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LOCKUPSOLENOID
SHUTTLEVALVE
OFF
FROMPARKING BRAKE
PUMP
TOLOCKUPCLUTCH
PRESSUREREDUCTION
VALVE
SELECTORPISTON
LOADPISTON
MODULATIONREDUCTION
VALVE
LOAD PISTONORIFICE
LOCKUP CLUTCH VALVETORQUE CONVERTER DRIVE
Service TrainingMALAGA
777D Off Highway Truck
AdolfoAugust 1997
III. POWER TRAIN
1. Components Layout2. Operation3. Maintenance4. Testing & Adjusting
CHAPTER : Power Train
777D Off Highway Truck
III-2Page:
TORQUECONVERTER
LOCKUPMODULATION
VALVE
INLET ANDOUTLET RELIEF VALVES
TORQUECONVERTER FILTER
TRANSMISSIONOIL FILTER
SOLENOIDSUPSHIFT
DOWNSHIFT
TRANSMISSIONPUMP
TRANSMISSION
TORQUE CONVERTERAND TRANSMISSION OIL
TORQUECONVERTER
LOCKUPCLUTCH
DRIVESHAFT
TRANSFERGEARS
TRANSMISSION
TRANSMISSIONCONTROL VALVE
TORQUECONVERTER
PUMP
DIFFERENTIAL ANDFINAL DRIVES
TYPICAL OFF-HIGHWAY TRUCKPOWER TRAIN
COMPONENT LOCATIONS
LOCKUPSOLENOID
CHAPTER : Power Train
777D Off Highway Truck
III-3Page:
FREEWHEELASSEMBLY
STATOR
IMPELLER
TURBINE
LOCKUP PISTON
TORQUE CONVERTERINLET OIL
TORQUE CONVERTERLOCKUP OIL PASSAGE
CONVERTER DRIVETORQUE CONVERTER
EN
GIN
E F
LYW
HE
EL
TO TRANSFER GEARS
CHAPTER : Power Train
777D Off Highway Truck
III-4Page:
FREEWHEELASSEMBLY
STATOR
IMPELLER
TURBINE
LOCKUPPISTON
TORQUECONVERTER
INLET OIL
TORQUECONVERTERLOCKUP OIL
PASSAGE
DIRECT DRIVETORQUE CONVERTER
EN
GIN
E F
LYW
HE
EL
TOTRANSFERGEARS
CH
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III-5P
age:
FROMPARKING BRAKE
PUMP
PRESSUREREDUCTION
VALVE
LOCKUPSOLENOID
SHUTTLEVALVE
SELECTORPISTON
LOADPISTON
MODULATIONREDUCTION
VALVE
LOAD PISTONORIFICE
ON
TOLOCKUPCLUTCH
SHIMS
LOCKUP CLUTCH VALVECLUTCH FILLING
CH
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III-6P
age:
FROMPARKING BRAKE
PUMP
TOLOCKUPCLUTCH
PRESSUREREDUCTION
VALVELOCKUP
SOLENOID
SHUTTLEVALVE
SELECTORPISTONLOAD
PISTON
MODULATIONREDUCTION
VALVE
LOAD PISTONORIFICE
LOCKUP CLUTCH VALVEDIRECT DRIVE
ON
CH
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III-7P
age:
PARKING BRAKERELEASE VALVE TORQUE
CONVERTER
OUTLETRELIEF VALVE
INLETRELIEF VALVE
TO BRAKECOOLINGCIRCUIT
LOCKUPMODULATION
VALVE
OUTLETPRESSURE
TAP
BRAKE COOLINGPRESSURE
INLETPRESSURE
CONVERTERCHARGING
PUMP
PARKINGBRAKE
RELEASEPUMP
CONVERTERSCAVENGE
PUMP
LOCKUP CLUTCHPILOT OIL PRESSURE
LOCKUP CLUTCHPRESSURE
SCREEN
PARKING BRAKERELEASE PRESSURE
TO BRAKECOOLING CIRCUIT
LOCKUPSOLENOID
LOCKUPCLUTCH
LOCKUPREDUCING
VALVE
SHIMS
PARKING BRAKERELIEF VALVE
769D - 777D TORQUE CONVERTER HYDRAULIC SYSTEMNEUTRAL
CH
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III-8P
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C
DOWNSHIFTSOLENOID
TANK
CHARGINGPUMP SCAVENGE
PUMP
