TUBE AS 4183756 - Caterpillar

Illustration 1 g00623774
The Conveyor Pump With The Pressure Compensator Valve (1) Drive shaft (2) Swashplate (3) Shoe plate (4) Bias piston (5) Piston (6) Bias spring (7) Spring (8) Spring (9) Spool for the differential pressure (10) Pressure compensator spool (11) Port plate (12) Actuator piston (13) Cylinder barrel (14) Piston shoeThe right and left conveyor pumps are automatically controlled piston pumps. The pumps sense both pressure and flow needs. Each side has one pump and both pumps are identical. When a conveyor drive system is not active, the pump is at the differential pressure.When the system is active, a load signal is sent from the control valve to pressure compensator spool (10). The spool now keeps the pump output at a level that is needed to fulfill system flow and pressure requirements.The actual system pressure will be greater than the highest pressure requirements unless the pump is at full stroke. Margin pressure is the difference between the required pressure and the higher supply pressure. The pressure compensator valve also limits maximum system pressure. This protects the conveyor system from damage due to high pressures.The pump has two control pistons, bias piston (4) and actuator piston (12). Bias spring (6) in the assembly for the bias piston causes swashplate (2) to upstroke the pump.The actuator piston (12) has a larger area than the bias piston. The larger actuator piston causes the swashplate to destroke the pump. Spool (9) for the differential pressure or pressure compensator spool (10) changes the pump output by regulating the pump discharge pressure that is acting on the actuator piston (12) .The differential pressure is maintained above the needs of the system pressure by spool (9) for the differential pressure. The control valve also controls the maximum pump output pressure.