Timing Belts

The term timing belt is also used for the more general case of any flat belt with internal teeth. Such belts are used for power transmission or to interchange rotary motion and linear motion, where either high loads or maintaining a specific drive ratio are important. Some engines use timing gears. A common non-automotive application is in linear positioning systems. in the internal combustion engine application, the timing belt connects the crankshaft to the camshaft which in turn controls the opening and closing of the engine's valves. A four-stroke engine requires that the valves open and close once every other turn of the crankshaft. The timing belt does this. It has custom teeth to turn the camshaft synchronized with the crankshaft and is specifically designed for a particular engine. In some engine designs, the timing belt may also be used to drive other engine components such as the water pump and oil pump. A gearing system can be used to connect the crankshaft to the camshaft at the correct timing. However gears and shafts constrain the relative location of the crankshaft and camshafts. A belt or chain allows much more flexibility in the relative locations of the crankshaft and camshafts. Furthermore, belts are cheaper than a gearing system. While chains may be more robust, rubber belts are quieter. A timing belt is a specific application of a synchronous belt used to transmit rotational power synchronously.