Service Manual Owner's manual

SECTION 3 - CHASSIS & TURNTABLE
3-62 – JLG Lift – 3121139
3.8 DRIVE BRAKE, 2WD - MICO (PRIOR TO
S/N 83331)
Disassembly
1. Remove pressure plate (3) from cover plate (16) by
removing cap screws (1) and washers (2).
PRESSURE PLATE IS UNDER SPRING TENSION OF APPROXI-
MATELY 907 KGF (2000 IBS). THE TWO CAP SCREWS MUST BE
LOOSENED EVENLY TO RELIEVE THIS FORCE. IF A HYDRAULIC
PRESS IS AVAILABLE, 1361 KGF (3000 IBS) MINIMUM, THE
PRESSURE PLATE CAN BE HELD IN POSITION WHILE REMOVING
THE CAP SCREWS. COVER PLATE (16) MUST BE SUPPORTED AS
SHOWN IN FIGURE 3-50.
2. Remove case seal (4) from cover plate (16).
3. Remove piston (7) from pressure plate (3).
4. Remove O-ring (5), back-up ring (6), O-ring (8) and
back-up ring (9) from piston (7).
5. Remove stator disc (11), rotor disc (12) and return
plate (13) from cover (16).
NOTE: Not all models use the same number of springs or
spring pattern.
6. Remove dowel pins (15) and springs (14) from cover
plate (16). Record this information for assembly pur-
poses.
7. Remove retaining ring (19) from cover plate (16).
8. Remove shaft (10) by pressing or using a soft mallet
on male end of shaft (10).
NOTE: Cover plate (16) must be supported as shown in FIG-
URE 3-50.
9. Remove retaining ring (20) from cover plate (16) and
press out oil seal (17) and bearing (18) if required.
NOTE: Cover plate (16) must be sup¦ported as indicated in
Figure 3-50.
Assembly
LUBRICATE ALL RUBBER COMPONENTS FROM REPAIR KIT WITH
CLEAN TYPE FLUID USED IN THE SYSTEM.
1. Use an alkaline wash to clean parts before assem-
bly.
2. Press oil seal (17) into cover plate (16) until it is flush
with bearing shoulder. Note direction of seal.
3. Press bearing (18) into position until it bottoms out
on borestep.
NOTE: Cover plate (16) must be supported as indicated in
Figure 1.
4. Install retaining ring (20) in cover plate (16).
5. Press shaft (10) into bearing (18) until it bottoms on
shoulder.
NOTE: Bearing (18) inner race and cover plate (16) must be
supported as indicated in Figure 1 during this opera-
tion.
6. Install retaining ring (19) on shaft (10).
7. Insert dowel pins (15) and springs (14) in cover plate
(16).
NOTE: Be sure to use the same number of springs and
spring pattern as recorded during disassembly.
8. Position return plate (13) on springs (14).
NOTE: Discs (11 & 12) and return plate (13) must remain
dry during installation. No oil residue must be
allowed to contaminate disc surfaces.
9. Install rotor disc (12) and stator disc (13).
10. Install o-ring (5), back-up ring (6), O-ring (8) and
back-up ring (9) on piston (7). Note order of O-rings
and back-up rings. Insert piston (7) into pressure
plate (3).
NOTE: Be careful not to shear o-rings or back-up rings. Be
careful not to scratch or mar piston.
11. Install new case seal (4) in cover plate (16).
12. Position pressure plate (3) on cover plate (16) align-
ing dowel pins (15) with holes in pressure plate.
13. Install cap screws (1) and washers (2) and tighten
evenly to draw pressure plate (3) to cover plate (16).
Torque cap screws 65.1-67.8 N-m (48-50 Ib-ft).
NOTE: A hydraulic press will simplify installation of pressure
plate on cover. Clamp pressure plate in position
while tighten¦ing the cap screws. Cover plate (16)
must be supported as indicated in Figure 3-50.
IF HYDROSTATIC BENCH TESTING IS PERFORMED ON THE
BRAKE ASSEMBLY, RELEASE PRESSURE MUST NOT EXCEED
134.5 BAR (500 PSI).