Ford Kuga

 Service Manual

Power Steering » Power Steering (System Operation and Component Description)
Component Description

Electro-hydraulic power steering pump

NOTE: The power steering pump must be filled and vented as specified.

The electro-hydraulic power steering pump comprises a brushless DC motor, the hydraulic pump and the power steering fluid reservoir.

The hydraulic pump is a gear pump; a resonance chamber incorporated into the pump body reduces noise emissions.

The operating pressure is also regulated by means of a pressure limiting valve which is integrated in the pump housing. The pressure limiting valve stabilizes the throughput to the steering gear to a particular level independently of engine speed.

The pressure relief valve will operate if the discharge from the pump is restricted, for example, steering held on full lock. If the output from the pump is blocked, all output is recirculated through the pump. As no fresh fluid from the reservoir is drawn into the pump in the process, the temperature of the power steering fluid in the pump quickly increases. Consequently, periods of holding the steering wheel at full lock should be kept to a minimum to prevent overheating of the pump and the power steering fluid within it.

The pressure limiting valve limits the pressure on the outlet side to 120 bar.

Integrated steering angle sensor - vehicles built up to 09/2009

The steering angle sensor is a inductive sensor.

The steering angle sensor monitors the steering wheel position and the rate of turn of the steering wheel. This information is sent to the power steering module.

On vehicles built from 09/2009 the power steering module uses the information from the steering angle sensor at the steering column. The required information is made available to the power steering module via the CAN bus.

Brushless DC motor with integral power steering module

In the electrohydraulic power steering system, a brushless 12 volt direct current motor drives the hydraulic pump. Higher pumping rates are only provided when they are required for steering manoeuvres. This avoids unnecessary energy consumption in the majority of phases in a drive cycle.

Commutation in the motor is done electronically.

As a result, there are no brushes to wear away.

The entire system is designed for maintenance-free operation.

In more than 85% of all driving situations, the power steering pump operates at standby speed and consumes less than 4A. However, pump speed can quickly increase to full rotational speed if emergency steering manoeuvres require it.

The system has a continuously variable pump rotational speed.

System Diagram

System Operation

Component Description