Which device is commonly used to support rotating shafts and reduce friction?

• A. Bearings
• B. Gears
• C. Belts
• D. Pulleys

Answer: (A)

Bearings provide a low-friction, pivoting surface that supports rotating shafts. They use rolling elements (like balls or rollers) or a smooth sleeve to replace sliding contact with rolling contact, which dramatically lowers friction, reduces wear, and allows the shaft to rotate smoothly and handle radial and/or axial loads. Lubrication and seals enhance this performance by further reducing friction and heat.

Gears, belts, and pulleys serve different roles: gears change speed and torque by meshing teeth; belts and pulleys transmit motion in drive systems. They rely on bearings to rotate quietly and efficiently, but their primary purpose isn’t to support the shaft with minimal friction.