 | |
| Illustration 1 | g01643975 |
Electrohydraulic Schematic Schematic with 261-3683 Main Control Valve (3-Function) (Ride Control) (1) 261-3683 Main Control Valve (3-Function) (Ride Control) (1A) 271-9248 Valve Manifold (Inlet) (2) 262-5265 Solenoid Valve (Drift Reduction) (Ride Control Accumulator) (3) Tilt cylinder (4) 332-1987 Relief Valve (Line) (5) 261-0018 Control Valve (Tilt) (6) 261-0019 Control Valve (Lift) (7) Lift cylinders (8) 253-4026 Ride Control Valve (9) 252-0737 Solenoid Valve (Ride Control) (Lift Cylinder) (10) Ride Control Accumulator (11) Auxiliary cylinders (12) 272-2334 Relief Valve (Line) (13) 261-0017 Control Valve (Auxiliary) (14) 225-0300 Solenoid Valve (Hydraulic Lockout) (15) 269-9398 Valve Manifold (End Cover) (16) 245-2975 Pilot Oil Accumulator (Dead Engine Lower) (17) 112-1817 Manual Valve (Dead Engine Lower) (18) 313-7668 Solenoid Valve (Pilot Proportioning) (19) Compensation and Load Check Valve (20) 4T-7581 Relief Valve (Ride Control) (21) 282-4349 Pressure Reducing Valve (22) 193-1665 Pressure Reducing Valve (Signal Duplication) (23) 247-8632 Relief Valve ( Load Sensing Signal) (24) 276-9072 Shuttle Valve (25) 260-6737 Valve Stem (Tilt) (26) 260-8590 Shuttle Valve Load Signal Resolver (27) 260-6738 Valve Stem (Lift) (28) 235-6157 Shuttle Valve (29) 252-0737 Solenoid Valve (Ride Control) (30) 260-6736 Valve Stem (Auxiliary) (31) 254-5789 Relief Valve (Pump Margin Pressure) (32) 246-6152 Piston Motor (Hydraulic Fan) (33) 244-1426 Check Valve (Oil Cooler Bypass) and Hydraulic Oil Cooler (34) 244-1031 Control Manifold (Brake Charge Pump) (Hydraulic Fan Control) (34A) 183-7595 Solenoid Valve (Hydraulic Fan) (35) Steering Circuit (36) 244-1031 Oil Filter (Hydraulic) (37) 254-5146 Piston Pump (Brake) (Hydraulic Fan) (38) Oil Filter (Hydraulic Case Drain) (39) 8C-3446 Fluid Sampling Valve (Hydraulic Oil) (40) 220-0814 Breaker Relief Valve (Hydraulic Tank) (41) 237-2742 Hydraulic Tank (42) 8T-6907 Shutoff Valve As (43) 254-4108 Piston Pump (Implement) (Pilot) or 292-8767 Piston Pump (Implement) (Pilot) (44) 241-9299 Piston Pump (Steering) (A) Implement ECM (B) Power Train ECM (C) Tilt lever position sensor (D) Lift lever position sensor (E) Auxiliary lever position sensor (F) Fine modulation switch (G) Switch (Hydraulic lockout) (H) Kickout set switch (J) Autodig trigger switch (K) Dig mode switch (L) Operation mode switch (Autodig System) (M) Autodig kickout set switch (N) Position sensor (lift) (P) Position sensor (tilt) (Q) Position sensor (auxiliary) (R) Pressure sensor (lift) | |
Note: Illustration 1 shows a machine with an auxiliary function. Machines without auxiliary functions (logging fork, side dump bucket, multipurpose bucket, etc) will not have auxiliary cylinders (11) . Machines without an auxiliary function will not have auxiliary section (13) on main control valve (1) . Machines without ride control will not have ride control valve (8) .
The electrohydraulic system is composed of the following systems:
- Implement electronic control system
- Main hydraulic system
- Ride control system
- Kickout system
- Hydraulic fan system
Hydraulic tank (41) is common to all of the systems.
The implement electronic control system is made up of the following components:
- (14) solenoid valve (hydraulic lockout)
- (18) solenoid valves (pilot proportioning)
- (21) pressure reducing valve
- (43) implement piston pump
- (A) implement ECM
- (C-E) control levers or joystick control
- (F-M) switches
- (N-R) sensors
ReferenceFor additional information about the implement electronic control system, refer to the Service Manual module Systems Operation, "Implement Electronic Control System" for the machine that is being serviced.