FILTERROTARY
ACTUATOR
SELECTOR VALVEGROUP
ROTARYSELECTOR
SPOOL
PRIORITYREDUCTION
VALVE
LUBERELIEF VALVE
PUMPPRESSURE
DOWNSHIFTPRESSURE
PILOT OILPRESSURE
LUBEPRESSURE
769D - 777D TRANSMISSIONHYDRAULIC SYSTEM
NEUTRAL
UPSHIFTPRESSURE
ON
PRESSURE CONTROLGROUP
TRANSMISSIONCASE
NEUTRALIZERVALVE
RELIEFVALVE
OIL COOLER
UPSHIFTSOLENOID
A
B
D
E
F
G
H
CHAPTER : Power Train
777D Off Highway Truck
III-9Page:
ROTARYSELECTOR
SPOOL
NEUTRALIZERVALVE
PRIORITYREDUCTION
VALVE
TRANSM.LUBE
RELIEFVALVE
RELIEFVALVE
LUBRICATIONPRESSURE
PILOTOIL
PRESSURE
SCREEN
769D - 777D TRANSMISSION SELECTOR VALVEGROUPNEUTRAL
CHAPTER : Power Train
777D Off Highway Truck
III-10Page:
ROTARYSELECTOR
SPOOL
PRIORITYREDUCTION
VALVE
LUBERELIEFVALVE
RELIEFVALVE
LUBRICATIONPRESSURE
PILOT OILPRESSURE
SCREEN
769C - 777C TRANSMISSION SELECTOR VALVEGROUP
STARTING IN FIRST SPEED FORWARD
NEUTRALIZERVALVE
CHAPTER : Power Train
777D Off Highway Truck
III-11Page:
C
A
B
D
E
F
G
H
769D - 777D PRESSURECONTROL GROUP
NEUTRAL
CH
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III-12P
age:
SELECTOR PISTON
LOAD PISTON
DECAY ORIFICE
LOAD PISTON PLUG
PILOT OILPASSAGE
FROM PUMPTO CLUTCH
MODULATIONREDUCTION
VALVE
LOAD PISTONORIFICE
BALL CHECK VALVE
PLUG
CLUTCH PRESSURE TAP
SLUG
VALVE STATIONCLUTCH RELEASED
CHAPTER : Power Train
777D Off Highway Truck
III-13Page:
VALVE STATIONCLUTCH ENGAGED
CHAPTER : Power Train
777D Off Highway Truck
III-14Page:
VALVE STATIONCLUTCH ENGAGED/WITH PIN
CHAPTER : Power Train
777D Off Highway Truck
III-15Page:
VALVE STATIONCLUTCH DECAY
DECAYORIFICE
CH
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III-16P
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FILTER
DOWNSHIFTSOLENOID
TANK
CHARGINGPUMP SCAVENGE
PUMP
ROTARYACTUATOR
SELECTOR VALVEGROUP
ROTARYSELECTOR
SPOOL
PRIORITYREDUCTION
VALVE
LUBERELIEF VALVE
PUMPPRESSURE
DOWNSHIFTPRESSURE
PILOT OILPRESSURE
LUBEPRESSURE
UPSHIFTPRESSURE
TRANSMISSIONCASE
NEUTRALIZERVALVE
RELIEFVALVE
OIL COOLER
UPSHIFTSOLENOID
A
B
D
E
F
G
H
C
PRESSURE CONTROLGROUP
769C - 777C TRANSMISSIONHYDRAULIC SYSTEMTHIRD SPEED FORWARD
CHAPTER : Power Train
777D Off Highway Truck
III-17Page:
VALVE STATIONPRIMARY PRESSURE
LOAD PISTONPLUG (REMOVED)
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777D SHIFT MODULATION CYCLETHIRD(3&6) TO FOURTH (1&5)
NORMAL SHIFT CYCLE
COMPLETE CLUTCH ENGAGEMENT
INITIAL CLUTCH ENGAGEMENT
NORMAL CLUTCH SLIP
PRIMARYPRESSURE
FILL TIMETIME
418
373353
265
50
0
CLUTCH 5
CLUTCH 1
CLUTCH 3
CLUTCH 6
PRESSURE
CH
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III-19P
age:
777C SHIFT MODULATION CYCLESECOND TO THIRD
NORMAL SHIFT CYCLE
COMPLETE CLUTCH ENGAGEMENT
INITIAL CLUTCH ENGAGEMENT
