Tensioner is a commonly used holding device in belt and chain transmission systems. Its characteristic is to maintain the appropriate tension of the belt and chain during the transmission process, thereby avoiding belt slippage or preventing synchronous belts from jumping or falling off teeth and dragging out. Or it can prevent the chain from loosening or falling off, and reduce the wear of sprockets and chains.

　　In terms of effectiveness, tensioners using spring structures are generally used due to their simple construction and low cost. However, tensioners using rubber components have a longer lifespan than springs due to the good elasticity of rubber. However, they have higher requirements for rubber performance and are relatively expensive, so they are less commonly used and are usually used in mechanical equipment.