The small editor will introduce the relationship between the crankshaft and the camshaft. (1) The upper camshaft is placed on the cylinder head, and the car engine is commonly used. The main advantages: less moving parts, camshaft to valve transmission chain is short, the whole mechanism of the stiffness, suitable for high-speed engine.
Main disadvantages: camshaft and crankshaft transmission distance is far, generally with toothed belt transmission or chain drive. (2) The center camshaft is located in the upper part of the cylinder block.
Compared to the camshaft downtype: reduced pushrod (or shorter pushrod), thus reducing the quality of reciprocating motion of the gas distribution mechanism, increasing the stiffness of the mechanism, and more suitable for higher speed engines. (3) The lower camshaft is located in the crankcase. The main advantages: camshaft from the crankshaft is closer, generally with a pair of gear drive. The main disadvantages: many moving parts, camshaft to valve transmission chain length, the whole mechanism of stiffness difference, more for lower speed engine.