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Wheel Hubs/Drums/Bearings

Hub Removal
Whenever the hub equipment on your axles must be removed for inspection or maintenance the following procedure should be used:

  1. Elevate and support the trailer using the four corner scissor jacks. Remove the wheels, one at a time for service.
  2. Remove the grease cap by unscrewing it counter-clockwise while holding the hub stationary.
  3. Bend the locking tang to the free position.
  4. Unscrew the spindle nut (counter-clockwise) and remove the spindle washer.
  5. Remove the hub from the spindle, being careful not to allow the outer bearing cone to fall out. The inner bearing cone will be retained by the seal.

Brake Drum Inspection
Inspect the drum surface where the brake shoes make contact during stopping. The drum surface should be inspected for excessive wear or heavy scoring. If worn more than .020" oversized, or the drum has worn out of round by more than .015", then the drum surface should be turned. If scoring or other wear is greater than .090" on the diameter, the drum just be replaced. When turning the drum surface, the maximum re-bore diameter (for 10" Brake Drums) is 10.090".

Note: It is important to protect the wheel bearing bores from metallic chips and contamination which result from drum turning operations. Ensure that the wheel bearing cavities are clean and free of contamination before reinstalling bearing and seals.

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 completely. If any pitting, spalling, or corrosion is present, then the bearing must be replaced. The bearing cup inside the hub must also be inspected.

Note: Bearings must always be replaced in sets of a cone and a cup.

Replace only with bearings as specified in the accompanying Bearing Replacement Chart.

CAUTION! CAUTION: Be sure to wear safety glasses when removing or installing force fitted parts. Failure to comply may result in serious eye injury.

Bearing Replacement Chart

Brake Size Bearing Dexter Part No.
Cup & Cone
Industry Part No.
Cup / Cone
10" x 2¼" Inner
Outer
31-33-3
31-31-4
L68111 / L68149
L44610 / L44649

Seal Inspection and Replacement
Whenever the hub is removed, inspect the seal to assure that it is not nicked or torn and is still capable of properly sealing the bearing cavity. If there is any question of condition, replace the seal. Use only the seal specified in the following Seal Chart.

Seal Replacement Chart

Brake Size Hub Size Seal Part No.
10 x 2¼ 4 or 5 Bolt 10-19

Bearing Lubrication
Along with bearing adjustment, proper lubrication is essential to the function and reliability of your trailer axles. Bearings should be lubricated every 12 months or 12,000 miles.
Mobilexhibit trailers are equipped with Reliable Sure Lube bearings and can be lubricated without removing the hubs from the axle. This feature consists of axle spindles that have been specially drilled and fitted with a grease zerk in their ends. When grease is pumped into the zerk, it is channeled to the inner bearing and then flows back to the outer bearing and eventually back out the grease cap hole.

The lubrication procedure is as follows:

  1. Place a standard grease gun onto the grease zerk located in the end of the spindle. Make sure the grease gun nozzle is fully engaged on the fitting.
  2. Pump grease into the zerk. The old, displaced grease will begin to flow back out the cap around the grease gun nozzle.
  3. When the new, clean grease is observed, remove the grease gun and wipe off any excess.
Note: If hubs are removed from an axle, it is imperative that the seals be replaced BEFORE bearing lubrication. Otherwise, the chance of grease getting on brake linings is greatly increased.

Recommended Bearing Lubrication:

Grease:
Thickener Type Lithium Complex
Dropping Point 230 C(446 F) Minimum
Consistency NLGI No. 2
Additives EP, Corrosion & Oxidation Inhibitors
Base Oil Solvent Refined Petroleum Oil
Base Oil Viscosity @40 C(104 F) 150cSt(695 SUS) Min.
Viscosity Index 80 Minimum
Pour Point -10 C(14 F) Minimum

Bearing Adjustment and Hub Replacement
If the hub has been removed or bearing adjustment is required, the following adjustment procedure must be followed:

  1. After placing the hub, bearings, washers, and spindle nut back on the axle spindle in reverse order as detailed in the previous section on hub removal, rotate the hub assembly slowly while tightening the spindle nut to approximately 50 lbs.-ft. (12" wrench with full hand force.)
  2. Then loosen the spindle nut to remove the torque. Do not rotate the hub.
  3. Finger tighten the spindle nut until just snug.
  4. Back the spindle nut out slightly until the first castellation lines up with the locking tang hole and insert tang.
  5. Nut should be free to move with only restraint being the locking tang.


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