HARNESS AS-CHASSIS 3255753 - Caterpillar

Destroking is a reduction in oil pressure when pump output decreases. Destroking occurs when the signal oil pressure through line (32) decreases from lower loads. While the steering control valve is in the NEUTRAL position, destroking occurs when the signal oil pressure through line (32) decreases to 0 kPa (0 psi) .When the pump oil pressure in passage (36) is greater than the force of signal oil pressure and of springs (15) , flow compensator spool (12) will move upward. This allows pressure oil in passage (35) to flow past spool (12) . The oil then flows through passages (30) and (31) . The oil then flows into the chamber of large actuator piston (29) .Large actuator piston (17) is larger than small actuator piston (8) . Because of this difference in size, the oil pressure that is acting against the large actuator piston exerts a greater amount of force than the combined oil and spring force that is acting against the small actuator piston.The oil pressure that is acting against the large actuator piston overcomes the force of spring (18) and the combined force of the oil and spring in chamber (34) . This causes large actuator piston (17) to move down.As large actuator piston (17) moves down, swashplate (3) moves toward the minimum angle. This causes the pump to destroke. As the angle of the swashplate moves toward the minimum angle, the pump output and the pump pressure decreases.Low Pressure Standby
Illustration 5 g00293183
Steering Pump and Pressure and Flow Compensator Valve (Low Pressure Standby) (2) Pump (3) Swashplate (7) Spring (8) Small actuator piston (9) Pressure and flow compensator valve (12) Flow compensator spool (margin spool) (15) Springs (17) Large actuator piston (18) Spring (21) Pressure compensator spool (cutoff spool) (24) Spring (26) Hydraulic tank for the steering and brake systems (27) Return line to the hydraulic tank (28) Drain line from the large actuator piston to the hydraulic tank (29) Chamber for the large actuator piston (30) Passage to the large actuator piston (31) Connecting passage between the pressure valve and the flow valve (32) Line for the signal oil from the control valve (33) Supply oil line for the steering pump (34) Spring chamber for the small actuator piston (35) Pressure oil passage to the flow compensator valve (36) Pressure oil passage to the flow compensator spool (37) Pump case drain line (38) Connecting passage between the flow compensator spool and the pressure compensator spool (39) Pressure oil passage to the pressure compensator spool (40) Pressure oil passage to the pressure compensator valve (41) Passage to the small actuator piston (42) High pressure oil line to the steering control valve (A) Pressure oil (B) Return oil (C) Supply oilWhile the engine is running and the steering control valve is in the NEUTRAL position, there is no signal oil pressure in line (32) . Because there is no signal oil pressure in the chamber of springs