BOOM RT765E-2 SERVICE MANUAL
4-22
Published 9-04-2014, Control # 422-08
NOTE: Refer to Lift Cylinder, page 2-64 for lift cylinder
Disassembly and Assembly procedures.
Maintenance not requiring removal of the cylinder
barrels, such as packing, may be performed
without removing the cylinders from the turntable.
However, all disassembly and assembly should be
conducted in a clean dust-free area.
Lift Cylinder Removal
1. Extend and set the outriggers and level the crane.
2. Elevate the boom slightly so that the lift cylinder is
extended approximately 1 ft (0.3 m).
3. Ensure the boom is fully supported by placing blocking
or cribbing under the boom. Rest the boom on the
blocking or cribbing.
NOTE: Refer to (Figure 4-3) for removal and installation of
lift cylinder.
4. Attach an adequate lifting/supporting device to the lift
cylinder.
5. Remove the two capscrews and washers, and the stop
plate securing the lift cylinder upper pivot shaft to the
boom.
6. Remove the capscrew and locknut securing the lift
cylinder lower pivot shaft to the turntable.
7. Remove the upper pivot shaft and any attached shims.
Activate the hydraulic system and retract the lift cylinder
enough to clear the upper attach point.
8. Tag and disconnect all the hydraulic lines to the cylinder.
Cap or plug all openings with high pressure fittings.
9. Pull the lower lift cylinder pivot shaft out far enough to
remove the cylinder.
10. Move the lift cylinder to a clean work area.
Disassembly and Assembly
Disassembly and assembly procedures of the lift cylinder
holding valve, and control valve are provided in Telescope
Cylinder Charge Valve Manifold (If Equipped), page 2-58
and Valves, page 2-30 respectively.
Lift Cylinder Installation
1. Attach an adequate lifting device to the lift cylinder and
position the cylinder over the attach fitting on the
turntable.
2. Lower the lift cylinder into the attach fittings on the
turntable and align the lift cylinder bushing with the
attach fitting holes.
NOTE: Install pivot shaft with tapped hole on the right side
of the crane, side opposite the cab.
3. Install the lift cylinder lower pivot shaft and secure with
the capscrew and locknut.
4. Connect the extend and retract hoses to the lift cylinder.
5. Activate the crane’s hydraulic system and align the lift
cylinder rod end with the attach point on the boom.
Install the upper pivot shaft through the cylinder and
boom attach points. Shut down the engine.
6. Shim lift cylinder, as needed, using thrust washer(s) on
each side.
7. Secure the upper pivot shaft with the stop plate,
capscrews and washers.
8. Remove the lifting and supporting devices from the
boom and lift cylinders. Activate the hydraulic system
and check the lift cylinders for proper operation and any
leaks.
9. Lubricate the pivot shafts using grease fittings.
6. Boom will not
lower.
a. Low hydraulic oil. a. Check system for leaks. Make repairs
as needed. Fill reservoir.
b. Main relief valve or circuit relief valve
damaged.
b. Repair or replace relief valve.
c. Worn or damaged hydraulic pump
section.
c. Repair or replace pump section.
d. Broken pump shaft. d. Replace pump shaft and seals.
e. Broken pump drive coupling. e. Replace drive coupling.
f. Broken control valve spool. f. Replace control valve.
Symptom Probable Cause Solution
WARNING
Ensure the lifting device is capable of supporting the
boom assembly. Death or serious injury may result if the
lifting device cannot support the load.
Reference Only
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