| 摘要 |
<p>The mechanism employs a pair of driven wheels (2-1, 2-2) rotating in a common plane about parallel axes, and a common rotating drive wheel (9) positioned between them and movable in a direction at right angles to the line joining the two latter parallel axes, to come into driving contact with one of the driven wheels (2-1, 2-2). The drive wheel (9) is rotated in a given direction via a band transmission from a drive motor and is attached to a pivoting arm (4) to bring it into contact with one of the driven wheels (2-1, 2-2) in dependence on the direction of rotation of the drive wheel (9). A spring (10) biases the drive wheel (9) towards the line joining the axes of the driven wheels (2-1, 2-2) with switching means (SW-1, SW-2) responsive to movement of the drive wheel (9) against the spring bias to control the drive motor to reverse the rotation of the drive wheel (9) or bring it to rest.</p> |
