JLG 600SC_660SJC Service Manual - Manual (Page 150)

SECTION 5 - HYDRAULICS
5-6 – JLG Lift – 3121607
Main Boom Lift Cylinder Removal
1. Place machine on a flat and level surface. Start engine
and place main boom in horizontal position. Shut down
engine and prop boom. (See Figure 5-1., Boom Position-
ing and Support, Cylinder Repair)
2. Remove hardware retaining cylinder rod attach pin to
boom. Using a suitable brass drift, drive out cylinder rod
pin.
3. Using auxiliary power, retract the lift cylinder rod com-
pletely.
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 sup-
ports, aligning attach pin mounting holes on the turnta-
ble.
2. Using a suitable drift, drive barrel end attach pin
through mounting holes in lift cylinder and turntable.
Secure in place with pin retaining hardware.
3. Remove cylinder port plugs and hydraulic line caps and
correctly attach lines to cylinder ports.
4. Using auxiliary power, extend cylinder rod until attach
pin hole aligns with those in the boom. Using a suitable
soft mallet, drive cylinder rod attach pin through the
boom and lift cylinder. Secure pin in place with attach-
ing hardware.
5. Remove boom prop and overhead crane. Activate
hydraulic system.
6. Using all applicable safety precautions, operate boom
functions. Check for correct operation and hydraulic
leaks. Secure as necessary.
7. Check fluid level of hydraulic tank. Adjust as necessary.
5.5 CYLINDER REPAIR
NOTE: Following are general procedures that apply to all cylin-
ders on this machine. Procedures that apply to a specific
cylinder are noted.
Disassembly
CYLINDER DISASSEMBLYSHOULD BE PERFORMED ON A CLEAN WORK SURFACE
IN A DIRT FREE WORK AREA TO PREVENT CONTAMINATION.
1. Connect a suitable auxiliary hydraulic power source to
cylinder port block fitting.
DO NOT FULLY EXTEND CYLINDER TO END OF STROKE. RETRACT CYLINDER
SLIGHTLY TO AVOID TRAPPING PRESSURE.
2. Operate hydraulic power source and extend the cylin-
der. Shut down and disconnect power source. Ade-
quately support cylinder rod, if applicable.
3. If applicable, remove cartridge-type holding valve and
fittings from cylinder port block. Discard O-rings.