planos

1. RENR8305-02VOL1of2
30Page,(Dimensions:39inchesx28inches)
ONE POSITION TWO POSITION THREE POSITION
VENTED PRESSURIZED RETURN ABOVE FLUID LEVEL RETURN BELOW FLUID LEVEL
LINES CROSSING LINES JOINING
TWO-WAY THREE-WAY FOUR-WAY
SPRING CONTROL VALVES RESTRICTION LINE RESTRICTION
(FIXED)
2-SECTION PUMP
MAIN AUX.
SPRING
(ADJUSTABLE)
VARIABILITY LINE RESTRICTION
(VARIABLE)
LINE RESTRICTION
VARIABLE and PRESSURE
COMPENSATED
PRESSURE
COMPENSATION
PUMP: VARIABLE and
PRESSURE COMPENSATED
ENERGY TRIANGLES
HYDRAULIC PNEUMATIC
MEASUREMENT
PRESSURE TEMPERATURE FLOW
ROTATING SHAFTS
UNIDIRECTIONAL BIDIRECTIONAL
PUSH-PULL LEVER PEDALGENERAL MANUAL PUSH BUTTON SPRING
MANUAL CONTROL SYMBOLS
HYDRAULIC MOTORS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
HYDRAULIC PUMPS
FLUID STORAGE RESERVOIRS
CROSSING AND JOINING LINES
VALVE ENVELOPES VALVE PORTS
BASIC COMPONENT SYMBOLS
FLUID CONDITIONERPUMP or MOTOR
FLUID POWER SYMBOLS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
VALVES
PILOT CONTROL SYMBOLS
RELEASED PRESSURE
EXTERNAL RETURN INTERNAL RETURN
REMOTE SUPPLY PRESSURE
SIMPLIFIED COMPLETE INTERNAL
SUPPLY PRESSURE
ACCUMULATORS
SPRING LOADED GAS CHARGED
SOLENOID
or MANUAL
SOLENOID
and PILOT
SOLENOID and
PILOT or MANUAL
COMBINATION CONTROLS
SOLENOID SERVO THERMAL DETENT
HYDRAULIC AND PNEUMATIC CYLINDERS
DOUBLE ACTINGSINGLE ACTING
BASIC
SYMBOL
SPRING
LOADED
CHECK VALVES
TWO
POSITION
INFINITE
POSITIONING
FLOW IN ONE
DIRECTION
FLOW ALLOWED IN
EITHER DIRECTION
THREE
POSITION
CROSS
FLOW
PARALLEL
FLOW
INTERNAL PASSAGEWAYS
NORMAL POSITION
A B
P T
A B
P T
SHIFTED POSITION INFINITE POSITION
CONTROL VALVES
ATTACHMENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
Hydraulic Symbols (Electrical)
Electrical Symbols Table
325-AG135 PK-14
Circuit Identification
Number
Wire Color Wire Gauge
Harness identification code
This example indicates
wire 135 in harness "AG".
325-PK-14
Wire Gauge
Wire Color
Circuit Number
Identification
Wire Number Identification Codes
Current Standard
Previous Standard
Electrical Schematic Example Hydraulic Schematic Example
325-PK
Wire ColorCircuit Number
Identification
B A
Wire
Wire
(EXAMPLE VALVE)
Current Standard
Transducer
(Fluid)
Transducer
(Gas / Air)
G
Generator
Electrical WirePressure Switch
M
Electric Motor
Pressure Switch
(Adjustable)
Temperature Switch
T
Pressure
Symbol
Temperature
Symbol
Level
Symbol
Flow
Symbol
Electrical Symbols (Electrical)
777F:
JRP1-UP
777F OEM:
JXP1-UP
Volume 1 of 2: Brakes and Hoist
©2010 Caterpillar
All Rights Reserved
Printed in U.S.A.
