A friction bearing should be fitted to a shaft to maintain what clearance?

The correct answer indicates that a friction bearing should maintain a clearance of 0.001 per inch of shaft diameter. This is based on the need for appropriate lubrication and heat dissipation in friction bearings.

When fitting a friction bearing, having a clearance of 0.001 per inch allows for a balance between allowing the shaft to rotate freely while ensuring there is enough space to accommodate any thermal expansion that may occur during operation. This clearance is also crucial for the proper distribution of lubrication, which helps reduce wear and overheating, thereby enhancing the performance and longevity of the bearing.

Adequate clearance avoids excessive friction and potential locking of the bearing to the shaft, which is critical for operation under various load conditions. It also takes into account manufacturing tolerances and potential misalignments that can occur during operation, allowing for smoother operation without risking damage to the components involved.