Bearings subject to selected axial preload (light [L], medium [M] or heavy [F]) and having flush side faces under preload are classed as Universal [U].

SNFA universal bearings have the suffix UL, UM, UF according to the required preload and offer users the possibility of forming groups of bearings in any required arrangement (DD, FF or T) by using their own stock, without having to make any ring face adjustment.

As a consequence of their manufacturing features, the resultant preload of groups of U bearings is obtained by multiplying the preload of the single U bearing by the following coefficients:

[twocol_one]Sets[/twocol_one] [twocol_one_last]Coefficient[/twocol_one_last]

[twocol_one]DD – FF[/twocol_one] [twocol_one_last]1.00[/twocol_one_last]

[twocol_one]TD – TF[/twocol_one] [twocol_one_last]1.35[/twocol_one_last]

[twocol_one]3TD – 3TF[/twocol_one] [twocol_one_last]1.60[/twocol_one_last]

[twocol_one]TDT – TFT[/twocol_one] [twocol_one_last]2.00[/twocol_one_last]

 

Above mentioned sets formed with “Universal” bearings, when compared to the “SNFA matched sets”, offer advantage for stocking requirements but their contact angle and bore/outer diameter tolerance do not maintain SNFA standards.

A variant, consisting of Duplex Universal bearings, coded DUL, DUM and DUF according to preload, is also available.

Its advantages can be summarized below:

  • the bearings of the same pair can be mounted in any configuration (DD, FF or T)
  • the contact angle difference between the two bearings is minimum (a significant advantage for a tandem configuration)
  • the difference in the actual bore and outside diameter, between the two bearings, is minimal (one third of overall tolerance)
  • Universal Duplex bearings from different sets may not exchanged between each other.

The speed, preload and rigidity values indicated in the bearing table refer to SNFA matched bearings. For asymmetrical groups (TD – TF), formed by single Universal bearings, these values must be calculated for each case, taking proper account of the preload correction coefficients mentioned above.