Types of Bearings

Types of Bearings Figure 10-119 shows a number of different types of journal bearings. A description of a few of the pertinent types of journal bearings is given here ... 

Three types of bearings will be discussed oil-film bearings, rolling-element bearings (also known as antifriction bearings), and magnetic bearings. 

A more generalized graph from a leading bearing manufacturer is reproduced in Figure 10.6, and covers practically all sizes and types of bearings to determine the relubricating period. 

Rq = relubricating interval in hours of operation K = a factor depending on type of bearing d = bearing bore diameter (mm)... 

Type of gas seals (inner seal) and oil seals Type of bearings (radial)... 

Speed is not limited by a surface speed as in the hydrodynamic bearing. Unfortunately, however, the stresses in the thrust collar pose one limit and the other is caused by need for an auxiliary bearing, which does have a limitation based on the type of bearing being used. 

Electric motors may incorporate either sleeve or rolling-element bearings. A narrowband window should be established to monitor both the normal rotational and defect frequencies associated with the type of bearing used for each application. 

A variety of bearing types is used in gearboxes. Narrowband windows should be established to monitor the rotational and defect frequencies generated by the specific type of bearing used in each application. 

The type of bearing used in a particular application is determined by the nature of the relative movement and other application constraints. Movement can be grouped into the following categories rotation about a point, rotation about a line, translation along a line, rotation in a plane, and translation in a plane. These movements can be either continuous or oscillating. 

As mentioned before, major bearing classifications are plain and rolling element. These types of bearings are discussed in the sections to follow. Table 60.4 is a bearings characteristics summary. 

The four-axial groove bearing is the most commonly used oil-lubricated sleeve bearing. The oil is supplied at a nominal gage pressure that ensures an adequate oil flow and some cooling capability. Figure 60.3 illustrates this type of bearing. 

There must be sufficient clearance between the journal and bearing in order to allow an oil film to form. An average diametral clearance of 0.001 inches per inch of shaft diameter is often used. This value may be adjusted depending on the type of bearing material, the load, speed, and the accuracy of the shaft position desired. 

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