| 摘要 |
A ratchet screw driver includes two rings secured in a handle and each having a number of ratchet teeth opposite to each other. A barrel is rotatably engaged in the rings. Two followers are slidably engaged on the barrel and rotated in concert with the barrel and each includes a number of ratchet teeth for engaging with that of the rings. A spring may bias the followers toward the rings. An extension is engaged with the barrel and may be rotated in an active direction by the handle. The followers are forced toward each other when the handle is rotated in a reverse direction.
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