HARNESS AS 5389857 - Caterpillar

Steering Hydraulic System
Illustration 1 g03124968
Location of components (1) Steering pump (2) Steering charge pump (3) Steering control lever (4) Pressure control valve (5) Steering motor (6) Steering charge loop filter (7) Hydraulic tank and filterThe implement hydraulic system and the differential steering system have separate pumps. The separate pumps provide better performance for combined operation and for simultaneous operation. The steering circuit is a closed loop hydraulic system that has a variable displacement axial piston pump with over-the-center capability.The steering hydraulic system is a load sensing, pressure compensated system. In a load sensing, pressure compensated system, oil flow does not change according to the load conditions. Cylinder speeds remain constant under all load conditions.The machine has the following features: pilot operated controls, steering motor with an internal flushing valve and variable displacement piston pump for the steering.When the steering circuit is not active, the pump is destroked. The destroked pump compensates for system leakage with a small output. If the steering circuit is activated, the pressure control valve senses the load increase. The signal from the pressure control valve causes the pump to upstroke.The steering control valve is controlled by a mechanical linkage from the steering control lever. The steering control has three positions: STEER RIGHT, HOLD and STEER LEFT POSITION.The steering motor is equipped with a flushing system. The flushing system uses oil that has passed through the oil cooler and implements. The flushing system also assists in cooling the steering motor.