JLG 4017PS Service Manual - Manual (Page 50)

Boom
3-12 3706PS, 3707PS, 4014PS, 4017PS, 33.7, 37.6, 37.7
3.6.1 Boom Removal
While the boom sections can be separated from each
other on the machine, it is much safer, more efficient and
more cost- effective to remove the complete boom
assembly from the machine and place it on suitable
supports for separation. Work can then progress at a
normal working height.
Note: When removing a complete boom assembly use
a hoist or crane with a minimum lift capacity of 6000 lbs.
1. Remove any attachment from the quick coupler
assembly. Refer to Operation & Safety Manual.
2. Park the machine on a hard, level surface, fully
retract the boom, raise the boom assembly to
access lift/lower cylinder pin, place the transmission
control lever in (N) NEUTRAL, engage the park
brake and shut the engine OFF.
3. Place a Do Not Operate Tag on both the ignition key
switch and the steering wheel.
4. Open the engine cover. Allow the system fluids to
cool.
5. Remove boom angle sensor arm. Refer to Section
9.12.7, “Boom Angle Sensor.”
6. Properly disconnect the battery.
7. Place a sling around the first boom section at the
balance point.
8. Take the weight off the boom assembly.
9. Label, disconnect and cap all hydraulic hoses
attached to the tubes on the bottom of the boom.
Cap all fittings and openings to keep dirt and debris
from entering the hydraulic system.
10. Label, disconnect and cap any electrical cables if
equipped.
11. Remove the pin from the rod end of each
compensation cylinder being careful not to drop the
cylinder. Lower each cylinder to a secure position.
12. Remove the pin from the rod end of the lift/lower
cylinder being careful not to drop the cylinder. Lower
the cylinder to a secure position.
13. Confirm that the boom assembly is balanced with
the sling and remove the boom assembly pivot pin.
14. Lift the boom assembly from the machine and lower
onto suitable supports
3.6.2 Second and Third Boom Section
Removal
1. Set the complete boom on level ground and by
repositioning the slings turn boom over on to the top
side. Set the complete boom on suitable stands to
begin tear down.
Note: With the complete boom setting upside down, the
removal and replacing of each boom section, tilt cylinder,
hoses, extend and retract chains and extend/retract
cylinder are made much easier.
2. Label, disconnect and cap the tilt circuit hoses from
the tilt cylinder at the front of the third boom section.
Label, disconnect and cap the auxiliary circuit hoses
from the quick disconnect fittings at the front of the
third boom section. Cap all fittings and openings to
prevent dirt and debris from entering the hydraulic
system.
3. Place a sling around the tilt cylinder and remove the
retaining rings and pin at the barrel end of the tilt
cylinder. Remove tilt cylinder.
4. Remove all wear pads, shims and backing plates
from the front inside of the first boom section. Label
and tag each set of wear pads being removed.
5. Disconnect both tilt hoses and (if equipped) both
auxiliary hoses (1) at the bottom of the first boom
section.Plug the hose ends and cap the tube ends to
prevent dirt and debris from entering the hydraulic
system. Pull the disconnected hoses from the rear of
the boom.
6. Loosen and remove the lock nut and jam nut (2) on
the retract chain at the front of the first boom section.
MAM0690
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