Manual Power Train Caterpillar 777d Off Highway Truck Components

Service Training MALAGA

777D Off Highway Truck LOCKUP CLUTCH VALVE TORQUE CONVERTER DRIVE

LOAD PISTON

MODULATION REDUCTION VALVE

SELECTOR PISTON

LOAD PISTON ORIFICE PRESSURE REDUCTION VALVE

LOCKUP SOLENOID OFF

SHUTTLE VALVE

TO LOCKUP CLUTCH

FROM PARKING BRAKE PUMP

III. POWER TRAIN 1. 2. 3. 4.

Components Layout Operation Maintenance Testing & Adjusting Adolfo August 1997

777D Off Highway Truck CHAPTER : Power Train

TYPICAL OFF-HIGHWAY TRUCK POWER TRAIN COMPONENT LOCATIONS LOCKUP MODULATION VALVE

LOCKUP SOLENOID

TRANSMISSION PUMP TORQUE CONVERTER SOLENOIDS UPSHIFT DOWNSHIFT

TRANSMISSION

TRANSMISSION OIL FILTER

TORQUE CONVERTER FILTER

TORQUE CONVERTER AND TRANSMISSION OIL

INLET AND OUTLET RELIEF VALVES

TRANSMISSION

DRIVE SHAFT

TRANSMISSION CONTROL VALVE DIFFERENTIAL AND FINAL DRIVES

LOCKUP CLUTCH TORQUE CONVERTER

Page:

III-2

TORQUE TRANSFER CONVERTER GEARS PUMP


TORQUE CONVERTER CONVERTER DRIVE

TURBINE LOCKUP PISTON

TORQUE CONVERTER INLET OIL IMPELLER TORQUE CONVERTER LOCKUP OIL PASSAGE

ENGINE FLYWHEEL

STATOR

FREEWHEEL ASSEMBLY

Page:

III-3

TO TRANSFER GEARS


TORQUE CONVERTER DIRECT DRIVE

TURBINE LOCKUP PISTON

TORQUE CONVERTER INLET OIL

IMPELLER

TORQUE CONVERTER LOCKUP OIL PASSAGE

ENGINE FLYWHEEL

STATOR

FREEWHEEL ASSEMBLY

Page:

III-4

TOTRANSFER GEARS

Page: III-5

LOCKUP CLUTCH VALVE CLUTCH FILLING

LOAD PISTON

SELECTOR PISTON SHIMS

LOAD PISTON ORIFICE

LOCKUP SOLENOID ON

SHUTTLE VALVE

TO LOCKUP CLUTCH


777D Off Highway Truck

PRESSURE REDUCTION VALVE

CHAPTER : Power Train


Page: III-6

LOCKUP CLUTCH VALVE DIRECT DRIVE

LOAD PISTON

SELECTOR PISTON

LOAD PISTON ORIFICE

LOCKUP SOLENOID ON

SHUTTLE VALVE

TO LOCKUP CLUTCH



PRESSURE REDUCTION VALVE



Page: III-7

769D - 777D TORQUE CONVERTER HYDRAULIC SYSTEM NEUTRAL

INLET RELIEF VALVE BRAKE COOLING PRESSURE

LOCKUP CLUTCH PILOT OIL PRESSURE

LOCKUP CLUTCH PRESSURE

LOCKUP MODULATION PARKING BRAKE VALVE RELIEF VALVE TO BRAKE COOLING CIRCUIT

OUTLET RELIEF VALVE

OUTLET PRESSURE TAP

INLET PRESSURE LOCKUP REDUCING VALVE

PARKING BRAKE RELEASE VALVE

CONVERTER CHARGING PUMP

PARKING BRAKE RELEASE PUMP

PARKING BRAKE RELEASE PRESSURE

LOCKUP CLUTCH

CONVERTER SCAVENGE PUMP SCREEN

TORQUE CONVERTER

SHIMS


TO BRAKE COOLING CIRCUIT


LOCKUP SOLENOID

Page: III-8

769D - 777D TRANSMISSION HYDRAULIC SYSTEM NEUTRAL

DOWNSHIFT PRESSURE

UPSHIFT PRESSURE

A DOWNSHIFT UPSHIFT SOLENOID SOLENOID ROTARY ACTUATOR

FILTER

E

ON PUMP PRESSURE

B NEUTRALIZER VALVE

OIL COOLER

F ROTARY SELECTOR SPOOL

C

SCAVENGE PUMP

G

D

RELIEF VALVE

H

TRANSMISSION CASE

TANK

LUBE RELIEF VALVE

SELECTOR VALVE GROUP LUBE PRESSURE

PRESSURE CONTROL GROUP


CHARGING PUMP

PRIORITY REDUCTION VALVE


PILOT OIL PRESSURE


769D - 777D TRANSMISSION SELECTOR VALVE GROUP NEUTRAL

NEUTRALIZER VALVE ROTARY SELECTOR SPOOL PRIORITY REDUCTION VALVE PILOT OIL PRESSURE SCREEN RELIEF VALVE

TRANSM. LUBE RELIEF VALVE

LUBRICATION PRESSURE

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III-9


769C - 777C TRANSMISSION SELECTOR VALVE GROUP STARTING IN FIRST SPEED FORWARD

NEUTRALIZER VALVE

ROTARY SELECTOR SPOOL


PILOT OIL PRESSURE SCREEN RELIEF VALVE

LUBE RELIEF VALVE

LUBRICATION PRESSURE

Page:

III-10


769D - 777D PRESSURE CONTROL GROUP NEUTRAL

A

E B

F

C

G D

H

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III-11

Page: III-12

VALVE STATION CLUTCH RELEASED

SELECTOR PISTON SLUG

BALL CHECK VALVE

LOAD PISTON

PILOT OIL PASSAGE

MODULATION REDUCTION VALVE FROM PUMP

LOAD PISTON PLUG

CLUTCH PRESSURE TAP TO CLUTCH


DECAY ORIFICE LOAD PISTON ORIFICE


PLUG


VALVE STATION CLUTCH ENGAGED

Page:

III-13


VALVE STATION CLUTCH ENGAGED/WITH PIN

Page:

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VALVE STATION CLUTCH DECAY

DECAY ORIFICE

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Page: III-16

769C - 777C TRANSMISSION HYDRAULIC SYSTEM THIRD SPEED FORWARD

DOWNSHIFT PRESSURE

UPSHIFT PRESSURE

A DOWNSHIFT UPSHIFT SOLENOID SOLENOID ROTARY ACTUATOR

FILTER

E PUMP PRESSURE

B

OIL COOLER CHARGING PUMP


F ROTARY SELECTOR SPOOL

C

SCAVENGE PUMP

G D RELIEF VALVE

H

TRANSMISSION CASE

TANK

LUBE RELIEF VALVE SELECTOR VALVE GROUP LUBE PRESSURE

PRESSURE CONTROL GROUP


PILOT OIL PRESSURE


NEUTRALIZER VALVE


VALVE STATION PRIMARY PRESSURE

LOAD PISTON PLUG (REMOVED)

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Page: III-18

777D SHIFT MODULATION CYCLE THIRD(3&6) TO FOURTH (1&5)

