A hub unit for detecting rotational velocity

摘要

A hub unit has a hub with a nut tightened at an axially inner end which is partly projected from the nut. A tone wheel is secured to the axially inner end of the hub. The tone wheel has an outer cylindrical portion provided around the nut and having magnetic properties changing alteratively in a circumferential direction with a uniform interval. An outer ring is provided, which has an axially inner open end. A cover covers the axially inner open end of the outer ring. The hub unit also has a sensor of a passive type supported by the cover and having a detecting portion facing to the outer periphery of the outer cylindrical portion of the tone wheel.