Belt Drive Timing Belt Tension Damper; Chain Drive Timing Chain Tensioner Belt Tensioner is used to guide and tighten the timing belt in the engine so as to keep it in an optimal state of tension. It is generally divided into two types of hydrauli tensioner and mechanical tensioner,which can be automatically to tighten the timing belt. Chain Tensioner is used to guide and tighten the timing belt in the engine so as to keep it in an optimal state of tension. It is generally divided into two types of hydrauli tensioner and mechanical tensioner,which can be automatically to tighten the timing chain.