Prelude L4-2.2L SOHC (1994)
Power Steering Pump Speed Sensor: Description and Operation
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's 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.
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 to the 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 assist is high.