PRESSURE NORMAL SHIFT CYCLE CLUTCH 1 418

CLUTCH 5

CLUTCH 3

COMPLETE CLUTCH ENGAGEMENT

PRIMARY PRESSURE 50

INITIAL CLUTCH ENGAGEMENT

0 FILL TIME NORMAL CLUTCH SLIP

TIME


265

CLUTCH 6


373 353

Page: III-19

777C SHIFT MODULATION CYCLE SECOND TO THIRD PRESSURE NORMAL SHIFT CYCLE

418 373

CLUTCH 3


80

PRIMARY PRESSURE

INITIAL CLUTCH ENGAGEMENT

0 FILL TIME NORMAL CLUTCH SLIP

TIME


CLUTCH 1 265


CLUTCH 6

Page: III-20

PRESSURE HIGH PRIMARY PRESSURE

RESTRICTED LOAD PISTON ORIFICE SLOW MODULATION P1


0

TIME

HIGH PRIMARY PRESSURE - HARSH SHIFT NORMAL CLUTCH SLIP LOW PRIMARY PRESSURE - CLUTCH SLIPPING

SHIFT MODULATION PROBLEMS RESTRICTED LOAD PISTON ORIFICE CLUTCH SLIPPING


NORMAL PRIMARY PRESSURE


LOW PRIMARY PRESSURE INITIAL CLUTCH ENGAGEMENT


LAB EXERCISES Lab A: Component Location and Identification Worksheet I 769D - 777D Off-highway Trucks Torque Converter Hydraulic System Directions: Refer to the Lab A Handout Illustration Worksheet V. Place the correct letter or number next to the component. During the slide presentation, use this sheet to take notes on the function of each component. ______ Torque Converter - example: Located on the rear of the engine. Provides a fluid coupling between the engine and the transmission and multiplies torque. Contains a lockup clutch for more efficient operation. ______ Torque Converter Pump (1. Scavenge, 2. Charging, and 3. Park Brake Release) -

______ Torque Converter Scavenge Screen -

______ Torque Converter Charging Filter -

______ Torque Converter Inlet Relief Valve -

______ Torque Converter Outlet Relief Valve -

______ Torque Converter Lockup Clutch Valve -

______ Parking Brake Release Valve -

______ Parking Brake Release Filter -

______ Lockup Clutch Solenoid Valve -

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III-21


LAB EXERCISES Lab A: Component Location and Identification Worksheet ID 769D - 777D Off-highway Trucks Transmission Hydraulic System Directions: Refer to the Lab A Handout Illustration Worksheet V. Place the correct letter or number next to the component. During the slide presentation, use this sheet to take notes on the function of each component. ______ Transmission Tank - example: Located on the left side of the truck. Contains a sight gauge for checking power train hydraulic level. ______ Transmission Pump -

______ Transmission Filter -

______ Transmission Magnetic Suction Screen -

______ Transmission Oil Cooler -

______ Transmission Control Valve -

______ Upshift Solenoid Valve -

______ Downshift Solenoid Valve -

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LAB EXERCISES Lab A: Component Location and Identification Worksheet V Torque Converter and Transmission Hydraulic Systems Component Identification

TYPICAL OFF-HIGHWAY TRUCK POWER TRAIN COMPONENT LOCATIONS

Page:

III-23



B. Parking Brake Release Pressure C. Lockup Clutch Pressure D. Outlet Pressure E. Pilot Pressure

Identify Components 1. Outlet Relief Valve

7. Inlet Relief Valve

2. Parking Brake Release Valve

8. Lockup Modulation Valve

3. Converter Charging Pump

9. Scavenge Pump

III-24

4. Torque Converter

10. Lockup Solenoid

5. Lockup Reducing Valve

11. Shuttle Valve

6. Parking Brake Release Pump

12. Lockup Clutch


Page:

Directions: Write the letter or number of the item in the correct blank on the schematic.

A. Inlet Pressure


Worksheet I: (769D - 777D)

Identify Test Ports

LAB EXERCISES

Lab B: Torque Converter Hydraulic System Component Identification


LAB EXERCISES Lab C: Torque Converter Hydraulic System Testing Shop Lab Exercise Procedure: Perform the following tests listed in the Power Train Testing and Adjusting Service Manual Module for the lab machine used: • Visual Checks (8) for the hydraulic system which include Brake Cooling, Torque Converter, and Hoist Hydraulic Systems • Torque Converter Outlet Pressure • Torque Converter Inlet Pressure • Parking Brake Release Pressure • Lockup Clutch Pilot Pressure • Lockup Clutch Leakage • Lockup Clutch Signal Pressure (785B - 793B) • Lockup Clutch Maximum Pressure • Lockup Clutch Primary Pressure Class notes Lab D Worksheets (I and II) Off-highway Truck Mechanic's tools The following test equipment: 1 - 8T0854 Gauge 1000 kPa (145 psi) 1 - 8T0850 Gauge 4000 kPa (580 psi) 1 - 8T0851 Gauge 16000 kPa (2300 psi) 1 - 6V3965 Nipple 1 - 6V4143 Valved Coupler 1 - 6V3079 Diagnostic Hose 1 - 6V3121 Multitach Group 1 - Oil container [approximately 19 l (5 gal.) capacity] 1 - Special Instruction "6V3121 Multitach Group" (Form SEHS7807)

Page:

