Rover DEFENDER 300Tdi, Workshop Manual

Page: 216 / 450

STEERING
3 DESCRIPTION AND OPERATION
Rotary valve operation
Rotary valve at neutral
The rotary valve assembly comprises a worm (1),
valve sleeve (2), input shaft (4) and torsion bar (5).
The valve sleeve is retained inside the worm by a trim
screw (3), and incorporates valve ports in its inner
bore. The input shaft is attached to the steering wheel
via a steering shaft and steering column and
incorporates valve ports in its outer diameter to align
with those in the sleeve.
The torsion bar, which is secured to the worm and
input shaft with pins (6) at each end, holds the valve
ports in neutral alignment when there is no demand
for assistance.
No demand for assistance (Valve at neutral)
When there is no demand for assistance the torsion
bar holds the input shaft and sleeve valve ports in
neutral relationship to one another, allowing equal
pump pressure (A) to both sides of the piston/rack (9).
Any excess fluid flow from the pump returns to the
reservoir via (B).