| 摘要 |
<p>The shaft of each tap carries four radial arms and three cams also spaced at 90 deg. but in different planes co-operating with respective switches. Three keys for each tap corresponds to full-on, half-on and off settings. As the rail reciprocates, two pegs are projected forward by a small square when an electromagnet is energised by an arm closing switch contacts at the respective ends of its travel. The pegs engage the tap arms to effect rotation in 90 deg. steps in accordance with the key positions. The motor which drives a crank causing the reciprocating motion is switched so that the rail comes to rest always in the same position, irrespective of the switching instant of each cam-operated switch.</p> |
