梃杆,凸子
Tappet \Tap"pet\, n. (Mach.) 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.
tappet n : a lever that is moved in order to tap something else