Pressure and flow control
The purpose of the control valve is to regulate the flow from the pump so that it remains constant, regardless of engine/pump RPM.
The control valve sits on one side, directly connected to the pump flow (A). At the outlet passage (B) of the pump, a restrictor is situated from which a connecting passage (1) leads to the other side of the valve, which contains a spring (2). When unattached, the valve presses against the outlet side. When pressure is high, an overflow valve (3) housed in the control valve is actuated by the power steering fluid pressure on the spring-loaded side of the control valve.
For the control valve to operate, a certain amount of power steering fluid must circulate through it continuously at (A) and (C), although not when the steering wheel is at full lock.
The operating pressure of the pump is 4--120 bar while maximum flow is approx. 7.2 liters per minute.