ratchet

1. N-COUNT In a tool or machine, a ratchet is a wheel or bar with sloping teeth, which can move only in one direction, because a piece of metal stops the teeth from moving backward. (防倒轉的)棘齒; 棘輪

The chair has a ratchet below it to adjust the height. 這把椅子下麪有一個棘輪來調整高度。

2. V-T/V-I If a tool or machine ratchets or if you ratchet it, it makes a clicking noise as it operates, because it has a ratchet in it. 使(工具或機器)發出嗒嗒聲; (工具或機器)發出嗒嗒聲

The rod bent double, the reel shrieked and ratcheted. 該操作杆加倍彎曲，線軸發出刺耳的嗒嗒聲。

She took up a sheet and ratcheted it into the typewriter. 她拿起一張紙，把它塞入打字機，發出一陣“嗒嗒”的聲音。