III-25


LAB EXERCISES Lab C: Torque Converter Hydraulic System Testing 769C - 777C Off-highway Trucks - Worksheet I Directions: Use this sheet to check off each of the steps listed in the Power Train Testing and Adjusting Service Manual Module. Machine Model______________________ Name/Code _________________________ Machine PIN (S/N)___________________ Transmission S/N ____________________ Engine S/N _________________________ S.M.H. ____________________________

Dealer ______________________________ Customer ___________________________ Job ________________________________ Application __________________________ Date _______________________________ Serviceman __________________________

VISUAL CHECKS ______ Check 1 - Oil levels in the hydraulic tank ______ Check 5 - Torque converter scavenge screen ______ Check 2 - External Leakage

______ Check 6 - Oil cooler screens

______ Check 3 - Parking brake release oil filter ______ Check 7 - Components inside hydraulic tank ______ Check 4 - Torque converter oil filter

TEST

______ Check 8 - Inspect return oil screen

SPECS

ACTUAL

Torque Converter Outlet Pressure at Stall Torque Converter Stall Speed Torque Converter Inlet Pressure Lockup Clutch Pilot Pressure Parking Brake Release Pressure Lockup Clutch Leakage Lockup Clutch Maximum Pressure Lockup Clutch Primary Pressure

Page:

III-26

Lab D: Tracing Torque Converter Oil System Flow (769D - 777D) Worksheet I Directions: Trace the flow of oil during the condition listed below using different colored pencils to show each path.


III-27



Page:

769D - 777D TORQUE CONVERTER HYDRAULIC SYSTEM TORQUE CONVERTER DRIVE

LAB EXERCISES


Lab D: Tracing Torque Converter Oil System Flow (769D - 777D) Worksheet II Directions: Trace the flow of oil during the condition listed below using different colored pencils to show each path.



III-28



LAB EXERCISES

Page:

769C - 777C TORQUE CONVERTER HYDRAULIC SYSTEM DIRECT DRIVE


LAB EXERCISES Lab E: Torque Converter Hydraulic System Operation (769D - 777D) Worksheet I Directions: Circle the letter of the correct statement that completes the sentence. Example: Torque converter leakage oil is removed from the torque converter by the: A. Parking brake release pump B. Scavenge pump C. Charging pump 1. The torque converter is in direct drive in the following speeds:

5. When the lockup solenoid opens and the shuttle valve moves, the shuttle valve:

A. REVERSE and FIRST

A. opens a passage to drain

B. second half of FIRST through SEVENTH

B. closes a passage to drain

C. NEUTRAL to FIRST

C. directs lockup clutch oil to the lockup clutch

2. If the torque converter lockup solenoid does not 6. Torque converter operating pressure is receive an electrical signal in SECOND SPEED maintained by the: FORWARD, the torque converter will: A. inlet relief valve A. stay in DIRECT DRIVE B. outlet relief valve B. go to DIRECT DRIVE C. parking brake release valve C. go to TORQUE CONVERTER DRIVE 7. Modulation of the lockup clutch is determined 3. The source of torque converter lockup oil is by the: from the: A. load piston A. transmission charging pump B. modulation reducing valve B. torque converter charging pump C. load piston orifice C. parking brake release pump 4. Excess oil pressure to the torque converter during a cold start-up is prevented by the _______. A. inlet relief valve B. outlet relief valve C. parking brake release valve

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A E

ON

B F C G

Identify Test Ports

Identify Components

6. Priority Reduction Valve

12. Neutralizer valve

7. Main Relief Valve

13. Oil Cooler

B. Pump Pressure

2. Pressure Control Group

8. Scavenge Pump

14. Filter

C. Lube Pressure

3. Rotary Selector Spool

9. Downshift Solenoid

15. Screen

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1. Charging Pump

Page:

A. Downshift Pressure

Worksheet I

Directions: Write the letter or D. Upshift Pressure number of the item in the correct blank on the schematic. E. Pilot Pressure

4. Upshift Solenoid

10. Rotary Actuator

5. Lube Relief Valve

11. Selector Valve Group

16. A to C and E to H


Lab F: Transmission Hydraulic System Component Identification (769D - 777D)


H

LAB EXERCISES

D

VALVE STATION

Lab F: Transmission Hydraulic System Component Identification Pressure Control Group Valve Station Worksheet III Directions: Write the letter or number of the item in the correct blank on the schematic.

