Belarus 80.1 Operation Manual page 159

Oil tank is combined oil tank 3 of hydraulic lift linkage (HLL) and hydraulic system of
HSC. Oil filtering is carried out through drain filter 5 (rated filter fineness 25 mcm) installed
in the HLL hydraulic system.
In drain hydraulic line "T" lock valve 2 is installed, intended for control of tractor rear
axle differential lock hydraulic coupling.
The connection between the steering wheel and the steering wheels is carried out
hydraulically by means of oil pipelines and high-pressure hoses connecting dosing pump
4, mounted on steering column, and differential hydraulic cylinder 11, mounted on the FDA
body or front axle.
When you turn the steering wheel to the left or right in dosing pump 4 compression
of the centering plate springs and displacement of the distribution grooves of the spool (the
spool is connected to the shaft of the steering wheel through the splines) relative to the
grooves of the sleeve occurs, as a result, oil from feed pump 7 enters under pressure the
corresponding cavity "R" or "L" of steering cylinder 11 through the dosing gerotor unit of
the dosing pump in the volume proportional to the rotation of the steering wheel, and oil
from the other cavity of hydraulic cylinder 11 enters the drain line "T" through the channels
in the spool and the sleeve and is drained into the oil tank.
When you stop turning the steering wheel the sleeve under action of the centering
plate springs of the dosing pump returns to neutral position relative to the spool, cylinder
hydraulic lines "L" and "R" are locked and oil from pressure hydraulic line "P" enters
through the channels in the spool and sleeve on drain "T", that provides pressure relief in
pressure hydraulic line "P" and relief of feed pump 7.
The locked volume of oil in the cavities of hydraulic cylinder 11 provides stability of
the direction of tractor travel when the steering wheels run-over the unevenness of
the road or soil.
Under normal operating conditions, when feed pump 7 provides the oil pressure re-
quired to turn the guiding wheels, the maximum force applied by the operator to turn the
steering wheel does not exceed 30 N.
If the oil flow from the feed pump is too low or absent (e.g. in case of the diesel en-
gine, feed pump malfunctions, pressure oil pipeline breakage or lack of oil in the tank),
dosing pump 4 acts as a manual pump when the steering wheel is rotated, pumping oil
from one cavity of hydraulic cylinder 11 to the other to ensure that the guiding wheels turn.
The steering force applied by the operator to create the required oil pressure in hydraulic
cylinder 11 during manual operation increases significantly, in some cases up to 600 N.
Table 3.12.1 – Technical characteristics of HSC
HSC parameter designation
Force on steering wheel, N, not more
Steering wheel play, degrees, not more
Speed of steering wheel "slip" in extreme posi-
tions when force of 100 N is applied
Feed pump:
-type
-direction of rotation
-operating volume, cm
Dosing-pump:
-type
-operating volume, cm
-safety valve adjustment pressure, MPa
-anti-shock valves adjustment pressure, MPa
Steering mechanism:
-piston diameter, mm
-rod diameter, mm
-rod stroke, mm
3 /r
3 /r
Parameter value
BELARUS-80.1/82.1
3 r/min, not more
10
gerotor, with open center, without reaction
100
Hydraulic cylinder and steering linkage
50
25
159
80-0000010B OM
BELARUS-820
30
25
gear-type
Left
14
160
14 +1
20 +2
63
30
200