NORMAL CLUTCH SLIP
PRIMARYPRESSURE
FILL TIMETIME
418
373
265
80
0
CLUTCH 1
CLUTCH 3
CLUTCH 6
PRESSURE
CH
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COMPLETE CLUTCHENGAGEMENT
INITIAL CLUTCHENGAGEMENT
NORMAL CLUTCHSLIP
HIGH PRIMARY PRESSURE - HARSHSHIFT
LOW PRIMARY PRESSURE - CLUTCHSLIPPING
HIGHPRIMARYPRESSURE
RESTRICTED LOAD PISTONORIFICE
SLOW MODULATION
TIME
NORMALPRIMARYPRESSURE
LOWPRIMARYPRESSURE
SHIFT MODULATIONPROBLEMS
PRESSURE
0
P1
RESTRICTED LOAD PISTONORIFICECLUTCH SLIPPING
CHAPTER : Power Train
777D Off Highway Truck
III-21Page:
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 numbernext to the component. During the slide presentation, use this sheet to take notes on the function of eachcomponent.
______ Torque Converter - example: Located on the rear of the engine. Provides a fluid couplingbetween the engine and the transmission and multiplies torque. Contains a lockup clutch formore 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 -
CHAPTER : Power Train
777D Off Highway Truck
III-22Page:
LAB EXERCISESLab 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 numbernext to the component. During the slide presentation, use this sheet to take notes on the function of eachcomponent.
______ Transmission Tank - example: Located on the left side of the truck. Contains a sight gauge forchecking power train hydraulic level.
______ Transmission Pump -
______ Transmission Filter -
______ Transmission Magnetic Suction Screen -
______ Transmission Oil Cooler -
______ Transmission Control Valve -
______ Upshift Solenoid Valve -
______ Downshift Solenoid Valve -
CHAPTER : Power Train
777D Off Highway Truck
III-23Page:
LAB EXERCISES
TYPICAL OFF-HIGHWAY TRUCKPOWER TRAIN
COMPONENT LOCATIONS
Lab A: Component Location and Identification Worksheet V
Torque Converter and Transmission Hydraulic Systems Component Identification
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III-24P
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LA
B E
XE
RC
ISE
S
TOBRAKE
COOLINGCIRCUIT
TO BRAKECOOLINGCIRCUIT
7. Inlet Relief Valve
8. Lockup Modulation Valve
9. Scavenge Pump
10. Lockup Solenoid
11. Shuttle Valve
12. Lockup Clutch
Lab B: Torque ConverterHydraulic SystemComponent Identification
Worksheet I: (769D - 777D)
Identify Test Ports
A. Inlet Pressure
B. Parking Brake Release Pressure
C. Lockup Clutch Pressure
D. Outlet Pressure
E. Pilot Pressure
Identify Components
1. Outlet Relief Valve
2. Parking Brake Release Valve
3. Converter Charging Pump
4. Torque Converter
5. Lockup Reducing Valve
6. Parking Brake Release Pump
Directions: Write the letteror number of the item in thecorrect blank on theschematic.
