MOTION & CONTROL™ Intelligently and reliably meeting the needs of a wide range of vehicle models.

1. Types and Features of Hub Unit Bearings 1-1. Categories of hub unit bearings·····································3 1-2. HUB I ·············································································5 1-3. HUB II ············································································7 1-4. HUB III ···········································································9 2. Selection of Hub Unit Bearings 2-1. Overview of selection···················································11 2-2. Selection of bearing types ···········································14 2-3. Types and characteristics...

1. Types and Features of Hub Unit Bearings 1-1. Categories of hub unit bearings Hub unit bearings for automobile wheels are comprised of bearing rings, rolling elements, and cages, similar to general-purpose rolling bearings. The first-generation hub unit (Hub I), second-generation hub unit (Hub II), and third-generation hub unit (Hub III) vary according to the integration of the bearings and their peripheral components. In addition, the forms are categorized by usage condition (rotations of outer rings or inner rings) and component location (for driven wheels or non-driven wheels). For driven...

1-2. HUB I For HUB I, NSK uses proprietary bearing-type designations such as “BWD” for ball bearings and “KWD” for tapered roller bearings. The HUB I units are double-row angular contact ball bearings (BWD) and double-row tapered roller bearings (KWD) with back-to-back duplex outer rings. No preload adjustments (including dimensional adjustments by shims) are required on the assembly line. The initial axial clearance is properly pre-set for the preload to fall within the specified range after mounting. In addition, the integral seal eliminates the need for automotive makers to externally apply...

1-3. HUB II For HUB II, NSK uses proprietary bearing-type designations such as “BWK” for ball bearings and “KWH” for tapered roller bearings. HUB II configurations are BWD or KWD HUB I with flanged outer rings. Outer ring rotation type (for non-driven wheels): Wheels and brake disks are mounted at the flanges. Spindles are inserted into the inner rings and fixed with nuts. Inner ring rotation type (for non-driven wheels): The flanges are fixed to the car body. Hub spindles are pressed into the inner rings and fixed with nuts. Inner ring rotation type (for driven wheels): The flanges are fixed to the axle...

1-4. HUB III For HUB III, NSK uses proprietary bearing-type designations such as “BWKH” for ball bearings. The HUB III configuration is a BWD HUB I with flanged inner and outer rings. Outer ring rotation type (for non-driven wheels): Wheels and brake disks are mounted at the outer ring flanges. The inner ring flanges are mounted on the car body, and the preload is pre-adjusted. Inner ring rotation type (for non-driven wheels): Wheels and brake disks are mounted at the inner ring flanges. The outer ring flanges are mounted on the car body, and the preload is pre-adjusted. Inner ring rotation type (for...

2. Selection of Hub Unit Bearings 2-1. Overview of selection While higher performance is demanded for hub unit bearings, the constraints and conditions of their application are becoming increasingly diverse. The selection of optimum bearing types satisfying such constraints and conditions requires the examination of various aspects. Please contact NSK for comprehensive technical services, such as functional evaluation, or technical consultations on design specifications in the development process, costs, and scheduling, for suitable selection of hub unit bearings. Fig. 1 shows the sample selection...