Bearing Types
It is good to know the types of bearings used in different applications as they are very important in our daily lives. It helps ease the burden of each machines mechanical stress and helps greatly in transferring the work from one part of the machine to another. Without them, we would be spending too much friction on our cars wheels and would have a rough ride every time we drive our car. Here is some type of bearing we used today.
1. Deep groove bearing. The most common type of roller bearing. In addition to the radial loads, axial loads can be imposed in either direction which is highly suitable for applications where high speeds and low power loss are required. In addition to open type bearings, these bearings often have steel shields or rubber seals installed on one or both sides and are pre-lubricated with grease.
2. Angle contact bearing. Bearings of this type are capable of taking radial loads and also axial loads in only one direction. They are available in four contact angles (15°, 25°, 30° and 40°). The higher the contact angle, the higher the axial load capacity, but for high speed operation, the smaller contact angle are preferred. Usually, two bearings are used in duplex pairs and the clearance between them must be adjusted properly. Angle contact bearings are intended to take heavy thrust loads.
3. Self-aligning bearing. Due to its construction, the axis of the inner ring, balls, and cage can deflect to some extent around the bearing center. This compensates for angular misalignments of the shafts and are recommended for radial loads and moderate thrust in either direction.
4. Cylindrical bearing. The rollers, which are cylindrical, are in linear contact with the raceways which results in a greater area carrying the load and hence have a high radial load capacity and are also suitable for high speeds.
5. Needle bearing. This type of bearing contains many slender rollers with a length of 3 to 10 times their diameter. The ratio of the bearing outside diameter to the inscribed circle diameter is small, and they have a rather high radial load capacity.
6. Tapered bearing. They uses a conical rollers guided by a back-face rib on the cone. They are capable of taking high radial loads and also axial loads in one direction. They are generally mounted in pairs in a manner similar to angular contact bearing. The proper internal clearance can be obtained by adjusting the axial distance between the cones or cups of the two opposed bearings, and since they are separable, the cones assemblies and cups can be mounted independently.
The boundary dimensions of roller bearings are the dimensions that define its external geometry. They include, among others, bore diameter, outside diameter and width. Other dimensions are also worth noticing such as bearing width, chamfer dimension… etc. It is necessary to know all of these dimensions when mounting a bearing on a shaft and/or in housing.
Poor fitting, usually using a brute force, accounts to almost 20% of all premature bearing failures. To avoid this, use a bearing tool kit as they are designed for quick and precise mounting of bearings and helps minimize the risk of bearing damage. The right combination of impact ring and sleeve allows effective transmission of mounting force to the bearing ring with the interference fit, minimizing the risk of damaging the bearings raceways or rolling elements. Sample of this kit is called the SKF bearing fitting tool kit TMFT 36. It contains 36 pieces of impact rings, 3 impact sleeves and a dead-blow hammer and is packed in a lightweight carrying case. This kit is not only used for bearing mounting but also used for mounting other types of components such as bushings, seals and pulleys.
To mount a bearing, drive the bearings with appropriate driving tool which balances the inner and outer race with equal pressure. Do not drive bearings on inner or outer race as it will shear the bearing balls, causes dents that leads to bearing seizure and permanent damage.
- By Joel Esteban | Associated Content
- Naiomi Solomon
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