressure sensor Location: Function: Parts Manual Name 2. Oil filter Location: Function: Parts Manual Name 3. Oil cooler Location: Function: Parts Manual Name 4. Crankcase breather Location: Function: Parts Manual Name 5. Dipstick
O
Location:
Function:
Parts Manual Name
U
S
Part No.
T K
O
P
Part No.
Part No.
Part No.
Part No.
STMG 775 1/04
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Handout No. 11
Cooling System Component Identification Directions: Use this worksheet during the visual presentation to take notes on the location and function of the components. During the lab exercise, place a check in the blank as each component is identified on the machine. If letters or numbers are used for component identification enter it in the blank instead. After locating the components use the Parts Manual or SIS and record the part name and number as time allows 1. Radiator Location: Function: Parts Manual Name 2. Coolant level sight gauge Location: Function: Parts Manual Name 3. Coolant fill/recovery tank Location: Function: Parts Manual Name 4. Radiator cap Location: Function: Parts Manual Name
U
S
Part No.
T K
O
P
Part No.
Part No.
Part No.
5. Coolant temperature sensor Location:
O
Function:
Parts Manual Name
6. Water pump
Location:
Part No.
Function:
Parts Manual Name
Part No.
7. Coolant thermostat
Location:
Function: Parts Manual Name
Part No.
STMG 775 1/04
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Handout No. 12
Electrical Component Identification Directions: Use this worksheet during the visual presentation to take notes on the location and function of the components. During the lab exercise, place a check in the blank as each component is identified on the machine. If letters or numbers are used for component identification enter it in the blank instead. After locating the components use the Parts Manual or SIS and record the part name and number as time allows 1. Batteries Location: Function: Parts Manual Name 2. Disconnect switch Location: Function: Parts Manual Name 3. Alternator Location: Function: Parts Manual Name 4. Starter motor Location: Function: Parts Manual Name 5. Starter relay Location:
O
Function:
Parts Manual Name
6. Alternator breaker
Location:
U
S
Part No.
T K
O
P
Part No.
Part No.
Part No.
Part No.
Function:
Parts Manual Name
Part No.
7. Diagnostic connector
Location:
Function: Parts Manual Name
Part No.
STMG 775 1/04
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Handout No. 13
Basic Engine Checks Directions: Using the Service Manual, perform the test according to the procedure in the Service Manual. Record the specifications and the results from the test in the chart below.
Machine Model
Date
Machine Serial Number
SMU
VISUAL CHECKS: Leaks?
Damage?
BASIC CHECKS CHECKS Engine Oil Level
Fuel Level
Drain Fuel Filter/Water Separator
Coolant Level
Air Filter Indicator
Pre-cleaner (if equipped)
Check Radiator for Debris
O
Check Belts
Check Battery Cables
Check Harness Connections
Check for Leaks
P
U
COMMENTS
T K
O
S
STMG 775 1/04
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Handout No. 14
Posttest: Machine Orientation NOTE: Besides the information in this presentation you may use sales information brochures (specalogs) to answer the following questions.
S
I. Directions Modified True / False: If the question is false, circle the word or words that make the statement incorrect and replace with the word(s) to make the statement correct.
1. The Tier II engine used in 953C and 963C is a 3126B equipped with a HEUI fuel system.
U
2. The electronically controlled engine uses a MAC-14 controller.
3. The monitoring system is flashable using Cat ET on the updated 953C and 963C Track Loaders.
P
4. The hystat pumps and the implement pump did not change from the previous machine. 5. The Engine ECM will always start the machine at High Idle.
O
6. The hystat system can be calibrated using switches found in the right console or through Cat ET.
T K
7. The diverter valve is solenoid controlled.
8. An optional electric fuel priming pump is available 9. The 963C uses one case drain filter.
10. Engine speed was reduced on the 953C and 963C with a Tier II engine. 11. The three engine calibrations that can be done using Cat ET are: Injector Code Calibrations, Pressure Sensor Calibration, and Timing Calibration.
O
12. The brake solenoid is mounted to the synchronization manifold. 13. Rotating Bushing Track (RBT) is standard on the 953C and 963C. 14. Maintenance intervals have been extended on the updated machine. 15. The 953C and 963C may be equipped with 5 ECM's.
STMG 775 1/04
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Handout No. 15
Posttest: 953C/963C Track Loader Hystat Components and Functions Directions: Match each component to the correct function. Component
Function
S
I
Hystat drive pumps
A. Limits maximum pressure in the charge circuit.
J
Charge pumps
B. Regulates flow of oil from the drive loops for flushing and cooling the motors.
H
Pump control valve
C. Relieves drive motor actuator pressure to maintain torque at high drive pressure on the 963C.
Drive motors
D. Transfers power from the engine to the pumps.
Drive motor flushing valve
E. Variable displacement and bi-directional flow. Converts hydraulic horsepower into mechanical horsepower.
E B
M
C
L A K
G D F
Transmission override solenoid Drive motor pressure override valve Flushing relief valve Charge relief valve
O
F. Allows pressures to equalize between both drive loops during straight travel.
Pilot spool in the pump
O
G. Controlled by signal oil from a steering solenoid on the 953C.
T K
Makeup/crossover relief valves
P
U
H. Controls the signal pressure to the pump actuator on a 963C. I. Variable displacement, bi-directional flow. Converts mechanical horsepower into hydraulic horsepower. J. Constant displacement. Supplies the power train with charge oil pressure. K. These allow charge pressure to pressurize the low pressure side of the drive loops. They also limit drive loop maximum pressure.
Splitter box/pump drive
L. Controls the minimum pressure in the low pressure drive loop.
Synchronization valve
M. When the Power Train ECM senses a fault, this valve is de-energized to block flow to the steering solenoids.
STMG 775 1/04
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Handout No. 16
Posttest: 953C/963C Track Loaders Hydraulic System Components and Functions Directions: Match each component to the correct function. Component Function
D
M
E
S
Attachment function levers
A. A vane-type pump. This pump supplies the implement system with hydraulic oil.
Caterpillar Monitoring System
B. Allows full charge pressure to reach the implement control levers. This component limits the maximum pressure allowed to reach the implement control levers.
Main control valve group
P
U
C. A gear-type pump that supplies the pilot circuit. B
Hydraulic system pressure reducing valve
N
Manual diverter valve
C
O
E. This valve group directs main system oil flow to the hydraulic cylinders.
Pilot pump
F. Cools the hydraulic oil used in the implement system
T K
A
Implement pump
K
Implement hydraulic oil cooler
O
D. Send pilot signals to the main control valve spools to control implement cylinder movement.
G. This system has a single warning light for the hydraulic system temperature. H. Manually set to divert implement oil from the multipurpose bucket to the ripper cylinders.
