MAINTENANCE AND LUBRICATION
4-25
Wheel Bearing Lubrication
and Adjustment
With semitrailer sitting level, the oil level must be checked
daily and maintained between the “ADD” and “FULL”
lines on the hub cap window. Check for cracked windows,
missing filler plugs, and oil leaks. Add hub oil through the
“POP-IN” filler plug located in the center of the hub
windows. Re-install the “POP-IN” plugs after filling each
hub. Adjust wheel bearings and change oil per
or with each brake lining replacement, whichever occurs
first.
Adjustment
1. With a drain pan under the hub cap, remove the hub
cap assembly allowing oil to drain.
2. Lift the wheel off of the ground.
3. Adjust slack adjuster to eliminate brake drag during
tire/wheel rotation.
4. Remove outer lock nut and inner nut and lock
washer.
5. Tighten the inner adjustment nut to a minimum of 75
ft.-lbs., while rotating wheel to insure proper seating
of the bearings and cups in the wheel hub.
6. Loosen the inner adjustment nut so that the wheel
will turn freely.
7. Retighten the inner adjustment nut to 50 ft.-lbs. while
rotating the wheel, to properly position the bearings
for the final adjustment.
8. Loosen the inner adjustment nut 1/3 turn.
9. Install the spindle nut lock washer so that the dowel
on the inner nut will align with a hole in the lock
washer and the washer tang fits in the spindle
keyway.
10. Install the outer lock nut and tighten to 250-300
ft.-lbs. End-play of .001" to .010" must be present in
the adjusted wheel bearing assembly.
DANGER
11. Install the hub cap with a new gasket and fill with oil
to the full mark
12. Adjust brakes according to
13. Check hub oil level after the wheel has set level in
one position for a few minutes to allow the oil to work
into the bearings.
Tire Maintenance
Tire Inflation
Tire inflation will cause tire to ground contact
characteristics as shown in
Figure 4-16.
Tire inflation
should be checked daily while the tire is cold, and during
road stops. Checking the tire pressures while tires are
hot will give a faulty increased pressure reading.
Adjusting tire air pressure to the specified amount while
tires are hot will produce improper tire to road contact
and thus abnormal wear. Do not exceed cold inflation
pressure listed on the semitrailer VIN plate located on the
front of the trailer. Exceeding cold inflation pressure will
result in damaged tire bodies, rims, and wheels. Replace
all valve stem caps when pressure checking/adjusting
has been completed. Remove any foreign objects from
between duals.
Figure 4-16: Tire Inflation Examples
Failure to torque the outer lock nut properly could
cause the wheel to come off during vehicle
operation resulting in property damage or loss of
life.
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