General Description

Power Steering Speed Sensor:

The power steering speed sensor is a trochoid-rotor, hydraulic pump combined with a relief valve and a one- way valve. It is driven by the speedometer gear shaft which in turn is driven by a helical gear on the differential,

The power steering speed sensor turns only when the car is moving, controlling the gain control valve.
The constant pressure is generated by the pressure control valve.
This pressure is used as a reference pressure for the response to the car speed. By introducing this pressure to the power steering speed sensor through the sensor orifice, the pressure downstream of the orifice is changed according to the speed of the car.
This pressure is then used to operate the gain control valve.

Power Steering Speed Sensor:

With the engine running at idle in a parked car, fluid flow through the sensor rotors is blocked because the rotors are not turning. Therefore the gain control valve moves left. On the gain control valve, the orifice resistance is high on pump side, while it is low on the reservoir side, with the result that pressure in the reaction chamber is lowered and steering wheel operation with easily.

Power Steering Speed Sensor:

As the car is driven, the rotors start turning and the fluid returns to the reservoir, reducing the fluid pressure at the gain control valve. Therefore, the gain control valve moves right, the orifice resistance on the pump and reservoir sides is appropriately balanced, with the result that the reaction chamber is in the medium range and the steering resistance is moderate.

Power Steering Speed Sensor:

When the car is moving at high speed, the sensor reduces the pressure further and the gain control valve moves right. The orifice pressure on the pump side is low and the pressure on the reservoir side is high, the fluid pressure in the reaction chamber is also high giving the steering wheel less assist.