Demand for assistance (Valve misaligned) (Steering) (page 2 of 2)

Pump and regulator valve operation No demand for assistance No flow, through box - High pressure

The pump which is belt driven from the engine is an eccentric roller type and also houses the pressure When the steering is turned, the rotary valve regulator and flow control valve. The pressure is effectively stops all fluid flow through the steering box, controlled by a spring loaded ball valve (3) which is thus causing an increase in pressure ’A’. This housed inside the flow control valve piston (4). increase in pressure is felt in the flow control valve spring chamber where, at a pre-determined pressure No demand for assistance the relief valve (3) will open and allow the pressure to High flow through box - Low pressure escape. The fall in pressure in the flow control spring chamber, allows the flow control valve to move to the With no demand for assistance the rotary valve in the right, which in turn allows pump output ’A’ to escape steering box acts as a pressure relief valve, allowing directly into the pump inlet ’B’. fluid ’A’ to flow freely through the steering box and back to the reservoir and pump inlet ’B’.

As soon as the steering wheel is released after making a turn, the system reverts to the free flow

1. 1. Reservoir condition and the road wheels are returned to the
2. 2. Pump straight ahead position by the mechanical steering
3. 3. Pressure control ball valve and spring geometry.
4. 4. Flow control valve and spring
5. 5. Press fit plug (ball bearing) In the event of any hydraulic failure steering control,
6. 6. Restrictor though heavy, will be maintained through the mechanical components in the steering box.

The ball plug (5) is pressed into the valve 4 during manufacture and determines the opening pressure of pressure relief valve (3).