Function of power steering pump - GF46.30-P-2100-01C
Power steering pump, function
When the drive shaft and the rotor connected with it are turned the vanes guided in it are also turned. Centrifugal force and oil under pressure, which can flow through holes and grooves from the pressure chamber to the inner face of the vanes, press them against the running surface of the cam ring. This separates the pump cells from one another whereby suction is formed as the volume increases and pressure as the volume decreases. From the two pressure chambers the oil travels to the chamber between the cover and end plate on the cover side, which is then pressed against the cam ring by the operating pressure and fed to the quantity control valve and the steering pressure line over a throttle.
Quantity control valve, function
At increasing speed or increasing pump output the pressure drop behind the throttle (1) increases; it also increases on the spring side of the valve piston. As soon as the hydraulic pressure in the pump exceeds the spring force, the piston moves against the spring so that excess oil pumped can flow back through the injection bore (4) which becomes free into the intake channel. For this reason the steering is kept at a nearly constant flow rate over the entire speed range. Limitation of the maximum pressure in the system (pump and steering) is accomplished by a small valve (2) in the quantity control valve piston (3). Here the oil also flows back through the same injection bore into the intake duct.