Komatsu F30791, Shop Manual

Page: 159 / 298

PC27R-8
20-43
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
Do not calibrate the valves when the circuits are
under pressure.
H To perform these adjustments, follow the proce-
dures described in the calibration control section.
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 - Loosen the lock nut (2) and turn 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 100 bar (102 kg/cm
2
).
2 - Lock the nut (2).
Nut: 8.8 w 1 Nm
PC20R-8 PC27R-8
RKPA2280
1
RKP06360
2
3
RKPA2300
1
3
RKP06430
2