120H, 12H, 135H, 140H, 143H, 160H and 163H Motor Graders Hydraulic and Steering System Location Of Components Caterpillar


Location Of Components
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1.1. Hydraulic and Steering System
2.2. Hydraulic Tank
3.2. Hydraulic and Steering Pump
4.2. Pressure and Flow Compensator Valve (Hydraulic and Steering)
5.2. Combination Valve
6.3. Steering Priority Valve
7.3. Steering Relief Valve
8.3. Implement Relief Valve
9.3. Load Check Valve
10.3. Signal Resolver Valve
11.3. Signal Relief Valve
12.3. Signal Purge Valve
13.2. Centershift Lock Cylinder
14.2. Steering Accumulator
15.2. Steering Metering Pump
16.2. Implement Control Valves
17.2. Fan Drive Pump

Hydraulic and Steering System



Illustration 1g00917159
Typical Location of Components
(1) Fan motor
(2) Articulation cylinder
(3) Fan speed solenoid
(4) Pressure and flow compensator valve (hydraulic and steering pump)
(5) Combination valve
(6) Steering accumulator
(7) Pressure and flow compensator (fan pump)
(8) Steering metering pump
(9) Left valve bank
(10) Blade tip cylinder
(11) Blade lift cylinder
(12) Circle drive
(13) Steering cylinder
(14) Oil pressure sensor
(15) Makeup valve
(16) Articulation cylinder
(17) Hydraulic Tank
(18) Hydraulic and steering pump
(19) Fan drive pump
(20) Right valve bank
(21) Centershift cylinder
(22) Sideshift cylinder
(23) Blade lift cylinder
(24) Swivel
(25) Steering cylinder
(26) Wheel lean cylinder

Note: Some of the motor graders may have different implements. The number of control valves in each valve group may vary.

Hydraulic Tank



Illustration 2g00920264

The hydraulic tank is not vented. The hydraulic tank contains a reverse flow element. The hydraulic tank is located directly behind the operator's cab.

Hydraulic and Steering Pump



Illustration 3g00920265

The hydraulic and steering pump is a variable displacement axial piston pump. The hydraulic and steering pump is located below the cab in front of the engine.

Pressure and Flow Compensator Valve (Hydraulic and Steering)



Illustration 4g00920277

The pressure and flow compensator valve for the hydraulic and steering keeps the pump pressure and the pump flow at the level that is needed to fulfill the requirements of the hydraulic and steering system. The pressure and flow compensator valve is attached to the hydraulic and steering pump.

Combination Valve



Illustration 5g00920267

The combination valve directs hydraulic fluid to the steering system and the implement system. The combination valve is located underneath the cab next to the hydraulic and steering pump.

Steering Priority Valve

The steering priority valve establishes a priority to the steering circuit before the implement circuit.

Steering Relief Valve

The steering relief valve limits the maximum pressure that is allowed to the steering circuit. The steering relief valve is set at 19300 ± 689 kPa (2800 ± 100 psi).

Implement Relief Valve

The implement relief valve protects the hydraulic and steering pump from excessively high pressures. The implement relief valve is set at 26900 kPa (3900 psi).

Load Check Valve

The load check valve maintains the steering accumulator pressure at the inlet of the steering metering pump. This pressure will allow a more responsive steering operation.

Signal Resolver Valve

The signal resolver valve selects the higher of the two signal pressures from the steering circuit and the implement circuit. The highest signal is then routed to the pressure and flow compensator valve.

Signal Relief Valve

The signal relief valve limits the maximum implement signal pressure. The signal relief valve is set at 22050 kPa (3200 psi).

Signal Purge Valve

The signal purge valve allows the signal pressure to go to the hydraulic tank when the implement controls are returned to the HOLD position.

Centershift Lock Cylinder



Illustration 6g00920877

Centershift lock cylinder is located on the rear of the link bar. When the lock pin is not engaged with the arm assembly, the arm assembly and the circle can be moved in order to place the blade in the correct position.

Steering Accumulator



Illustration 7g00920270

The steering accumulator prevents the momentary interruption in the steering operation that is caused by sudden changes in pump demand. The steering accumulator is mounted to the combination valve.

Steering Metering Pump



Illustration 8g00920271

The steering metering pump directs hydraulic oil to the right steering cylinder and to the left steering cylinder. The steering metering pump is located inside the steering column.

Implement Control Valves



Illustration 9g00920274

There are typically eight implement control valves on each machine. There is a maximum of fourteen implement control valves that can be installed on each machine. The implement control valves direct oil to the corresponding implement. The implement control valves are located underneath the cab.

Fan Drive Pump



Illustration 10g00923120

The fan drive pump is a variable displacement axial piston pump. The fan drive pump is mounted on the hydraulic and steering pump.

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