What is the function of a bearing in a rotating shaft system?

• A. Stores electric charge
• B. Reduces friction and supports shafts
• C. Regulates voltage
• D. Converts mechanical energy

Answer: (B)

The main idea is that a bearing’s job in a rotating shaft system is to reduce friction and support the shaft. Bearings provide a smooth, low-friction contact surface that lets the shaft spin with minimal resistance, which lowers wear, controls heat, and helps keep the shaft properly aligned. They also carry the loads placed on the shaft—radial loads from the shaft’s weight and operating forces, and sometimes axial (thrust) loads—while maintaining position inside the housing. Without bearings, the shaft would rub directly on supports, leading to rapid wear and possible seizure.

Storing electric charge isn’t something a bearing does; that’s a job for electrical components like capacitors. Regulating voltage is handled by voltage regulators or control circuits, not by bearings. Converting mechanical energy to electrical energy (or the reverse) is the function of motors and generators, not bearings. So reducing friction and providing support is the correct, defining function of a bearing in a rotating shaft system.