Steering (Operation): Description and operation

Operation

PAS Pump Operation

A B

4 5 6

2

1

1

M57 1017

1 Inlet port 2 Roller vane chamber 3 Discharge port

C 3

3

4 Cam 5 Carrier 6 Roller vanes

As the pump rotates, centrifugal force causes the roller vanes to move outwards in the slots in the carrier and contact the cam ring. As the carrier rotates, the cam ring form causes the space between the rollers to increase. The increasing volume between the roller vanes causes a depression which draws fluid into the space between the rollers.

As the carrier continues to rotate, the inlet port is closed to the roller vanes which have drawn the fluid, trapping the fluid between the rollers. As the carrier rotates further, the cam form causes the space between the roller vanes to decrease, pressurizing the fluid between the rollers.

On further rotation of the carrier the roller vanes reach the discharge port and fluid is displaced under pressure from between the roller vanes into the discharge port. The space between each pair of rollers is subjected to this cycle twice for every revolution of the pump.