Komatsu F30791, Shop Manual

Page: 158 / 298

PC20R-8
20-42
TESTING AND ADJUSTMENTS
CONTROL AND REGULATION OF THE PRESSURES
IN THE HYDRAULIC CIRCUITS
Valve adjustment
H The unloading valve cannot be re-adjusted, only sub-
stituted.
1. Adjustment of the main relief valve
If the pressures measured for the working equipment
and machine travel do not fall within normal values,
adjust the main relief valve (1) as follows:
2 - Loosen the lock nut (2) and rotate the adjusting
screw (3).
.
To INCREASE pressure, turn in a CLOCK-
WISE direction.
.
To DECREASE pressure, turn in a COUN-
TER-CLOCKWISE direction.
H Each turn of the adjusting screw (3) varies the
pressure by about 125 bar (128 kg/cm
2
).
3 - Lock the nut (2).
Nut: 59 w 10 Nm
H After adjustment, check the adjustment of the
main relief valve with the same procedures as
used for the measurements.
2. Adjustment of the safety valve of the swing mo-
tor
If the pressures measured for the swings to the right
and to the left do not come within the normal values,
adjust the safety valve (1) of the swing motor as fol-
lows:
1 - Remove the cap nut (2).
2 - Loosen the lock nut (3) and turn the adjusting
screw (4).
.
To INCREASE pressure, turn in a CLOCK-
WISE direction.
. To DECREASE pressure, turn in a COUN-
TER-CLOCKWISE direction.
3 - Lock the nut (3) and replace the cap nut (2).
H After the adjustments, check the setting of the
safety valves following the same procedure used
for the measurements.
PC20R-8 PC27R-8
RKPA2280
1
RKP06360
2
3
RKPA2290
1
1
RKP04920
2 3
4