02 Transmission System LG958L

LG958L Training material Chapter IV ZF Transmission Tuesday, May 19, 2015

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RELIABILITY IN ACTION

CONTENTS Structure and Principle of Torque Converter Structure and Principle of Transmission Oil Supply and Lubrication System of ZF Transmission Electric Control System of ZF Transmission Operation and Maintenance of ZF Transmission Common Malfunctions and Troubleshooting of ZF Transmission

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Section I Structure and Principle of Torque Converter 1

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3

4

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Figure 4-1 Diagram of Transmission System for LG958L Loader

1. Torque converter 2. Rear drive axle 3. Transmission 4. Drive shaft 5. Front drive axle

The hydraulic torque converter is installed between the engine and transmission and is mainly function to change the torque outputted by the engine so that the torque output of the turbine will probably exceed the input torque of engine via pump impellor so as to improve the power performance of loader and ensure the stable transmission. 3


Figure 4-2 Internal Structure Diagram of ZF Torque Converter

Torque converter: It’s mainly composed of pump impellor, turbine, idler pulley (commonly referred to as three-element part.), and housing and it’s capable of automatically regulating the torque output and speed output of the engine.

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Pump impellor

Guide pulley

Turbine

Working principle of torque converter: Some blades are uniformly arranged within each working impellor of the torque converter. These blades work together with each other to form an enclosed annular space, in which the fluid can recirculate. When the engine flywheel drives the rotation of pump impellor, the blades of the pump impellor drives the rotation of fluid. Under the action of the centrifugal force, the fluid flows from the inner edges of blades to the outer edges to impact the turbine blades and drive the rotation of turbine for torque output. The flowing fluid flows from the outer edges of blades to the inner edges of blades within the turbine to impact the blades of guide pulley and then returns to the pump impellor along the blades of guide pulley for next cycle. The torque conversion of the hydraulic torque converter is attributed to the presence of guide pulley. The guide pulley is connected with the torque converter housing via fixed guide pulley seat and the torque converter is connected with engine flywheel via elastic plate.

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Section II Structure and Principle of Transmission 1. Characteristics of ZF transmission: ● 4 forward gears and 3 reverse gears ● High working efficiency ● Low repair rate ● Ultra-long service life ● Low fuel consumption ● Low noise

Structural diagram of ZF transmission 6


Connecting flange with torque converter and engine

ZF transmission Torque converter

ZF transmission Transmission

ZF transmission Gearshift operating lever

2. Structure of transmission

The ZF transmission is mainly composed of electronic control units (gearshift operating lever, electric control box, and gearshift valve) and mechanical gearshift transmission (6 clutches and drive gears and output shaft).

ZF transmission 7

ZF


Rear view of transmission

1 power takeoff port st

Oil filter

1 power 2 power takeoff port takeoff port st

nd

Clutch K1 Clutch KV Clutch KR

Optional emergency pump port Output speed sensor

Clutch K2 Clutch K3 Clutch K4

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Clutch KV Transmissio n filler port Output flange, fitted with parking brake

Removed part on right side of transmission


Press once KD button

Use of KD button function of ZF transmission in actual applications 9


Electric control box of ZF transmission

Gearshift valve of ZF transmission (including pressure measuring point)

M4 Oil pipe to twostage pressure pilot control valve 1Mpa reducing valve Clutch K3 Two-stage pressure control valve System pressure Clutch K1

During electric welding of main unit for repair, unplug the connector of electric control box 10

Solenoid valve (resistance: 90±10Ohm)

Clutch K2

Reverse clutch KR

K4 clutch

Forward clutch KV


Clutch KV

Clutch K1 Power drive gear

Clutch KV and K1 of ZF transmission

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Schematic diagram of clutch


Clutch KV and K1 of ZF transmission 12


Clutch KR and K2 of ZF transmission 13


Clutch K3 and K4 of ZF transmission 14


The travel for pistons of various clutches is 1.8~2.4mm.

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The axial clearance is 0.1~0.3mm after assembly of various shafts. 16


3. Route diagram for various gears of ZF transmission Internal structural diagram of ZF transmission

Route diagram for various gears of ZF transmission (4 forward gears and 3 reverse gears) 1st forward Output

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gear

Route diagram for various gears of ZF transmission (4 forward gears and 3 reverse gears) 2nd forward gear Output

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3rd forward gear

Output


Route diagram for various gears of ZF transmission (4 forward gears and 3 reverse gears)

Countershaft

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4th forward Output gear

1st

Output reverse gear


Route diagram for various gears of ZF transmission (4 forward gears and 3 reverse gears) 2nd reverse gear

Output

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3rd reverse Output gear


Section III Oil Supply and Lubrication System of ZF Transmission

Oil recirculation schematic diagram of transmission with two-stage pressure control valve

