A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. Bearings are “parts that assist objects’ rotationâ€. They support the shaft that rotates inside the machinery. Machines that use bearings include automobiles, airplanes, electric generators and so on. Journal bearing – Simplest type of bearing, comprising just a bearing surface and no rolling elements. Hinge – Mechanical bearing connecting two objects. Main bearing. Needle roller bearing – Type of roller bearing which uses long, thin cylinders as rollers.