RENR8305-02
June 2010
777F and 777F OEM Off-Highway Truck
Hydraulic System
Item
Number
Description
Part
Number
Schematic
Location
1 TANK GP (HYD & TRANS) 258-9852 A-4
2A PUMP GP (BRAKE CHARGING) 255-5478 B-5
2B PUMP GP (BRAKE CHARGING) 256-0561 B-4
3 PUMP GP (BRAKE COOLING) 255-5478 B-4
4A PUMP GP (HOIST) 255-5478 B-4
4B PUMP GP (HOIST) 256-0561 B-4
5 VALVE GP- ACCUMULATOR CHARGING 257-0273 D-5
6 VALVE GP-MTG & (PARKING BRAKE) 289-0585 F-6
7 CONTROL GP-HYD (BRAKE RETRACT) 222-4744 D-7
8 ADJUSTER GP- SLACK 205-0557 D-8
9 ADJUSTER GP-SLACK 8X-7921 D-2
10 BRAKE GP-SERVICE & PARK 243-5545 B-8, F-8
11A BRAKE GP-SERVICE (FRONT BRAKES) 8X-3810 D-1, F-1
11B BRAKE GP-SERVICE (FRONT BRAKES) 243-5551 D-1, F-1
12 VALVE GP (CAB MANIFOLD) 261-1316 F-4
13 VALVE GP-CHECK 249-5521 E-4
14 SWITCH AS.- PRESSURE 3E-7806 E-4
15 PUMP GP-ELECTRIC (BRAKE RETRACT) 230-2637 D-5
16 VALVE GP-DIVERTER 3G-2887 E-6
17 VALVE GP-RELIEF 228-7839 E-5
18 FILTER (BREATHER) 8X-4575 A-6
19 SWITCH AS.-PRESSURE 160-2609 F-6
20 ACCUMULATOR GP (BRAKE) 220-5692 E-5
21 PEDAL GP-BRAKE VALVE 261-1317 F-3
22 VALVE GP-CONTROL (HOIST) 245-1668 B-3, C-3, D-3
23 CYLINDER GP-TELESCOPING (HOIST) 171-1232 A-3
24 PLATE-ORIFICE (HOIST) 8X-7224 A-3
26 SCREEN AS. 7J-3723 A-4
27 SCREEN AS. (BRAKE COOLING) 6E-6640 B-6, C-7
28 CORE AS.-OIL COOLER 141-4109 B-6, C-7
29 FILTER GP-OIL 155-6061 C-5
35 PUMP GP-ELECTRIC (STEERING) 230-2637 D-6
47 SCREEN AS. 7J-0725 A-5
54 PUMP GP-ELECTRIC (ENGINE OIL) 230-2637 D-5
58 VALVE GP-CHECK 185-4026 E-5
59 VALVE AS.-SHUTTLE 8J-6875 E-3
Component Locations (Volume 1)
Tap
Number
Description
Schematic
Location
A LEFT REAR SERVICE BRAKE F-8
B RIGHT REAR SERVICE BRAKE B-8
C REAR SLACK ADJUSTER INPUT D-8
D CAB MANIFOLD RESOLVER OUTPUT F-4
E ACCUMULATOR CHARGING OUTPUT D-4
F BRAKE CHARGING PUMP OUTPUT D-4
G LEFT PARK BRAKE D-7
H RIGHT PARK BRAKE C-7
I FRONT SLACK ADJUSTER INPUT E-1
J DRY FRONT BRAKE INPUT E-1
K CYLINDER HEAD END A-3
L CYLINDER ROD END A-3
M HOIST PUMP OUTPUT C-4
N HOIST VALVE RAISE PILOT D-3
O HOIST VALVE LOWER PILOT B-3
P BRAKE COOLING INPUT B-7
Tap Locations
Pressure, Sampling, and Sensor (Volume 1)
Purge Solenoid
COMPONENT LOCATIONS
BRAKING HOIST
10
7
2324
16
126
17
18 234 205 14 1129
9
21
12 14
3515 54
27 28
11
8
619
22
10
2324 59
Shown in the visual is the new location of the hoist pump (4A, 4B). The hoist pump is
a gear type pump and is attached to the brake cooling pump (3) and the brake charg-
ing pump (2A, 2B). The hoist pump is now driven by the gears at the back of the
engine.
