Valvetrain

thumb|A set of cams on a camshaft operating two valves

right|thumb|Cutaway of a dual overhead camshaft engine thumb |1969 AMC V8 engine|AMC V8 overhead valve engine. The rocker cover has been removed, so elements of the pushrods, rocker arms, valve springs, and valves are visible.

oscillating lever in engine

thumb|Roller tappet (shown in red) in an internal combustion engine

device for maintaining zero valve clearance in an internal combustion engine