CHAPTER : Power Train
777D Off Highway Truck
III-25Page:
LAB EXERCISES
Lab C: Torque Converter Hydraulic System Testing
Shop Lab Exercise
Procedure:
Perform the following tests listed in the Power Train Testing andAdjusting 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 Nipple1 - 6V4143 Valved Coupler1 - 6V3079 Diagnostic Hose1 - 6V3121 Multitach Group1 - Oil container [approximately 19 l (5 gal.) capacity]1 - Special Instruction "6V3121 Multitach Group" (Form
SEHS7807)
CHAPTER : Power Train
777D Off Highway Truck
III-26Page:
LAB EXERCISES
______ Check 1 - Oil levels in the hydraulic tank
______ Check 2 - External Leakage
______ Check 3 - Parking brake release oil filter
______ Check 4 - Torque converter oil filter
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
TEST 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
______ Check 5 - Torque converter scavenge screen
______ Check 6 - Oil cooler screens
______ Check 7 - Components inside hydraulic tank
______ Check 8 - Inspect return oil screen
Lab C: Torque Converter Hydraulic System Testing769C - 777C Off-highway Trucks - Worksheet I
Directions: Use this sheet to check off each of the steps listed in the Power Train Testing andAdjusting Service Manual Module.
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III-27P
age:
LA
B E
XE
RC
ISE
S
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.
TO BRAKECOOLINGCIRCUIT
TO BRAKECOOLINGCIRCUIT
769D - 777D TORQUECONVERTER
HYDRAULIC SYSTEMTORQUE CONVERTER
DRIVE
CH
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III-28P
age:
LA
B E
XE
RC
ISE
SLab 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.
TOBRAKE
COOLINGCIRCUIT
TO BRAKECOOLINGCIRCUIT
769C - 777C TORQUE CONVERTERHYDRAULIC SYSTEM
DIRECT DRIVE
CHAPTER : Power Train
777D Off Highway Truck
III-29Page:
LAB EXERCISESLab 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
5. When the lockup solenoid opens and the shuttlevalve moves, the shuttle valve:
A. opens a passage to drain
B. closes a passage to drain
C. directs lockup clutch oil to the lockup clutch
6. Torque converter operating pressure ismaintained by the:
A. inlet relief valve
B. outlet relief valve
C. parking brake release valve
7. Modulation of the lockup clutch is determinedby the:
A. load piston
B. modulation reducing valve
C. load piston orifice
1. The torque converter is in direct drive in thefollowing speeds:
A. REVERSE and FIRST
B. second half of FIRST through SEVENTH
C. NEUTRAL to FIRST
2. If the torque converter lockup solenoid does notreceive an electrical signal in SECOND SPEEDFORWARD, the torque converter will:
A. stay in DIRECT DRIVE
B. go to DIRECT DRIVE
C. go to TORQUE CONVERTER DRIVE
3. The source of torque converter lockup oil isfrom the:
A. transmission charging pump
B. torque converter charging pump
C. parking brake release pump
4. Excess oil pressure to the torque converterduring 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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III-30P
age:
LA
B E
XE
RC
ISE
S
C
A
B
D
E
F
G
H
ON
Lab F: TransmissionHydraulic SystemComponentIdentification(769D - 777D)
Worksheet I
Directions: Write the letter ornumber of the item in thecorrect blank on the schematic.
Identify Test Ports
A. Downshift Pressure
B. Pump Pressure
C. Lube Pressure
D. Upshift Pressure
E. Pilot Pressure
Identify Components
1. Charging Pump
2. Pressure Control Group
3. Rotary Selector Spool
4. Upshift Solenoid
5. Lube Relief Valve
12. Neutralizer valve
13. Oil Cooler
14. Filter
15. Screen
16. A to C and E to H
6. Priority Reduction Valve
7. Main Relief Valve
8. Scavenge Pump
9. Downshift Solenoid
10. Rotary Actuator
11. Selector Valve Group
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III-31P
age:
LA
B E
XE
RC
ISE
S
VALVE STATION
FROM PUMPTO CLUTCH
Identify Test PortsA. Primary and Clutch Pressures
B. Pilot Pressure
Identify Components1. Ball Check Valve
2. Selector Piston
3. Load Piston Plug
4. Pilot Oil Passage
5. Pin
6. Pilot Oil Plug
7. Load Piston Orifice
8. Load Piston
9. Decay Orifice
10. Clutch Pressure Tap
11. Slug
12. Modulation Reduction Valve
Lab F:TransmissionHydraulic SystemComponentIdentification
Pressure ControlGroup Valve Station
Worksheet III
Directions: Write theletter or number of theitem in the correctblank on the schematic.
