Service Manual Instruction Manual

SECTION 5 - HYDRAULICS
5-10 – JLG Lift – 3121616
Tower Lift Cylinder Installation
1. With main boom and tower boom positioned and sup-
ported as in Figure 5-1., Boom Positioning and Support,
Cylinder Repair, place tower lift cylinder in position on
turntable. Secure in place using slings.
2. Align holes in turntable and lift cylinder. Install cylinder
barrel pin using a suitable rubber mallet. Install keeper
pin and bolt.
3. Connect auxiliary power source to cylinder. Extend cyl-
inder rod until cylinder rod bushing aligns with bush-
ings on boom.
4. Drive rod attach pin through aligned bushings using an
appropriate brass drift. Secure pin with attaching hard-
ware.
5. Remove caps from cylinder hydraulic lines. Install lines
to cylinder as previously tagged.
6. Remove boom prop and overhead crane. Activate
hydraulic system.
7. Operate boom functions following all applicable safety
precautions. Check for correct operation and hydraulic
leaks. Secure as necessary.
8. Check fluid level of hydraulic tank. Adjust as needed.
Tower Telescope Cylinder Removal
1. Place machine on a flat and level surface, with main
boom horizontal. Shut down engine and prop boom See
Figure 5-3., Telescope and Lift Cylinder Installation.
2. With aid of an assistant, manually override Plunger Valve
with a pry bar. From Ground Control, using auxiliary
power, extend tower telescope to access fly attach pin.
3. Remove lower cover plate.
4. Remove mounting hardware securing powertrack to
tower boom assembly. Slide powertrack back to move
holes and wiring harness for access to telescope cylin-
der.
5. Tag, disconnect, and cap hydraulic hoses to Tower Tele-
scope Cylinder. Plug cylinder ports.
6. Remove mounting hardware securing upper cylinder
pin to fly boom. Drive out cylinder rod pin using a suit-
able brass drift.
7. Remove mounting hardware attaching retaining plates
to base boom. Remove plate.
8. Carefully slide telescope cylinder from boom. Place cyl-
inder on a suitable work area.
Tower Telescope Cylinder Installation
1. With boom positioned as in Figure 5-3., Telescope and
Lift Cylinder Installation, slide telescope cylinder into
boom, aligning cylinder port block end with slotted
holes in Base Boom. Secure telescope cylinder with
mounting hardware.
2. Remove caps and plugs from hydraulic lines and ports.
Connect hydraulic lines to cylinder as tagged during
Removal. Reinstall cover plate.
3. Start engine. With aid of an assistant, manually override
the plunger valve. Activate Tower telescope out to align
attaching pin holes in Fly Boom. Shut down engine.
4. Using a brass drift, drive in the attach pin. Secure in
place with mounting hardware.
5. Align holes in base boom and powertrack. Secure the
powertrack with mounting hardware.
6. Remove boom prop and overhead crane. Activate
hydraulic system.
7. Using all applicable safety precautions, operate boom
functions. Check for correct operation and hydraulic
leaks. Secure as necessary.
8. Check hydraulic tank fluid level. Adjust as needed.