JLG 534D-10 - Manual (Page 52)

Boom
3.24 534D-9, 534D-10 & 544D
4. Loosen and remove the front wear pads and
supports from the third boom section. Tag each pad,
backing plate, shim and bolts from each location.
5. Carefully pull the fourth boom section out of the third
boom section, taking care to protect the chains.
6. Disconnect the chains when the boom sections are
free from each other.
7. Place the fourth boom section on suitable supports.
Note: Before reassembly of the boom, check the bores,
pins and bushings for damage. Repair as needed. Also
check the diameters of the pins and bushings.
3.10.7 Hydraulic Sub-Assembly
The hydraulic sub-assembly locates primarily in the
fourth boom section. It is fastened to the bottom of the
fourth boom section and at the rear of the third boom
section. It’s function is to control hose (and optional
electric cable) movement as the boom sections extend
and retract.
Components on the left side of the assembly control the
tilt cylinder of the machine. Components on the right side
of the assembly control the auxiliary and electric options
on the machine.
As the boom extends or retracts, the hydraulic carrier
(fastened to the bottom of the fourth boom section moves
to the front or rear of the hydraulic carrier fastened to the
back of the third boom section. The moveable hose
carrier rolls forward or backward, protecting the looped
hoses as they extend and retract.
a. Hydraulic Sub-Assembly Removal
1. Remove the guide bracket from the front of the
hydraulic sub-assembly.
2. Install a sling on the hydraulic sub-assembly at the
rear of the boom. Slowly pull it loose from the bottom
bracket located on the bottom plate of the fourth
boom section.
3. When the sub-assembly is approximately 25% free
of the boom, fasten the two hose carriers together
(using nylon tie-wraps or nylon straps) to keep them
from separating.
Note: Do Not wrap the hose carrier since it will not
prevent the two hydraulic carriers from moving apart
sideways.
4. Continue to withdraw the sub-assembly, fastening
the hydraulic carriers together (using nylon tie-wraps
or nylon straps) to keep them from separating.
5. When the hydraulic carrier is 75% tied together, pull
the assembly free of the boom and set on suitable
supports.
Note: Hydraulic and Electrical Options
Hoses and electric cables for options are installed on the
right hand side of the sub-assembly per installation for
the standard machine.
The electrical cable for that option should be centered
between the hydraulic hoses as they pass through the
hose carrier. The electric tubing is mounted above the
hydraulic tubing. To prevent excessive cable movement,
the cable should be well tensioned at assembly.
b. Hydraulic Sub-Assembly Installation
1. Clean and lubricate the inside of the boom sections
where the hydraulic sub-assembly rides.
2. Install the guide bracket.
3. Collapse the hydraulic sub-assembly fully.
4. Fasten both hydraulic carriers together using nylon
tie-wraps or nylon straps.
5. Using a sling, lift the balanced hydraulic sub-
assembly and slowly insert it into the fourth boom
section.
6. As the first tie-wrap nears the boom, remove the tie-
wrap and continue inserting the sub-assembly and
removing each tie-wrap until the sub-assembly is
fully inserted.
Note: Be certain the hydraulic sub-assembly locks in
place on the pin bracket at the bottom of the fourth boom
section.
7. Re-connect the hydraulic hoses and any optional
circuits.
8. Re-install the guide bracket.
Note: Use a long threaded rod and nuts (3/8x16) to aid
in pulling the guide bracket into place if it protrudes too
far from the back of the boom.
9. Reinstall the hose take-up compression spring.
Torque the jam nut to 100 lb-ft (135 Nm). There
should be 1 in. (25 mm) from the back of the jam nut
to the end of the threads on the hose take-up
weldment.