CHAPTER : Power Train
777D Off Highway Truck
III-32Page:
LAB EXERCISES
Lab G: Transmission Hydraulic System Testing
Shop Lab Exercise
Procedures:
Perform the following tests listed in the Power Train Testing andAdjusting 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 Group1 - 1U5482 Pressure Adaptor Group1 - 3B7282 Nipple1 - 3B6552 Nipple1 - 6V4142 Unvalved Nipple1 - 6V6064 or FT1775 Transmission Test Cover
CHAPTER : Power Train
777D Off Highway Truck
III-33Page:
LAB EXERCISESLab 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 AdjustingService 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__________________________
______ Check 5 - Transmission case oil quantity
______ Check 6 - Transmission oil tank debris
______ Check 1 - Oil levels in the hydraulic tank
______ Check 2 - External leakage
______ Check 3 - Oil filter examination
______ Check 4 - Magnetic screen debris
VISUAL CHECKS
DUAL STAGE RELIEF LOCKUP CLUTCH DEACTIVATED
SPECS ACTUAL
LOWIDLE
HIGHIDLE
LOWIDLE
HIGHIDLE
PUMP PRESSURE
DUAL STAGE RELIEF LOCKUP CLUTCH ACTIVATED
SPECS ACTUAL
LOWIDLE
HIGHIDLE
LOWIDLE
HIGHIDLE
PUMP PRESSURE
SPECS ACTUAL
LOWIDLE
HIGHIDLE
LOWIDLE
HIGHIDLE
PILOT PRESSURE NO NO
LUBE PRESSURE
CHAPTER : Power Train
777D Off Highway Truck
III-34Page:
LAB EXERCISES
Lab G: Transmission Hydraulic System Testing769D - 793C Off-highway Trucks - Worksheet II
Directions: Use this sheet to check off each of the steps listed in the Power Train Testing and AdjustingService Manual Module.
CLUTCH CHART
N
R
1
2
3
4
5
6
7
PRIMARY CLUTCH PRESSUREAT LOW IDLE
(LOAD PISTON PLUG REMOVED)STATION CLUTCH SPECS ACTUAL
A
B
C
D
E
F
G
H
PRIMARY CLUTCH PRESSURE AT LOW IDLE(LOAD PISTON PLUG INSTALLED)
SPECS ACTUAL
STATION CLUTCH LOWIDLE
HIGHIDLE
LOWIDLE
HIGHIDLE
A
B
C
D
E
F
G
H
CHAPTER : Power Train
777D Off Highway Truck
III-35Page:
POSTTEST
1. Load Piston
2. Pilot Oil Passage
3. Decay Orifice
4. Load Piston Plug
5. Modulation Reduction Valve
6. Load Piston Orifice
7. Ball Check Valve
8. Clutch Pressure Tap
9. Pilot Pressure Plug
10. Selector Piston
11. Slug
As this component moves and closes a drain passage, modulation will begin
Removal of this component allows the technician to check pilot pressure
Allows oil from the rotary selector spool to move theselector piston
Controls the rate of clutch engagement
Works with the modulation reduction valve to control clutch pressure
Allows clutch pressure to be directed into the center chamber of the modulation reduction valve
Allows the technician to check clutch pressure
Removal of this component causes the clutch pressure toremain at the primary pressure
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 thatmake the statement incorrect and replace with word(s) to make the statement correct. (Each question isworth 2 points.)
