| 摘要 |
<p>A primary air distribution manifold for an air seeder's pneumatic distribution system, wherein the primary air distribution manifold is provided with a top rank of venturis and a bottom rank of venturis for receiving an air stream from a blower which is divided into a top rank air stream and a bottom rank air stream. A selector valve is located above the top rank of venturis immediately below a product meter. The selector valve selectively directs metered product to either the top rank of venturis or the bottom rank of venturis. In a first position the selector valve directs metered product to the top rank of venturis in its second position the selector valve directs metered product to the bottom rank of venturis. Each selector valve is also provided with first and second air valves. In the selector valve's first position, the first air valve is open and directs air tapped from the top rank air stream to the product tank feeding product to the top rank of venturis. The second air valve is closed as it taps air from the bottom rank air stream. Similarly if the selector valve is in its second position, the first air valve is closed and the second air valve opened so that bottom rank air is directed to the product tank feeding product to the bottom rank of venturis.</p> |
