| 摘要 |
<p>PRECIPITATOR RAPPER A rapper for striking a target in a precipitator includes a hammer having a hub pivotally attached to a frame. The rapper also has a drive sprocket rotatably mounted in the frame. The sprocket has a driving plurality of spaced teeth distributed on the sprocket along a given peripheral sector. The latter cover less than the entire periphery of the sprocket. The teeth of the sprocket are distributed to mesh with and then release the hub of the hammer.</p> |
