| 摘要 |
A screwdriver is composed of a handle, a magnetic member, a shank, and an adjusting device. The handle is provided with an axial hole in which the magnetic member is disposed. The shank is pivotally disposed in the axial hole such that the shank is fastened at one end thereof with a blade, and that another end of the shank is capable of a mutual attraction with the magnetic member. The magnitude of the mutual attraction is adjusted by the adjusting device to determine a pre-set desired torsional moment. The handle and the shank are capable of turning relative to each other at the time when a torsional moment exerting on the screwdriver is greater than the pre-set desired torsional moment.
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