Camshaft is used to operate valves. It consists of a cylindrical rod running the length of the cylinder with a number of oblong lobes protruding from it, one for each valve.

The pushrod also functions as a portal for transferring lubricating oil though the valve lifter and up to the cylinder head. This is quite a basic function, since the pushrod only acts as a pipe.

The tappet are also termed a cam follower, or valve lifter, It is that part that runs on the camshaft and is made to move vertically by the action of the rotating cam.

A rocker arm is an oscillating lever that conveys radial movement from the cam lobe into linear movement at the valve to open it. One end is raised and lowered by a rotating lobe of the camshaft.

A connecting rod is a rigid member which connects a piston to a crank or crankshaft in a reciprocating engine. Together with the crank, it forms a simple mechanism that converts reciprocating motion into rotating motion.