4A
3
2A
4B
2B
20
Shown in the visual are the three brake accumulators for the 777F. The accumulators
(20) are charged by the brake charging pump and supply the required oil flow to
disengage the front and rear brakes. The outer accumulators are for the rear service
brakes. The middle accumulator is for the parking brake and front service brakes.
A check valve in the circuit between the parking accumulator and the rear service
accumulators allows only the parking brake accumulator to be filled when using the
secondary electric pump.
6
This visual shows the parking brake valve (6) for the 777F which is located on the
inside left frame rail behind the middle cross member. The parking brake release
valve no longer works off pressurized air. This valve receives oil flow from the parking
brake accumulator. Contained within the valve is a parking brake solenoid valve (3)
and a purge solenoid valve (4).
Parking Brake Solenoid
B
F
The accumulator charging valve (5) is located on the left side of the frame by the brake accumulators This valve
directs oil to the brake accumulators, brake cooling, and the tank. Once the accumulators are charged, the
excess oil flow is sent to cool the brakes before returning to the tank.
The Brake ECM monitors the pressure in the service brake accumulators with pressure switch. If the pressure
in the service brake accumulators are low, the pressure switch will open and the Brake ECM will signal the
monitoring system to turn on the brake system-check indicator.
Pressure tap (B) is used to check the oil pressure in the service brake accumulators. Pressure tap (F) is used
to check the charge oil pressure from the pump.
The accumulator charging valve contains a CUT-IN/CUT-OUT spool. Once the maximum brake system
pressure is reached, the spool will shift and send the excess flow to brake cooling. As the system pressure
continues to drop to the CUT-IN pressure setting, the spool will shift again and the system will charge to the
CUT-OUT pressure setting. This process will continue to repeat as often as needed to keep the brake system
fully charged. The CUT-IN/CUT-OUT pressure is checked at pressure tap (B).
The relief valve setting is set slightly higher than the CUT-OUT pressure setting. In the event that the
CUT-IN/CUT-OUT valve spool fails, the relief valve will protect the system from extreme pressure. Relief valve
can only be tested on a hydraulic test bench.
If the charge oil pressure is low at pressure tap (F), or the brake system never reaches the proper CUT-OUT
pressure, check relief valve. If relief valve is set properly and the brake system is not reaching the specified
CUT-OUT pressure, replace the accumulator charging valve. The CUT-IN/CUT-OUT spool is not adjustable.
5
Relief Valve
Pressure Switch
29
The brake system filter (29) is located on the left outer frame rear next to the left rear strut mount.
The brake system filter has a bypass switch.
8
9
The 777F has two slack adjusters. The top visual is of the rear slack adjuster (8). The rear slack adjuster is
located above the rear differential. The slack adjuster maintains a consistent feel and application of the brakes
as the brake discs wear.
The lower visual is of the front slack adjuster (9). The front slack adjuster is located on the left strut frame
support. The slack adjuster maintains a consistent feel and application of the brakes as the brake discs wear.
Shown in this visual is the diverter (towing) valve (16) for the 777F. The diverter valve functions the
same however has changed locations. The diverter valve for the 777F is now located on the left
frame rail in front of the left front strut. The diverter valve must be manually shifted before towing.
Once the valve is shifted, oil flow from the electric secondary pump is directed to the parking brake
valve to release the parking brake. The relief valve (17) limits the maximum pressure when using
the towing pump.
16
17
4A 4B
Shown in the visual is the new location of the hoist pump (4A, 4B).
Shown in the visual is the new location of the hoist control valve (22). The valve (22) is located behind the engine on
the right side of the frame. The valve (22) will function the same as the hoist control valve on the 777D.
22
N
O
L K
Shown in the visual to the left are the pressure taps for the hoist control
valve. The pressure tap (N) checks the pilot pressure for the hoist lower
solenoid. The pressure tap (O) checks the pilot pressure of the raise
solenoid.
Shown in the visual to the right are the pressure taps for the hoist
cylinders. These pressure taps are located on the cross-tube between
the lower hoist cylinder mounts. The pressure tap (L) checks the
pressure of the cylinder lower circuit. The pressure tap (K) checks the
pressure of the cylinder raise circuit.
