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Lay-out and principle of operation of the power steering system.

System of steering control with the hydraulic booster has been developed to assist the more comfortable and precise control over the car in various operative conditions as well as for increasing the movement safety.There are two types of modern passenger car steering systems: rack-and-pinion steering and anglular system.

Each of them can be equipped with the hydraulic boosting.

Design of the SERVOTRONIC system rack and angular hydraulic boosters.

The advantages of the power steering systems in comparison with the unpowered control become speakingly apparent at parking and low speed driving.

There are two types of power steering systems: constant boost ratio systems and the speed-dependent boost ratio (SERVOTRONIC).

Power steering system consists of the following components:

     1. Electronic speedometer (SERVOTRONIC system only).
     2. Electronic control device(SERVOTRONIC system only).
     3. Electrohydraulic converter (SERVOTRONIC system only).
     4. Steering device equipped with the hydrocylinder.
     5. Hydraulic pump.
     6. Oil container.
     7. Low pressure oil-duct.
     8. High pressure oil-duct.

Power steering systems principles of operation.

Power steering systems principles of operation are examined on the rack type steering control sample. Hydraulic liquid from the oil container (6) comes into the hydraulic pump (5), where it is compressed and, further, under the pressure (70 - 180 bars, depending on model) forwards towards the steering device (4) through the high pressure oil-duct.

The steering device is equipped with the flow distribution unit (slides), which has two basic operation modes:

condition reaction of system
No force is being applied to the steering wheel (quiescent state). The feed and drainage oil-ducts are combined in the slide unit. From the high pressure oil-duct the liquid spills over into the oil container (6) without operating.
Rotation of the steering wheel (action).

Depending on the rotation direction, the oil-ducts in the slide device are being commuted correspondingly. The liquid is drawn into the working cylinder under pressure and, bringing pressure to the actuating piston, creates an auxiliary exertion of shift shaft displacement shift (hydraulic press principle). Concurrently, the chamber of the piston reverse side is matching the low pressure oil-duct, through which the liquid is spilt over into the oil container. As soon as the impact onto the steering wheel is discontinued, the system reverts to the neutral position (See phase 1).


Slide device (flow distribution unit).


Working cylinder.

 © PowerSteering 2004
 © Design by IT-Demo