Overhead Camshaft (OHC)

Also known as Overhead Cam.

A type of valvetrain arrangement in which the engine's camshaft is placed in the cylinder head, above the combustion chambers. It drives the valves or lifters directly instead of using pushrods, enabling them to open and close more rapidly and the engine to run at higher rpm.

There are two overhead camshaft layouts: single-overhead-cam (SOHC) layout, where one camshaft actuates all of the valves in a cylinder head, and double-overhead-camshaft (DOHC), where one camshaft actuates the intake valves, and one camshaft operates the exhaust valves.

See also Single Overhead Camshaft and Double Overhead Camshaft.