a transmissionExample: 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-36P
age:
PO
ST
TE
ST
VALVE STATION
FROM PUMPTO CLUTCH
Test Ports
Primary Pressure
Pilot Pressure
Clutch Pressure
Components
Load Piston
Pilot Oil Passage
Decay Orifice
Load Piston Plug
Modulation Reduction Valve
Load Piston Orifice
Ball Check Valve
Clutch Pressure Tap
Pilot Oil Plug
Selector Piston
Slug
Pin
Directions: Match thecomponents and test ports withthe associated number or letter.(Each question is worth 1 point.)
13
15 14 10
11
7
9
3128
4
652
1
CHAPTER : Power Train
777D Off Highway Truck
III-37Page:
POSTTEST
Directions: Use the schematic on page 38. After each statement, circle the correct sequence of eventsthat occurs.
Example: The operator makes a shift from NEUTRAL to FIRST FORWARD.
A. 1-Pilot oil movesselector piston
2-Selector piston closesdrain
3-Load piston movesreducing valve
4-Modulation begins
B. 1-Selector piston closesdrain
2-Pilot oil movesselector piston
3-Modulation begins
4-Load piston movesreducing valve
A. 1-Rotary selector spoolopens pilot oil passageto drain
2-Load piston oil isdirected throughdecay orifice
3-Selector piston opensdrain
A. 1-Pump oil is directedthrough load pistonorifice
2-Pump oil is directed toclutch
3-Modulation reductionvalve moves
B. 1-Pump oil is directed toclutch
2-Modulation reductionvalve moves
3-Pump oil is directedthrough load pistonorifice
C. 1-Modulation reductionvalve moves
2-Pump oil is directed toclutch
3-Pump oil is directedthrough load pistonorifice
B. 1-Rotary selector spoolopens pilot oil passageto drain
2-Selector piston opensdrain
3-Load piston oil isdirected throughdecay orifice
C. 1-Selector piston opensdrain
2-Load piston oil isdirected throughdecay orifice
3-Rotary selector spoolopens pilot oil passageto drain
C. 1-Modulation begins
2-Load piston movesreducing valve
3-Selector piston closesdrain
4-Pilot oil movesselector piston
CHAPTER : Power Train
777D Off Highway Truck
III-38Page:
POSTTESTTorque Converter Hydraulic System Posttest
(769D - 777D)
Directions: Match the component to its primary function.
Maintains high oil pressure to the lockup reducing valve
Supplies oil for hydraulic energy transfer
Maintains working pressure within the torque converter
When energized, supplies pilot oil to initiate direct drive
Relieves excess pressure to the torque converter
Provides a controlled rate of engagement of the lockup clutch
Transfers engine power to the transmission
Reduces pump supply pressure to pilot pressure
Supplies oil to the lockup clutch
Directions: Modified True/False. If a statement is false, underline or circle the word or words thatmake the statement incorrect and replace with word(s) to make the statement correct.
a power trainExample: 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.
1. Lockup Solenoid
2. Inlet Relief Valve
3. Torque Converter
4. Lockup Reducing Valve
5. Parking Brake Release Valve
6. Outlet Relief Valve
7. Lockup Modulation Valve
8. Converter Charging Pump
9. Diverter Valve
10. Parking Brake Release Pump
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III-39P
age:
PO
ST
TE
ST
Test Ports
Parking Brake Release Pressure
Pilot Pressure
Outlet Pressure
Inlet Pressure
Lockup Clutch Pressure
Components
Lockup Solenoid
Inlet Relief Valve
Torque Converter
Lockup Reducing Valve
Parking Brake Release Valve
Outlet Relief Valve
Lockup Modulation Valve
Converter Charging Pump
Scavenge Pump
Parking Brake Release Pump
Shuttle Valve
Directions: Match thecomponents and test ports withthe associated number or letter.