The main hydraulic system is made up of the following components:
- (1) main control valve
- (3) tilt cylinder
- (7) lift cylinders
- (11) auxiliary cylinders
- (23) load sensing signal relief valve
- (43) implement piston pump
ReferenceFor additional information about the main control valve, refer to the Service Manual module Systems Operation, "Main Control Valve" for the machine that is being serviced.
The ride control system is made up of the following components:
- (7) lift cylinders
- (8) ride control valve
- (10) ride control accumulator
- (B) power train ECM
ReferenceFor additional information about the ride control system, refer to the Service Manual module Systems Operation, "Ride Control System" for the machine that is being serviced.
The kickout system is made up of the following components:
- (21) pressure reducing valve
- (A) implement ECM
- (C, D) control levers or joystick control
- (N) lift linkage position sensor
- (P) tilt linkage position sensor
The hydraulic fan system is made up of the following components:
- (32) hydraulic fan motor
- (33) hydraulic oil cooler
- (34A) solenoid valve (hydraulic fan)
- (36) hydraulic oil filter
- (37) hydraulic fan pump
- engine ECM
ReferenceFor additional information about the hydraulic fan system, refer to the Service Manual module Systems Operation, RENR8874, "Hydraulic Fan System" for the machine that is being serviced.
 | |
| Illustration 2 | g01644035 |
Right Side View of the Machine (1) Main Control Valve (3) Tilt cylinder (7) Lift cylinders (10) Ride Control Accumulator (16) 245-2975 Pilot Oil Accumulator (Dead Engine Lower) (17) 112-1817 Manual Valve (Dead Engine Lower) (32) 246-6152 Piston Motor (Hydraulic Fan) (33) 244-1426 Check Valve (Oil Cooler Bypass) and Hydraulic Oil Cooler (34) 244-1031 Control Manifold (Brake Charge Pump) (Hydraulic Fan Control) (36) 244-1031 Oil Filter (Hydraulic) (37) 254-5146 Piston Pump (Brake) (Hydraulic Fan) (38) Oil Filter (Hydraulic Case Drain) (39) 8C-3446 Fluid Sampling Valve (Hydraulic Oil) (40) 220-0814 Breaker Relief Valve (Hydraulic Tank) (41) 237-2742 Hydraulic Tank (42) 8T-6907 Shutoff Valve As (43) 254-4108 Piston Pump (Implement) (Pilot) or 292-8767 Piston Pump (Implement) (Pilot) (44) 241-9299 Piston Pump (Steering) (A) Implement ECM (B) Power Train ECM (C) Tilt lever position sensor (D) Lift lever position sensor (E) Auxiliary lever position sensor (F) Fine modulation switch (G) Switch (Hydraulic lockout) (H) Kickout set switch (J) Autodig trigger switch (K) Dig mode switch (L) Operation mode switch (Autodig System) (M) Autodig kickout set switch (N) Position sensor (lift) (P) Position sensor (tilt) | |
Implement piston pump (43) and steering piston pump (44) are located under the cab. Pump (43) and pump (44) are mounted in-line to the torque converter housing.
Hydraulic tank (41) is located on the right side of the machine. Breaker relief valve (40) is mounted on hydraulic tank (41) . When the operator depresses the breaker relief valve the pressure inside the hydraulic tank is released.
The ride control system provides a means for dampening the bucket forces which produce a pitching motion as the machine travels over a rough terrain.
ReferenceFor additional information on the operation of the ride control system, refer to Systems Operation, "Ride Control System" for the machine that is being serviced.
Manual valve (17) for the dead engine lower is located in front of the articulation joint. The manual valve is used in order to lower the lift arms when there is an electrical failure.
Implement ECM (A) is located on the right side and the rear of the cab.
Implement piston pump (43) provides pump supply oil to main control valve (1) . A remote pressure tap for measuring implement pressure is located at the articulation joint on the right side.
Implement piston pump (43) also supplies pilot oil pressure to the pilot system. A pressure tap for measuring pilot pressure is located by the main control valve near the pilot oil accumulator.
Main control valve (1) is mounted on the front end frame.
Load sensing signal relief valve (23) is mounted on the main control valve. Line relief valves (4) and (12) are also attached to the main control valve. The main control valve controls the pump supply oil to the implement cylinders.
ReferenceFor additional information about the main control valve, refer to the Service Manual module Systems Operation, "Main Control Valve" for the machine that is being serviced.
 | |
| Illustration 3 | g01201230 |
Right armrest (C) Tilt control. (D) Lift control. (E) Auxiliary control. (G) Switch (Hydraulic lockout). | |
Switch (G) for the hydraulic lockout valve, tilt control (C) , lift control (D) , and auxiliary control (E) are located to the right of the operator's seat. The switch (hydraulic lockout) is located in the identical place on the joystick control.
