JLG 80HX_HX+6_HXER Service Manual - Manual (Page 79)

SECTION 2 - PROCEDURES
3120863 – JLG Lift – 2-57
10. Remove o-rings (15,17) and back-up rings (14,16)
from piston O.D. and I.D. grooves. Back-up rings will
be damaged and should not be removed if replace-
ment is not planned.
11. Pressure relief valve (23) can be removed and
inspected to assure spring loaded ball moves freely
and is contamination free.
Cleaning and Inspection
1. Clean all parts thoroughly.
2. Closely inspect all parts for excessive wear, cracks,
and chips. Replace parts as necessary.
3. Discard seals and o-rings.
4. Closely inspect bearings and bearing contact sur-
faces. Replace as necessary.
NOTE: Bearings may be reused if, after thorough inspection,
they are found to be in good condition.
Assembly
NOTE: Lubricate all seals, o-rings, cylinder of the power
plate and piston with clean hydraulic oil prior to
assembly.
1. Assemble piston (13) into power plate (21) using a
shop press, being careful not to damage the o-rings
or back-up rings. Visually align the center of the cut-
outs in piston (13) with torque pin (8) holes in power
plate (21). Avoid pushing the piston all the way to
the bottom of the cylinder in the power plate. Try to
keep the top surface of the piston flush to 1/8"(0.32
cm) below the machined surface of the power plate.
2. When pressing the bearing onto the shaft, press on
the inner race of the bearing and support the shaft
properly.
3. Rotating discs must be clean and dry. Worn or
heavily scored rotating discs must be replaced.
4. Press bearings (3) into housing 1. Bearing must be
seated against shoulder in housing.
5. Using a shop press install seal (4) by pressing
evenly around O.D. of seal. Use care to avoid cock-
ing.
6. Install shaft (7) into housing. Support the inner race
of bearing (3) when pressing shaft into bearing.
7. Install gasket 2. Align properly. After installing all the
remaining internal components of the brake, install
bearing (18). Properly support the shaft when press-
ing the bearing onto shaft.
8. Install the power plate sub-assembly. Use a shop
press to evenly lower plate into position. There
should be no gap at the O.D. when the power plate
is properly seated against housing. If a shop press is
not available, use the assembly bolts (22). Tighten
sequentially one turn at a time until the power plate
is properly seated. Torque to 50-60 ft. lbs. (68-81
NM).
9. If replacement of pressure relief valve is necessary,
install 1/2 to 3/4 turns beyond finger tight.
10. Bleed air from brake via bleeder screw.
2.21 DRIVE BRAKE, MICO - MACHINES BUILT
FROM 1992 TO PRESENT
Disassembly
1. Remove end cover (13) from housing (7) by remov-
ing capscrews (12).
END COVER IS UNDER SPRING TENSION OF APPROXIMATELY
2000 POUNDS (907 KG). THE FOUR CAPSCREWS SHOULD BE
LOOSENED EVENLY TO RELIEVE THIS FORCE. IF A HYDRAULIC
PRESS IS AVAILABLE (3000 LBS (1362 KG) MAXIMUM), THE
COVER CAN BE HELD IN POSITION WHILE REMOVING THE CAP-
SCREWS.
2. Remove case seal (11) from housing (7) then
remove bleeder screw (14) from end cover (13).
3. Remove piston (24) from end cover (13).
4. Remove o-ring (20), back-up ring (21), o-ring (18)
and back-up ring (19) from piston (24).
5. Remove separators (10) from housing (7).