JLG 740A, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3-12 – JLG Lift – 3121160
3.5 DRIVE BRAKE - AUSCO (PRIOR TO S/N
56875)
Disassembly
1. With shaft protrusion downward, disassemble the
parts in the following order; bolts (24 alternately,
washers (23), power plate (21), and gasket.
2. Remove the following parts; stationary discs (14),
rotating discs (12), primary disc (11), torque pins (3),
springs (8&9), and the spring retainer (7).
NOTE: If the bearing and seal are removed for any reason,
both must be replaced.
3. Further disassembly is not recommended and
should not be attempted unless necessary to
replace the bearing (4), the seal (6), or the shaft (10).
If further disassembly is needed, proceed as follows;
a. The shaft (10) may be removed by pressing on
the end of the shaft with a shop press.
b. Using an appropriate tool, pry the seal (6) out
from the inside of the brake. Take care not to
damage the bore. Remove the retaining ring (5).
Tap the bearing (4) out with a plastic mallet.
4. Remove the piston (15) from the power plate (21) by
introducing low pressure air into the hydraulic inlet
and make sure the piston is directed away from the
operator. Remove the o-rings (17&19) and backup
rings (16&18) from the piston O.D. and I.D. grooves.
Do not remove backup rings (16&18) unless
replacement is necessary because they will be dam-
aged. With shaft protrusion downward, remove the
end cover (13) by removing capscrews (12).
Inspection
1. Clean all parts thoroughly.
2. Closely inspect all parts for excessive wear, cracks
and chips. Replace parts as necessary.
3. Discard seals and o-rings.
4. Closely inspect bearings and bearing contact sur-
faces. Replace as necessary.
NOTE: Bearings may be reused if, after thorough inspection,
they are inspection, they are found to be in good
condition.
Assembly
NOTE: Lubricate all seals and o-rings with clean hydraulic
oil prior to assembly.
THERE MAY BE MORE PARTS IN A SERVICE KIT THAN YOUR
BRAKE REQUIRES. CHECK THE PARTS LIST CAREFULLY FOR THE
EXACT QUANTITY. IN THE CASE OF SPRINGS, SPACE THE
SPRINGS AS SHOWN IN FIGURE 3-4.
1. Worn o-rings and damaged or worn Teflon backup
rings must be replaced prior to assembly.
2. The cylinder of the power plate, piston, and o-rings
must be clean prior to assembly and pre-lubed with
the system hydraulic fluid.
THE DEPTH THE PISTON IS INSTALLED INTO THE POWER PLATE
IS CRITICAL. THE SURFACE OF THE PISTON AT THE CUTOUTS
MUST BE FLUSH TO 0.120 IN.(3.0 MM) BELOW THE SURFACE OF
THE POWER PLATE. DO NOT EXCEED THE 0.120"(3.0 MM) DEPTH
OR THE PISTON WILL COCK RESULTING IN COMPLETE LOSS OF
BRAKING.
3. Assemble the piston (15) into the power plate (21)
using a shop press, being careful not to damage the
o-rings or Teflon back-up rings. Visually align the
center of the cutouts in the piston with the torque pin
(3) holes in the power plate (21).
4. For replacement of the seal;
a. Use a shop press to install the bearing (4) into
the housing. Press the outer surface of the bear-
ing only. Install the retaining ring (5) into the
groove.
b. Press the seal (6) into the housing (1) until it is
flush with the face of the housing. The lip of the
seal must face towards the bearing.
5. Press the shaft into the housing until it stops on the
bearing. Support the inner race of the bearing dur-
ing the press operation.
6. Rotating discs must be clean and dry. The lining
material and mating surfaces of the stationary discs
must be thoroughly clean and free of debris. Worn
or scored rotating discs must be replaced.
7. Install bolts (24) with washers (23) in the power plate
(21. Tighten sequentially, one turn at a time, until the
power plate is properly seated. Torque 105-115 Ft.
Lbs.(142.4-155.9 Nm)