HYDRAULIC SYSTEM
TB20J Plus Maintenance Manual 107
© Feb. 2023
8.5 HYDRAULIC OIL HIGH-PRES-
SURE FILTER
It is recommended to replace the hydraulic oil high-pres-
sure filter element after the first 50 hours of operation
and every 3 months or 250 hours of operation thereafter.
The replacement interval should be shorter in harsh
working environments.
1. Turn off the machine.
2. Open the turntable cover and locate the high-pres-
sure filter.
3. Place an appropriate oil-collecting vessel under the
high-pressure filter.
4. Use a wrench to remove the filter housing.
5. Remove the filter element from the housing.
6. Check the seal on the mounting surface of the hous-
ing and, if necessary, replace the seal.
7. Install a new filter element into the housing and
tighten it securely.
8. Clean the hydraulic oil spilled during the process.
9. Start the machine from the ground.
10. Check the high-pressure filter and related compo-
nents for leakage.
8.6 OSCILLATING CYLINDER
EXHAUSTING
Perform oscillating cylinder exhausting before the ma-
chine is put into service for the first time, and after the
oscillating cylinder or counterbalance valve is replaced.
1. Make sure the machine is in stowed position.
2. Place a 120mm (4.7in) beveled wooden block in
front of the machine.
3. Drive machine to make the left front wheel moving
onto the wooden block and then moving off the
wooden block.
4. Drive machine to make the right front wheel moving
onto the wooden block and then moving off the
wooden block.
5. Repeat steps 3 and 4 until the left/right oscillating
cylinders are exhausted successfully.
6. Perform a counterbalance valve locking check.
8.7 OSCILLATION FUNCTION
CHECK
A counterbalance valve locking check shall be per-
formed after oscillating cylinder exhausting. The oscillat-
ing function must be checked every 3 months or 250
hours of operation, or after any system components is
replaced, or when abnormal system operation is found.
Check Counterbalance Valve Locking
It is recommended to check the counterbalance valve
locking before the machine is put into use for the first
time, and every 3 months or 250 hours of operation
thereafter. If any hydraulic component such as oscillat-
ing cylinder or counterbalance valve is replaced later,
the counterbalance valve must also be checked for
locking.
1. Place a 120mm (4.7in) beveled wooden block in
front of the machine.
2. Extend the boom appropriately to place the machine
in operating position.
3. Drive machine to make the left front wheel moving
onto the wooden block.
4. Slowly rotate the turntable about 90° to the right.
5. Then, the reverse position indicator will be on. Move
the corresponding function switch to adjust the
boom horizontal and fully extended.
6. Check the oscillating cylinder: the oscillating cylin-
der on the stressed side shall not retract.
7. Retract the boom completely.
8. After moving the reverse position travel switch, drive
the machine off the wooden block.
9. The auxiliary personnel on the ground check
whether the left front wheel or right rear wheel is still
off the ground and remains raised.
10. Slowly rotate the turntable to the center position (be-
tween two drive wheels).
11. To drive the machine forward or backward, release
the left front wheel oscillating cylinder to make the
wheel descends to the ground and fits tightly with
the ground.
12. Repeat the above steps to check the right front
wheel oscillating cylinder.
13. If the oscillating cylinder works abnormally, ask
qualified maintenance personnel to correct the fault
before further operation.
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