A tensioner is a mechanical device that maintains or applies tension to another component, such as a belt, rope, cable, or wire. It typically consists of an adjustable pulley system with springs or other means to create and maintain the desired level of tension. Tensioners are commonly used in automotive applications, where they help keep drive belts tight and prevent slippage or failure. They can also be found in various industrial settings, such as manufacturing equipment, where they ensure proper tension on conveyor belts, transmission lines, or other components that require consistent tension for optimal performance.