JLG 660SJ Service Manual - Manual (Page 214)

SECTION 5 - HYDRAULICS
5-4 – JLG Lift – 3121202
10. Align holes in rod end of the telescope cylinder with
holes in push bar. Install push bar pin and secure
with mounting hardware.
11. Align holes in push bar with holes in turntable. Install
push bar pin and secure with mounting hardware.
NOTE: Boom cables must be torqued after installation of the
telescope cylinder. (See Section 4.1, Boom Rope
Torquing Procedures)
Main Boom Lift Cylinder Removal
1. Place the machine on a flat and level surface. Start
the engine and place the main boom in the horizon-
tal position. Shut down engine and prop the boom.
(See Figure 5-1., Boom Positioning and Support,
Cylinder Repair)
2. Remove the hardware retaining the cylinder rod
attach pin to the boom. Using a suitable brass drift,
drive out the cylinder rod attach pin.
3. Using auxiliary power, retract the lift cylinder rod
completely.
4. Disconnect, cap and tag the main boom lift cylinder
hydraulic lines and ports.
5. Remove barrel end attach pin retaining hardware.
Using a suitable brass drift drive out the barrel end
attach pin from the turntable.
6. Remove the cylinder from the turntable and place in
a suitable work area.
Main Boom Lift Cylinder Installation
1. Install lift cylinder in place using suitable slings or
supports, aligning attach pin mounting holes on the
turntable.
2. Using a suitable drift, drive the barrel end attach pin
through the mounting holes in the lift cylinder and
the turntable. Secure in place with the pin retaining
hardware.
3. Remove cylinder port plugs and hydraulic line caps
and correctly attach lines to cylinder ports.
4. Using auxiliary power, extend the cylinder rod until
the attach pin hole aligns with those in the boom.
Using a suitable soft mallet, drive the cylinder rod
attach pin through the boom and lift cylinder. Secure
the pin in place with attaching hardware.
5. Remove boom prop and overhead crane. Activate
hydraulic system.
6. Using all applicable safety precautions, operate the
boom functions. Check for correct operation and
hydraulic leaks. Secure as necessary.
7. Check fluid level of hydraulic tank and adjust as nec-
essary.
5.4 CYLINDER REPAIR
NOTE: The following are general procedures that apply to
all of the cylinders on this machine. Procedures that
apply to a specific cylinder will be so noted.
Disassembly
DISASSEMBLY OF THE CYLINDER SHOULD BE PERFORMED ON A
CLEAN WORK SURFACE IN A DIRT FREE WORK AREA.
1. Connect a suitable auxiliary hydraulic power source
to the cylinder port block fitting.
DO NOT FULLY EXTEND CYLINDER TO THE END OF STROKE.
RETRACT CYLINDER SLIGHTLY TO AVOID TRAPPING PRESSURE.
2. Operate the hydraulic power source and extend the
cylinder. Shut down and disconnect the power
source. Adequately support the cylinder rod, if appli-
cable.
3. If applicable, remove the cartridge-type holding
valve and fittings from the cylinder port block. Dis-
card o-rings.