tappet

n projection in a piece of machinery that causes a certain movement by tapping against sth, used eg to open and close a valve 挺杆.

tantamount, tantrum, tap, tap-dance, tap-dancer, tap-dancing, tap-root, tap-water, tape, tape deck, tape recorder, tape-measure, tape-recorder, tape-recording, taper, tapestried, tapestry, tapeworm, tapioca, tapir, taps, tar, taradiddle, taramasalata, tarantella, tarantula, tarboosh, tardily, tardiness, tardy, tare, target, tariff, Tarmac, tarn, tarnish, tarnished, taro, tarot, tarpaulin,