47
58
CAB

2. RENR8305-02VOL1of2
30Page,(Dimensions:39inchesx28inches)
DRAIN / RETURN LINE
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
ELECTRICAL CIRCUITS
BRAKE CHARGING CIRCUIT PUMP
LOCK-UP CLUTCH VALVE PUMP CIRCUIT
BRAKE COOLING
HOIST PUMP CIRCUIT
PUMP SUPPLY LINE
HOIST CYLINDERS CIRCUIT
BRAKE CIRCUIT (FRONT AND REAR)
THIS SCHEMATIC IS FOR THE 777F AND 777F OEM OFF-HIGHWAY TRUCK
PART #: 255-6188 CHG 04
Components are shown installed on a fully operable machine with the key and engine off and transmission
shifter in neutral.
Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
CALLOUTS
Taps (Pressure, Sampling,Sensor) by letter
Components by number
YY
52
7
78 6 5 4 3 2 1
A
B
C
D
E
F
1234568
F
E
D
C
B
A
A
B
D
E 59
8
From Torque Converter
Lock-up Clutch Pilot
(Volume 2, F-3)
ADJUSTER GP - SLACK
RIGHT REAR
LEFT REAR
M
P
T
A
1
4
5
P1
T1
A1
PARK BRAKE
SOLENOID
BLEEDDOWN
SOLENOID
3
ECM
P2
LEFT
FRONT
RAISE SOLENOID
LOWER, FLOAT,
SNUB SOLENOID
BRAKE COOLING RELIEF
LOWER
FLOAT
SNUB
HOLD
RAISE
RAISE RELIEF
LOWER RELIEF
DUAL STAGE
SIGNAL SPOOL
MAIN RELIEF
DUMP SPOOL
7
10
10
28 27
11A
11A
9
20 13
14
5
2B 4B
1535 54
11B
11B
2324
22
1
4A32A
28 27
12
21
FRONT BRAKES
WET DRY
LEFT
FRONT
RIGHT
FRONT
RIGHT
FRONT
17
16
58
6
H
G
P
18
M
N
O
LK
D
E
F
29
C
B
A
J
From Torque Converter
Lock-up Clutch.
(Volume 2, F-3)
From Torque Converter
Lock-up Clutch. (Volume 2, E-2)
From Torque Converter
(Volume 2, F-4)
See Note A
See Note A
See Note A
19
47 26
14
I
Note A: Dry brake configuration

3. RENR8305-02VOL2of2
30Page,(Dimensions:39inchesx28inches)
ONE POSITION TWO POSITION THREE POSITION
VENTED PRESSURIZED RETURN ABOVE FLUID LEVEL RETURN BELOW FLUID LEVEL
LINES CROSSING LINES JOINING
TWO-WAY THREE-WAY FOUR-WAY
SPRING CONTROL VALVES RESTRICTION LINE RESTRICTION
(FIXED)
2-SECTION PUMP
MAIN AUX.
