Design of associated components

If bearings of the NN design, fitted with two cages of polyamide or brass or two pin-type steel cages, have to be able to accommodate axial displacements of the shaft relative to the housing, space must be provided at both sides of the bearing (fig 1). This prevents the cages from fouling adjacent components, for example, which would damage the bearing arrangement. The smallest value for the depth of this free space can be obtained from

Ca min = 1,3 s


Ca min=minimum depth of free space [mm]
s=permissible axial displacement from the central position (see product table) [mm]
To facilitate mounting and dismounting bearings with tapered bore having bore diameters of some 80 mm or larger, the use of the SKF oil injection method, where oil under high pressure is injected between the mating surfaces, is recommended. This considerably reduces the forces required and practically eliminates any risk of damaging the bearing or its seat on the shaft.
For bearings with cylindrical bore, the oil injection method is only used for dismounting.
In order to be able to apply the oil injection method it is necessary to provide the necessary oil ducts and distributor grooves (fig 2). Details of suitable dimensions for these as well as the thread for the connection will be found in the section Application of bearings - Designing associated components.
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