| 摘要 |
<p>The unit comprises a marker fitted each side of the tractor or its attachment; each marker has a pivoting arm. Each marker is also connected to a central lever by a chain. Each chain (10a,10b) is attached to a cam (13,14), both cams being mounted side-by-side. When one cam (13) is against its stop (19), its marker is down and the other marker is up. The control lever linkage (32) pushes this first cam up, its profile riding over the other cam. The second cam (14) contacts its stop (20) and the first marker is held up.</p> |
