| 摘要 |
<p>A device consists of an annular shifting member (6) positioned upon a hub (2) of the upper gear (5) and is provided with lateral teeth engaging into lateral teeth of the upper gear (5). Said upper gear wheel is loosely fit on the upper eccentric shaft (1), and, a pen (3) is inserted between the upper eccentric shaft (1) and its hub (2). The hub (2) is enclosed by a spring (4) pressing upon the shifting member (6). The shifting member (6) has a tangential groove (7). The upper eccentric shaft (1) is preferably provided with a scale.</p> |
