JLG 120-SXJ ANSI Service Manual - Manual (Page 76)

SECTION 5 - HYDRAULICS
5-4 – JLG Lift – 3121105
Lift Cylinder Removal
1. Place the machine on a flat and level surface. Start
the engine and place the boom in a horizontal posi-
tion. Shut down the engine and attach a suitable
support device to the boom.
2. Tag, disconnect and cap the lift cylinder hydraulic
lines and ports.
3. Remove the bolt, flatwasher and lockwasher secur-
ing the cylinder rod attach pin retaining plate to the
boom.
4. Remove the two bolts and two lockwashers securing
the pin retaining plate to the pin. Using a suitable
brass drift drive out the cylinder rod attach pin.
5. Using auxiliary power, retract the lift cylinder rod
completely.
6. Remove the barrel end attach pin retaining plate and
hardware. Using a suitable brass drift drive out the
barrel end attach pin from the upright.
7. Remove the cylinder from the boom and place in a
suitable work area.
Lift Cylinder Installation
1. Install lift cylinder in place using suitable slings or
supports, aligning attach pin mounting holes on the
upright.
2. Using a suitable drift, drive the barrel end attach pin
through the mounting holes in the lift cylinder and
the upright. Secure in place with the pin retaining
plate and 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 drift, drive the cylinder rod attach
pin through the aligned holes, taking care to align
the grooved pin holes. Secure the pin in place with
the bolt, lockwasher and nut.
5. Place boom in the stowed position and shut down
engine. Check hydraulic fluid level and adjust
accordingly.
Master Level Cylinder Removal
1. With the main boom positioned to horizontal and
properly supported, prepare to remove the upright
level cylinder.
2. Remove the bolt, lockwasher and nut securing the
level cylinder rod attach pin to the tower boom.
Using an appropriate brass drift, drive out the level
cylinder rod attach pin.
3. Tag, disconnect and cap hydraulic lines to level cyl-
inder.
NOTE: When disconnecting hydraulic lines, any residual
hydraulic fluid should be drained into a suitable con-
tainer.
4. Make up two temporary hose assemblies (3/8 In. x
10 ft.) to carry power from the turntable swing motor
supply hoses to the lift cylinder. Couple temporary
hoses to swing motor supply hoses, using reducer
fittings if necessary. Plug ports in swing motor.
5. After installing temporary hoses, activate swing func-
tion, using auxiliary power, to fully retract level cylin-
der rod.
6. Remove temporary hoses from level cylinder and
cap them. Plug cylinder ports.
7. Using slings, restrain level cylinder.
8. Remove retaining plate and bolts from upright cylin-
der attach pin.
9. Using an appropriate brass drift, drive out the
upright attach pin. Carefully remove restraining
slings and remove level cylinder from boom.
Master Level Cylinder Installation
1. With the boom positioned at horizontal and properly
supported, place the master level cylinder in posi-
tion on the boom and secure in place using slings.
2. Align barrel end bushing with pin attach blocks in
turntable upright and install upright attach pin using
appropriate brass drift. Secure pin with retaining
plate and retaining plate bolts.
3. Remove caps from temporary hydraulic lines and
attach to level cylinder ports. Using auxiliary power,
activate swing function and extend cylinder rod until
rod bushing aligns with boom lift cylinder rod end
attach bushing.
4. Using an appropriate brass drift drive the rod attach
pin through the aligned bushings of the cylinder rod
and boom lift cylinder rod end attach plate, taking
care to align holes for bolt attachment. Secure rod
end attach pin with bolt, lockwasher and nut.
5. Remove restraining slings from level cylinder.
6. Remove temporary hydraulic lines from cylinder
ports and turntable swing motor hydraulic supply.
Reattach hydraulic supply to swing motor.
7. Remove caps from cylinder hydraulic lines and cor-
rectly install lines to cylinder.
8. Remove boom support. Place boom in stowed posi-
tion. Check hydraulic fluid level and adjust accord-
ingly.