2
4
1
7
TO BRAKECOOLINGCIRCUIT5
8D
A
3
6
9
E
C
B
TO BRAKECOOLING CIRCUIT
10
11
769D - 777D TORQUE CONVERTERHYDRAULIC SYSTEM
12
CHAPTER : Power Train
777D Off Highway Truck
III-40Page:
POSTTESTDirections: Use the schematic on page 41. After each statement, circle the correct sequence of eventsthat occurs.
Example: The operator makes a shift from NEUTRAL to FIRST FORWARD and the ground speed increases.
A. 1-Torque converter is inTC drive
2-Ground speedincreases and thelockup clutchmodulation valve isactivated
3-Lockup clutch engages
B. 1-Lockup clutch engages
2-Ground speedincreases and thelockup clutchmodulation valve isactivated
3-Torque converter is inTC drive
C. 1-Ground speedincreases and thelockup clutchmodulation valve isactivated
2-Lockup clutch engages
3-Torque converter is inTC drive
C. 1-Parking brake releasepump directs oil tolockup reducing valve
2-Pilot oil directed tolockup solenoid valve
3-Parking brake releaseoil directed to lockupmodulation valve spool
A. 1-Parking brake releaseoil directed to lockupmodulation valve spool
2-Pilot oil directed tolockup solenoid valve
3-Parking brake releasepump directs oil tolockup reducing valve
B. 1-Parking brake releaseoil directed to lockupmodulation valve spool
2-Parking brake releasepump directs oil tolockup reducing valve
3-Pilot oil directed tolockup solenoid valve
B. 1-Lockup solenoid valveopens
2-Shuttle valve movesand blocks drain
3-Load piston moves
A. 1-Shuttle valve movesand blocks drain
2-Load piston moves
3-Lockup solenoid valveopens
C. 1-Load piston moves
2-Lockup solenoid valveopens
3-Shuttle valve movesand blocks drain
A. 1-Shuttle valve movesand opens drain
2-Lockup solenoid valvecloses
3-Load piston moves
C. 1-Lockup solenoid valvecloses
2-Shuttle valve movesand opens drain
3-Load piston moves
B. 1-Load piston moves
2-Shuttle valve movesand opens drain
3-Lockup solenoid valvecloses
CHAPTER : Power Train
777D Off Highway Truck
III-41Page:
POSTTEST
1. Charging Pump
2. Pressure Control Group
3. Rotary Selector Spool
4. Upshift Solenoid
5. Oil Cooler Relief Valve
6. Priority Reduction Valve
7. Main Relief Valve
8. Scavenge Pump
9. Downshift Solenoid
10. Rotary Actuator
11. Selector Valve Group
12. Neutralizer Valve
13. Oil Cooler
14. Filter
15. Manifold
16. A through H
Regulates pressure inside oil cooler
Reduces temperature of transmission oil
Removes oil from transmission case
Maintains pilot oil pressure
Removes debris from transmission oil
Supplies modulated pressures to clutches
Directs oil to move rotary actuator vane clockwise
Maintains maximum system pressure
Chooses appropriate clutch combinations for each speed
Six valve clutch stations
Moves rotary selector spool
Keeps machine from moving if transmission is started ingear
Supplies oil to all clutches
Directs oil to move rotary actuator vane counterclockwise
Maintains and directs oil pressures to the pressure control group
Directions: Match the component to its primary function.
CHAPTER : Power Train
777D Off Highway Truck
III-42Page:
POSTTEST
Directions: Modified True/False. If a statement is false, underline or circle the word or words thatmake the statement incorrect and replace with word(s) to make the statement correct.
a transmissionExample: 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.
CH
AP
TE
R : P
ow
er Train
777D O
ff Hig
hw
ay Truck
III-43P
age:
PO
ST
TE
ST
Test Ports
Pump Pressure
Upshift Pressure
Downshift Pressure
Pilot Pressure
Lube Pressure
Components
Scavenge Pump
Priority Reduction Valve
Rotary Selector Spool
Neutralizer Valve
Lube Relief Valve
A to C and E to H
Pressure Control Group
Main Relief Valve
Charging Pump
Downshift Solenoid
Filter
Selector Valve Group
Upshift Solenoid
Oil Cooler
Rotary Actuator
Screen
Directions: Match thecomponents and test ports withthe associated number or letter.
