| 摘要 |
A safety arrangement for a power tool having a tool holding chuck and a key with transversely disposed pinion and handle portions for tightening and loosening the chuck and having a control switch and an operating member therefor that is shifted between spaced positions corresponding to the on and off conditions respectively of the power tool, the combination of the tool casing having a slot adjacent the switch which slot is adapted to receive the key handle portion with the pinion portion then being exposed, a casing wall located adjacent the slot allowing rotation of the inserted key in one direction only, a leaf spring supported by the casing with a cantilevered portion located adjacent the positioned key handle portion and further having a tab formed on the spring and located adjacent the operation member, the spring tab operating under the normal bias of the spring when no key is in the unit to interfer with the operating member thereby precluding shifting of same from the off position to the on position, and the key handle portion operating when positioned in the slot and upon key rotation to displace the spring tab from interference with the operating member thereby allowing shifting of the operating member for desired operation of the power tool.
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