If not specified, to what maximum temperature in degrees Fahrenheit should bearings be heated?

• A. 200
• B. 350
• C. 250
• D. 150

Answer: (C)

When mounting a bearing by heating, the aim is to expand the bearing bore enough so it slides onto the shaft easily without forcing or damaging components. If no specific temperature is given, a practical maximum is about 250°F. This limit provides sufficient expansion to ease installation while keeping the steel’s hardness and temper from being degraded, and it helps protect seals and lubricants from damage. Heating beyond this can soften or anneal the bearing material, alter dimensions, and shorten life, while heating too little may not allow the bearing to slip on cleanly. Use uniform, controlled heating and a reliable temperature check, and seat the bearing promptly while it’s hot.