In the modern ball bearings, the machine designer has available, also, many widely varying specific characteristics. According to different bearing types, over and above the general advantages commonly listed as attributes of anti-friction bearings as a whole.
In this way, they are particularly adaptable to a great many specialized fields. Slight variations here and there enabling them to meet satisfactorily those factors of operation or service requiring special consideration.
Ball bearings in various types and sizes are able to carry either radial loads or thrust loads in nearly any practical magnitude. In general, they afford maximum load capacity in the smallest possible space. Most of them will have the ability, furthermore, to carry both radial and thrust loads at the same time, in various proportions and totals.
Requirements may demand that people locate shafts positively under light thrust loads. Or it may be necessary to provide a very positive location even under considerable thrust. Specific types of ball bearings offer these possibilities. For example, the standard Single Row Type is satisfactory for locating shafts end-wise in assemblies, where slight end-wise or axial deflection under load is not serious. On the other hand, if under load practically no movement of the shaft is permissible, and you must assure great rigidity. You can employ the Double Row Angular-Contact Bearing or perhaps a Duplex Unit. Procure these qualities of definite axial location with certain types of bearings without sacrificing their capacity for radial and thrust loads as well.
Thrust in both directions — as experienced with reversing worm drives — more than one type of bearing can carry it. But other bearing designs are not suitable at all.
Where it involves the speed factor it may still require other characteristics. And this proper selection can obtain, some bearings carry greater loads at higher speeds than others, due to their internal design.
Radial rigidity of shaft — as well as the end-wise rigidity mentioned — various types of assemblies can offer, including preloaded bearing combinations, for the extreme rigidity of machine tool spindles, etc. You must adjust shafts endwise on the initial assembly to compensate for certain demands.
Adjustable bearings are available to meet particular requirements, but on the whole, adjustment of bearings is a negative feature. Since the principle of ball bearing design permits of virtually non-wearing operation. The majority of bearing types are non-adjustable, requiring no adjustment either in mounting or in service. Even though their useful life may be extended over many years.
The extreme degree of precision which may be obtained with ball bearings is well known. And in many bearing applications is the determining factor in their use.
Compared with other bearing types, ball bearings occupy very little space on the shaft. This is a key point in the selection of bearings. Especially attractive to mechanical designers.
The foregoing constitutes a rough outline of the specific characteristics which to one degree or another are a feature of each ball bearing type and design. All of which must be considered in selecting the proper bearing in view of the service demands to be made upon it.