SPRING
(ADJUSTABLE)
VARIABILITY LINE RESTRICTION
(VARIABLE)
LINE RESTRICTION
VARIABLE and PRESSURE
COMPENSATED
PRESSURE
COMPENSATION
PUMP: VARIABLE and
PRESSURE COMPENSATED
ENERGY TRIANGLES
HYDRAULIC PNEUMATIC
MEASUREMENT
PRESSURE TEMPERATURE FLOW
ROTATING SHAFTS
UNIDIRECTIONAL BIDIRECTIONAL
PUSH-PULL LEVER PEDALGENERAL MANUAL PUSH BUTTON SPRING
MANUAL CONTROL SYMBOLS
HYDRAULIC MOTORS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
HYDRAULIC PUMPS
FLUID STORAGE RESERVOIRS
CROSSING AND JOINING LINES
VALVE ENVELOPES VALVE PORTS
BASIC COMPONENT SYMBOLS
FLUID CONDITIONERPUMP or MOTOR
FLUID POWER SYMBOLS
FIXED
DISPLACEMENT
VARIABLE DISPLACEMENT
NON-COMPENSATED
UNIDIRECTIONAL
BIDIRECTIONAL
VALVES
PILOT CONTROL SYMBOLS
RELEASED PRESSURE
EXTERNAL RETURN INTERNAL RETURN
REMOTE SUPPLY PRESSURE
SIMPLIFIED COMPLETE INTERNAL
SUPPLY PRESSURE
ACCUMULATORS
SPRING LOADED GAS CHARGED
SOLENOID
or MANUAL
SOLENOID
and PILOT
SOLENOID and
PILOT or MANUAL
COMBINATION CONTROLS
SOLENOID SERVO THERMAL DETENT
HYDRAULIC AND PNEUMATIC CYLINDERS
DOUBLE ACTINGSINGLE ACTING
BASIC
SYMBOL
SPRING
LOADED
CHECK VALVES
TWO
POSITION
INFINITE
POSITIONING
FLOW IN ONE
DIRECTION
FLOW ALLOWED IN
EITHER DIRECTION
THREE
POSITION
CROSS
FLOW
PARALLEL
FLOW
INTERNAL PASSAGEWAYS
NORMAL POSITION
A B
P T
A B
P T
SHIFTED POSITION INFINITE POSITION
CONTROL VALVES
ATTACHMENT
MANUAL SHUTOFF
SHUTTLE PILOT
CONTROLLED
Hydraulic Symbols (Electrical)
Electrical Symbols Table
325-AG135 PK-14
Circuit Identification
Number
Wire Color Wire Gauge
Harness identification code
This example indicates
wire 135 in harness "AG".
325-PK-14
Wire Gauge
Wire Color
Circuit Number
Identification
Wire Number Identification Codes
Current Standard
Previous Standard
Electrical Schematic Example Hydraulic Schematic Example
325-PK
Wire ColorCircuit Number
Identification
B A
Wire
Wire
(EXAMPLE VALVE)
Current Standard
Transducer
(Fluid)
Transducer
(Gas / Air)
G
Generator
Electrical WirePressure Switch
M
Electric Motor
Pressure Switch
(Adjustable)
Temperature Switch
T
Pressure
Symbol
Temperature
Symbol
Level
Symbol
Flow
Symbol
Electrical Symbols (Electrical)
© Printed in U.S.A.
777F:
JRP1-UP
777F OEM:
JXP1-UP
Volume 2 of 2: Steering and Power Train
2010 Caterpillar
All Rights Reserved
RENR8305-02
June 2010
777F and 777F OEM Off-Highway Truck
Hydraulic System
Item
Number
Description
Part
Number
Schematic
Location
1 TANK GP (HYD & TRANS) 258-9852 C-4
15 PUMP GP-ELECTRIC (BRAKE RETRACT) 230-2637 D-6
18 FILTER (BREATHER) 8X-4575 C-4
25 FILTER GP-OIL 249-2306 D-2
30 TANK GP-HYD (STEERING) 249-2925 A-7
31 PUMP GP-PISTON (STEERING) 261-5630 B-6
32 VALVE GP-CHECK (STEERING) 175-7050 E-7
33 PUMP GP-METERING (STEERING) 195-6617 E-7
34 CYLINDER GP-(STEERING) 105-2440 F-7
35 PUMP GP-ELECTRIC (STEERING) 230-2637 D-6
36
SWITCH AS.- PRESSURE
(STEERING PUMP OIL LOW PRESSURE)
313-5104 D-8
37 SWITCH AS.- PRESSURE (SECONDARY STEERING) 9X-4455 E-6
38 FILTER GP-OIL (STEERING) 173-0159 B-7
39 FILTER GP-HYD (STEERING) 249-2334 C-8
40 VALVE-BREAKER RELIEF 9T-0818 B-5
41 PUMP GP-GEAR (TORQUE CONV. SCAVENGE) 256-6123 D-3
42 FILTER GP 4T-4760 D-3
43 VALVE GP-MODULATING 244-3114 E-3
44 FILTER GP-OIL 244-0121 F-3
45 FILTER GP-OIL 270-5181 F-3
46 SWITCH AS.-LIQUID LEVEL 172-8660 B-2
47 SCREEN AS. 7J-0725 C-2
48 CONVERTER GP-TORQUE 249-5539 D-4
49 VALVE GP-RELIEF 3P-0349 F-4
50 PUMP GP-GEAR (TORQUE CONV. CHARGE) 256-6123 D-3
