Patent attributes
A lubricant circulation pump (46) which is driven by an electric motor (47) is provided in the course of a circulation path (41A, 41B) for circulating lubricant oil to a wheel mounting case (19) which is rotated together with a rear wheel (7). Turning on and off the lubricant circulation pump is controlled according to rotational speed of the rear wheel. When lubricant oil in the wheel mounting case sticks on inner peripheral surfaces thereof under the influence of centrifugal force as a result of the increased vehicle speed, the electric motor is turned off to suspend operation of the lubricant circulation pump. Consequently, the lubricant circulation pump does not suck lubricant oil in the wheel mounting case through an inlet opening (42A) of an intake pipe (42), thereby preventing the lubricant circulation pump from being put in a dry idling operation.
