ROLLER BEARINGS & BALL BEARINGS - Part 1
|Figure 4 - Conrad-type ball bearing, left, and maximum-capacity (filling slot) type, right.|
|Figure 5 - Flat-race, flat-seat thrust ball bearing, A, and grooved-race, flat-seat thrust ball bearing, B.|
Rolling-element bearings rely on either balls or rollers to support loads. The rolling motion produces much less friction than plain bearings. For this reason, rolling-element bearings are often called anti-friction bearings. As with plain bearings, rolling-element bearings are available for radial loads, thrust loads, or a combination of radial and thrust loads.
Radial ball bearings - There are two basic types of radial ball bearings: the non-filling slot or Conrad type, and the filling slot or maximum capacity ball bearings, Figure 4.
Conrad ball bearings have a deep, uninterrupted raceway in inner and outer rings. This design carries heavy radial and moderate bidirectional thrust loads. The filling slot or maximum capacity ball bearing contains more balls than an equivalent-sized Conrad type, and therefore, a higher radial load capacity. However, because of the filling slots, thrust loads must be light and applied only in combination with a heavier radial load. Exceeding rated thrust causes balls to roll over the filling slots, causing severe damage to the ball bearing. Ball Bearings feature a load capacity, which can also be increased by using double row ball bearings instead of the max type.
To select a proper radial ball bearing for an application, analyze the following variables:
Load: Is load applied as radial, thrust, or a combination? What is its magnitude? What is its nature (uniform, light shock, heavy shock)? When load is applied as a combination of radial and thrust forces, convert these factors into a single equivalent radial load using formulas in the engineering section of manufacturers' catalogs.
Ball Bearings - Speed: How high is speed? Is it constant or variable? Ball bearings feature speeds, which are limited by tolerance grade, lubricant used, retainer design, and type of bearing seal.
Roller Bearings & Ball Bearings