Zoomlion ZT20J, Service And Maintenance Manual

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5- 12
a. The standby power is used to drive the boom lowering function, so that the lifting cylinder is retracted
to the head of the piston rod and can be better supported on the boom support base of the turntable.
With the assistance of lifting equipment, support the end of the luffing cylinder piston rod on the arm
support and protect it.
b. Remove the bolts of the rear link and the front link lock pin. Use lifting equipment to adjust the
boom to release the pin force acting between the boom and the connecting rod.
c. Remove the pin 2 and pin 3 that connect the connecting rod to the boom, slowly and carefully remove
the boom assembly from the turntable and place it on a suitable support.
Extrusion hazard.
If the lifting equipment fails to reliably support the boom assembly, when the pin is removed or
disassembled, the boom may fall and cause personal injury and equipment damage. When removing, keep
personnel away from the area near the boom.
5.2.5.2 Inspection
a. Inspect the shaft pin for wear, scratches, taper, ovality or other damage and replace the pin if
necessary.
b. Inspect the inner ring of the bearing for scratches, distortion, wear or other damage and replace the
bearing if necessary.
c. Inspect all threaded parts for damage such as stretching, thread deformation or distortion and replace
if necessary.
Refer to the Pin and Bearing Inspection Instructions in the Section 3 for pin and bearing
inspection.
5.2.5.3 Installation
a. Follow the reverse steps of disassembly. The interface of the hydraulic pipe joint and balance valve
before installation should be cleaned to prevent contaminants from entering the hydraulic system.
b. A hydraulic system pipe joint equipped with a sealing device needs to replace a sealing device before
the hydraulic line is connected.
Threaded fasteners should be tightened in place according to the torque values in Section 2
Specifications.
5.2.6 Telescopic cylinder
5.2.6.1 Disassembly