B. Pilot Pressure

7. Load Piston Orifice

9. Decay Orifice

3. Load Piston Plug 4. Pilot Oil Passage

10. Clutch Pressure Tap

III-31

8. Load Piston

Page:

2. Selector Piston

5. Pin

11. Slug

6. Pilot Oil Plug

12. Modulation Reduction Valve


Identify Components Identify Test Ports 1. Ball Check Valve A. Primary and Clutch Pressures


TO CLUTCH

LAB EXERCISES

FROM PUMP


LAB EXERCISES Lab G: Transmission Hydraulic System Testing Shop Lab Exercise Procedures: Perform the following tests listed in the Power Train Testing and Adjusting Service Manual Module for the lab machine used: • Visual Checks (6) • Transmission Pump Pressure • Transmission Lubrication Pressure • Pilot Pressure • Pressure Control Group Clutch Pressures • Primary Clutch Pressures • Dual Stage Relief Valve Pressure Class notes Lab G Worksheets (I and II) Off-highway Truck Mechanic's tools The following test equipment: 1 - 1U5481 Pressure Gauge Group 1 - 1U5482 Pressure Adaptor Group 1 - 3B7282 Nipple 1 - 3B6552 Nipple 1 - 6V4142 Unvalved Nipple 1 - 6V6064 or FT1775 Transmission Test Cover

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LAB EXERCISES Lab G: Transmission Hydraulic System Testing 769D - 793C Off-highway Trucks - Worksheet I Directions: Use this sheet to check off each of the steps listed in the Power Train Testing and Adjusting Service Manual Module. All tests should be run with the transmission in NEUTRAL. Machine Model______________________ Name/Code _________________________ Machine PIN (S/N)___________________ Transmission S/N ____________________ Engine S/N _________________________ S.M.H. ____________________________

Dealer ______________________________ Customer ___________________________ Job ________________________________ Application __________________________ Date _______________________________ Serviceman __________________________

VISUAL CHECKS ______ Check 1 - Oil levels in the hydraulic tank ______ Check 5 - Transmission case oil quantity ______ Check 2 - External leakage

______ Check 6 - Transmission oil tank debris

______ Check 3 - Oil filter examination ______ Check 4 - Magnetic screen debris DU AL S TAGE RELIEF

LOCKU P CLU TCH DEACTIVATED S PECS LOW IDLE

HIGH IDLE

ACTU AL LOW IDLE

HIGH IDLE

PU MP PRES S U RE DU AL S TAGE RELIEF

LOCKU P CLU TCH ACTIVATED S PECS LOW IDLE

HIGH IDLE

ACTU AL LOW IDLE

HIGH IDLE

PU MP PRES S U RE S PECS LOW IDLE PILOT PRES S U RE

HIGH IDLE NO

ACTU AL LOW IDLE

HIGH IDLE NO

LU BE PRES S U RE

Page:

III-33


LAB EXERCISES Lab G: Transmission Hydraulic System Testing 769D - 793C Off-highway Trucks - Worksheet II Directions: Use this sheet to check off each of the steps listed in the Power Train Testing and Adjusting Service Manual Module.

CLU TCH CHART N

PRIMARY CLU TCH PRES S U RE AT LOW IDLE (LOAD PIS TON PLU G REMOVED) STATION CLUTCH SPECS ACTUAL

R

A

1

B

2

C

3

D

4

E

5

F

6

G

7

H

PRIMARY CLU TCH PRES S U RE AT LOW IDLE (LOAD PIS TON PLU G IN S TALLED) S PECS ACTU AL S TATION

CLU TCH

LOW IDLE

HIGH IDLE

LOW IDLE

HIGH IDLE

A B C D E F G H

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POSTTEST As this component moves and closes a drain passage, modulation will begin

1. Load Piston 2. Pilot Oil Passage

Removal of this component allows the technician to check pilot pressure Allows oil from the rotary selector spool to move the selector piston Controls the rate of clutch engagement Works with the modulation reduction valve to control clutch pressure

3. Decay Orifice 4. Load Piston Plug 5. Modulation Reduction Valve 6. Load Piston Orifice 7. Ball Check Valve

Allows clutch pressure to be directed into the center chamber of the modulation reduction valve

