Key takeaways: 1. Bearings are differentiated by their design and functionality, with the key distinctions lying in their ability to handle various loads (radial, thrust, or a combination), their alignment capabilities, and the number of rolling elements, which directly influence their suitability for specific applications ranging from automotive parts to industrial machinery. 2. The contact angle of a bearing, typically at 15°, 30°, or 40°, is a critical design feature that determines its axial load capacity and suitability for high-speed rotation, with larger angles favoring greater axial loads and smaller angles optimizing for high-speed applications. 3. The choice of bearing type, such as deep groove ball bearings for high-speed, low-load applications or tapered roller bearings for heavy, shock-load scenarios, is essential for optimal machinery performance, highlighting the importance of understanding bearing characteristics to ensure reliability and efficiency in mechanical systems.
Bearings are crucial components in machinery and equipment, serving the purpose of supporting rotating mechanical bodies to decrease the friction coefficient of the equipment during transmission and reduce the mechanical load.
Bearings are categorized into different types based on several factors. These include the direction of the bearing or its nominal contact angle, which divides bearings into radial and thrust bearings.
Additionally, bearings can be classified based on the type of rolling body, with options being ball bearings and roller bearings.
The ability to align is another factor, leading to the division into aligning and non-aligning (rigid) bearings.
The number of rows of rolling elements is another factor that leads to the division into single-row, double-row, and multi-row bearings.
The separability of the parts is another factor, leading to the division into separable and non-separable bearings.
There are also classifications based on structure shape and size.
This article primarily focuses on the features, differences, and appropriate applications of 14 common types of bearings.
1. Angular Contact Ball Bearing
The contact angle between the ferrule and the ball is one of the key factors in determining the characteristics of a bearing. There are three standard contact angles: 15°, 30°, and 40°. A larger contact angle provides a higher axial load capacity, while a smaller contact angle is better suited for high-speed rotation.
A single-row bearing can support radial loads and unidirectional axial loads. By combining two single-row angular contact ball bearings on the same axis, the structure can support both radial and bidirectional axial loads. The inner and outer rings are shared between the two bearings, providing a more robust and versatile solution.
Single Row: Machine tool spindle, high-frequency motor, gas turbine, centrifugal separator, front wheel of small cars, differential pinion shaft.
Double Row: Oil pump, Roots blower, air compressor, various transmissions, fuel injection pump, printing machinery.
2. Spherical Ball Bearing
Double-row steel balls have an inner spherical type outer ring raceway, allowing for automatic adjustment of misalignment caused by deflection or misalignment of the shaft or housing.
Tapered roller bearings, designed for easy mounting using fasteners, mainly bear radial loads.
- Woodworking machinery
- Textile machinery transmission shafts
- Vertical self-aligning bearings with housings.
3. Spherical Roller Bearing
This type of bearing features spherical rollers located between the outer ring of the spherical raceway and the inner ring of the double raceway. It is divided into four types based on its internal structure: R, RH, RHA, and SR. As the outer ring raceway’s arc center is aligned with the bearing center, it has self-aligning capabilities.
This allows for automatic adjustment of axis misalignment caused by the deflection or misalignment of the shaft or housing, and it can support both radial loads and bidirectional axial loads.
- Papermaking machinery
- Reduction gears
- Railway vehicle axles
- Rolling mill gear box seats
- Rolling mill roller tables
- Vibrating screens
- Printing machinery
- Woodworking machinery
- Various industrial reducers
- Vertical self-aligning bearings with boxes, and more.
4. Thrust Spherical Roller Bearings
In this type of bearings, spherical rollers are arranged obliquely. The raceway surface of the raceway is spherical and has self-aligning performance, allowing the shaft to tilt slightly. This bearing has a large axial load capacity and can bear several radial loads while under axial load. It is generally lubricated with oil during use.
Hydro-generators, vertical electric motors, propeller shafts for ships, reducers for rolling screws of rolling mills, tower cranes, coal mills, extruders, and forming machines.
5. Tapered Roller Bearing
These bearings are equipped with cylindrical rollers that are guided by the large ribs on the inner ring. The points where the tapered surfaces of the inner ring raceway, the outer ring raceway, and the roller rolling surface intersect are designed to be on the centerline of the bearing. Single-row bearings can handle radial and one-directional axial loads, while double-row bearings can handle radial and bi-directional axial loads, making them suitable for handling heavy and shock loads.
- Automotive: front and rear wheels, transmissions, differential pinion shafts
- Machine tool spindles, construction machinery, large agricultural machinery, railway vehicle gear reduction devices, rolling mill roll necks, and reduction devices.
6. Deep Groove Ball Bearing
In this type of bearing, each ring has a continuous, grooved raceway that forms a cross-section approximately one-third the equator circumference of the ball.
