【电学】操作电触点的棘轮机构

automatic spiral ratchet screwdriver

spiral ratchet screw driver

pawl-and-ratchet type drive

heavy duty ratchet bit brace

lever switch with a ratchet mechanism

positive feed with pawl and ratchet of character-spacing mechanisms inselective printers

reversible ratchet handle【机】

screwdriver with ratchet action