8. Clutch Pressure Tap

Allows the technician to check clutch pressure

9. Pilot Pressure Plug

Removal of this component causes the clutch pressure to remain at the primary pressure

10. Selector Piston 11. Slug

Controls the rate of clutch release Works with load piston to control clutch pressure Directions: Modified True/False. If a statement is false, underline or circle the word or words that make the statement incorrect and replace with word(s) to make the statement correct. (Each question is worth 2 points.) a transmission Example: F 1. This is an engine class. 1. To initiate clutch filling, pilot oil moves the selector piston. 2. The size of the modulation reducing valve determines the rate of clutch modulation. 3. To check the primary clutch pressure, remove the load piston plug. 4. Pins in a clutch station increase the modulation time. 5. Clutch release time is determined by the decay orifice.

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III-35

Directions: Match the components and test ports with the associated number or letter. (Each question is worth 1 point.)

13

Test Ports

1

Primary Pressure

VALVE STATION

15

14

Pilot Pressure

10

Clutch Pressure

11

Components

Load Piston Plug

9

Modulation Reduction Valve Load Piston Orifice Ball Check Valve Clutch Pressure Tap Page:

Pilot Oil Plug Selector Piston

III-36

Slug Pin

2

6 5 FROM PUMP

4 TO CLUTCH

3 8

12


Decay Orifice


7

Pilot Oil Passage

POSTTEST

Load Piston


POSTTEST Directions: Use the schematic on page 38. After each statement, circle the correct sequence of events that occurs. Example: The operator makes a shift from NEUTRAL to FIRST FORWARD. C. 1-Modulation begins A. 1-Pilot oil moves B. 1-Selector piston closes selector piston drain 2-Load piston moves reducing valve 2-Selector piston closes 2-Pilot oil moves drain selector piston 3-Selector piston closes drain 3-Load piston moves 3-Modulation begins reducing valve 4-Pilot oil moves 4-Load piston moves selector piston 4-Modulation begins reducing valve

A. 1-Rotary selector spool opens pilot oil passage to drain 2-Load piston oil is directed through decay orifice 3-Selector piston opens drain

A. 1-Pump oil is directed through load piston orifice 2-Pump oil is directed to clutch 3-Modulation reduction valve moves

B. 1-Rotary selector spool opens pilot oil passage to drain

C. 1-Selector piston opens drain

2-Selector piston opens drain

2-Load piston oil is directed through decay orifice

3-Load piston oil is directed through decay orifice

3-Rotary selector spool opens pilot oil passage to drain

B. 1-Pump oil is directed to clutch

C. 1-Modulation reduction valve moves

2-Modulation reduction valve moves

2-Pump oil is directed to clutch

3-Pump oil is directed through load piston orifice

3-Pump oil is directed through load piston orifice

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POSTTEST Torque Converter Hydraulic System Posttest (769D - 777D) Directions: Match the component to its primary function. Maintains high oil pressure to the lockup reducing valve

1. Lockup Solenoid

Supplies oil for hydraulic energy transfer

2. Inlet Relief Valve

Maintains working pressure within the torque converter

3. Torque Converter

When energized, supplies pilot oil to initiate direct drive

4. Lockup Reducing Valve

Relieves excess pressure to the torque converter

5. Parking Brake Release Valve

Provides a controlled rate of engagement of the lockup clutch

6. Outlet Relief Valve

Transfers engine power to the transmission

7. Lockup Modulation Valve

Reduces pump supply pressure to pilot pressure

8. Converter Charging Pump

Supplies oil to the lockup clutch

9. Diverter Valve 10. Parking Brake Release Pump

Directions: Modified True/False. If a statement is false, underline or circle the word or words that make the statement incorrect and replace with word(s) to make the statement correct. a power train Example: F 1. This is an engine class. 1. The inlet relief valve controls the maximum pressure in the torque converter. 2. The parking brake release pump supplies oil to the lockup modulation valve. 3. Lockup clutch oil pressure is controlled by the parking brake release valve. 4. Transmission oil pressure is used to pressurize the torque converter lockup clutch when the torque converter is in direct drive. 5. When the transmission is in REVERSE, the torque converter is in direct drive. 6. Direct drive is in gears FIRST through SEVENTH.

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Directions: Match the components and test ports with the associated number or letter.

