| 摘要 |
<p>On the head of a conventional drawing apparatus, ratchet means consist of a toothed circular plate (1) integral with the rule-carrier, a circular plate (2) integral with the turning handle, the plates (1, 2) being concentric and rotating in a same plane, and a third toothed plate (3), forced towards the rules by springs (4) which mesh on the plates (1) and (2) making them integral with each other. This plate (3) is movable along a hub (E), perpendicularly 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 small disc (3) by columns (8). </p> |
