Roller bearings are a type of rolling-element bearing designed to facilitate smooth motion between two or more components. They use cylindrical, tapered, spherical, or needle-shaped rollers as the rolling elements between the inner and outer races (also known as rings) to reduce friction and distribute loads evenly. Roller bearings are widely used in a variety of applications to support radial, axial, and combined loads. Here are the primary types of roller bearings:

1. Cylindrical Roller Bearings: These bearings feature cylindrical rollers, which are typically longer than their diameter. They are used to support radial loads and are particularly well-suited for applications requiring high radial load capacity. Cylindrical roller bearings can be single-row, double-row, or multi-row configurations.
2. Tapered Roller Bearings: Tapered roller bearings have conical rollers and raceways, with the cones and cups angled to facilitate axial (thrust) as well as radial loads. They are often used in applications where both radial and axial loads are present, such as in automotive wheel hubs and gearboxes.
3. Spherical Roller Bearings: Spherical roller bearings have barrel-shaped rollers and raceways on the inner and outer rings that are aligned in a way that allows them to handle misalignment, radial loads, and some axial loads. They are frequently used in applications where alignment and high load-carrying capacity are essential.
4. Needle Roller Bearings: Needle roller bearings use cylindrical rollers with a significantly larger length-to-diameter ratio. They are used in applications where space is limited and high radial load capacity is needed, such as in automotive transmissions and small appliances.
5. Thrust Roller Bearings: Thrust roller bearings, which include cylindrical thrust roller bearings and spherical thrust roller bearings, are designed to handle axial loads. They use cylindrical or barrel-shaped rollers to support axial loads in a single direction.
6. Cam Followers and Yoke Rollers: These are variations of roller bearings with a stud or shaft, commonly used in track-type applications, where the bearing needs to follow a predefined path while providing support and guidance to the load.

Roller bearings have numerous applications across various industries, including:

• Automotive: In wheel hubs, transmissions, engines, and suspension systems.
• Industrial Machinery: In pumps, compressors, gearboxes, and conveyor systems.
• Aerospace: In aircraft engines, landing gear, and flight control systems.
• Rail Transportation: In locomotives, rolling stock, and railcar wheel assemblies.
• Construction and Mining: In heavy machinery like excavators, bulldozers, and crushers.
• Marine and Offshore: In ship propulsion systems, winches, and crane systems.

When selecting roller bearings, it’s essential to consider factors such as the type of load (radial, axial, or combined), load magnitude, speed, temperature, and any specific environmental conditions in the application to ensure that the bearing meets the desired performance criteria.