US Patent 7574945 Mounting structure for rotary member

A rotary member mounting structure is configured for mounting a speedometer worm gear closely adjacent to a drive gear that is supported on an output shaft. The rotary member mounting structure basically has a rotation preventing structure, a first fastening ring and a second fastening ring. The rotation preventing structure is configured to prevent the drive gear from rotating relative to the output shaft 1 and to prevent the worm gear from rotating relative to the output shaft. The first fastening ring is configured to prevent the drive gear from sliding axially toward the worm gear and to prevent the worm gear from sliding axially toward the drive gear; and a second fastening ring is configured to prevent the worm gear from sliding axially in the direction opposite (i.e., away from) the drive gear.