Releasing Residual Pressure From Hydraulic Circuit - Komatsu PC130-8 Shop Manual

SEN04114-06
Releasing residual pressure from
hydraulic circuit
1. Releasing residual pressure from hydraulic
tank
Since the hydraulic tank is enclosed
and pressurized, release the residual
pressure from it when removing a hose
or a plug connected 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.
2. Releasing residual pressure from hydrau-
lic piping
When disconnecting a pipe between a hydrau-
lic cylinder and the control valve, release the
remaining pressure from the piping according
to the following procedure.
Without anti-drop valve
1) Lower the work equipment to the ground
and release the remaining pressure in the
hydraulic tank. For details, see "Release
remaining pressure in hydraulic tank".
a Leave the oil filler cap of the hydraulic
tank removed.
2) Turn the starting switch to ON position, set
the work equipment lock lever to FREE
position, and operate the right and left
work equipment control levers forward
and backward, and to the right and left.
a The work equipment is operated by
the pressure in the accumulator.
Pressure in the accumulator is lost by
operating the work equipment 2 or 3
times.
3) Set the work equipment lock lever to
LOCK position, start the engine, and run it
with the fuel control dial at MIN (Low idle)
position for approximately 5 seconds to
increase the pressure in the accumulator.
50
4) Repeat step 2 and 3 several times, and all
remaining pressure is released from the
1
piping completely.
With anti-drop valve of boom
k
Place the machine on a level ground.
1) Check the function of PPC accumulator
1] Retract arm cylinder and bucket cylin-
der to the stroke ends, and hold the
work equipment at height (a) above
the ground.
a: 1.5 m
2] Keep the arm cylinder and bucket cyl-
inder retracted to the stroke ends,
turn the starting switch to OFF posi-
tion, and stop the engine.
3] Turn the starting switch to ON posi-
tion.
4] Set the work equipment lock lever in
FREE position.
5] Check that the work equipment is
lowered to the ground by slowly oper-
ating the work equipment control
lever to the boom LOWER direction
fully to the stroke end.
a If the work equipment is lowered
a Pressure of accumulator drops
30 Testing and adjusting
under its weight to the ground,
the accumulator is normal.
gr adu ally a fte r stop ping th e
engine. Be sure to perform this
PC130-8