Rolling bearings

Rolling bearings

Roller or rolling bearings are those in which rolling elements are arranged between two pieces that move with relative motion. All types of rolling bearings consist of an inner ring, an outer ring and rolling elements (balls, cylindrical rollers, needle rollers, tapered rollers and spherical rollers). The rolling elements are guided by a cage that keeps them at a uniform distance from each other and prevents reciprocal contact; in the case of radial self-aligning bearings, it also ensures that the axis of the rolling elements is positioned correctly. Depending on specific requirements, the bearings can be supplied with side shields or seals.

The rolling bearings are classified according to the SHAPE OF THE ROLLING ELEMENTS, to the DIRECTION OF THE LOAD, to the FLEXIBLE DEFORMATIONS of the SHAFT and to the NUMBER OF ROWS.

Generally speaking, they comprise the following types:

Rolling bearings Load direction Alignment capacity Number of rows

Radial Stiff/Oscillating 1 row /2 rows
Axial Stiff/Oscillating 1 row
Oblique Stiff 1 row /2 rows
Cylindrical rollers Radial Stiff 1 /2 / 4 rows
Axial Stiff 1 row /2 rows
Tapered rollers Radial / Axial Stiff 1 row /2 rows
Spherical rollers Radial Oscillating 1 row /2 rows
Axial Oscillating 1 row
Needle rollers  Radial Stiff/Oscillating 1 row /2 rows
Axial Oscillating 1 row
Combined Oscillating 2 rows


The choice of the right type of bearing is mainly dictated by its constructional features, which make it more or less suitable for a given application. First and foremost, one has to consider its size and the load that the bearing has to carry. The size and the load are often tied to the application as a whole, which may involve certain limits and conditions that consequently breakdown the field of choice.

It is impossible to lay down general rules for the choice of a bearing, because many factors have to be taken into consideration and which are all related to the conditions and types of use of the bearing. Some focus points may however be pinpointed, which can be referred to based on the application involved.

Therefore, when choosing the right type of bearing, it is important to know and evaluate the available space, the working conditions and the loads involved, as well as the operating speed, durability requirements and other factors concerning the operating conditions (noise, vibrations, dusty workplace, high temperatures and so forth).



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