51 PUMP GP-GEAR (LOCK-UP CLUTCH VALVE PILOT) 256-6123 D-3
52 PUMP GP-GEAR (TRANSMISSION SCAVENGE) 256-6123 D-2
53 PUMP GP-GEAR (TRANSMISSION CHARGING) 256-6123 D-2
54 PUMP GP-ELECTRIC (ENGINE OIL) 230-2637 D-5
55 VALVE GP-RELIEF 3P-0348 C-3
56 CORE GP- OIL COOLER 4W-5056 C-2
57 VALVE GP-CHECK 268-3451 C-2
60 VALVE GP-RELIEF 268-3998 E-2
61 VALVE GP-MTG & 277-8869 C-8
Component Locations (Volume 2)
Tap
Number
Description
Schematic
Location
Q HMU INPUT E-7
R STEERING LOAD SENSE PILOT D-8
S LOCK-UP CLUTCH E-3
T LOCK-UP CLUTCH FILTER OUTPUT D-3
U TRANS CHARGE FILTER OUTPUT F-3
V TORQUE CONVERTER OUTLET RELIEF VALVE F-4
W SOS C-8
X SOS D-2
Y TRANSMISSION CHARGE PRESSURE E-2
Tap Locations
Pressure, Sampling, and Sensor (Volume 2)
Shown in the visual to the left is the electric
secondary steering pump (35) on the 777F. The
pump and motor are the same as the 777D
however the location has changed. The pump and
motor are now located on the front crossmember.
The secondary pressure switch (36) is also
mounted next to the secondary steering pump.
The pressure switch (36) detects if the wheels are
being turned via the steering wheel when second-
ary steering is applied. When the wheel is turned
in a secondary steering condition, the pressure
switch (36) will signal the Transmission/Chassis
ECM and the QuickEvac function will be disabled.
Relief ValveRelief Valve
Steering Disable
Solenoid
53 52
55
49 43
51 50 41
42
Shown in the left visual is the 777F transmission charge filters. The 777F has two filters mounted on the
cross member on the right side of the machine. Port (U) is an S•O•S port. Port (Y) is a pressure tap. The
pressure indicated at tap (Y) is charge pressure for the transmission control valves. The rear filter housing
also has a bypass switch. The bypass switch provides an input signal to the Caterpillar Monitoring System,
which informs the operator if the filter is restricted.
Shown in this visual is the 777F torque converter charging filter (42). The charging filter is located on the
right frame rail, behind the right front tire. The S•O•S port is located on the torque converter filter. S•O•S Port
draws a sample from the outlet of the filter.
Shown in the top visual is the new five section gear pump. The gear pump is a different design then the
previous 777D. The gear pumps are for the following circuits:
Torque converter scavenge (41)
Torque converter charge (50)
Lockup clutch valve pilot circuit (51)
Transmission scavenge (52)
Transmission charge (53)
Shown in the lower visual are some of the torque converter system components for the 777F. The torque
converter systems are similar between the 777D and 777F. The torque converter inlet relief valve (55) and
the outlet relief valve (49) will function the same. The lockup clutch valve (43) on the 777F is now an ECPC
valve.
This view shows the torque converter lockup clutch filter. Port (X) is an S•O•S port. Port (T) is a pressure tap.
The pressure indicated at tap (T) is pump pressure for the lockup clutch pilot circuit.
X T
a b c d e f g h j
U
Y
Shown in this visual is the 777F ECPC transmission. This new transmission has pressure taps located
on the outside of the transmission. This feature will aid in preventing contamination from entering the
transmission as well as saving time when checking the pressures on the 777F transmission.
Lube oil pressure can be checked at tap (3).
