Abstract: A transmission assembly is provided for rotating a driver pulley connected to a belt by a driven pulley such that the two pulleys define an action plane. The assembly includes a rotatable output shaft having one end adapted to be connected to the driven pulley and extending in a direction perpendicular to the action plane. The output shaft is mounted on a pivotal axis parallel to the action plane for pivotal movement in a plane perpendicular to the action plane. A rotatable input shaft is provided which is adapted to have a torque applied thereto. Finally, a mechanical coupling is provided for coupling the input shaft to the other end of the output shaft such that the two shafts angularly intersect. As a consequence of this arrangement, the torque applied to the input shaft is resolvable into a couple, one force of which passes through the pivot axis and the other of which passes through the driver pulley for applying tension to the belt.