Oshkosh JLG 400S, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3-50 – JLG Lift – 3120895
3.14 SWING BRAKE (PRIOR TO S/N 64802)
The multi disc brake is spring loaded to apply the brake
and hydraulic pressure is required to release or hold off
the brake. Normal operation is to have the brake pressur-
ized in the released position with the vehicle hydraulic
system running. Any function which reduces the system
pressure below the release pressure of the brake will
cause the brake to be applied.
FOR CORRECT OPERATION, HYDRAULIC PRESSURE TO THE
BRAKE MUST FALL TO ZERO PSI. ANY RESIDUAL BACK PRES-
SURE APPLIED TO THE BRAKE WILL DEGRADE FUNCTION AND
MAY RESULT IN A HAZARDOUS CONDITION.
Installation
1. Assemble brake between motor and gearbox. Place
mounting gaskets on mounting faces before assem-
bly. If needed, the brake shaft can be rotated by
applying hydraulic pressure to the piston inlet port.
2. Insert four 1/2” dia. bolts (Grade 5) and lock wash-
ers through the motor flange, The gasket, and the
threaded holes in the gear reducer. make sure that
the bolts are not too long so they do not bottom out
in the gear reducer threaded holes before clamping.
3. To prevent binding, run the bolts in alternately until
snug. Torque the bolts to 75-85 ft. lbs. (102-115 Nm).
4. With brake bolted together, connect inlet hydraulic
line. Brake inlet is 1/4” tubing, straight thread O-ring
boss (7-16-20 unf).
Brake Disassembly
1. Dissemble in the following order: Bolts (alternately),
power plate, gasket, stationary discs, rotating discs,
primary disc, torque pins, compression springs, and
spring retainer.
2. Further dissemble is not recommended and should
not be attempted unless necessary to replace the
bearing. The seal, or the shaft. If further dissemble is
needed, proceed as follows:
NOTE: If the bearing and seal are removed for any reason,
both must be replaced.
a. The shaft must be removed by pressing on the
end of the shaft with a shop press.
b. Using an appropriate tool. Pry the seal out from
the inside of the brake. Take care not to damage
the bore. Remove the retaining ring and tap out
the bearing with a plastic mallet.
3. Remove the piston from the power plate by introduc-
ing low pressure air (15 psi) into the hydraulic inlet.
Make sure the piston is directed away from the oper-
ator. Do not remove O-ring unless replacement is
necessary because the will be damaged.
Assembly Information
THERE MAY BE MORE PARTS IN A SERVICE KIT THEN YOUR
BRAKE REQUIRES. CHECK THE PARTS LIST CAREFULLY FOR THE
EXACT QUANTITY.
NOTE: All parts must be thoroughly cleaned prior to reas-
sembly.
Use the reverse of the dissemble procedure with the fol-
lowing notes and additions:
1. Worn and damaged O-rings, or worn Teflon backup
rings must be replaced prior to reassembly.
2. Cylinder of the power plate, piston, and O-rings
must be clean and pre-lubed prior to reassembly.
3. Piston Assembly: Assemble piston into power plate
using a shop press. Being careful not to damage the
O-ring or Teflon backup rings. Visually align the cen-
ter of the cutouts in the piston with the torque pin
holes in the power plate.
THE DEPTH THAT THE PISTON IS INSTALLED INTO THE POWER
PLATE IS CRITICAL. THE PISTON CUTOUTS MUST BE FLUSH
TO.120 (3 MM) BELOW THE SURFACE OF THE POWER PLATE OR
PISTON WILL COCK RESULTING IN A COMPLETE LOSS OF BRAK-
ING.
4. Bearing Assembly: Use a shop press to press the
bearing into the shaft. Press only on the inner race of
the bearing.
5. Lip Seal Assembly: Lip of seal must face the bearing
to seal the brake.
6. Rotating, Stationary, Primary Disc Assembly: Rotat-
ing Disc must be clean. The lining material and mat-
ing surfaces of the Stationary Discs must be
thoroughly clean and free from debris. Worn or
scarred Rotating Discs must be replaced.
7. Install Bolts in the Power Plate. Tighten sequentially,
one turn at a time, until Power Plate is properly
seated. Torque to 85-90 ft. lbs.(115-122 Nm).