Hub cap comprises stationary outer ring which clips on to wheel rim, rotating disk fitted into this being attached to hub and ball bearings being mounted between two sections

摘要

The hub cap comprises a stationary outer ring (2) which clips on to the wheel rim (1). A rotating disk (3) is fitted into this and attached to the hub (5). Ball bearings are mounted between the two sections. Sections of the disk may be punched out to form blades so that the disk rotates in the opposite direction to the wheel in the slipstream.