Abstract: An apparatus for use with motor-driven assemblies is described. The motor-driven assembly comprises a motor, a pulley driven by the motor, a driven element and a belt drive connecting the pulley and the driven element. The apparatus comprises a motor base and a pivot base. The motor is arranged on the motor base such that, due to the positioning of its mass, the motor will pivot away from the drive element. However, pivoting in this direction is opposed by the belt drive. Thus, as the belt drive tension reduces, the motor will pivot away from the drive element, thereby tightening the belt. A one-way restraining means connecting the pivot base and the motor base prevents the motor from pivoting back toward the drive element, thereby keeping the belt drive taut and retaining drive design expectations.