Camshaft-mounted valve train: The camshaft is arranged on the cylinder head. The camshaft drives the valve directly through the rocker arm, without tappets and push rods, which greatly reduces the mass of the reciprocating motion, and has the lowest requirements on the camshaft and valve springs, so it is suitable for high-speed enhanced engines.
Camshaft transmission
Camshafts are rotated by the crankshaft, and they can be driven by timing gears, timing chains, or timing belts. Every time a four-stroke engine completes a working cycle, the crankshaft rotates twice, and the intake and exhaust valves of each cylinder are opened once, that is, the camshaft only rotates once, so the transmission ratio of the crankshaft to the camshaft is 2:1.