86
1-steering gear case; 2-nut; 3,10-bearings; 4-packing rings; 5-slide valve body; 6-back pressure valve; 7-
ball; 8-distributor unit case; 9-bushing; 11,20-shim washers; 12-sleeve; 13-retaining ring; 14-ring; 15-
shaft; 16,23-pins; 17-torsion bar; 18-packing ring; 19-cap; 21-rams; 22-slide valve; 24-screw;
а
-groove for
the service fluid intake from the pump; b-groove for the service fluid removal from the pump;
с
,d-grooves
for the service fluid intake (off take) to/from the booster unit cavities;
е
,
к
,f-circular grooves; m,n-bores for
the connection of the casing cavities and the distributor unit cap with the drainage piping; t-clearance
Fig. 62. Hydraulic steering booster distributor unit
5.4.1.4 Steering operation. With the truck’s direct movement when there is no steering
effort on the steering wheel, the slide valve is in the neutral position in the casing.
The service fluid from the pump goes to the middle groove «
е
» (see Fig. 62). In this posi-
tion of the slide valve the grooves «
е
», «k» and «f» are interconnected, the oil fills the grooves
and the reaction chambers, goes from the distributor valve through the boundary grooves «k» and
«f» and the groove «b», then it is poured into the oil tank. With the steering turn to the right, e.g.,
the bushing 9 with the slide valve 22 fixed on it offsets to the left affected by the threaded joint (in
the direction of the steering unit).
At the beginning of the movement when the pressure in the hydraulic system is not high,
the steering effort on the steering wheel is basically created by the torsion bar twist which directly
affects the shaft 15. The threaded joint moves the slide valve and bears nearly no load. When the
slide valve whose travel is limited by the clearance «t» in the splined joint, moves, the service
fluid supply to the circular groove «f» shuts off. The fluid is pumped to the middle groove «
е
»,
then through the groove «d» in the casing and along the piping to the head end of the booster unit
21 (see Fig. 60).
The effort from the booster unit is transferred to the steering knuckle lever of the front
steerable axle. The wheels are turned to the right.
From the rod end of the booster unit the fluid is delivered in the pipelines through the
groove «
с
» (see Fig. 62) of the distribution unit to the circular groove «k» and further through the
groove «b» to the tank.
When the wheel turn resistance is increased, the pressure in the hydraulic system as well
as in the reaction chambers rises. It creates proportional effort on the steering wheel.
