PISTON RIGHTWARDS DISPLACEMENT (open steering limiting valves, very reduced oil pressure)
HYDRAULIC STEERING LIMITING (both steering limiting valves are closed)
T. Right steering limiting valve — U. Left steering limiting valve — V. Right cylinder chamber — W. Left cylinder chamber —
X. Left adjustment screw — B. Piston — Y. Right adjustment screw.
Hydraulic steering limiting
Two valves (T and U) are axially arranged in the piston (B,
Figure 6) for steering limiting. They are equipped with small
spring-loaded pistons, whose stems project from right and left
front piston surfaces.
If the piston is rightwards or leftwards displaced along limit
stop direction, the stems can reach the adjustment screws (X
and Y) in the case and cover, and move. Both limiting valves
remain closed till one of the stems touches the adjustment
screw. If for example the piston is rightward displaced
(Figure 7), the right steering limiting valve (T) is opened by
screw (X) before the piston reaches the limit stop.
In such a way, the pressurised oil being present in the left
operating cylinder chamber can penetrate into its right
chamber, flowing around the displaced valve piston (U) and
through the open right valve (T), and then reach the return
circuit. If the piston is leftwards displaced, the valve (U) is
opened after the pre-established stroke and the pressurised
oil in the right cylinder chamber can flow into the return
cylinder, thereby reducing the pressure into the circuit
chamber.
When the steering limiting valve is open, hydraulic
servoassistance is strongly reduced and the steering wheel can
be rotated only with a higher effort till wheel or drive stop.
27202
27203
Figure 6
Figure 7
E
URO
C
ARGO
T
ECTOR
12-26 t
STEERING
13
Base - February 2003