AT REPORT
BEARING MAINTENANCE & SERVICE
HUB INSPECTION AND REMOVAL
Removal of Hub
- Remove wheel
- Remove grease cap or bearing buddy
- Remove cotter pin or straighten tang on tang washers
- Unscrew the spindle nut counter clockwise
- Remove spindle washer and tang washer
- Remove hub from spindle
Seal Inspection and Replacement
- Seals should be replaced each time the hub is removed.
- Pry the seal out of the hub with a screwdriver.
- Tap new seal into place.
Bearing Maintenance, Adjustments, and Replacement
- Inspect for corrosion and wear.
- If any rust or wear exists on the bearing then remove and replace.
- If bearings are found to be in good condition, then cleaning and repacking the grease is all that is needed. Note: Do not spin bearings with compressed air.
- Hand pack each bearing individually using a premium water resistant wheel bearing grease.
- Reinstall the hub, reversing the procedure above using the bearing adjustment procedures below.
- If you have the Bearing Buddy system remove the rubber cover and place grease gun (no air powered grease guns) onto the zerk. Pump in new grease until you see the spring starting to compress (see manufactures instructions). Wipe off grease with a towel. Be sure to re-install rubber cover.
Bearing Maintenance, Adjustments, and Replacement
- Inspect for corrosion and wear.
- If any rust or wear exists on the bearing then remove and replace.
- If bearings are found to be in good condition, then cleaning and repacking the grease is all that is needed. Note: Do not spin bearings with compressed air.
- Hand pack each bearing individually using a premium water resistant wheel bearing grease.
- Reinstall the hub, reversing the procedure above using the bearing adjustment procedures below.
- If you have the Bearing Buddy system remove the rubber cover and place grease gun (no air powered grease guns) onto the zerk. Pump in new grease until you see the spring starting to compress (see manufactures instructions). Wipe off grease with a towel. Be sure to re-install rubber cover.
Bearing Adjustment
- Recommended Setting - The typical trailer hub uses a washer and slotted hex nut for bearing adjustment. Hubs are usually set with a free-running clearance or endplay of 0.001" to 0.020". The use of a dial indicator is the only satisfactory method of checking adjustment. (The average human hair is 0.004").
- Feel and Drag Method - Tighten slotted nut until hub drags slightly when rotated. (Rotating the hub while tightening the nut seats the bearing.) Loosen the slotted nut 1/6 turn (I hex) to align nut slot with the cotter pin hole. Wheel should turn freely. Insert new cotter pin through nut and spindle. If necessary loosen, never tighten, nut to align slot with the hole in the spindle. Bend one leg of cotter pin over the end of the spindle and the other leg over the nut. Tap legs slightly to set. Cotter pin must be tight.
- Torque Wrench Method - Make sure nut is loose. Tighten nut with torque wrench to an initial torque of 50 ft. lbs.
- Loosen nut from initial torque and finger tighten. Insert new cotter pin or tang washer through nut and spindle. If necessary loosen, never tighten, nut to align slot with the hole in the spindle. Bend one leg of cotter pin over the end of the spindle and the other leg over the nut. Tap legs slightly to set. Cotter pin must be tight.
- Perform Dial Indicator Test - Attach Dial Indicator block to the wheel. With both hands, push the wheel towards the trailer. Set the sensory tip of the dial indicator against the outer edge of the spindle. Set the dial indicator to zero. Grasp the tire at the top and bottom and gently pull out. Check the reading on the dial indicator for the amount of endplay present in the bearing. (0.001" to 0.020") Readjust the bearing if required.
MAINTENANCE SCHEDULE
This maintenance schedule was designed for on road trailers. Off road trailers owners should inspect the trailer components more frequently. For additional information on off road trailer maintenance schedules see;
http://www.atreport.com/st3.html
ITEM |
FUNCTION |
3 MONTHS |
6 MONTHS |
12 MONTHS |
Brakes |
Test that they are functioning |
Before every use |
Before every use |
Before every use |
Brake Adjustment |
Adjust to proper operating clearance |
4 |
|
|
Brake Magnets |
Inspect for wear and current draw |
|
4 |
|
Brake Linings |
Inspect for wear and contamination |
|
|
4 |
Brake Controller |
Check for correct amperage and modulation |
|
4 |
|
Trailer Brake wiring |
Inspect for bare spots, fray, etc. |
|
|
4 |
Breakaway Systems |
Check battery charge and switch operation |
|
|
4 |
Hub/Drum |
Check for abnormal wear or scoring |
|
|
4 |
Wheel Bearings & Cup |
Inspect for corrosion or wear; clean and repack |
|
|
4 |
Seals |
Inspect for leakage; replace if removed |
|
|
4 |
Springs |
Inspect for wear |
|
|
4 |
Suspension Parts |
Inspect for bending, loose fasteners. wear |
|
4 |
|
Wheel Nuts and Bolts |
Tighten to specified torque values |
|
4 |
|
Wheels |
Inspect for cracks, dents, or distortion |
4 |
|
|
Tire Inflation |
Inflate tires to mfg’s. specifications |
|
4 |
|
Tire Condition |
Inspect for cuts, wear, building, etc |
4 |
|
|
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