在 正時皮帶或正時鏈條的傳動下，凸輪軸驅動氣門在正確的時間開閉，配合活塞完成進氣、壓縮、做功和排氣四個過程。由于正時皮帶和正時鏈條在中高速運轉時會發生跳動，而且正時皮帶在長期使用中會因為皮帶的材質和受力，發生拉長、變形產生跳牙導致配氣正時的不準確，從而引起車輛費油、無力、爆震等故障。當跳牙過多時因為氣門 過早打開或過晚關閉還會使氣門和上行的活塞碰撞損壞發動機。為了能讓正時皮帶和正時鏈條保持合適的漲緊度，即不因過松而跳牙也不因過緊而發生損壞，有一個專門的漲緊系統，由漲緊器和漲緊輪或導軌組成。漲緊器提供指向皮帶或鏈條的壓力，漲緊輪與正時皮帶直接接觸，而導軌直接與正時鏈條 接觸，它們在隨皮帶或鏈條運轉的同時將漲緊器提供的壓力施加在其上，使它們保持合適的漲緊程度。
under the timing belt or timing chain drive, camshaft drive valve at the right time to open and close, with the piston to complete the intake, compression, work and exhaust four processes. Because of the timing belt and timing chain in high-speed operation will occur when the beating, and timing belt in the long-term use because of belt materials and stress, deformation, occurrence of elongated teeth caused valvetiming inaccurate, causing the vehicle costs oil, weakness, detonation. When the valve is too long or the valve is too early to open or close the valve and the piston will crash the engine damage. In order to make the timing belt and timing chain to maintain the appropriate tension, that is, not too loose because of jumping teeth and not too tight and damage, there is a special tension system, by the tensioner and the tension wheel or rail composition. Tensioner provided to the belt or chain pressure, timing belt tensioner and direct contact, and direct and guide the timing chain contact with them in the belt or chain operation will also provide the tensioner pressure exerted on it, so that they maintain appropriate tension degree.