STEERING DESCRIPTION AND OPERATION 57-23 When the engine is started, the PAS pump draws fluid from the reservoir down the low pressure suction line. The fluid passes through the pump and is delivered, via a hose, to the steering rack valve unit. The pressurised fluid flows through a connecting bore in the valve and, via the feed fluid radial groove and the transverse bores in the valve sleeve, passes to the feed fluid control groove of the valve rotor. In the neutral (straight ahead) position , the fluid passes over the open feed fluid control edges to all valve sleeve axial grooves. The fluid then passes through the open return fluid control edges and the return fluid control grooves of the valve rotor. The fluid then passes via connecting bores to the return fluid chamber and to the reservoir via an external hose. Simultaneously, the radial grooves of the valve body and their associated pipes provide a connection between the left and right power assist cylinders.