Abstract: The present invention employs, in a preferred embodiment, a pair of pulleys, one of which is fixed and the other of which is movable and each of which has substantially the same diameter. The pulleys each have an axial aperture which holds a bearing arrangement including a shaft. Mounted across the two shafts is a pair of plates which are interconnected and therefore act together as a rigid body. The rigid body, or rigid member, is movable in a rotary fashion. In addition, there is a flexible band member which loops a substantial section of the movable pulley and, in a preferred embodiment, is disposed to come in frictional contact with the movable pulley and the fixed pulley. The ends of the band are secured to the fixed pulley and are held in tension.