Common transmission methods between the camshaft and the crankshaft include gear transmission, chain transmission and toothed belt transmission. The transmission between the lower camshaft and the middle camshaft and the crankshaft is mostly driven by cylindrical timing gears. Generally, only one pair of gears is needed to drive from the crankshaft to the camshaft. If the diameter of the transmission gear is too large, an additional intermediate gear can be added. Idler. In order to mesh smoothly and reduce working noise, the timing gears are mostly helical gears.
The chain drive is commonly used between the overhead camshaft and the crankshaft, but its working reliability and durability are not as good as the gear drive. Toothed tapes are widely used instead of drive chains on high-revving engines, but chain drives are still used on some high-power engines. Toothed tape has the characteristics of low noise, reliable operation and low cost. For DOHC, generally the exhaust camshaft is driven by the crankshaft through a timing toothed belt or chain, the intake camshaft is driven by the exhaust camshaft through a metal chain, or both the intake camshaft and the exhaust camshaft are driven by the crankshaft. Driven by the crankshaft via toothed belts or chains.