Common transmission modes between camshaft and crankshaft include gear drive, chain drive and tooth belt drive. The transmission between the lower camshaft and the middle camshaft and the crankshaft mostly adopts cylindrical timing gear transmission, generally from the crankshaft to the camshaft only needs 1 pair of gear transmission, if the transmission gear diameter is too large, you can add 1 intermediate idler. In order to engage smoothly and reduce working noise, the timing gear is mostly used bevel gear.
Chain drive is commonly found between the overhead camshaft and the crankshaft, but its reliability and durability are not as good as gear drive. In recent years, toothed tape has been widely used to replace the transmission chain on high-speed engines, but chain transmission is still used on some high-power engines. Toothed tape has the characteristics of low noise, reliable operation and low cost. For dual overhead camshafts, the exhaust camshaft is generally driven by the crankshaft through the timing tooth tape or chain, the intake camshaft is driven by the exhaust camshaft through the metal chain, or the intake camshaft and the exhaust camshaft are both driven by the crankshaft through the tooth tape or chain.
When installing the camshaft, pay attention to the timing mark on the camshaft pulley or sprocket. Some engines do not have obvious timing marks, maintenance personnel can mark the exact position of the crankshaft and camshaft before removing the camshaft, and some engines require special tools to adjust the timing.
