JLG M4069 ANSI Service Manual - Manual (Page 57)

SECTION 3 - CHASSIS & SCISSOR ARMS
3121122 – JLG Lift – 3-29
3.9 DRIVE BRAKE - MICO
Disassembly
1. After removing the brake from its installation, place
brake on a clean dry work bench with mounting
plate uppermost.
2. Remove pressure plate (3) from cover (21) by
removing cap screws (1) and washers (2).
PRESSURE PLATE IS UNDER SPRING TENSION OF APPROXI-
MATELY 680 KG (1500 LB). THE FOUR CAP SCREWS SHOULD BE
LOOSENED EVENLY TO RELIEVE THE FORCE. IF A HYDRAULIC
PRESS IS AVAILABLE, 3000 LBS (1361 KGF) MINIMUM, THE
PRESSURE PLATE CAN BE HELD IN POSITION WHILE REMOV-
ING THE CAP SCREWS AND WASHERS.
3. Remove case seal (4) from cover (21).
4. Remove piston (7) from pressure plate (3).
5. Remove o-rings (5, 8) and back-up rings (6, 9) from
piston (7).
IF THE SENSOR RING (12) IS DAMAGED OR NEEDS REPLACED,
THE ENTIRE BRAKE MUST BE REPLACED AS A UNIT. THE SEN-
SOR RING IS NOT AVAILABLE AS A SERVICE PART.
6. Remove stack assembly, consisting of stator disc
(11), sensor ring (12), rotor disc (13), and plate (14)
from cover (21).
7. Remove dowel pins (20), springs (15), and spring
retainer (16) from cover (21).
NOTE: Not all models use the same number of springs or
spring pattern. Record this information for reassem-
bly purposes.
8. Remove retaining ring (17) from cover (21).
9. Remove shaft (10) by pressing or using a soft mallet
on male end of shaft (10).
10. Remove retaining ring (19) and bearing (18) from
shaft (10).
11. Press rotary oil seal (22) from cover (21).
Assembly
NOTE: Lubricate all rubber type components from repair kit
with clean type fluid used in the system.
1. Clean all parts thoroughly before assembly.
2. Press new rotary oil seal (22) into cover (21) taking
note to direction of seal.
3. Install new bearing (18) and retaining ring (19) on
shaft (10).
4. Install shaft assembly and retaining ring (17) in
cover (21).
5. Install dowel pins (20), spring retainer (16) and
springs (15) in cover (21).
NOTE: Be sure to use the same number of springs and
spring pattern as recorded during disassembly.
6. Position plate (14) on springs (15). Hole in plate (14)
must line up with hole in cover (21).
NOTE: Discs
(13, 11) and plate (14) must remain dry during
installation. No oil residue must be allowed to con-
taminate disc surfaces.
7. Press sensor ring (12) on rotor disc (13). Place a
new rotor disc (13) on shaft (10) until it contacts
plate (14). Install stator disc (11).
8. Install new o-rings (5, 8) and new back-up rings (6,
9) on piston (7). Note order of o-rings and back-up
rings. Insert piston (7) into pressure plate (3). Be
careful not to shear o-rings or back-up rings.
9. Install new case seal (4) in cover (21).
10. Position pressure plate (3) on cover (21) aligning
dowel pins (20) with holes in pressure plate.
11. Install cap screws (1) and washers (2) and tighten
evenly to draw pressure plate (3) to cover (21).
Torque cap screws to 55 lb ft (74.6 NM).
NOTE: A hydraulic press will simplify the installation of the
pressure plate. Clamp pressure plate in position
while tightening the cap screws.
IF HYDROSTATIC BENCH TESTING IS PERFORMED ON THE
BRAKE ASSEMBLY, RELEASE PRESSURE SHOULD NOT EXCEED
2000 PSI (137.9 BAR) UNLESS TWO ADDITIONAL BOLTS ARE
USED FOR SUPPLEMENTAL CLAMPING.
Bleeding
I
1. Install brake in system and connect pressure lines.
2. Bleed pressure release section of brake by pressur-
izing side inlet port and allowing air to escape from
top port. Pressure should not exceed 100 psi (6.9
bar) during bleeding.
3. Apply sufficient pressure to release brake and check
for proper operation in system.
NOTE: If damaged, replace the input and output gaskets
before assembling the brake to the hub and motor.
(See Figure 3-13. and Figure 3-16.)