Hubs, Drums, Wheel Bearings; Hub Removal; Brake Drum Inspection; Bearing Inspection - JLG T500J Service And Maintenance Manual

3.6

HUBS, DRUMS, WHEEL BEARINGS

The wheel bearing configuration consists of opposed tapered
roller bearing cones and cups, fitted inside of a precision
machined cast hub. This configuration requires a minimal
amount of end play be provided at assembly, which is essen-
tial to the longevity of the bearing service life. This design is
lubricated with grease packed into the bearings.

Hub Removal

1. Elevate and support the machine.
FOLLOW MAINTENANCE PROCEDURES TO PREVENT DAMAGE TO IMPORTANT
STRUCTURAL COMPONENTS. DAMAGE TO CERTAIN STRUCTURAL COMPO-
NENTS SUCH AS WHEEL BEARINGS CAN CAUSE THE WHEEL END TO COME OFF
OF THE AXLE. LOSS OF A WHEEL END WHILE THE MACHINE IS MOVING CAN
CAUSE A LOSS OF CONTROL AND LEAD TO AN ACCIDENT, WHICH CAN RESULT
IN SERIOUS INJURY OR DEATH.
2. Using adequate support to the wheel, Remove the nut
securing wheel to hub.
3. Remove the wheel.
4. Remove the grease cap by carefully prying progressively
around the flange of the cap.
5. Remove the cotter pin from the spindle nut.
6. Unscrew the spindle nut (counterclockwise) and remove
the spindle washer.
7. Remove the hub from the spindle, being careful not to
allow the outer bearing cone to fall out. The inner bear-
ing cone will be retained by the seal.

Brake Drum Inspection

1. The drum surface (where the brake shoes make contact)
should be inspected for excessive wear or heavy scoring.
If worn more than 0.020 in. (0.50 mm) oversized, or the
drum has worn out of round by more than 0.015 in. (0.38
mm), then the drum surface should be re-machined. If
scoring or other wear is greater than 0.090 in. (2.28 mm)
on the diameter, the drum must be replaced (i.e. for a 10
in [25.400 cm] drum, no greater than 10.090 in.[25.628
cm]).
NOTE: It is important to protect the wheel bearing bores from
metallic chips and contamination which result from drum
turning. Ensure the wheel bearing cavities are clean and
free of contamination before reinstalling the bearing and
seals. The presence of these contaminants will cause pre-
mature wheel bearing failure.
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SECTION 3 - CHASSIS & TURNTABLE

Bearing Inspection

Wash all grease and oil from the bearing cone using a suitable
solvent. Dry the bearing with a clean, lint-free cloth and
inspect each roller assembly.
NEVER SPIN THE BEARING WITH COMPRESSED AIR. THIS CAN DAMAGE THE
BEARING.
If any pitting, spalling, or corrosion is present, then the bearing
must be inspected.
BEARINGS MUST ALWAYS BE REPLACED IN SETS OF A CONE AND CUP.
BE SURE TO WEAR SAFETY GLASSES WHEN REMOVING OR INSTALLING FORCE
FITTED PARTS. FAILURE TO COMPLY MAY RESULT IN SERIOUS EYE INJURY.
When replacing the bearing cup proceed as follows:
1. Place the hub on a flat work surface with the cup to be
replaced on the bottom side.
2. Using a brass drift punch, carefully tap around the small
diameter end of the cup to drive out.
3. After cleaning the hub bore area, replace the cup by tap-
ping in with the brass drift punch. Be sure the cup is
seated all the way up against the retaining shoulder in
the hub.

Bearing Lubrication

Bearings should be lubricated every 12 months or 12,000
miles. The procedure to repack bearing cones is as follows:
1. Place a quantity of grease into the palm of your hand.
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