The combine sieve consists of several layers of screens or meshes that are arranged in a series of layers. Each layer has a different size of mesh or screen, and each layer performs a specific function. The grain passes through the screens, while the chaff and debris are removed and collected in a separate compartment.
The first layer of the combine sieve is the concave, which is a curved metal plate with slits or perforations that allow the grain to pass through. The concave is designed to thresh the grain, separating it from the straw and husks. The concave also helps to break up the straw and husks into smaller pieces, making it easier for them to be separated from the grain in the next stage.
The second layer of the combine sieve is the top sieve, which is a flat mesh or screen that allows the grain to pass through while retaining the chaff and debris. The top sieve also helps to separate any remaining straw or husk fragments from the grain.
The third layer of the combine sieve is the bottom sieve, which is a larger mesh or screen that allows the chaff and debris to pass through while retaining the grain. The bottom sieve helps to remove any remaining plant debris and chaff from the grain before it is collected.
The combine sieve is operated by a series of rotating shafts and belts that move the grain and chaff through the different layers of screens. The grain is first threshed by the concave and then moved onto the top sieve, where it is separated from the chaff and debris. The remaining chaff and debris are then moved onto the bottom sieve, where they are separated from the grain before being collected and discarded.
In summary, the combine sieve is an essential component of a combine harvester that separates the grain from the chaff and other debris. It consists of several layers of screens or meshes that are arranged in a series of layers, each with a different size of mesh or screen, and each performing a specific function. The combine sieve is operated by a series of rotating shafts and belts that move the grain and chaff through the different layers of screens, resulting in a clean and separated harvest of grain.
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