Bearing removal and component inspection

Remove the bearings. Clean end bell bearing housings and shaft bearing journals with lint-free cloths and approved solvent. Use steel wool or a wire brush to remove any rust, paint, or other contaminants.

Measure bearing housings with a bore gage. Record the results. Take corrective action for housings not within recommended limits. Compare your measurements with the chart on Bearing Housing Diameter Limits.

Measure shaft journals with a snap gage. Record the results. Take corrective action for journals not within recommended limits. Compare your measurements with the chart on Bearing Shaft Diameter Limits.

Clean the shaft, end bells, bearing retainers, armature laminations, and field housing mating edges with lint-free cloth and approved solvent.

Inspect the shaft, end bells, bearing retainers, armature laminations, and other component parts for any condition necessitating replacement, machine shop work, or any other corrective maintenance. Take corrective action.

Inspect all mating surfaces for conditions necessitating replacement, machine shop work, hand dressing, or any other maintenance. Take corrective action.

Inspect the brush rigging for cleanliness, evidence of arcing or crystallizing of insulators, or loosening of brush holder supports. Clean the brush rigging by wiping it with a lint-free cloth dipped in approved solvent or by vacuuming. Signs of arcing, crystallizing, or other insulation breakdown will require replacement of the brush rigging.

Inspect the brush holders for the condition of brush arms and springs, signs of arcing, or mechanical damage. Repair or replace the brush holders as necessary.

Inspect the brushes for frayed shunts (pigtails), cracks, chips, signs of overheating, condition of hammer clips or riveted shunt connections, condition of contact surface, and length. Replace any brushes that are mechanically damaged, have frayed or loose shunts, or have faulty hammer clips. Brush length replacement criteria are below.

•  Brushes with riveted connections or hammer clips will be replaced when worn to 1/8 inch of the metallic part.

•  Brushes having tamped connections and without hammer clips will be replaced when worn to within 50 percent of their original length.

•  Brushes having spring-enclosed shunts will be replaced when worn to within 40 percent of their original length.