Electromechanical Power Steering (EPS) (Ver. 1): Notes
The difference between electromechanical power steering (EPS) and conventional hydraulic steering lies in the type of steering servo assist. EPS assists the driver using an electrical servomotor instead of a hydraulic pump. The servomotor is only activated during steering wheel movements. This means the steering uses no power during straight-ahead driving.
Electromechanical power steering offers the following advantages:
- lower steering forces on parking
- Integrated, vehicle speed dependent steering servo (Servotronic):
Ordered as optional equipment or can be enabled after handover to the customer by the dealer organization using the enabling code.
- lower bumpiness when cornering as well as lower steering wheel vibrations
- active steering wheel return
- Fuel economy 1 to 2 % and thus lowering of the CO2 emission
- no hydraulic fluid necessary
The electromechanical power steering is also available for the first time as variable sport steering (optional equipment SA2VL) with integrated Servotronic. As opposed to with the basic version of the EPS, the more direct steering gear ratio results in a smaller required steering angle. The vehicle subsequently responds more directly and exhibits increased agility. This is of particular benefit for avoidance maneuvers, for example.
The variable steering gear ratio is realized through a stroke-dependent rack gearing geometry. While directional stability is stable, the steering remains true to the center position of the steering gear. For steering angles away from the center position, the ratio becomes ever more direct.
| Item | Explanation |
|---|---|
| 1 | Rack for basic version of the EPS (constant gearing geometry) |
| 2 | Rack for variable sport steering (variable gearing geometry) |
| A | More indirect steering gear ratio for variable sport steering |
| B | More direct steering gear ratio for variable sport steering |
| x | Steering angle |
| y | Steering gear ratio |