Power Steering Pump: Description and Operation

Regulated steering hydraulics

The Cayenne models are equipped with a regulated power-steering pump with variable geometric delivery rate. The demand-controlled delivery rate reduces energy consumption and thus lowers fuel consumption.

Function







The pump delivers a constant volume flow to the hydraulic power steering when the engine is idling. When the engine speed increases, this causes the internally rising pump pressure to open the control valve (11), apply pressure on the cam ring (5) and reduce eccentricity with respect to the rotor (3). As a result, the pump chambers become smaller and only produce a reduced delivery rate. This restricted pump function prevents overproduction of pressure oil and significantly less energy is required at higher pump speeds due to reduced power consumption. This makes it possible to simplify cooling measures in the steering system. As the engine speed decreases, the pressure differential that exists between the left and right chambers increases the eccentricity between the rotor (3) and the cam ring (5). As a result, the geometric delivery rate increases continuously again.