JLG 740A, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3-72 – JLG Lift – 3121160
3.17 SWING BRAKE (S/N 0300068040 TO
PRESENT)
Disassembly
1. Remove pressure plate (2) from cover (16) by
removing washer head cap screws (1).
PRESSURE PLATE IS UNDER SPRING TENSION OF APPROXI-
MATELY 907 KGF (2000 LBS.) THE TWO WASHER HEAD CAP
SCREWS MUST BE LOOSENED EVENLY TO RELIEVE THIS FORCE.
IF A HYDRAULIC PRESS IS AVAILABLE, 1361 KGF (3000 LBS.)
MINIMUM, THE PRESSURE PLATE CAN BE HELD IN POSITION
WHILE REMOVING THE WASHER HEAD CAP SCREWS.
2. Remove case seal (3) from cover (16).
3. Remove piston (6) from pressure plate (2).
4. Remove o-ring (4), back-up ring (5), o-ring (7) and
back-up ring (8) from piston (6).
5. Remove stack assembly, consisting of stator disc
(10), rotor disc (11) and return plate (12) from cover
(16).
6. Remove dowel pins (15), springs (13) and spring
retainer (14) from cover (16).
NOTE: Not all models use the same number of springs or
spring pattern. Record this information for assembly
purposes.
7. Remove retaining ring (19) from cover (16).
8. Remove shaft by pressing or using a soft mallet on
the male end of the shaft (9).
9. Remove retaining ring (20) from cover (16) and
press out oil seal (17) and bearing (18) if required.
Assembly
NOTE: 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 (16)until it is flush with
bearing shoulder. Note direction of seal.
3. Press bearing (18) into position until it bottoms out
on borestep.
4. Install retaining ring (20) in cover (16).
5. Press shaft (9) into bearing (18) until it bottoms on
the shoulder. Bearing (18) inner race must be sup-
ported during this operation.
6. Install retaining ring (19) on shaft (9).
7. Insert dowel pins (15), spring retainer (14) and
springs (13) in cover (16).
NOTE: Be sure to use the same number of springs and the
same spring pattern as recorded during disassem-
bly.
8. Position plate (12) on spring (13).
NOTE: Discs (10 & 11) and plate (12) must remain dry dur-
ing installation. No oil residue must be allowed to
contaminate disc surfaces.
9. Install rotor disc (11) and stator disc (10).
10. Install o-ring (4), back-up ring (5), o-ring (7) and
back-up ring (8)on piston (6). Note order of o-rings
and back-up rings. Insert piston (6) into pressure
plate (2).
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 (3) in cover (16).
12. Position pressure plate (2) on cover (16) aligning
dowel pins (15) with holes in pressure plate.
13. Install washer head cap screws (1) and tighten
evenly to draw pressure plate (2) to cover (16).
Torque washer head cap screws 55 ft. lbs. (74.6
Nm).
NOTE: A hydraulic press will simplify installation of pressure
plate on cover. Clamp pressure plate in position
while tightening the washer head cap screws.
IF HYDROSTATIC BENCH TESTING IS PERFORMED ON THE
BRAKE ASSEMBLY, RELEASE PRESSURE MUST NOT EXCEED
137.9 BARS (2000 PSI) UNLESS TWO ADDITIONAL BOLTS ARE
USED FOR SUPPLEMENTAL CLAMPING.