Wheel-end primer

THE CARNAGE CAUSED BY hurricanes Katrina and Rita included thousands of tractors and trailers that were exposed to water submersion.

What happens to those units? As they are evaluated for salvage or rebuild, special consideration should be given to the evaluation and work procedures used, being careful not to put any unit into service that has not had a complete wheel-end inspection and/or repair. If wheel ends are not properly repaired, wheel-end performance could degrade to the point of catastrophic wheel-end failure.

STEMCO offers the following guidelines for inspection, rebuild, and reassembly of submerged trailer wheel ends:

Protect against exposure to contaminated wheel ends.

Technicians should wear protective equipment and consult with local Environmental Protection Agency (EPA) officials regarding proper handling and disposal procedures for the contents of contaminated wheel ends. All hazardous waste from affected wheel ends should be disposed of per EPA requirements.

Identify wheel type and conditions.

Is the wheel end equipped with Sentinel hub cap technology? Is the wheel end lubricated with oil or grease? Does the wheel end contain a pre-set bearing package? Some pre-set wheel ends have limited rebuild capabilities. If you have this type of wheel end, contact the pre-set wheel-end manufacturer for rebuild instructions. Water, especially salt water, is corrosive to wheel ends and may degrade lubricant.

General steps.

Inspect all wheel ends, not just a random sampling. Clean the exterior of wheel end, washing off potential chemical or other contamination in a location with approved drainage and run-off collection capabilities. In all cases where lubricant is drained or removed from a wheel end, properly dispose of that lubricant. Disposal may differ depending on level and type of chemical contamination in the lubricant.

Sentinel-type hub cap

STEMCO offers hub caps with Sentinel technology (Sentinel hub cap and ESP plugs), which provide water resistance to the internal hub cavity via a filter membrane. It is identifiable by the word Sentinel written on the non-removable red plastic or ESP on the blue removable plug. Wheel ends equipped with Sentinel technology are likely to have little, if any, contamination inside. However, under these extreme conditions, this should be confirmed using the following procedure:

Remove the hub cap. Drain the wheel-end lubricant into an approved receptacle. Inspect lubricant for water contamination and dispose of lubricant properly. If no lubricant contamination is found, install the hub cap with a new gasket and refill to the proper level. (Refer to TMC RP 631A.)

Follow the recommended annual procedure for grease wheel ends. (Refer to TMC RP 631A.) This involves removing the outer bearing and inspecting the hub cavity for proper lubricant level and condition. If no contaminants are present, assure proper grease level and reassemble. If the lubricant is determined to be contaminated, follow the complete disassembly practice.

Non-Sentinel-type hub cap

Other hub caps may not provide the same level of water resistance and, when submerged, it is likely that contamination will enter the wheel end.

Remove the hub cap. Drain wheel end lubricant (oil or grease) into approved receptacle and dispose of properly. Disassemble the wheel end. Inspect the bearings and races for any signs of rust of discoloration. If there is any sign of rust or pitting, both the bearing and the cup have to be replaced. On aluminum hubs, a special procedure is used to install bearing cups. Refer to the hub manufacturer for their recommended procedure.

Inspect the axle and hub for any signs of rust or discoloration. If rust is present, clean the surface with emery cloth to remove rust. This is especially important on the axle-bearing journals and seal shoulder and in the hub bearing and seal bores.

Clean all components to be reused in solvent and properly dry these parts. Never use compressed air to spin the bearing — this can cause injury to the technician and/or damage to the bearing. Lubricate bearing rollers and axle with the same type of lubricant (oil or grease) to be used in the hub.

Reassemble the wheel end using proper assembly procedures. Refer to TMC's RP 618 for bearing adjustment. Verify that wheel-end bearing adjustment is 0.001" to 0.005" end play using a dial indicator. Refer to TMC's RP 631A for lubricant fill procedures.

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