Ball bearings are mainly divided into:
Radial ball bearings are the most commonly used bearings for radial loads, especially in the single row version. By virtue of the geometry of the raceways they can also withstand axial loads (to be verified for each application) even bidirectional, at the same time reaching high rotation speeds and, with adequate lubrication, low noise levels. There are also shielded versions of the radial ball bearings with stop rings on the external diameter, versions in stainless steel and with sealing rings of suitable material.
Suitable for bearing axial loads only. They consist of a shaft washer (WS series) and a housing washer (GS series) with grooves in which the rolling elements (in this case balls) roll, guided and centred by a cage that can be built in different materials depending on use and working conditions. In this configuration they are called "single acting".
There are also double-acting versions which are obtained by interposing two cages complete with balls and a central washer between the two external washers which are generally the same, so as to allow the absorption of bidirectional axial loads.
There are several possible executions:
Angular contact ball bearings (double row)
Are comparable to two single row angular contact bearings arranged back-to-back but with a smaller size; these bearings have different contact angles and therefore bear axial loads in both directions proportional to the contact angle and of the same value for those without filling groove. Bearings with this groove on one side must respect a mounting direction that directs the main axial load onto the race without groove.
Four-point contact ball bearings
Judging from the raceway geometry, these bearings can be considered similar to angular contact bearings. They support bidirectional axial loads and low radial clearance; they can then be dismounted, in fact they have an external ring, balls and cage integral and independent from the internal part, which is made up of two half rings specially coupled to the external group and therefore not interchangeable with others, even if of the same series and size. The four-point contact ball bearings have a reduced axial thickness, a high axial load capacity and an inner ring in two halves which facilitates assembly and disassembly operations. The cage can be in brass for working conditions from -30 ° C to + 150 ° C or in polyamide loaded with glass fibre for temperatures up to a maximum of + 120 ° C.
Directable radial ball bearings
Self-aligning radial ball bearings withstand bidirectional radial and axial loads and are not separable. The outer ring has a spherical raceway, two rows of balls (which in some cases, with a brass cage, may protrude slightly laterally to the bearing) which are held and guided by a cage which can be in polyamide reinforced with glass fibre for operating temperatures up to + 120 ° C, or in brass for operating temperatures from -30 ° C up to + 150 ° for bearings without shielding and up to + 100 ° C if the abovementioned screens are present. The inner ring can have a cylindrical hole or with a taper of 1:12. These bearings can be mounted directly on the conical shaft or on a cylindrical shaft, in the latter case through an adapter sleeve and ring nut with safety washer.
Radial ball bearings with thin rings
These bearings are also available as ball bearings, four-point contact, angular contact. They have an “ultra-small” section for the majority with a square proportion, which remains constant for each series, even when the size of the tree varies. They offer precision, high load capacity and quiet operation.
