A variable Speed V-belt to be used for a dry type transmission. It comprises at least one endless load carrier with cogs at the underside thereof and a plurality of blocks with slots in which said load carrier is fitted. Said load carrier and said blocks are engaged with each other in a lengthwise direction of the belt by engagement of a curved convexed surface of a slot under surface of the block with a curved concaved part which is a valley between adjoining cogs of the load carrier.
A Variable Speed V-belt transmission basically has a driving pulley, a driven pulley and a V-belt wound around the pulleys. The frictional engagement between the pulleys and the V-belt is controlled by regulating pulley axial thrusts to the pulleys. The V-belt has a plurality of torque transmitting connected by an annular ring. The detected boundary position is used to estimate the pulley axial thrust applied by the driving pulley against the V-belt, and to control the pulley axial thrust to a lower limit which ensures that the V-belt will not slip upon application of the maximum torque.