Test Ports Parking Brake Release Pressure Pilot Pressure E

Outlet Pressure Inlet Pressure

1


Lockup Clutch Pressure

7 10


A 5

Components

Parking Brake Release Valve

2

12 6 B 3

Outlet Relief Valve Lockup Modulation Valve Converter Charging Pump Page:

Scavenge Pump

III-39

Parking Brake Release Pump Shuttle Valve

9

769D - 777D TORQUE CONVERTER HYDRAULIC SYSTEM


11

Torque Converter


Inlet Relief Valve

POSTTEST

4

Lockup Solenoid

Lockup Reducing Valve

D

C

8


POSTTEST Directions: Use the schematic on page 41. After each statement, circle the correct sequence of events that occurs. Example: The operator makes a shift from NEUTRAL to FIRST FORWARD and the ground speed increases. A. 1-Torque converter is in TC drive 2-Ground speed increases and the lockup clutch modulation valve is activated 3-Lockup clutch engages

A. 1-Parking brake release oil directed to lockup modulation valve spool 2-Pilot oil directed to lockup solenoid valve 3-Parking brake release pump directs oil to lockup reducing valve

A. 1-Shuttle valve moves and blocks drain 2-Load piston moves 3-Lockup solenoid valve opens

A. 1-Shuttle valve moves and opens drain 2-Lockup solenoid valve closes 3-Load piston moves

B. 1-Lockup clutch engages 2-Ground speed increases and the lockup clutch modulation valve is activated 3-Torque converter is in TC drive

B. 1-Parking brake release oil directed to lockup modulation valve spool 2-Parking brake release pump directs oil to lockup reducing valve 3-Pilot oil directed to lockup solenoid valve

B. 1-Lockup solenoid valve opens 2-Shuttle valve moves and blocks drain 3-Load piston moves

B. 1-Load piston moves 2-Shuttle valve moves and opens drain 3-Lockup solenoid valve closes

C. 1-Ground speed increases and the lockup clutch modulation valve is activated 2-Lockup clutch engages 3-Torque converter is in TC drive

C. 1-Parking brake release pump directs oil to lockup reducing valve 2-Pilot oil directed to lockup solenoid valve 3-Parking brake release oil directed to lockup modulation valve spool

C. 1-Load piston moves 2-Lockup solenoid valve opens 3-Shuttle valve moves and blocks drain

C. 1-Lockup solenoid valve closes 2-Shuttle valve moves and opens drain 3-Load piston moves

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III-40


POSTTEST Directions: Match the component to its primary function.

Regulates pressure inside oil cooler Reduces temperature of transmission oil Removes oil from transmission case

1. Charging Pump 2. Pressure Control Group 3. Rotary Selector Spool 4. Upshift Solenoid

Maintains pilot oil pressure Removes debris from transmission oil Supplies modulated pressures to clutches

5. Oil Cooler Relief Valve 6. Priority Reduction Valve 7. Main Relief Valve 8. Scavenge Pump

Directs oil to move rotary actuator vane clockwise Maintains maximum system pressure Chooses appropriate clutch combinations for each speed

9. Downshift Solenoid 10. Rotary Actuator 11. Selector Valve Group 12. Neutralizer Valve

Six valve clutch stations Moves rotary selector spool Keeps machine from moving if transmission is started in gear

13. Oil Cooler 14. Filter 15. Manifold 16. A through H

Supplies oil to all clutches Directs oil to move rotary actuator vane counterclockwise Maintains and directs oil pressures to the pressure control group

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III-41


POSTTEST Directions: Modified True/False. If a statement is false, underline or circle the word or words that make the statement incorrect and replace with word(s) to make the statement correct. a transmission Example: F 1. This is an electrical test. 1. In NEUTRAL, no clutches are engaged. 2. If the machine is started IN GEAR, the neutralizer valve stops the flow of pilot oil. 3. Clutch pressure is maintained by the relief valve. 4. Reverse is an upshift. 5. During a shift, clutches are always drained and then refilled. 6. REVERSE and the first half of FIRST are torque converter drive.

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Test Ports Pump Pressure

Directions: Match the components and test ports with the associated number or letter.