ReferenceFor additional information on the switch (hydraulic lockout), refer to Systems Operation, "Switches" for the machine that is being serviced.
 | |
| Illustration 4 | g01201232 |
Implement Electronic Control (C) Tilt control. (D) Lift control. (E) Auxiliary control. | |
Note: Illustration 4 shows a machine with an auxiliary function. Machines without an auxiliary function will not have auxiliary control lever (E) .
ReferenceFor information on the implement control levers, refer to Systems Operation, "Electrohydraulic Control" for the machine that is being serviced.
 | |
| Illustration 5 | g01201231 |
Joystick Control (C) Tilt control. (D) Lift control. (E) Auxiliary control. | |
The machine can be equipped with a joystick control. The joystick control can be equipped with either two-position sensors or three-position sensors. The sensor for the third function is controlled by the thumb wheel that is built into the joystick handle. The position sensors send the position of the joystick handle to the implement (ECM). Also, the joystick control is not equipped with electromagnets for detents. The joystick control is equipped with soft detents. For additional information about the operation of the joystick control and the soft detents, refer to the Systems Operation, "Sensors".
The joystick control can be arranged in four different combinations. The joystick control can be either a two-function joystick or a three-function joystick. Also, either joystick function can be equipped with the Autodig System. If the machine is equipped with the Autodig System, refer to the Systems Operation, "Switches" for the location of the Autodig trigger switch on the joystick control.
ReferenceFor additional information on the joystick control, refer to Systems Operation, "Electrohydraulic Control" for the machine that is being serviced.
ReferenceFor additional information on the operation of the autodig system, refer to Systems Operation, "Aggregate Autodig" for the machine that is being serviced.
 | |
| Illustration 6 | g01644051 |
Right Side View of the Engine Compartment (37) Location of hydraulic fan pump. | |
 | |
| Illustration 7 | g01201796 |
Right Side View of the Engine Compartment (34) 244-1031 Control Manifold (Brake Charge, Hydraulic Fan Control) (34A) 183-7595 Solenoid Valve (Hydraulic Fan) | |
Hydraulic fan pump (37) is located on the right side of the engine. The fan pump supplies high pressure oil to fan motor (32) . Solenoid valve (34A) controls the signal pressure to the fan pump. The fan motor rotates the fan in order to cool the hydraulic oil. The hydraulic oil cooler and oil cooler bypass valve (33) are located to the rear of the engine.
 | |
| Illustration 8 | g01644040 |
Filter Group (38) Hydraulic Oil Filter. (39) Fluid sampling valve. | |
Hydraulic oil filter (38) is located on the right side of the machine behind the service door. The sampling valve is located on the hydraulic oil filter. The hydraulic oil filter is in the return line from the hydraulic fan system. Fluid sampling valve (39) is located above the hydraulic oil filter. Fluid sampling valve (39) is available in order to check the quality of the hydraulic oil.
ReferenceFor additional information about the hydraulic fan system, refer to the Service Manual module System Operation, "Hydraulic Fan System" for the machine that is being serviced.
ReferenceFor additional information about the hydraulic fan system, refer to the Service Manual module Testing and Adjusting, "Hydraulic Fan Speed - Test and Adjust" for the machine that is being serviced.
The following features can be enabled in Caterpillar Electronic Technician. These features are flashed into the ECM.
- The Full Rack Angle Control is a feature in the software that keeps the work tool from tilting back too far, when you raise the lift arms. This is accomplished by the ECM. The ECM reads the command from the operator. The ECM then compares the maximum allowable command that is based on the lift and tilt cylinder lengths with the command of the operator. This feature will help prevent material from spilling over the back of the work tool. Full Rack Angle control is an option that is available to the operator. Full Rack Angle Control must be enabled through Caterpillar Electronic Technician. Full Rack Angle control can only be enabled on machines that are not equipped with the payload control system.
- Dump Stop Snubbing is a feature in the software that keeps the lift arms from being retracted by a dumping motion. Dump Stop Snubbing is an option that is available to the operator. Dump Stop Snubbing must be enabled through Caterpillar Electronic Technician.
- "Dump Rate Control" is a feature in the software that dumps the work tool with a constant dump speed. This feature controls the work tool to dump with a smooth flow. "Dump Rate Control" is an option that is available to the operator. "Dump Rate Control" must be enabled through Caterpillar Electronic Technician.
Shutoff valve (42) can be opened in order to help prime the pump after a new pump is installed or the hydraulic oil is changed.
Note: Shutoff valve (42) must be closed during normal operation of the machine. Failure to close the valve will allow unfiltered case drain oil to return to the hydraulic tank.