Releasing Residual Pressure In Hydraulic Circuit - Komatsu PC130-7 Shop Manual

TESTING AND ADJUSTING
RELEASING RESIDUAL
PRESSURE IN HYDRAULIC
CIRCUIT
1. Releasing residual pressure in hydraulic tank
k Since the hydraulic tank is enclosed and
pressurized, release the residual pressure
in it when removing a hose or a plug con-
nected to it.
1) Lower the work equipment to the ground in a
stable position and stop the engine.
2) Loosen oil filler cap (1) of the hydraulic tank
gradually to release the air in the tank.
a If you open the pump room cover, you
can loosen the oil filler cap from the right
side of the machine.
2. Releasing residual pressure in hydraulic cyl-
inder circuit
k When disconnecting a pipe between a
hydraulic cylinder and the control valve,
release the residual pressure in the piping
according to the following procedure.
1) Release the residual pressure in the hydrau-
lic tank. For details, see RELEASING
RESIDUAL PRESSURE IN HYDRAULIC
TANK.
a Keep the oil filler cap of the hydraulic
tank removed.
2) Turn the starting switch ON and set the
safety lock lever in the FREE position, and
then operate the work equipment control
levers on both sides forward, backward, to
the right, and to the left.
a The control valve is operated by the
pressure in the accumulator. The pres-
sure in the accumulator is used up, how-
ever, after the control valve is operated 2
– 3 times.
3) Run the engine at low idling for 10 seconds
to heighten the pressure in the accumulator.
20-142
(1)

RELEASING RESIDUAL PRESSURE IN HYDRAULIC CIRCUIT

4) Repeat steps 2) and 3) above 2 – 3 times,
and the residual pressure in the piping is
released completely.
3. Releasing residual pressure in swing motor
circuit
a The residual pressure in the swing motor cir-
cuit can be released by performing the oper-
a t i o n
PRESSURE IN HYDRAULIC CYLINDER
CIRCUIT (Operate the lever in the swing
direction only, however).
4. Releasing residual pressure in travel motor
circuit
a Since the control valve spool of the travel
motor circuit is open, the pressure in this cir-
cuit can be released by performing RELEAS-
I N G
HYDRAULIC TANK.
f o r R E L E A S I N G R E S I D U A L
R E S I D U A L P R E S S U R E I N
PC130-7