| 摘要 |
The handpiece ( 1 ) includes at the front a collet ( 10 ) arranged for strongly gripping the shank of a removable tool housed in guide bores ( 23, 25 ). The collet includes two or several arms ( 26 ) attached to an annular part ( 22 ) of the collet to grip the tool shank. Preferably, the collet arms are levers each having a support surface which is far from the jaw ( 20 ) and on which a gripping mechanism ( 17 ) exerts a force which is multiplied by the lever. The gripping mechanism includes a sliding sleeve ( 40 ) having an inner conical surface ( 44 ) which produces said force on the collet levers via balls ( 45 ). This arrangement enables a smaller gripping spring ( 42 ) to be used, or such spring to be omitted. The balls ( 51 ) of the releasing mechanism are guided in helical slots ( 57 ) having a flexible lateral strip ( 58 ) which holds the gripping mechanism in position via a snap fit.
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