System pressure can be checked at tap (4).
Clutch 6 pressure can be checked at tap (5).
Clutch 5 pressure can be checked at tap (6).
Clutch 7 pressure can be checked at tap (7).
Clutch 4 pressure can be checked at tap (8).
Clutch 3 pressure can be checked at tap (9).
Clutch 2 pressure can be checked at tap (10).
Clutch 1 pressure can be checked at tap (11).
4544
V44
45
31
32
35 36
30
Q
61
Shown in this visual is the steering pump (31) for the 777F. The steering pump is now mounted on the back of the new C32
ACERT engine. The steering pump is still a load sensing, pressure compensated, piston-type pump
Shown in this visual is the steering valve (32) for the 777F. The 777F uses the same steering valve as the 777D. The steering
valve is located in the same place however the steering valve is mounted differently. The pressure tap (Q) checks the pressure
in the supply line to the HMU. If the supply oil pressure to the HMU is below specification, the relief valve
many need to be adjusted.
The steering disable valve (61) is located behind the shock on the right frame rail. When the steering disable solenoid valve is
energized, the flow from the steering to the steering valve is blocked by the steering disable valve (61). This allows servicing
behind the
S
Shown in the this visual is pressure tap (S) for the lockup clutch valve and pressure tap (V) for the outlet
relief valve. The pressure indicated at tap (S) is the pressure in the lockup clutch. The pressure indicated
at tap (V) is the pressure inside the torque converter.
CAB
1264647 59 5225 6018
33
34 15 35 37 54
34
56
32 36 6131 42 3038394044 45
53 57515041
4955 4348
Shown in the visual to the right is the 777F
steering system tank. The tank is located on the
right platform. The 777F steering tank functions
the same as the the 777D steering tank.
S•O•S
NOTE: The taps shown in this visual
do not appear on the schematic.
COMPONENT LOCATIONS
POWER TRAIN
STEERING SYSTEM

4. RENR8305-02VOL2of2
30Page,(Dimensions:39inchesx28inches)
DRAIN / RETURN LINE
HYDRAULIC CIRCUIT COLOR DESCRIPTIONS
ELECTRICAL CIRCUITS
STEERING PUMP CIRCUIT
TRANSMISSION AND TORQUE CONVERTER SCAVENGE PUMP CIRCUIT
LOCK-UP CLUTCH VALVE PUMP CIRCUIT
BRAKE COOLING
PUMP SUPPLY LINE
TRANSMISSION CHARGE PUMP CIRCUIT
TORQUE CONVERTER CHARGE PUMP CIRCUIT
SECONDARY STEERING PUMP CIRCUIT
THIS SCHEMATIC IS FOR THE 777F AND 777F OEM OFF-HIGHWAY TRUCK
PART #: 255-6188 CHG 04
Components are shown installed on a fully operable machine with the key and engine off and
transmission shifter in neutral.
Refer to the appropriate Service Manual for Troubleshooting, Specifications and Systems Operations
LINE PATTERNS
Drain / Return Lines
Component Group
Pilot / Load Sensing Pressure
Pressure Line
Attachment
Air Line
CALLOUTS
Taps (Pressure, Sampling,Sensor) by letter
Components by number
YY
52
8 6 5 4 3 2 1
A
B
C
D
E
F
1234568
F
E
D
C
B
A
7
7
ECM
M
B
AC
D
E
A
B
LOAD SENSE STEERING SYSTEM
POWERTRAIN:
TRANSMISSION AND TORQUE CONVERTER
15
35
54
535251
5041
55
4726 46
48
42
1
43
25
18
49
60
44 45
S
39
30
38
31
61
40
Q
33
32
37
34
V
T
U
R
W
HYDRAULIC
CONTROLS
TORQUE
CONVERTER
TRANSMISSION
LOCK UP
VALVE
LOCK-UP CLUTCH
PRESSURE
TO BRAKE
COOLING
TO BRAKE
COOLING
To Traction Control Valve
To Hoist Pilot
Signal Resolver
To Rockford Fan
Clutch Control
(Attachment)
36
56
57
X
Y