JLG 1230ES Service Manual - Manual (Page 112)

SECTION 6 - MAST COMPONENTS
6-12 – JLG Lift – 3121222
Multi-Stage Hydraulic Cylinder - Cylinder Bleeding
Procedure
T H E T H R E E S T A G E C Y L I N D E R M U S T B E B L E D I N T H E
SEQUENCE OF CYL. #1, THEN CYL. #2, THEN CYL. #3.
1. First check that hydraulic oil level is between the
min./max. markings on the side of the pump reser-
voir.
2. In the platform, if necessary, remove the mast cover
from the top of the mast assembly.
3. Place the proper size 90° angled line wrench on the
bleeder valve of cylinder #1. (See Figure 6-3.) for
orientation of bleeder valves.
4. Attach a plastic tube to the bleeder valve on cylinder
#1, use a tube long enough to hang over the side of
the mast assembly and place the loose end into a
container to catch the hydraulic fluid.
5. Power up the machine.
6. Loosen the bleeder valve on the cylinder being bled.
Be certain the other end of the bleeder tube is in the
catch container.
7. Set the platform control station to platform lift mode
and push the joystick to lift the platform. Do not
allow the platform to lift to far off the stowed position,
re-lower and lift again if necessary.
8. Watch the bleeder tube, when a constant flow of oil
(no bubbles) is visible, close the bleeder valve.
9. Remove the bleeder tube and line wrench and move
to the next cylinder in sequence. Repeat steps 6
through 8 until all three cylinders are bleed.
10. It is recommended that the platform be cycled up
and down a few full lifts. Then repeat step 1.
11. Finally repeat steps 6 through 10 again then cylinder
bleeding is completed.
Mast Installation Completion
Once mast is installed and properly bled to remove the air
from the hydraulic lift system, wipe off any excess hydrau-
lic oil from accessible surfaces of the mast and hydraulic
cylinder. If necessary, check the lift system hydraulic pres-
sure setting. Cycle the mast up and down a few times then
check at the top and bottom of the mast for any hydraulic
oil leaks.