我周五安裝一個rocking chair，用到rachet,發現它在狹小的空間裏非常好用，我感動的快哭了

美國機械設計和製造真的厲害。

 

In 1863, the American J.J. Richardson patented the first design for a ratcheting wrench with different-sized sockets that could be swapped out for each other. Originally, these wrenches had square-shaped sockets, as they were easier to make.