Electro Hydraulic Power Steering (EHPS)

Steering
The MINI features a power assisted steering system (EHPS) on all models. EHPS is a system not previously seen on BMW vehicles. The steering rack is of conventional rack and pinion design. The steering column has two collapsible mechanisms and tilt adjustment. The twin spoke steering wheel is common to all models although there are small differences depending on the model and equipment level. The steering column has 54 mm of tilt adjustment manually controlled by a lever beneath the column. The electrically driven power steering pump is the main difference.

Purpose of the System
The Steering System is designed to offer smooth operation with maximum feedback to the driver. The Electro Hydraulic Power Steering, driven by an electric motor rather than the conventional belt, conserves valuable engine power and provides a 3% savings in fuel economy.

The main components of the steering system are:
- Electro Hydraulic Power Steering Pump (EHPS)
- Rack and Pinion
- Steering Column
- Steering Wheel

System Components

EHPS
All models and derivatives are equipped with Electro Hydraulic Power Steering (EHPS). This system uses an electric motor to drive the hydraulic pump. This replaces the customary design whereby the pump is permanently driven from the engine via the auxilary belt.




The EHPS motor weighing 5.5 kg is mounted by four rubber insulators and is positioned in front of the steering rack.







The hydraulic pump displaces 1.25cm 3/revolution developing a pressure of 105 bar at a maximum pump motor speed of 4,200 rpm. The hydraulic pump has an incorporated pressure relief valve. The smaller metal pipe from the aluminum bodied pump is the high pressure side and the flexible pipe fitted to the plastic reservoir on the pump is the low pressure side.




There is a small reservoir fitted to the end of the pump with a remote reservoir fitted to the bulkhead. The system is filled with Pentosin CHF 11 S. For top-up and refill use the same oil.