This Resource Centre provides general guidance only. Always follow the equipment manufacturer’s instructions, the product technical data sheet and your site’s safe system of work. Isolate stored energy before maintenance. For safety-critical, regulated or uncertain applications, ask a competent engineer or the product manufacturer to confirm the specification.
Bearing fitting: common mistakes to avoid
Correct fitting protects the raceways before the machine even starts. A small dent, particle or incorrect fit can become noise, heat and early failure.
Keep the bearing and work area clean
Leave the bearing in its packaging until it is needed. Clean the shaft, housing, shoulders and tools, then inspect for burrs, corrosion and damage. Do not use lint-producing cloths on critical surfaces.
Apply force to the ring being fitted
When fitting an inner ring to a shaft, apply force to the inner ring. When fitting an outer ring into a housing, apply force to the outer ring. Never drive mounting force through the balls or rollers; this can mark the raceways.
Use an appropriate fitting tool, press, induction heater or approved hydraulic method. Do not strike the bearing directly with a hammer.
Check shaft and housing fits
A seat that is too loose can creep and wear. A fit that is too tight can reduce internal clearance and cause heat. Measure the actual shaft and housing rather than assuming they remain within tolerance.
Control heating
Where heat mounting is appropriate, use controlled, even heating and follow the bearing manufacturer’s temperature limits. Avoid an open flame, which creates uneven temperature and can damage the bearing.
Do not mix up matched or directional components
Angular-contact bearings, tapered roller bearings and paired sets may require a particular orientation, preload or end float. Mark components before removal and follow the machine instructions during assembly.
Lubricate correctly
Use the specified lubricant, amount and application method. Too little can starve the contact; too much grease can churn and overheat. Keep grease guns, transfer containers and fittings clean.
Verify after installation
Before returning the machine to service:
- rotate the assembly by hand where safe;
- confirm free movement and correct end float or preload;
- check guards and lubrication connections;
- run under controlled conditions;
- monitor noise, vibration and temperature against a known-good baseline.
Stop and investigate a rapid temperature rise, abnormal noise or roughness.
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