Driving wheel counter clockwise, requested for the belt does not slip in the transmission process, static friction is the friction between belt and pulley, friction with the belt in the direction of movement relative to the pulley in the opposite direction. "The direction of relative motion" is assumed when there is friction between belt and pulley, belt direction of motion relative to the pulley. Now known wheel was turning counterclockwise, thus belt in relation to the direction of relative motion of pulley is clockwise, it can be concluded that the driving wheels in the direction of the static friction force on the belt counterclockwise. In the presence of static friction, belt counterclockwise rotation. For the right gear, belt friction direction is clockwise. Belt under the two pulley friction, round the top of the belt tension wheel below the belt is slack, and surrounded by belts of each pulley wrap angle are less than π.