Zoomlion ZT20J, Service And Maintenance Manual

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5- 6
a. Adjust the posture of the boom and the jib to the level.
b. Mark and disconnect the hydraulic line connecting the leveling cylinder balancing valve, collect the
hydraulic oil in the pipeline with a suitable container, and seal the port of the pipeline after collecting.
c. Use the appropriate lifting equipment to support the head of the cylinder rod of the leveling cylinder,
disassemble the pin shaft 1 and 2, and remove the jib (Follow the jib removal step).
d. Disassembling the pin 3 fixing the upper leveling cylinder on the telescopic boom.
e. With the assistance of lifting equipment, slowly and carefully remove the upper leveling cylinder
from the telescopic arm to avoid damage from the collision between the leveling cylinder and the
inner cavity of the telescopic arm.
f. Use a suitable plug to block the connector of the upper leveling cylinder balancing valve to prevent
dust and other pollutants from entering the oil line.
5.2.2.2 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.
5.2.2.3 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.
c. Threaded fasteners should be tightened in place according to the torque values in Section 2
Specifications.
5.2.3 Lower leveling cylinder
5.2.3.1 Disassembly