Introduction to the characteristics of the camshaft

The undercarriage camshaft usually uses a star gear set (so-called "control wheel"), and the roller chain or rack is connected to the crankshaft. In order to control noise, the larger diameter camshaft end drive wheel is usually made of plastic or light metal, while the smaller diameter crankshaft end drive wheel is mostly made of steel.

Chain connections are also more common. This is visible on both the bottom and top camshafts. In order to reduce the noise (generally the "wobble noise" generated by the chain during the movement), a hydraulic pressing device and a plastic guide rail are usually attached.

A more common type of overhead camshaft construction is a plastic chain link. This rack chain is located outside the engine oil chamber and comes with steel inserts that help tension with an adjustable roller.

There is also a structure that is relatively rare due to the excessive loss and complexity of the power during transmission. This configuration connects the overhead camshaft to the crankshaft via an eccentric link, a star gear set or a bevel gear set with an intermediate shaft.

Common transmission methods between the camshaft and the crankshaft include gearing, chain drive, and toothed belt drive. Most of the transmission between the lower camshaft and the center camshaft and the crankshaft is driven by a cylindrical timing gear. Generally, only one pair of gears is required from the crankshaft to the camshaft. If the diameter of the transmission gear is too large, one more intermediate can be added. Idler. In order to achieve smooth engagement and reduce operating noise, timing gears mostly use helical gears.

Chain drives are commonly found between overhead camshafts and crankshafts, but their operational reliability and durability are not as good as gearing. In recent years, toothed tape has been widely used in high-speed engines instead of drive chains, but chain drives are still used on some high-power engines. Toothed tape has the characteristics of low working noise, reliable operation and low cost. For dual overhead camshafts, typically 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 Driven by a crankshaft through a toothed tape or chain.

When installing the camshaft, be sure to pay attention to the timing marks on the camshaft pulley or sprocket. Some engines have no obvious timing marks, and maintenance personnel can mark the exact position of the crankshaft and camshaft before disassembling the camshaft. Some engines require special tools for timing adjustment.