V-belt-type automatic transmission for vehicle

摘要

A V-belt-type automatic transmission for a vehicle is provided with a drive pulley and a driven pulley, wherein a plurality of centrifugal weights are arranged between a movable pulley piece of the drive pulley and a cam plate. The centrifugal weights are moved in a radial direction by centrifugal force. A wrapping radius of a V-belt wound around the drive pulley and the driven pulley is changed depending on a maximum gear ratio in a low-speed rotation range and a minimum gear ratio in a high-speed rotation range that are set. The movement in a radial direction of the centrifugal weight beyond a predetermined radial distance prevented by a stopper surface at the rotational speed in a middle-speed rotation range, and at least one middle gear ratio is thereby set. This arrangement provides a V-belt automatic transmission providing noise reduction, reduction of machinery wear and facilitates smooth power transmission.