FILM GP-CAB 1400101 - Caterpillar

Illustration 1 g03412867
Steering Hydraulic System "STRAIGHT TRAVEL"
(1) Check valve
(2) Counterbalance valve
(3) Steering cylinder
(4) Shuttle valve
(5) Steering control valve
(6) Compensator spool
(7) To side cutter
(8) From side cutter
(9) Steering pump
(10) Warm-up valve
(11) Steering shunt valve
(12) Margin spool
(13) Main relief valve
(14) Shuttle valve
(15) Steering manifold When the engine is running, steering pump (9) sends flow to port "P" of steering manifold (15). Supply oil passes through a filter and is directed to warm-up valve (10), margin spool (12), and compensator spool (6). If differential pressure across the filter exceeds 700 kPa (102 psi), a bypass check valve opens.When the steering system is enabled, steering shunt valve (11) will be energized and closed. In this case, all supply oil is directed to compensator spool (6) and warm-up valve (10). When the parking brake is applied, the steering system is disabled. In this condition, the shunt valve is not energized, and all oil flow is directed to the hydraulic tank.When hydraulic oil temperature is less than 20 °C (68 °F), warm-up valve (10) is energized. This valve allows the steering system to warm up the hydraulic oil. The warm-up valve opens and directs supply oil to the demand side of margin spool (12). The margin spool closes and supply pressure increases to the setting of main relief valve (13). The relief valve opens and directs supply oil to the hydraulic tank. In this case, the relief valve serves to warm-up the hydraulic oil.When hydraulic oil temperature is greater than 25 °C (77 °F), warm-up valve (10) de-energizes.Margin spool (12) is a load-sensing valve. This valve compares the hydraulic pressure supplied to the steering system with the highest pressure demand being placed on the system. When the operator is not steering the machine, steering control valve (5) is not energized, and the demand pressure is at hydraulic tank pressure. In this case, the margin spool shifts and directs the supply oil to the hydraulic tank.If the steering system experiences a shock load, check valve (1) in the low-pressure side of steering cylinder (3) opens. This action allows oil to enter the low-pressure side of the hydraulic cylinder, preventing cylinder cavitation. Counterbalance valves (2) limit the maximum pressure in the steering cylinder to 20000 kPa (2900 psi).Main relief valve (13) limits the maximum pressure in the steering system to 20000 1000 kPa (2900 145 psi).
Illustration 2 g03412869
Steering Hydraulic System "RIGHT TURN"
(1) Check valve
(2) Counterbalance valve
(3) Steering cylinder
(4) Shuttle valve
(5) Steering control valve
(6) Compensator spool
(7) To side cutter
(8) From side cutter
(9) Steering pump
(10) Warm-up valve
(11) Steering shunt valve
(12) Margin spool
(13) Main relief valve
(14) Shuttle valve
(15) Steering manifold When the operator turns the steering wheel, the machine ECM number-one sends signals to the solenoids in steering control valve (5). The steering control valve has two solenoids. One solenoid extends steering cylinder (3), turning the machine to the right. The other solenoid retracts the steer cylinder, turning the machine to the left. When neither solenoid is energized, the steering valve is spring-returned to the center position. In the