| 摘要 |
<p>The pipe shutter comprises a main plate (3) which can pivot about an axis (4) across a pipe (1), and a drive plate (5) which is able to turn about the same axis and engage mechanically with the main shutter to cause it to rotate. The main shutter plate has a hole (6) through it which is closed by the drive plate, with the main shutter opening only after the drive plate has turned through a given angle.</p> |
