JLG 740A, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3121160 – JLG Lift – 3-17
3.7 DRIVE BRAKE (S/N 83332 TO
PRESENT)
Disassembly
1. Supporting brake on face A:, remove the six socket
head capscrews and washers [Items 13 & 14) In
equal increments to ensure the spring pressure
within the brake is reduced gradually and evenly.
If a press is available, the cylinder housing (8) can
be restrained on face B while removing the six cap-
screws and washers (13 & 14).
The brake assembly can now be fully dismantled
and the parts examined.
2. Remove cylinder housing (8) and piston (9) subas-
sembly and dismantle if required, removing O-ring
seals (15 & 17) and backing rings (16 & 18) as nec-
essary.
3. Remove gasket (7) from housing (2).
4. Remove friction plates (3 & 6) and pressure plate
(4).
5. Remove 2 dowel pins (19).
6. Remove springs (22 & 23).
7. Should it be necessary to replace ball bearing (10)
or shaft seal (12), reverse remainder of brake subas-
sembly, supporting on face C of housing (2).
8. Remove internal retaining ring (11).
9. Using arbor press or similar to break Loctite seal,
remove brake shaft (1) from housing (2) and lay
aside.
10. Reverse housing (2) and press out ball bearing (10).
Shaft seal (12) can also be removed if necessary.
Inspection
1. Inspect friction plates (3 & 6) and friction surface on
pressure plate (4) for wear or damage.
2. Examine friction plates (3) and brake shaft (1) for
wear or damage to the splines.
3. Examine input and output splines of brake shaft (1)
for wear or damage.
4. Examine compression springs (22 & 23) for damage
or fatigue.
5. Check ball bearing (10) for axial float or wear.
6. Examine O-ring seals (15 & 17) and backing rings
(16 & 18) for damage.
Assembly
1. Lightly lubricate rotary shaft seal (12) and assemble
to housing (2) taking care not to damage seal lip.
2. Apply ring of Loctite 641 or equivalent adhesive to
full circumference of housing (2) bearing recess
adjacent to shoulder.
Apply complete coverage of Loctite 641 to outside
diameter of bearing (10) and assemble fully In hous-
ing (2), retaining with internal retaining ring (11).
Remove excess adhesive with a clean cloth.
Press shaft (1) through bearing (10), ensuring bear-
ing inner ring Is adequately supported.
3. Assemble correct quantity of springs (22 & 23) in ori-
entation required.
4. Lubricate O-ring seals (15 & 17) with Molykote 55M
(or equivalent) silicon grease and assemble together
with backing rings (16 & 18) to piston (9). To ensure
correct brake operation. It is important that the back-
ing rings are assembled opposite to the pressurized
side of piston.
5. Correctly orientate piston (9) aligning spaces with
the two dowel pin holes and, assemble into cylinder
housing (8) taking care not to damage seals and
carefully lay aside.
6. Locate 2-off pins (19) in housing (2) followed by
pressure plate (4) and friction plates i.e. an inner (3)
followed by an outer (6) in correct sequence.
7. Position gasket (7) in correct orientation.
8. Align two holes in cylinder with dowel pins (19) and
assemble piston & cylinder sub-assembly to remain-
der of brake securing with 6 capscrews and washers
(13 & 14). Torque to 55 ft.Ibs. (75 Nm).
NOTE: The use of a suitable press (hydraulic or arbor)
pressing down on cylinder end face B will ease
assembly of the capscrews (13).