HYDRAULIC POWER STEERING OPERATION DIAGRAM: NEUTRAL POSITION
The hydraulic cylinder (1) is integral part of the hydraulic power steering, The double-acting piston (2) (integral with the rack rod)
slides in the hydraulic cylinder and divides it into two separate chambers A and B.
The power steering is obtained by sending oil under pressure into one of the hydraulic cylinder chambers and discharging it into the
other one. The power generated by the oil pressure on the side surface of the piston causes the movement of the piston and, as
a result, of the rack. The feeding of one of the two hydraulic cylinder chambers occurs when the torque applied to the steering wheel
causes the wrench of the bar; in this condition, the port of the drive shaft and the relevant ports of the distributing valve are joined
depending on the rotary direction of the steering wheel. If the amount of torque applied to the steering wheel does not cause the
wrench of the bar (low wheel resistance), the power steering does not intervene and the steering operates as a mechanical one.
24105
24106
Figure 4
Figure 5
The oil coming from the pump through the joint (3) goes into the distributing valve, circulates in it and returns in the tank through
the joint (4), simultaneously passing through the chambers (2) and (1).
The drive shaft (A), since it is not subject to wrench, is centred with respect to the distributing valve (B) and drives the oil coming
from the pump directly into the tank through the ports (C). The chokes caused by the shaft (A) position with respect to the
distributing valve (B) cause a pressure of ~ 3.5 bar in the right and left chamber through the ports (D) and (E).
HIGH PRESSURE
LOW PRESSURE
12
STEERING GEAR
D
AILY
Base - May 2004