Mechanical Design
The electric power steering is an absolutely identical fit with the previously used hydraulic power steering as far as the connections between it and the vehicle are concerned.
For comparison, a hydraulic power steering system and the new EPS with parallel mounted motor are illustrated below.
Scheme 1
| Index | Explanation |
|---|---|
| 1 | Hydraulic-fluid reservoir |
| 2 | Steering column |
| 3 | Torsion bar and valve actuator |
| 4 | Track rod |
| 5 | Hydraulic power steering pump |
| 6 | Steering rack |
INDEX EXPLANATION REFERENCE CHART
Scheme 2
| Index | Explanation |
|---|---|
| 1 | Steering rack |
| 2 | Steering torque sensor |
| 3 | Steering column |
| 4 | Track rod |
| 5 | EPS control unit |
| 6 | Electric motor with position sensor |
| 7 | Reduction gear |
INDEX EXPLANATION REFERENCE CHART
The EPS system essentially consists of the following components
Scheme 3
- Steering torque sensor
- EPS control unit
- Electric motor with position sensor
- Reduction gear
- Steering rack
| Index | Explanation |
|---|---|
| 1 | Ball-screw drive (part of reduction gearing) |
| 2 | Rack |
| 3 | Pinion |
| 4 | Steering torque sensor |
| 5 | Gaiter |
| 6 | Track rod |
| 7 | Thrust piece |
| 8 | Signal and power lead for steering torque sensor |
| 9 | EPS control unit |
| 10 | Electric motor |
| 11 | Toothed-belt drive (part of reduction gearing) |
| 12 | Reduction-gear housing |
INDEX EXPLANATION REFERENCE CHART
Note. These components form a preassembled unit (often referred to as "EPS steering rack assembly") that can only be replaced as a complete unit. To do so, the unit has to be disconnected from the tie rods and the lower end of the steering column.
Scheme 4
| Index | Explanation |
|---|---|
| 1 | DSC control module |
| 2 | Steering torque sensor with redundant back-up |
| 3 | Electric motor |
| 4 | Motor position sensor |
| 5 | EPS control unit |
| 6 | DME control unit |
| 7 | Junction box |
| 8 | Fuse in boot (power supply for EPS) |
| 9 | Steering column switch cluster with steering-angle sensor |
| 10 | Instrument cluster |
| 11 | CAS control unit |
INDEX EXPLANATION REFERENCE CHART