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Cast aluminum gearshift control valve with 5 solenoid valves and two-stage pressure control valve

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Section IV Electric Control System of ZF Transmission

1. ZF built-in electric system

1. Electric control box EST-17T 2. Transmission 3. Gearshift operating lever DW-2 4. Connecting port to circuits of complete machine 5. To transmission solenoid valve 6. To output speed sensor

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2. ZF built-in harnesses and connectors Gearshift operating

Yellow

lever connector

Blue

Cable electric control Purple

box connector Sensor 2

(I)

Red

Green

Grey

Lever 5 Black Pink Solenoid valve connector

Sensor 1

Complete machine wire connector Lever 8

Lever 7 Lever 9 Lever 10 Lever 4

Lever 6

Starter interlocker 584

Lever 2

Pressure switch 600

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3. ZF peripheral electric system To electric control box

Intermediate relay (power cutoff)

Intermediate relay (starter interlocker)

Intermediate relay (reversing)

Parking brake indicator switch

To starter relay To brake signal terminal lamp To starter relay terminal G2 To instrument panel electric control box working indicator

Brake switch (left) To brake lamp Brake switch (right)

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4. Gear selector The gear selector is the gear signal input device of the ECU. Its normal functioning directly influences the normal functioning of the system. Use the multimeter for measurement and judgment. KD button

Neutral gear locking switch

● Neutral start interlocking function ● Neutral locking function. Rotate the red neutral gear locking switch. Lock direction ● Power cutoff function during braking at 1st gear or 2nd gear. ● Kick-down function (KD button)

Gearshift operating lever of ZF transmission

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The continuity and logic relationships between the red wire in the harness of gear selector and other wires and various gears are as below: With red

FI

F2

F3

F4

R1

R2

R3

Blue

√

×

×

√

√

×

×

Green

×

×

√

√

×

×

√

Black

√

√

√

√

√

√

√

Yellow

√

√

√

√

×

×

×

Grey

×

×

×

×

×

×

×

Pink

×

×

×

×

√

√

√

Purple

×

×

×

×

×

×

×

If the grey wire is under continuity state, the complete machine can’t be started. The purple is the KD function, the pink is the control of reverse gear, and the yellow is the forward gear.

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5. Electric control box •

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As the main control part for judgment of gear, the electric control box analyzes the signal of selector and issues command to the solenoid valve.


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6. Gearshift valve The gearshift valve is the actuator unit that engages and disengages the control gear of the solenoid valve as per the command of ECU.

1) Sequence of solenoid valve: 4, 3, 5, 2, and 1 from top to bottom. 2) If the O-ring is not properly seated, it will easily cause oil leakage at side cap. 3) The resistance of solenoid valve is 90±10Ω. 30


Clutch for various gears

Control solenoid valve 31

KV

K1

K2

K3

K4

KR

M3

M2 and M4

M4

\

M5

M1


7. Speed sensor

Transmission speed sensor

• Resistance of speed sensor: 1020±100Ω

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Section V Operation and Maintenance of ZF Transmission

1. Operation Precautions

(1) To check the transmission oil level, the engine shall idle run (at approximate 1,000r/min) and the oil temperature shall be at normal working temperature.

(2) When the oil temperature is at 40ºC, the oil level shall be between the middle mark and lower mark of the oil dipstick.

When the oil temperature is at 80ºC, the oil level shall be between the middle mark and upper mark of the oil dipstick. Hot oil level zone

Cold oil level zone

(3) Periodically replace the transmission oil and replace the filter strictly as per the maintenance schedule. (4) Before starting the engine, ensure that the operating lever is at neutral gear. (5) Before starting up the machine each time, release the parking brake.

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(6) When it's necessary to hoist the transmission to fit the engine with transmission or separate the engine from the transmission, avoid the fall-off of the torque converter. (7) While parking the machine, the gearshift operating lever shall be at neutral gear.

(8) The normal working oil temperature shall be within 80~110ºC. Under heavy load, the oil temperature is allowed to rise to 120ºC for a short time. Pay special attention to the controlling oil pressure of the transmission. Upon detection of any abnormality in the transmission during operation, immediately stop the machine for checking.

(9) When the electric welding is required for repair in event of the machine malfunction, make sure to disconnect the cable connector from the EST – electronic control unit (to cut off the current to the electronic control unit), or the impact current during the electric welding will probably burn out the electronic control unit.

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2. Operations

(1) Preparations and maintenance before driving •

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•

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Before the operation of the transmission, make sure to add an appropriate amount of lubricating oil as per the specified specification of lubricating oil. While adding oil to the transmission for the first time, make sure to take into consideration that the oil radiator, filter, and connecting pipeline must be fully filled with oil. Therefore, the lubricating oil amount to be added for the first time will be much more than the lubricating oil amount to be added during normal maintenances.

