Variable speed hydraulic pump assembly - uses regulator valve where recycling circuit detects pressure to move differential piston

摘要

A hydraulic flow is varied by auto control of the pressure. This allows pumps and hydraulic motors with fixed cylinders to be driven at variable speeds in order to vary the flow. The demanded speed is maintained under varying lead or torque conditions. A fluid flow from a pump enters an inlet (10) and is directed towards a regulator valve (10) and to a recycling circuit. The valve allows the demanded flow or speed to be adjusted in the motor flow circuit (14). The recycling circuit detects the pressure upstream of a valve (12) which restricts the flow to allow a differential piston (16) to move. Fluid flow is thus controlled via an evacuation tube (17) conducting the flow to a cistern outlet (19) and to the motor return circuit (18).