Bearings are crucial components in mechanical devices. Their primary function is to support the rotational motion of machinery, reducing the mechanical load friction coefficient during the transmission process. Bearings are classified based on load direction or nominal contact angle into radial and thrust bearings. Based on the type of rolling elements, they are categorized as ball bearings and roller bearings. According to their ability to self-align, bearings are divided into self-aligning and non-self-aligning bearings (rigid bearings). Depending on the number of rows of rolling elements, they can be single-row bearings, double-row bearings, or multi-row bearings. Bearings are also classified based on whether their components can be separated, leading to separable and non-separable bearings. Additionally, there are classifications based on structural shape and size.
This article primarily shares characteristics, differences, and corresponding applications of 14 common types of bearings.
1. Angular Contact Ball Bearings
Angular contact ball bearings have a contact angle between the inner ring and the balls. The standard contact angles are 15°, 30°, and 40°. A larger contact angle enhances axial load-bearing capacity, while a smaller angle is favorable for high-speed rotation. Single-row bearings can handle radial and unidirectional axial loads. Structurally, two single-row angular contact ball bearings with back-to-back arrangement share the inner and outer rings, allowing them to handle radial and bidirectional axial loads.
Main Applications:
Single-row: Machine tool spindles, high-frequency motors, steam turbines, centrifuges, small car front wheels, differential pinion shafts.
Double-row: Oil pumps, Roots blowers, air compressors, gearboxes, fuel injection pumps, and printing machinery.
2. Self-Aligning Ball Bearings
These bearings feature double rows of steel balls, with the outer ring raceway having a spherical shape. As a result, they can automatically accommodate shaft or housing misalignment. Tapered bore bearings can be conveniently mounted on a shaft using fasteners, mainly bearing radial loads.
Main Applications: Woodworking machinery, textile drive shafts, vertically mounted self-aligning bearings.
3. Spherical Roller Bearings
Spherical roller bearings have spherical rollers between the outer ring's spherical and double inner raceways. They come in R, RH, RHA, and SR types based on internal structure. Due to their self-aligning capability, they can automatically adjust to shaft or housing misalignment and handle radial and bidirectional axial loads.
Main Applications: Papermaking machinery, reduction gears, railway vehicle axles, rolling mill gearboxes, rolling mill roll necks, crushers, vibrating screens, printing machinery, woodworking machinery, various industrial reducers, vertically mounted self-aligning bearings.
4. Thrust Spherical Roller Bearings
These bearings have inclined rows of spherical rollers. The raceway surface of the seat ring is spherical, enabling significant axial load capacity and allowing for some shaft misalignment. They can carry substantial axial loads while supporting radial loads, typically using oil lubrication.
Main Applications: Hydraulic generators, vertical motors, ship propeller shafts, rolling mill screw-down gearboxes, tower cranes, coal crushers, extruders, and forming machines.
5. Tapered Roller Bearings
Tapered roller bearings feature conical rollers guided by the large end of the inner ring. The design ensures that the vertex of each conical surface intersects at the bearing's centerline. Single-row bearings can handle radial and unidirectional axial loads, while double-row bearings can handle radial and bidirectional axial loads. They are suitable for heavy and shock loads.
Main Applications: Automotive: front and rear wheels, transmissions, differential pinion shafts. Machine tool spindles, construction machinery, large agricultural machinery, rolling mill roll necks, and reduction units.
6. Deep Groove Ball Bearings
Deep groove ball bearings have continuous grooved raceways on each ring, with a cross-sectional shape approximately one-third of the equatorial circumference of a ball. They primarily handle radial loads and can also support some axial loads. When the radial clearance of the bearing increases, it exhibits properties similar to angular contact ball bearings, capable of withstanding alternating axial loads in both directions. Compared to other bearings of the same size, these bearings have low friction, high-speed capabilities, and high precision, making them a preferred choice for many applications.
Main Applications: Automobiles, tractors, machine tools, motors, water pumps, agricultural machinery, textile machinery, and more.
7. Thrust Ball Bearings
Thrust ball bearings consist of washers with raceways, balls, and cage assemblies. The washer that mates with the shaft is called the shaft washer, while the one that mates with the housing is called the seat washer. Bidirectional bearings have a central washer. Single-direction bearings can handle unidirectional axial loads, while bidirectional bearings can handle bidirectional axial loads (neither can handle radial loads).
