The Loren Cook 778542 Rotary Belt Tensioner is a mechanical replacement component designed for compatible Loren Cook ventilation and exhaust fan systems. It maintains proper drive belt tension by applying consistent pressure to help keep the belt securely aligned around the pulleys during operation. This component supports efficient power transmission between the motor and fan assembl... https://www.partshnc.com/778542-loren-cook-rotary-belt-tensioner