The rolling bearing, in its present form, was developed at the end of the 19th century. Initially, they were manufactured by hand. Today, approaches are one of the most widely used pieces of machinery, as their rotary motion facilitates all movements and helps to reduce friction between the various moving parts.

Bearings have two main functions:

They transfer motion, i.e., they support and guide components that rotate relative to each other.

They transmit forces

The rotating element used in the manufacture of the bearing can be a ball, roller, or needle roller bearing. In bearings, the rotary motion, depending on the direction of the stress it supports, can be axial, radial, and axial-radial.

A radial bearing is the one that supports radial forces, which are efforts of average direction to the direction that passes through the center of its axis; like a wheel, it is axial if it supports efforts in the direction of its axis, for example, in the hub, and axial-radial if it can help them in both, alternatively or combined.

The manufacture of ball bearings is the one that occupies an extraordinary place in technology, given the procedures to achieve the perfect sphericity of the ball. The major manufacturers of this type of bearings use vacuum for this purpose. The material is subjected to abrasive treatment in absolute vacuum chambers. Nowadays, there are water lubricated bearings that reduce friction and wear.

Each bearing type shows characteristic properties, which depend on its design and make it more or less suitable for a given application. For example, deep groove ball bearings can support moderate radial loads as well as small axial loads. Moreover, they have low friction and can be produced with high precision. Therefore, they are preferred for small and medium-sized electric motors. On the other hand, spherical roller bearings can support hefty radial loads and oscillate, allowing them to assume shaft deflections between two approaches supporting the same shaft. These properties make them very popular for applications in, e.g., heavy engineering, where the loads are heavy and the deformations produced by the loads; in large machines, some misalignment between bearing supports is also joint.

Deep groove ball bearings

They are used in a wide variety of applications. They are easy to design, non-separable, capable of operating at high and even very high speeds, and require little attention or maintenance in service. These characteristics, coupled with their price advantage, make these bearings the most popular of all directions.

Single row angular contact ball bearings

The single row angular contact ball bearing has its raceways arranged so that the pressure exerted by the balls is applied obliquely to the shaft. As a result of this arrangement, the approach is particularly suitable for supporting radial loads and large axial loads and must be mounted in contrast to another bearing that can receive axial load in the opposite direction. In addition, water lubricated bearings have high resistance to shock, edge load, and vibration problems.

Needle roller bearings

These are bearings with cylindrical rollers that are very thin and long about their smaller diameter. Despite their small cross-section, these bearings have a high load-carrying capacity and are eminently suitable for applications where radial space is limited.

Tapered roller bearings

Due to the oblique position of the rollers and raceways, the tapered roller bearing is particularly suitable for withstanding simultaneous radial and axial loads. For cases where the axial load is significant, there is a series of poses whose angle is very open. This bearing must be mounted in opposition with another approach capable of supporting axial forces in the opposite direction. The bearing is dismountable; the inner ring with its rollers and the outer ring are mounted separately.