| 摘要 |
PURPOSE:To promote the increase of rigidity and clamping force, by forming one acting cam in either outer ring or inner ring differential cam into a protrusive shape and the other into a recessed shape and even a passive cam of a jaw into recessed or protrusive shape while providing active and passive cam parts respectively in every plural quantity. CONSTITUTION:If a driving disc 10 is turned, differential cams 8, 9 are turned in a condition that they are locked by planetary gears 11 when each top jaw 6 is all idle. Here the top jaw 6 in one diametric direction is adapted to a workpiece, and if the jaw stops, the planetary gear 11, while it rotates on its own axis, revolves around a shaft differentially actuating the other differential cam and moving its master jaw 5. And if the top jaw 6 stops, the differential cams 8, 9 are placed in a condition that they are locked by the planetary gears 11. In this way, the workpiece is simultaneously tightened by equally tightening force. While, forming one active cam part of either the differential cam 8 or 9 into a protrusive shape and the other into a recessed shape while passive cam parts of the jaws 5, 6 into recessed or protrusive part, the protrusive-shaped active cam part, eliminating a material broken part, increases rigidity.
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