The oil level can be checked only when the operating level is at neutral gear. While checking the oil level, insert the oil dipstick to the dead end of the dipstick tube. While cleaning the filter of main oil line, pay attention to prevent the ingress of dirt and sediments into the oil circuit. Therefore, place a cover plate to guard the parking brake against being dipped by the oil. While installing the filter, pay attention not to tighten excessively.


(2) Driving and gearshift •

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To start the engine, make sure that the gearshift operating lever is at neutral gear. For the purpose of safety, before starting the engine, the parking brake shall be under braked state to prevent the startup of machine due to the start of engine. After the engine is started, release the parking brake, select the driving direction and gear, and depress the throttle slowly to start up the machine. During the traveling of the machine, the torque converter substitutes the function of main clutch. When the road condition is good, it‘s possible to travel at higher gear.

If the machine stops traveling, but the engine is still running and the transmission is shifted to a gear other than neutral gear, the engine will not stop at that time. On a straight road, the machine will probably crawl, as the idling of engine will generate a certain traction force via the torque converter. The appropriate method is to place the parking brake at braked state whenever the machine is parked.

To park the machine for a long period, make sure to shift the operating lever to neutral gear. During the traveling of the machine, make sure to release the parking brake. Due to the influence of the torque converter, while shifting from a high speed gear to a low speed gear, the engine speed will increase, especially at the time of gear jump. Therefore, whenever the condition permits, while shifting from a high speed gear to a low speed gear, depress the foot brake for slow deceleration before the gearshift. When the machine is traveling at high speed or changing driving direction, lower the engine speed.


(3) Driving and gearshift

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The maximum oil temperature at outlet of torque converter shall not exceed 120ºC. For non-malfunctioned control subassembly and transmission with sufficient traveling mileage, the temperature shall not be too high. If the oil temperature exceeds 120ºC, make sure to stop the machine and check for presence of external oil leakage. At the same time, shift the transmission to neutral gear and run the engine at 1,200~1,500rpm. In such case, the oil temperature will lower rapidly to the normal value (approximate within 2~3min). If the oil temperature fails to drop, certain portion within the system is malfunctioned. Make sure to resolve the malfunction before proceeding the operations.

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Normal range for gearshift oil pressure: 1.6~1.8MPa (16~18bar). To monitor the control pressure, make sure to install a pressure gauge or pressure monitoring unit. If the pressure drops to below the specified minimum pressure after a certain gear is engaged and the clutch is depressed (though the pressure at moment of gearshift will drop automatically temporarily), make sure to resolve the cause of pressure drop. The under-low control pressure will lead to damage of clutch, as the clutch is short of sufficient contact pressure and the continual skid of friction plate leads to over-heating.


3. Maintenance (1) Check the oil level. - Park the machine on a level place. - Shift the gearshift operating lever of the transmission to neutral gear “N” and set the parking brake at braked position. - Idle run the engine at approximate 1,000r/min. - Counterclockwise the oil dipstick and take out and wipe clean the oil dipstick. - Insert the oil dipstick into the oil dipstick tube and tighten to place. Wait for 3s and take it out (measure for at least two times). - When the oil temperature is at 40ºC, the oil level shall be between the middle mark and lower mark "Cold” of the oil dipstick. - When the oil temperature is at 80ºC, the oil level shall be between the middle mark and upper mark "Hot” of the oil dipstick. Caution: Checking the oil level under cold state is to ensure sufficient recirculation flow for transmission and torque converter and the decisive criterion for oil level is to meet the oil level requirement under hot state. •

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(2) Replace the oil. Make sure to replace the oil for the first time after the machine is working for the first 100 hours. Afterwards, replace the oil once every 1,000 working hours or once a year. At the replacement of oil, park the vehicle at a level place. Under the working temperature of the transmission, take out the oil drainage plug and seal ring and fully drain the used oil. - Start the engine and idle run the engine. - Shift the transmission operating lever to neutral gear “N”. - Add oil to the upper mark of the oil range “Cold”. - Set the parking brake at safe place. - Shift to every gear for once. - Check the oil level and when necessary add the oil. Part Name Transmission (4WG200)

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Initial oil replacement After 100 working hours. Replace filter as well.

Normal oil replacement

At interval of 1,000 working hours, but no more than 1 year. Replace filter as well.

Oil specification Mobil Delvac 1300 SAEl5W40 or Titan universal oil HD15W-40 (manufactured by Shanghai Desi Oils Co., Ltd.)

Checking of oil level Before operation each day


(3) Replace oil filter.

Make sure to replace ZF fine filter at the replacement of oil each time. Replace as per the following requirements:

- Apply a thin film of oil onto the seal ring.

- Push in the filter, till it comes into contact with the sealing surface on the transmission, and then tighten for approximate 1/3~1/2 turn with hand. - Add oil.

