Bearing

A bearing is a mechanical component that allows relative motion between two surfaces while minimising friction and supporting load. Bearings are everywhere — in car wheels, electric motors, hard drives, bicycle hubs, and industrial machinery.

How it works

A bearing separates two moving surfaces (typically a rotating shaft and a stationary housing) with a low-friction interface. Instead of the shaft grinding directly against the housing, rolling elements (balls or rollers) or a lubricated surface (plain bearing) carry the load and allow smooth movement.

Common types

• Ball bearing: Uses spherical balls rolling between an inner and outer race. Low friction, suitable for high speeds and moderate loads. The most common bearing type.
• Roller bearing: Uses cylindrical, tapered, or spherical rollers instead of balls. Larger contact area means higher load capacity but higher friction than ball bearings.
• Thrust bearing: Designed to handle axial (parallel to shaft) loads rather than radial loads. Used in turntables, screw jacks, and automotive clutches.
• Plain bearing (bushing): A simple sleeve with no rolling elements — relies on lubrication between the shaft and the bearing surface. Cheap, compact, and adequate for low-speed, moderate-load applications.
• Needle bearing: Uses very thin, long rollers (needles) for high load capacity in a very compact space.
• Magnetic bearing: Uses magnetic levitation to support the shaft without contact — zero friction, used in high-speed turbomachinery.

Why bearings matter

Without bearings, every rotating machine would generate enormous friction, heat, and wear. Bearings are what make modern machinery possible — from the tiny bearings in a wristwatch to the massive bearings in a wind turbine.