Main Applications: Automotive steering pivots, machine tool spindles.
8. Thrust Roller Bearings
Thrust roller bearings are primarily used for shafts that carry axial loads but allow some radial load. Compared to other thrust roller bearings, they have lower friction, higher speed capability, and self-aligning ability. The rollers in the 29000 series bearings are asymmetrical spherical rollers, reducing relative sliding between rollers and raceways during operation. They have long rollers, large diameters, and a high load capacity, typically using oil lubrication, although some low-speed applications may use grease lubrication.
Main Applications: Hydraulic generators, cranes.
9. Cylindrical Roller Bearings
Cylindrical roller bearings usually have rollers guided by two flanges on a bearing ring. The roller and cage assembly forms a complete unit and can be separated from the other bearing ring, making it a separable bearing. This bearing type is convenient for installation and removal, especially when tight fits are required between the inner and outer rings and shaft or housing. These bearings are generally used for radial loads, with only single-row bearings with flanges on both the inner and outer rings able to handle small, steady axial loads or larger intermittent axial loads.
Main Applications: Large motors, machine tool spindles, axle boxes for railway cars, diesel engine crankshafts, automobiles, gearboxes with overhung loads, and more.
10. Four-Point Contact Ball Bearings
These bearings can handle both radial loads and bidirectional axial loads. A single bearing can replace either face-to-face or back-to-back paired angular contact ball bearings. They are suitable for applications with pure or predominantly axial loads since they form an angle of contact when subjected to any axial load direction. Consequently, the inner and outer rings always have three contact points along any contact line.
Main Applications: Aircraft jet engines, steam turbines.
11. Thrust Cylindrical Roller Bearings
Consisting of washer-shaped raceway rings (shaft and seat washers) and cylindrical rollers, thrust cylindrical roller bearings use convexly machined rollers for even pressure distribution between the rollers and raceway surfaces. They can handle unidirectional axial loads with high load-carrying capacity and axial rigidity.
Main Applications: Petroleum drilling rigs, iron and steel machinery.
12. Thrust Needle Roller Bearings
Separable thrust needle roller bearings comprise raceway rings, needle rollers, and cage assemblies. They can be combined with thin-walled raceway rings produced by stamping or thick-walled raceway rings produced by machining. Non-separable thrust needle roller bearings are one-piece from precision-stamped raceway rings, needle rollers, and cage assemblies. They can handle unidirectional axial loads and occupy less space, facilitating compact mechanical designs. They often consist of needle rollers and cage assemblies, using the shaft and housing mounting surfaces as raceways.
Main Applications: Automobiles, plows, machine tools, and other transmission equipment.
13. Thrust Tapered Roller Bearings
These bearings feature conical rollers (with the larger end being spherical) guided by raceway rings (shaft and seat washers) with accurately positioned flanges. The design ensures that the vertex of each conical surface intersects at the bearing's centerline. Unidirectional thrust tapered roller bearings can handle unidirectional axial loads, while bidirectional bearings can handle bidirectional axial loads.
Main Applications:
Unidirectional: Crane hooks and rotary swivels for petroleum drilling rigs.
Bidirectional: Rolling mill roll necks.
14. Insert Ball Bearings with Housings
Insert ball bearings with housings consist of two sealed outer ball bearings and cast (or stamped steel) bearing housings. The internal structure of the outer ball bearings is the same as that of deep groove ball bearings. However, the inner ring is wider than the outer ring, and the outer ring has a spherical outer surface that matches the concave spherical surface of the bearing housing, allowing for self-alignment.
Main Applications: Mining, metallurgy, agriculture, chemicals, textiles, printing and dyeing machinery, conveyor systems, and more.
Understanding the features and uses of these bearings helps engineers and manufacturers choose the most suitable type for their needs, enhancing the performance and longevity of mechanical equipment. We hope that the information provided in this article can assist you in gaining a better understanding of different types of bearings and their applications in various fields. Whether it's the automotive industry, aerospace, construction, or other sectors, bearings are an integral part of modern engineering. For engineers and manufacturers, choosing the appropriate bearing type will contribute to more efficient and reliable machinery.
