5.1.1. Principle of action of EPS

Electrohydraulic steering with the amplifier reduces effort to the steering mechanism. The hydraulic system works also as well as the system of steering with the amplifier used on other models however is the hydraulic pump with the electric drive its part, independent of the car engine. The control unit and the pump of a hydraulic system make the uniform module and can be replaced only assembled.

The effort from EPS is regulated by the control unit as function of frequency of rotation of the engine and according to the three-dimensional adjusting characteristic of the engine.

On the car two various EPS systems are used.

EPS of production of TRW is used on versions with petrol engines of small power and Z 17 DTL and does not join in system of the tire of CAN. For diagnostics, this system has own line of diagnostics (a conclusion of diagnostics 7). EPS of production of TRW provides two-level, depending on loading, regulation of speed of rotation of the pump (2 speeds). The size of loading is determined by current which the electric motor consumes from electric system of the car.

EPS of production of ZF is used on petrol engines of big power and Z 17 DTH and is connected with HS CAN tire. EPS of production of ZF works depending on the speed and loading and uses two various adjusting cards. The corresponding traffic conditions are determined by car speed as function of shift of a steering wheel, and servousily steering decreases at increase in speed of the movement. On cars with the sports chassis, the second adjusting card can be made active by the button of inclusion of the sports mode.