In the industrial development of agriculture, the combine harvester machine is one of the most impactful technical inventions. As the name reveals it comes from combining 3 different harvesting operations (mowing, threshing, and cleaning seeds) into one single process. The combine can harvest a wide variety of different crops such as corn, grain, oats, sunflowers, and rye. The straw that remains after the harvesting is left on the land to dry. When the straw is dry the farmer can spread and plowed back into his land. Alternatively, he can process the straw into round bales and collect them as food for his horses and/or cows.
Throughout the 20th century, the machine technology has changed a lot. In the beginning, the cutting tables were not as large as they are today. In the meantime, tables with widths of 10 meters or more are no exception.
The combine harvesters today are most efficient and very easy to handle. Some machines even have GPS. Machine makers are always looking for new innovative ways to harvest with the most advanced technologies to make the most productive combine in the industry. It seems however that by now max capacities are reached. What always matters is to develop such a system that on the one hand maximizes performance and on the other hand improves the quality of the crops collected and the straw remaining, all of this at minimal loss. Most improvements are now made in the threshing system or applying electrical systems.
The combines today are equipped with large removable headers or cutting tables installed at the front of the machine. Every header is specially made to cut and process a specific crop. For cutting and processing grain there is the standard header which basically cuts the crop and guides it into a drum for threshing. The cutting table of the header is equipped with a knife cutter bar and feature conveyor chain with steel bars to cause the harvested crop to fall into the threshing drum once it is cut. Some special headers use PVC conveyor-belts to speed up the feeding of the auger or rubber conveyor-belt instead of a cross auger. These headers allow faster feeding, leading to higher throughputs.
Threshing comes after mowing and works as follows: The friction between the threshing drum and the jacket separates the grain-seed from the straw. The straw then falls on „shakers” that are shaking the grains out of the straw to fall through on the first sift.
And there are several sifts below that too. The holes in the sift go from top to bottom from large holes to small holes. With a fan air is blown through the sifts, so that only heavier seeds fall through the sifts. This cleaning process with air and sifting is separating the chaff from the wheat so that the machine collects the seeds as clean as possible. In the meantime, the longer and lighter straw is carried along through the machine to be cut and ejected back to the field.