| 摘要 |
A screwdriver including a handle, a driving block fastened to the handle at one end, a front cap enclosing and rotatably fastened to the driving block, and a transmission shaft having a ratchet wheel at one inserted into a hole on the driving block and a square tip at an opposite end extended out of the front cap for turning screws, and two stop blocks controlled by rotation of the front cap to simultaneously or alternatively engage the ratchet wheel thus permitting the transmission shaft to be turned by the driving block in both clockwise and counter-clockwise direction, or permitting it to be turned in only a clockwise or counter-clockwise direction.
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