What is the purpose of a sleeve bearing in a shaft-bearing arrangement?

• A. To increase friction
• B. To support the rotating shaft and reduce friction with a lubricated surface
• C. To cool the motor
• D. To seal the lubrication

Answer: (B)

A sleeve bearing provides a smooth, lubricated sliding surface for a rotating shaft, supporting the shaft while minimizing friction and wear. The bearing sits inside the housing and the lubricant forms a film between the shaft and the bearing bore, carrying the load and keeping metal surfaces separated. This combination of support and a lubricated interface is what lets the shaft rotate with much less resistance and wear. It isn’t primarily about cooling or sealing the lubrication; those can be related outcomes, but the main function is to provide a low-friction, load-bearing surface through lubrication.