| 摘要 |
This contra-angle head of a dental handpiece comprises means for axially locking the dental instrument, in the form of a hollow guide member enclosing the upper portion of the driving pinion inside the head casing, this guide member being mounted for axial movement in the casing and rotating with the pinion by means of at least two wedge members disposed in the guide member and adapted to engage an annular groove of the dental instrument and to bear against the upper edge of this groove. A spring constantly urges the guide member away from the casing so that the instrument is pushed inwardly in the pinion by the wedge members for engagement with a shoulder formed in the pinion bore and acting as a stop means, the wedge members thus exerting a constant play take-up function.
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