The collection of parts that make the valves operate. The valvetrain includes the camshaft(s) and all related drive components, the various parts that convert the camshafts rotary motion into reciprocating motion at the valves, and the valves and their associated parts.

Refers to all the components that operate the valves (including the valves) in the engine's cylinder head.

The collection of parts that make the valves operate. The valve train includes the camshaft(s), related drive components, the various parts that convert camshaft's rotary motion into reciprocating motion, and the valves and their associated parts.

The many parts making up the valve assembly and its operating mechanism.

A traditional reciprocating internal combustion engine uses valves to control air and fuel flow into and out of the cylinders, facilitating combustion. Valvetrain is an all-encompassing term used to described the mechanisms and parts which control the operation of the valves.