tappet
n. தட்டியக்கப் பிதுக்கம்.
Tap"pet, n. (Mach.) Defn: A lever or projection moved by some other piece, as a cam, or intended to tap or touch something else, with a view to produce change or regulate motion. G. Francis. Tappet motion, a valve motion worked by tappets from a reciprocating part, without an eccentric or cam, -- used in steam pumps, etc.