| 摘要 |
A drive assembly for an electric hand tool uses a ratchet and two opposed, spring-loaded pawls. The ratchet is integrally formed as a dovetail flange on the tool shaft inside a hollow rotor. The pawls are asymmetrical and pivotally mounted inside a recess in the rotor such that the centrifugal force generated by the rotation of the rotor causes the appropriate pawl to engage the ratchet and rotate the tool in the appropriate direction. When the rotor stops rotating, the spring causes the pawl to disengage from the ratchet and return to a rest position. This drive assembly is advantageous in that it completely does away with the noise generated by the gears in the conventional drive assembly and is much cheaper and more convenient to repair.
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