Detection of the natural descending part of the excavator working device
(Arm Boom Bucket cylinder)
If
the excavator working device (cylinder) has a natural drop, check and determine
if the cylinder seal is damaged or if there is an internal leak in the main
valve.
1,
check the cylinder seal
(1)
Check the boom and bucket cylinders:
1.
Adjust to the same state as when measuring the natural drop, and the engine is
turned off.
2.
Operate the boom lever to the lift position and operate the bucket lever to the
bucket lift position.
A.
If the speed of the increase is increased, the cylinder is poorly sealed.
B.
If there is no change, the boom holding valve (boom) or the main valve (the
spool of the control boom and the bucket) is faulty.
2) Check
the arm cylinder:
1
The arm cylinders are all retracted and the engine is turned off.
2
Operate the joystick to the stick digging position.
A.
If the descending speed increases, the cylinder is poorly sealed.
B.
If there is no change, the main valve (the spool of the control stick) is
damaged.
2.
Check of the boom retaining valve
(1)
Adjust the working device to the maximum radius, and the top of the boom is
level, then turn off the engine; lock the safety lock lever to release the
pressure in the hydraulic tank.
(2)
Remove the pilot hose of the boom retaining valve. If the open port leaks oil,
it can be judged that the boom retaining valve is faulty.
3.
Check the PPC valve
When the engine is running and the safety lock lever is in the locked position or released, the natural drop amount is different, and the PPC valve is faulty.
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