BOOM AND PLATFORM ASSEMBLY
TB20J Plus Maintenance Manual 51
© Feb. 2023
Jib Boom Assembly
• Before loosening or disassembling the hy-
draulic parts (especially the counterbalance
valve on the cylinder), ensure that the hydraul-
ic pressure of all hydraulic lines is released
and that the hydraulic oil is completely cooled
down.
• Disassemble the hydraulic components
slowly to prevent the hydraulic oil from splash-
ing and injuring people.
Remove jib boom assembly
1. Adjust the main boom to horizontal, and remove the
platform assembly.
2. Support the jib boom and upward leveling cylinder
with suitable lifting equipment.
3. Mark and disconnect the hydraulic pipelines on the
jib boom and collect the hydraulic oil in the pipelines
with a suitable vessel. Then seal the pipelines and
ports.
4. Remove the bolt at the pivot pin #7 of the upward
leveling cylinder, and knock out the pivot pin #7 with
a brass rod and mallet.
5. Remove the bolt and nut at the pivot pin #6, and
knock out the pivot pin #6 with a brass rod and
mallet.
6. Slowly remove the jib boom assembly with the aid
of the lifting equipment.
Remove jib boom lift cylinder
1. Support the jib boom lift cylinder with suitable lifting
equipment.
2. Remove the bolt and nut at the pivot pin #3 and
knock out the pivot pin #3 with a brass rod and
mallet.
3. Remove the bolt and nut at the pivot pin #5 and
knock out the pivot pin #5 with a brass rod and
mallet.
4. With the assistance of lifting equipment, slowly re-
move the jib boom lift cylinder from the jib boom.
When disassembling the cylinder, take care to
prevent damage caused by the cylinder falling
and impacting, and also prevent the high-
pressure oil leakage due to impacting.
Inspection
• Inspect the jib boom pivot pin for wear, scratches,
deformation or other damage. Replace the pivot pin
if necessary.
• Check the inner diameter of the pivot pin bearing for
scratches, deformation, wear or other damage. Re-
place the bearing if necessary.
• Check the connecting pin of jib boom lift cylinder for
wear, scratches, deformation or other damage. Be-
fore installation, ensure that the surface of the pin
has received protective treatment. Replace the pin if
necessary.
• Check the inner diameter of the platform swing cylin-
der bearing for scratches, deformation, wear or other
damage. Replace the bearing if necessary.
• Check all threaded parts for elongation, thread defor-
mation, torsion or other damage. Replace the part if
needed.
• Check all structures of the jib boom assembly for de-
formation, cracks, weld separation or other damage.
Replace the structure if necessary.
Installation
Follow the reverse order of the disassembly procedures.
Swing Cylinder
Check the swing cylinder fasteners
The swing cylinder fasteners are essential for the nor-
mal and safe operation of the machine. It is recom-
mended to check the swing cylinder fasteners every 3
months or 250 hours of operation.
1. Make sure the machine is in stowed position. Locate
the swing cylinder at the connection of platform and
boom.
2. Check if the bolts at positions #1 and #2 of the cylin-
der are tightened with the correct torque. Refer to
the Torque Specifications section for the tighten-
ing torques.
3. If any fastener is replaced, make sure to tighten the
fastener with the torque as indicated in the Torque
Specifications section and apply Loctite 272 threa-
dlocking adhesive.
Disassembly
1. Remove the platform assembly.
2. Mark and disconnect the hydraulic pipelines on the
swing cylinder and collect the hydraulic oil in the
pipelines with a suitable vessel. Then seal the pipe-
lines and ports.
3. Support the swing cylinder with suitable lifting
equipment.
4. Remove the fastening bolts and nuts at the pivot
pins #3 and #4 of the swing cylinder.
5. Knock out pivot pins #3 and #4 with a brass rod and
mallet.
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