Single row angular contact ball bearings of spindle bearing design are intended to be used and mounted either in pairs or in bearing sets. NKE spindle bearings of universal design (suffix UL) feature a light preload when mounted in pairs or sets either face to face or back to back. NKE spindle bearings of the universal design are also available on order request in preload, see groups in the table below. Suffix Pre-Loading UL Light UM Medium US Heavy To enable simple mounting, even when the conditions are the mass assembly of machines and in order to maintain certain characteristics of the spindle bearing arrangement NKE also produce complete sets (i.e. matched and graded) of spindle bearings. Such sets consist of careful matched spindle bearings in different arrangements depending on the application requirements. Examples of different bearing arrangements are shown on the next page. Both the number of bearings per set and the arrangement of the individual bearings within the set is indicated by suffixes shown on next page. The NKE designation system for spindle bearings consist of two or three digit symbols. The first letter indicates the number of individual bearings of the set.   Sets, consisting of each 2 bearings (D): DT Set of 2 bearings, Tandem arrangement. DF Set of 2 bearings,Face to Face arrangement DB Set of 2 bearings,Back to Back arrangementTriple bearing Sets (T): TBT Combination of a Back to Back arrangement and a Tandem arrangementTFT Combination of a Face to Face arrangement and a Tandem arrangement TT 3 bearings in Tandem arrangementQuadruple bearing Sets (Q): QBC Set of 4 bearings Back to Back arrangementQFC Set of 4 bearings. Face to Face arrangement. QT 4 bearings in Tandem arrangement QBT 4 bearings in a combination of a Back to Back arrangement and a Tandem arrangement QFT 4 bearings in a combination of a Face to Face arrangement and a Tandem arrangement. The bearing sets are supplied in bundles. The individual bearings must not, under any circumstances, be mixed up with bearings from other sets. Single row angular contact ball bearings in spindle bearing design must not be exposed to any misalignments. Tolerances NKE spindle bearings of the series 719, 70 and 72 are produced to tolerance class P4 (ABEC 7) as standard. On request these bearings may also be produced to closer tolerances, up to tolerance class P2 (ABEC 9). NKE spindle bearings are fitted with phenolic resin cages, identified by a suffix T unless otherwise specified, This cage is suitable for permanent operating temperatures up to 100 deg C. For special applications, NKE produces spindle bearings with different cage materials such as light metal alloy cages identified by a suffix L. Speed ratings. The values of speed ratings given in the bearing tables apply to single mounted, lightly preloaded NKE spindle bearings (i.e. operating at zero clearance). The values given may be exceeded under certain circumstances such as optimum lubrication, adequate heat dissipation and the use of closer tolerance class.

All information courtesy NKE Bearings Austria www.nke.at