Working Principle - Chery automobile Service Manual

1. Torsion Bar
2. Input Shaft
3. Valve Bush

WORKING PRINCIPLE

Middle Position
·When the vehicle moves straight (the steering wheel does not turn), the hydraulic oil
which is supplied by the oil pump enters the oil inlet through the pre-opened
clearance of the rotary valve. As the rotary valve keeps immovable, the hydraulic oil
flows back to the oil reservoir from the return oil inlet. No power is produced
because the oil pressures of the two chambers of the steering gear are same.
Steering Process
·When the steering wheel turns, the clearance of the valve spool between the valve
bush and the input shaft will be changed, so the hydraulic oil which flows to the two
oil chambers forms the oil pressure difference. This difference acts on the piston and
pushes it to overcome the steering resistance and make movements. Therefore, the
steering link assy is moved to realize power steering.
Return Process
·Once the steering is completed, the force on the steering wheel will disappear. As the
effect of the torsion bar elasticity, the input shaft returns to the relative balance
position of the valve bush and the oil pressure difference between the two oil
chambers of the steering gear follows to disappear. And then the vehicle will convert
to straight-line motion by the effect of the vehicle self aligning torque of the front
wheels until it enters the straight-line position.
Road Sense Effect
·The road sense effect is also called the ability of feeling steering. The driver applies
the force on the steering wheel, which also act on the torsion bar of the steering gear
and makes it deform. The amount of deformation which increases as the steering
resistance grows, depends on the wheel steering resistance. Therefore, the driver can
judge the variation of the steering resistance by the force applied on the steering
wheel to obtain the road sense effect.
To Left Chamber
Oil Inlet Return oil inlet
To Right Chamber
N-3
Figure 2