Komatsu PC130-7, Shop Manual

Page: 45 / 342

PC130-7
20-127
TESTING AND ADJUSTING
5. While running the engine at high idling, measure
the pump discharge pressure and PC valve out-
put pressure (servo piston inlet pressure) simul-
taneously.
•
Working mode: A
• Swing lock switch: LOCK (2-stage relief
valve is turned ON and relief pressure is set
high)
• Work equipment, swing, and travel circuits:
Relieve arm circuit by moving arm IN.
a
Method of judgment:
If the pump discharge pressure and PC valve
output pressure (servo piston output pres-
sure) are in the following ratio, they are nor-
mal.
a
If the PC valve or the servo piston is abnor-
mal, the PC valve output pressure (servo pis-
ton inlet pressure) is "the same as the pump
discharge pressure" or "almost 0".
6. After finishing measurement, remove the mea-
suring instruments and return the removed parts.
ADJUSTING
Adjusting PC valve
a
If either of the following phenomena occurs and
the PC valve seems to be defective, adjust PC
valve (3) according to the procedure shown
below.
•
As the working load increases, the engine
speed lowers remarkably.
• The engine speed is normal but the work
equipment speed is low.
a
The figure shows the hydraulic pump seen from
the front side of the machine.
1. Loosen hose fixing (4).
2. Fixing sleeve (5), loosen locknut (6).
3. Turn sleeve (5) to the right or left to adjust the
pump absorption torque.
a
If the sleeve is
•
turned to the right, the pump absorption
torque increases.
• turned to the left, the pump absorption
torque decreases.
a
Limit the turning angle of the sleeve to the
following range.
•
Right turning: Max. 1 turn (360°)
• Left turning: Max. 1/2 turn (180°)
a
Change of servo piston stroke per turn of
sleeve: 1.5 mm
4. Fixing sleeve (5), tighten locknut (6).
3
Locknut: 88 – 113 Nm {9 – 11.5 kgm}
Measured oil pressure Ratio of oil pressure
Pump discharge pressure 1
PC valve output pressure
(Servo piston inlet
pressure)
Approx. 3/5
(1)
TESTING AND ADJUSTING OIL PRESSURE
IN PUMP PC CONTROL CIRCUIT