Oshkosh Corporation JLG 450AJ Service And Maintenance Manual Download

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SECTION 3 - CHASSIS & TURNTABLE

3121659

– JLG Lift –

3-33

3.5

DRIVE BRAKE

Refer to Figure 3-30., Drive Brake.

Disassembly

Supporting the brake on Face A, remove the socket
head capscrews and washers (13 & 14) in equal incre-
ments to ensure the spring pressure within the break is
reduced gradually and evenly.

If a press is available, the cylinder housing (8) can be
secured on Face B while removing the capscrews and
washers (13 & 14).

Remove the cylinder housing (8) and piston (9) subas-
sembly and disassemble if necessary, removing O-ring
seals (15 & 17) and backing rings (16 & 18) as necessary.

Remove the gasket (7) from the housing.

Remove the friction plates (3&6) and pressure plate (4).

Remove the dowel pins (19).

Remove the springs (22 & 23). Note the color and
arrangement of the springs so they can be assembled in
the same order.

If it’s necessary to replace the ball bearing (10) or shaft
seal (12), and reverse the brake position so it is sup-
ported on Face C of the housing (2).

Remove the internal retaining ring (11).

Using a press or similar device, remove the brake shaft
(1) from the housing (2) and lay it aside.

10.

Reverse the position of the housing (2) and press out the
ball bearing (10). if necessary, the shaft seal (12) can be
removed.

Inspection

Inspect the friction plates (3 & 6) and friction surface on
the pressure plate (4) for wear or damage.

Examine the friction plates (3) and brake shaft (1) for
wear or damage to the splines.

Examine the input and output splines of the brake shaft-
for wear or damage.

Examine the compression springs (22 & 23) for damage
or fatigue.

Check the ball bearing (10) for axial float or wear.

Examine O-ring seals (15 & 17) and backing rings (16 &
18) for damage.

Assembly

Lightly lubricate the rotary shaft seal (12) and assemble
it to the housing (2) taking care not to damage the seal
lip.

Apply a ring of Loctite 641 or equivalent adhesive to the
outside diameter of bearing (10) and assemble fully in
the housing (2). Secure the bearing in place with the
retaining ring (11). Remove any excess adhesive with a
clean cloth. Press the shaft (1) through the bearing (10),
ensuring the bearing inner ring is adequately sup-
ported.

Assemble the springs into position as recorded during
Disassembly.

Lubricate the )-rings (15 & 17) with Molykote 55M or
equivalent silicone grease and assemble them, with the
backing rings (16 & 18) to the piston (9). To ensure cor-
rect brake operation, it is important that the backing
rings are assembled opposite to the pressurized side of
the piston (9).

Correctly orient the piston aligning spaces with the two
dowel pin holes and install into the cylinder housing (8)
taking care not to damage the seals. Carefully lay these
parts aside.

Install the dowel pins (19) in the housing (2) followed by
the pressure plate (4) and friction plates. For example, in
inner plate (3) followed by an outer plate (6) in the cor-
rect sequence.

Position the gasket (7) in the correct location.

Align the two holes in the cylinder with the dowel pins
(19) and assemble the piston and cylinder subassembly
to the remainder of the brake. Secure in place with the
capscrews and washers (13 & 14). Torque to 55 ft.lbs. (75
Nm).

NOTE:

The use of a suitable press on cylinder end Face B will ease
installation of the capscrews (13).