There are several varieties of bearings, each utilized for a certain purpose and built to carry a specific sort of load, either radial or thrust. Plain bearings, rolling element bearings, jewel bearings, fluid bearings, magnetic bearings, and flexure bearings are the six most common varieties. They all act on different principles but all serve the same basic function: to allow two surfaces to rotate with respect to one another.
Rolling element bearings consist of an inner ring, an outer ring, and multiple balls or cylindrical rollers positioned between the two rings. These bearings can be single-row or multi-row. In single-row ball bearings, only one row of balls is used; in multi-row ball bearings, several rows are used. The number of rows varies depending on the application but typically ranges from three to eight. Rolling element bearings are commonly used where low maintenance costs are important, such as in appliances, machinery, and vehicles. They are also used in high-speed applications because they are less likely to suffer from premature failure than other bearing types.
Jewel bearings are made up of an inner ring and an outer ring with a series of jewels located between the two rings. Each jewel has a circular hole that allows the passage of a shaft but prevents any contact between the jewel and the shaft. This type of bearing is designed for use where very little space is available or where long life under heavy loads is required.
The most common form of bearing is a ball bearing, which can take both radial and thrust stresses. Deep-groove single-row or Conrad bearings are other names for ball bearings. These are the only types of bearings used in manual typewriters.
Radial load capacity depends on the size of the bearing but generally speaking, they can support up to their own weight plus that of any attached parts. For example, if you put a 1-inch diameter ball bearing on a shaft that's 2 inches in diameter, the bearing will weigh more than enough to support its own radius while allowing the shaft to rotate freely. Of course, the larger the bearing, the greater the weight it can support.
Thrust loads are also dependent on the size of the bearing but they can support many times their own weight. For example, if you attach a small motor to a shaft and then pass the shaft through a hole in the center of a ball bearing, the bearing will be able to take up to 20 times its own weight in thrust stress from the motor without damage. As with radial loads, larger bearings can support more thrust.
Ball bearings can sustain higher speeds of rotation than other types of bearings because they do not contain moving parts like levers or screws that might bind at lower speeds.
Bearings are classified into five types: rolling and spherical.
4 Bearing Types for Machine Tool Applications
Ball bearings are the most common form of bearing and may be found in a wide range of daily products, including skateboards, blenders, bicycles, DVD players, and photocopiers. This type of bearing is often employed in high-speed, low-load applications. They are also useful in heavy machinery where large amounts of movement between relatively stationary parts are required.
The next type of bearing is a spherical roller bearing. These are usually found in appliances such as washers, dryers, and refrigerators because they need to provide continuous rotation while being able to absorb small irregularities in alignment that might cause friction if using balls. They can also be used in equipment where large loads are present but very little movement is required (such as fan motors).
Another type of bearing is a cylindrical roller bearing. These are commonly used in gearboxes and other mechanisms where there is relative motion between two parts with one positioned above the other. The upper part has cylindrical rollers attached to it while the lower part has a similar shape with holes instead of balls. The part with the holes fits tightly against the upper part and can move up and down but cannot rotate independently.
A third type of bearing is a needle bearing. These are usually found in appliances with very high load capacities or small sizes. They are shaped like a ring with rows of needles protruding from it.
Ball bearings are categorized into two categories based on their bearing ring configurations: deep groove type and angular contact type. Rolling bearings are further classed based on the direction of load application; radial bearings carry radial loads, whereas thrust bearings carry axial loads. Finally, linear motion bearings can be subdivided into ball-races and rail systems.
Bearings can also be classified by size. The three most common sizes are small (less than 1/4 inch in diameter), medium (1/4 to 3/8 inch), and large (more than 3/8 inch). Bearings may also be designated as metric or imperial, such as 10mm or 15mm. Metric bearings are generally smaller in diameter than their imperial counterparts.
Deep-groove ball bearings consist of an inner and outer race with balls positioned in a deep channel between them. The races do not touch, so they can spin freely inside a housing. The balls run in the channel, which is usually made from steel or synthetic material. This type of bearing is used when high rotational speeds and minimal friction are required. They are available in a wide variety of diameters and numbers of balls per circle.
Angular contact ball bearings have an outer race and an inner race that rotate relative to each other around a fixed axis. There are several types of angular contact ball bearings, but cylindrical roller bearings are the most common.
Flange bearings are classified into three types: Two-bolt flange bearings with a diamond form; three-bolt flange bearings with a tri-cornered design; and four-bolt flange bearings, which are commonly square or round in shape. Flange bearings are installed on a cast iron flange. The number of bolts required depends on the size of the bearing and the distance between the holes in the flange for mounting it.
Bearing manufacturers often use descriptive names for their products that indicate different qualities such as "ball", "roller", "self-aligning", and "anti-friction". These names can be used to describe various bearing shapes and materials. For example, a "ball" bearing has a circular cross section with no other parts included; therefore, there is no need for specific mounting holes. A "roller" bearing has an inner ring with one or more rows of rolling elements (balls or rollers) spaced by small gaps. This type of bearing requires special mounting holes because the rows of balls or rollers do not touch each other and cannot slide across each other. A "self-aligning" bearing has a body with two parts: an outer race that fits inside a hole in its associated structure and an inner race that fits inside the outer race but can move relative to it. When the two races are placed together with their centers aligned, they form a gap that will contain a fluid when the bearing is mounted in its intended location.