NSK tapered roller bearings are designed so the apices of the cones formed by the raceways of the cone and cup and the conical rollers all coincide at one point on the axis of the bearing. When a radial load is imposed, an axial force component occurs; therefore, it is necessary to use two roller bearings in opposition or some other multiple arrangement.
For metric-design medium-angle and steep-angle NSK tapered roller bearings, the respective contact angle symbol C or D is added after the bore number. For normal-angle tapered roller bearings, no contact angle symbol is used. Medium-angle NSK tapered roller bearings are primarliy used for the pinion shafts of differential gears of automobiles.
Amone those with high load capacity (HR series), some NSK roller bearings have the basic number suffixed by J to conform to the specifications of ISO for the cup back face raceway diameter, cup width, and contact angle. Therefore, the cone assembly and cup of bearings with the same basic number suffixed by J are internationally interchangeable.
Among metric-design NSK tapered roller bearings specified by ISO 355, there are those having new dimensions that are different than the dimension series 3XX used in the past. Part of them are listed in the NSK bearing size tables. They conform to the specifications of ISO for the smaller end diameter of the cup and contact angle. The cone and cup assemblies are internationally interchangeable. The NSK bearing number formulation, which different than that for past metric design, is as follow:
Example: T 7 F C 045
- T: Symbol representing tapered roller bearings
- 7: contact angle
- F: Diameter symbol
- C: Width symbol
- 045: Bore diameter symbol (bore diameter in mm)
Besides metric design NSK tapered roller bearings, there are also inch design bearings. For the cone assemblies and cups of inch design NSK bearings, except four-row tapered roller bearings, the bearing numbers are approximately formulated as follows:
Example: LM 1 19 49
- LM: Load limit symbol
- 1: contact angle symbol
- 19: Series No.
- 49: Design No.
- Additional symbol