- Start the engine.

- Idle run the engine (at approximate 1,000r/min). When the transmission oil temperature reaches working temperature, check the transmission oil level. - Check whether the filter is tightened. If necessary, tighten again with hand.

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(4) Assembly precautions for ZF transmission: I. Fitting and connection between ZF transmission and engine 1. Wipe clean the anti-rusting oil from the engine flywheel and the inside of flywheel housing to be fitted. 2. Place the transmission at the fitting station and disassemble the fixing wood plate from the torque converter middle flange on the transmission (It's absolutely prohibited to slide outward the torque converter and its middle flange). 3. While fitting and connecting the transmission with engine, without moving the transmission, fit the flywheel housing of engine with the torque converter connecting housing on the transmission and ensure that the middle flange of torque converter enters into the junction surface of the engine flywheel.

Fall-off of torque converter

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4.

Completely fit and fix the connecting housing of torque converter and flywheel housing of engine with three bolts and then tighten the connecting bolts of torque converter middle flange and engine flywheel in turn. 5. Finally tighten all connecting bolts of torque converter connecting flange and engine flywheel housing. 6. Through the square observation port on the connecting housing of the torque converter, check the connecting elastic plate between torque converter and its middle flange for presence of squeezed deformation (Under normal status, the plane of elastic plate shall be perpendicular to the axis of middle flange). 7. Control size for connecting the connecting housing of transmission with engine flywheel housing: 39.6±0.5. II. Precautions for installation from transmission and radiator oil pipe The tightening depth for the connection between pipe connector and transmission shall not come into contact with the core of the backpressure valve. If the insertion depth exceeds 21mm, it will cause working failure of the backpressure valve due to blockage of core and obstruct the recirculation oil line between transmission torque converter and radiator so that the working oil of the torque converter can’t be sufficiently recirculated for heat radiation to cause over-high oil temperature of the torque converter.

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III. Installation of torque converter temperature sensor 1.

While installing the temperature sensor at the oil temperature measuring point of the torque converter, upon detection that the top of the sensor is pushed against the core of backpressure valve, do not forcibly screw in the sensor. Please timely notify the technician to solve the malfunction, in order to prevent the damage of sensor and valve core due to interference.

IV.

Fluid within side cap of gearshift operating valve

1.

After the engine is started, a part of oil in the gearshift operating oil system will overflow and return to the tank via the oil line within the side cap of the gearshift operating valve. Therefore, when the side cap is opened during the running of the engine, the oil will spray from the valve body. Therefore, while installing the side cap, make sure properly seat the O-ring of side cap and clamp the hoop to the required place, in order to prevent the so-called valve leakage symptom.

2.

Do not open the side cap of gearshift operating valve at will.

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V. 1.

2.

Speed sensor The gap between the end of speed sensor and the tooth top of gear is 0.5~0.8mm. The disassembly of sensor without prior consent and the incorrect installation will lead to damage of the sensor. Do not disassemble the speed sensor without prior consent. The service personnel is disallowed to add or remove the adjustment washer at the time of assembly. Speed sensor

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VI. ZF cables 1. 2.

While arranging the cables, ensure that the cables at all positions are free of friction with any other part. The cables at all positions shall be correctly fixed.

VII. Electric control box 1. 2.

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At the time of electric welding, unplug the connector of electric control box to disconnect the electric control box from circuits and prevent the burnout of electric control box. Guard the electric control box against moisture and rainfall.


Section VI Cause Judgment and Troubleshooting for Common Malfunctions of ZF Transmission 1. No gear, though the complete machine can be started.

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Check oil level

Check the cable for presence of worn damage. Check the connectors and fuses

Check whether the power voltage is at a stable normal value. Check the parking brake for normal functioning.

Check for normal power connection between engine and torque converter. Check for normal gearshift oil pressure.

Check for normal functioning of gearshift operating lever. Check for normal functioning of solenoid valve.


2. No 3rd gear or 4th gear is available, though the 1st gear and 2nd gears are available in complete machine. » Check oil level

» Check cable connectors for normal connections. » Check cables for worn damage.

» Check speed sensor for normal functioning. » Check lever for normal functioning.

3. No 1st gear or 2nd gear is available, though the 3rd gear and 4th gears are available in complete machine. » Check the cables for normal connection.

» Check pressure sensor for normal functioning.

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4. Noise of transmission » Check oil level

» Check the connecting bolts between transmission and frame and engine for presence of looseness. » Check the drive shaft and its support for normal functioning. » Check the hydraulic pump for abnormality.

» Check the articulations for normal functioning. 5. Weak complete machine » Check oil level

» Check whether the gearshift pressure is at 1.6~1.8MPa. » Check for normal power of engine.

» Check the oil for improper trademark, deterioration, and presence of air bubble.

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THE END

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02 Transmission System LG958L

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