C
8
13
9 4
1
1410
11
3
12
6
5
7
A
B
D
E
F
G
H
B
A
E
C
D
ON
2
15 16
769D- 777D TRANSMISSIONHYDRAULIC SYSTEM
CHAPTER : Power Train
777D Off Highway Truck
III-44Page:
Directions: Use the schematic on page 45. After each statement, circle the correct sequence of eventsthat occurs.
Example: The operator has moved the shift lever from NEUTRAL to FIRST FORWARD.
A. 1-Downshift solenoid isde-energized
2-Upshift solenoid isenergized
3-Rotary actuator movesto FIRST SPEEDFORWARD
B. 1-Rotary actuator movesto FIRST SPEEDFORWARD
2-Downshift solenoid isde-energized
3-Upshift solenoid isenergized
C. 1-Upshift solenoid isenergized
2-Rotary actuator movesto FIRST SPEEDFORWARD
3-Downshift solenoid isde-energized
1. The engine is started with the transmission in NEUTRAL.
2. The engine is started with the gear shift lever in FIRST SPEED FORWARD.
3. During an upshift, the following occurs:
A. 1-Neutralizer valvemoves
2-Pilot oil flows throughrotary selector spool toone station
3-Downshift solenoid isenergized
B. 1-Pilot oil flows throughrotary selector spool toone station
2-Downshift solenoid isenergized
3-Neutralizer valvemoves
C. 1-Downshift solenoid isenergized
2-Neutralizer valvemoves
3-Pilot oil flows throughrotary selector spool toone station
A. 1-Charge pump oil flowsto priority reductionvalve
2-Pilot oil flows toneutralizer valve
3-Rotary selector spoolblocks charge pump oilto neutralizer valve
C. 1-Pilot oil flows toneutralizer valve
2-Rotary selector spoolblocks charge pump oilto neutralizer valve
3-Charge pump oil flowsto priority reductionvalve
B. 1-Rotary selector spoolblocks charge pump oilto neutralizer valve
2-Pilot oil flows toneutralizer valve
3-Charge pump oil flowsto priority reductionvalve
A. 1-Charge pump movesthe upshift valve
2-Upshift solenoid isenergized
3-Rotary actuator oilmoves the downshiftvalve
B. 1-Upshift solenoid isenergized
2-Charge pump oilmoves the rotaryactuator
3-Rotary actuator movesthe rotary selectorspool
C. 1-Rotary actuator oilmoves the downshiftvalve
2-Upshift solenoid isenergized
3-Charge pump movesthe upshift valve
CHAPTER : Power Train
777D Off Highway Truck
III-45Page:
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 T Frotary actuator.
1. On some ICM transmissions, the Dual Stage Relief Valve is activated T Fduring torque converter lockup.
2. On all ICM transmission controls, REVERSE is an upshift from T FNEUTRAL and the downshift solenoid is activated whenever the shift lever is in NEUTRAL.
3. When the transmission shift lever is in a speed other than NEUTRAL, T Fthe rotary selector spool provides a path to drain for two clutches.
4. On all ICM transmission controls, the priority reduction valve controls T Fthe pressure of the "pilot oil" that is used to shift the selector pistonin each station.
5. The load piston orifice in an ICM transmission is a "cascade-type" and T Fcontrols the modulation of clutch engagement.
6. In an ICM transmission, the "primary pressure setting" in each station T Fcan cause harsh shifts when too low and clutch slipping when too high.
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 T Fis low, the load piston springs should be replaced.
10. When manually rotating the rotary selector spool with the engine T Frunning, power to the shift solenoids must be disconnected.
Service TrainingMALAGA
777D Off Highway TruckStudent book
AdolfoAugust 1997
SYSTEMS