© Mar. 2023
68 AB16EJ Plus Maintenance Manual
HYDRAULIC SYSTEM
7.8 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.
Check Tie Rod of Oscillation Multi-way
Valve
Visually check whether the tie rod of oscillation multi-
way valve is properly tightened.
Test Oscillating Outrigger Function
1. Make sure the boom is in stowed position.
2. Place a 120mm (4.7in) beveled wooden block in
front of the machine.
3. Drive machine to make the right steering wheel
moving onto the wooden block.
4. The auxiliary personnel check the other three
wheels on the ground, and the tires should all be in
close contact with the ground.
5. Drive the machine off the wooden block.
6. Drive machine to make the left steering wheel mov-
ing onto the wooden block.
7. The auxiliary personnel check the other three
wheels on the ground which should all be in close
contact with the ground.
8. Drive the machine off the wooden block.
9. Place a 120mm (4.7in) beveled wooden block in
front of each steering wheel of the machine.
10. Drive machine to make the two steering wheels
moving onto the wooden blocks.
11. The auxiliary personnel check the other two wheels
on the ground which should all be in close contact
with the ground.
7.9 INSPECT CYLINDER DRIFT
The cylinder will drift down due to leakage, and the drift
is normal within a certain range. In order to ensure the
normal operation of the machine, it is recommended to
conduct drift inspection on the platform every 3 months
or after 250 hours of operation to determine whether cyl-
inder drift inspection is required.
Fully extend the main boom and place the rated load on
the platform to measure the drift from the platform to the
ground with the machine powered off. If the platform
drifts down more than 50mm (1.97in) in 10 minutes,
carry out cylinder drift inspection as per the following
procedures.
1. Place the cylinder in an environment with stable am-
bient temperature.
2. Make the cylinder apply normal cylinder load to the
platform.
3. Measure drift at cylinder piston rod with a calibrated
dial indicator.
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