Upshift Pressure Downshift Pressure Pilot Pressure Lube Pressure Components Scavenge Pump Priority Reduction Valve

D

A

A

Rotary Selector Spool

9

4

14

Neutralizer Valve

12

Pressure Control Group Main Relief Valve

1

6

E 13

F 3

C

8 G

Charging Pump D

7

Downshift Solenoid

H

Filter Selector Valve Group Page:

Upshift Solenoid

15

16

5 11 C

Oil Cooler Rotary Actuator

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Screen

769D- 777D TRANSMISSION HYDRAULIC SYSTEM

2


A to C and E to H


B

POSTTEST

B

Lube Relief Valve

E

10

ON

777D Off Highway Truck CHAPTER : Power Train Directions: Use the schematic on page 45. After each statement, circle the correct sequence of events that occurs. Example: The operator has moved the shift lever from NEUTRAL to FIRST FORWARD. A. 1-Downshift solenoid is de-energized 2-Upshift solenoid is energized

B. 1-Rotary actuator moves to FIRST SPEED FORWARD

3-Rotary actuator moves to FIRST SPEED FORWARD

C. 1-Upshift solenoid is energized

2-Downshift solenoid is de-energized

2-Rotary actuator moves to FIRST SPEED FORWARD

3-Upshift solenoid is energized

3-Downshift solenoid is de-energized

1. The engine is started with the transmission in NEUTRAL. A. 1-Neutralizer valve moves 2-Pilot oil flows through rotary selector spool to one station

B. 1-Pilot oil flows through rotary selector spool to one station 2-Downshift solenoid is energized

3-Downshift solenoid is energized

3-Neutralizer valve moves

C. 1-Downshift solenoid is energized 2-Neutralizer valve moves 3-Pilot oil flows through rotary selector spool to one station

2. The engine is started with the gear shift lever in FIRST SPEED FORWARD. A. 1-Charge pump oil flows to priority reduction valve

B. 1-Rotary selector spool blocks charge pump oil to neutralizer valve

C. 1-Pilot oil flows to neutralizer valve

2-Pilot oil flows to neutralizer valve

2-Pilot oil flows to neutralizer valve

2-Rotary selector spool blocks charge pump oil to neutralizer valve

3-Rotary selector spool blocks charge pump oil to neutralizer valve

3-Charge pump oil flows to priority reduction valve

3-Charge pump oil flows to priority reduction valve

3. During an upshift, the following occurs: A. 1-Charge pump moves the upshift valve 2-Upshift solenoid is energized 3-Rotary actuator oil moves the downshift valve

B. 1-Upshift solenoid is energized 2-Charge pump oil moves the rotary actuator 3-Rotary actuator moves the rotary selector spool

C. 1-Rotary actuator oil moves the downshift valve 2-Upshift solenoid is energized 3-Charge pump moves the upshift valve

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777D Off Highway Truck CHAPTER : Power Train Directions: After each statement, circle T if the statement is TRUE, and F if the statement is FALSE. Example: When activated, the shift solenoids allow oil to flow to the rotary actuator.

T

F

1. On some ICM transmissions, the Dual Stage Relief Valve is activated during torque converter lockup.

T

F

2. On all ICM transmission controls, REVERSE is an upshift from NEUTRAL and the downshift solenoid is activated whenever the shift lever is in NEUTRAL.

T

F

3. When the transmission shift lever is in a speed other than NEUTRAL, the rotary selector spool provides a path to drain for two clutches.

T

F

4. On all ICM transmission controls, the priority reduction valve controls the pressure of the "pilot oil" that is used to shift the selector piston in each station.

T

F

5. The load piston orifice in an ICM transmission is a "cascade-type" and controls the modulation of clutch engagement.

T

F

6. In an ICM transmission, the "primary pressure setting" in each station can cause harsh shifts when too low and clutch slipping when too high.

T

F

7. The "primary pressure settings" are the same for all ICM clutch stations.

T

F

8. Final clutch pressure is adjusted with shims.

T

F

9. If the "primary pressure setting" is correct and the final clutch pressure is low, the load piston springs should be replaced.

T

F

T

F

10. When manually rotating the rotary selector spool with the engine running, power to the shift solenoids must be disconnected.

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Service Training MALAGA

777D Off Highway Truck Student book

SYSTEMS Adolfo August 1997

Manual Power Train Caterpillar 777d Off Highway Truck Components

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