| 摘要 |
PCT No. PCT/EP79/00034 Sec. 371 Date Jan. 15, 1980 Sec. 102(e) Date Jan. 15, 1980 PCT Filed May 11, 1979 PCT Pub. No. WO79/01076 PCT Pub. Date Dec. 13, 1979.On the head of a conventional drawing apparatus, locking means consist of a toothed circular plate 1 integral with the support C, a toothed circular plate 2 integral with the turning handle and rule carrier, the plates 1,2 being concentric and rotating in a same plane, and a third toothed plate 3, forced towards the plates 1 and 2 by springs 4 so as to mesh with the plates 1 and 2 making them integral with each other. This plate 3 is movable axially along a hub E, while maintained perpendicular to the axis of said hub; it may be disengaged from the plates 1 and 2 by exerting a pressure on a pusher 5 which actuates a lever 6 which lifts a small plate 7 connected to the plate 3 by columns 8.
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