Deep groove ball bearings primarily support radial loads but can also withstand some axial loads. When radial clearance increases, they exhibit angular contact ball bearing characteristics and can handle axial loads in two alternating directions.
Compared to other bearings of the same size, deep groove ball bearings have a low friction coefficient, high limiting speed, and high accuracy, making them a popular choice among users.
automobiles, tractors, machine tools, motors, pumps, agricultural machinery, and textile machinery.
7. Thrust Ball Bearings
It consists of a washer-shaped raceway ring with a raceway, a ball, and a cage assembly. The raceway ring that works with the shaft is referred to as the shaft ring, and the raceway ring that works with the housing is called the seat ring. Two-way bearings align the center ring with a solid shaft. One-way bearings can handle unidirectional axial loads, while two-way bearings can handle bidirectional axial loads (neither can handle radial loads).
- Automotive steering pins
- Machine tool spindles.
8. Thrust Roller Bearing
Thrust roller bearings are designed for shafts that primarily experience axial loads. It can also handle combined loads in the axial direction, but the load in the axial direction should not exceed 55% of the total load.
This type of bearing has lower friction coefficient, higher operating speed, and the ability to self-align. The 29000 type rollers are asymmetrical spherical rollers that reduce the relative sliding between rollers and raceways during operation and are large in diameter and length.
These bearings have a high load capacity due to a large number of rollers and are typically lubricated with oil. Low-speed operations can be lubricated with grease.
hydraulic generators, crane hooks, etc.
9. Cylindrical Roller Bearing
Cylindrical roller bearings are typically guided by two ribs on a bearing ring. The cage roller and guide ring form a separable assembly that can be separated from the other bearing ring. This type of bearing is easy to install and disassemble, particularly when the inner and outer rings need to have an interference fit with the shaft and housing.
These bearings are mainly used to support radial loads, but single-row bearings with ribs on both the inner and outer rings can withstand small steady axial loads or large intermittent axial loads.
Large motors, machine tool spindles, axle boxes, diesel crankshafts, automobiles, transformers, etc.
10. Four-point Contact Ball Bearing
This type of bearing is capable of bearing radial loads and bidirectional axial loads. A single bearing can replace a combination of angular contact ball bearings, either in front or back. It is ideal for bearing pure axial loads or loads with a large axial load component.
This type of bearing forms one of the contact angles under axial loads in any direction, so the retainer and the balls are always in three-point contact on both sides of the contact line.
- Aircraft jet engines
- Gas turbines
11. Thrust cylindrical roller bearing
It is comprised of a washer-shaped raceway ring (shaft washer and seat ring), cylindrical rollers, and a cage assembly. The cylindrical rollers have a convex surface, resulting in uniform pressure distribution between the rollers and the raceway surface. This type of bearing can withstand unidirectional axial loads and has high axial load capacity and strong axial rigidity.
include petroleum rigs and iron and steel machinery.
12. Needle Thrust Bearing
The needle roller bearing can either be separate or integral. The separate bearing consists of a raceway ring, needle roller, and cage assembly that can be combined with either a stamped thin raceway or a cut thick raceway. On the other hand, the integral bearing is made up of a precision-stamped raceway ring, needle roller, and cage assembly and can support unidirectional axial loads.
This type of bearing has a small footprint, making it ideal for compact machine design. Most needle roller bearings only consist of the needle roller and cage components and utilize the shaft and housing mounting surface as the raceway surface.
Automotive transmissions, tillers, machine tools, etc.
13. Taper Roller Thrust Bearing
This type of bearing features a spherical roller (the larger end is spherical), which is precisely guided by the raceway ring (shaft ring and seat ring) ribs.
The design aligns the apex of each conical surface of the shaft washer, the roller surface of the saddle ring, and the rolling surface of the rollers to intersect at a single point on the centerline of the bearing.
One-way bearings are capable of supporting unidirectional axial loads, while two-way bearings are capable of supporting bidirectional axial loads.
One-way: Cranes, hooks on oil rigs.
Two-way: Roll necks in rolling mills.
14. Outer Spherical Ball Bearing with Housing
Outer spherical ball bearings with housing consist of sealed outer spherical ball bearings on both sides and cast (or stamped steel plate) bearing housings. The internal structure of the outer spherical ball bearing is similar to that of a deep groove ball bearing, with the exception of the inner ring being wider than the outer ring. The outer ring has a truncated spherical outer surface, allowing it to self-align with the concave spherical surface of the bearing seat.
These bearings are commonly used in industries such as mining, metallurgy, agriculture, chemical, textile, printing and dyeing, transportation machinery, and others.
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