STRUCTURE, FUNCTION, & MAINTENANCE STANDARD CONTROL VALVE Basic principle 1) Control of pump swash plate The pump swash plate angle (pump discharge amount) is controlled so that LS differential pres- sure PLS (the difference between pump pressure PP and control valve outlet port LS pressure PLS ) (load pressure of actuator) is constant.
(LS pressure PLS = Pump discharge pressure PP – LS pressure PLS ) If LS differential pressure PLS becomes lower than the set pressure of the LS valve (when the actuator load pressure is high), the pump swash plate moves towards the maximum position; if it becomes higher than the set pressure of the LS valve (when the actuator load pressure is low), the pump swash plate moves towards the minimum position. PC210/240-7K 10-81