Combine harvesters: classification and how do they work
The combine harvester is a highly specialized agricultural machinery used for grain harvesting. They combine several functions: grain harvesting, grain cleaning, and grinding. Thanks to full automation, it is possible to complete the harvest in a short time, which is important to maintain the quality and nutritional value of the harvested product.
The first combines were manufactured in the United States in the mid-19th century. These were wheeled carts that were capable of reaping, threshing, and winnowing cereal grain. Despite their high productivity and large size, they do not create anthropogenic soils, carefully process both the grain itself and the chaff, and minimize human involvement in this process.
Today, the range of grain harvesting equipment has expanded so much that it is difficult to say which combine is better. Given the importance of the matter, we will provide detailed information on the type, characteristics, and technical characteristics of this type of agricultural machinery.
The classification of combine harvesters is carried out according to different measures.
- type of harvesters
- the direction of cut mass
- a grinding-separation unit
According to the types of combine harvesters
- A self-propelled harvesting combine is a self-contained unit with an engine over it.
- Pull type harvesting combines are pulled by a farm tractor.
Pull type with an auxiliary engine is pulled by a tractor but a separate engine is mounted on the harvesting combine which supplies power to cutting, thrashing, and other requirements.
According to the grinding-separation process:
- Conventional straw walker which used a rotating cylinder at the front-end which knocked the seeds out of the heads, and then used the rest of the machine to separate the straw from the chaff, and the chaff from the grain.
- Rotary ones do not have the mill, but instead a longitudinal rotor is installed;
- Hybrid is a combination of conventional and rotary.
Let's take a closer look at each of the 3 groups.
How does a conventional combine work?
The scheme of conventional combines is considered a classic that used a rotating cylinder at the front-end which knocked the seeds out of the heads, and then used the rest of the machine to separate the straw from the chaff, and the chaff from the grain. The main disadvantage of traditional combines is poor productivity. Compared to rotary ones, they can process two or even three times less area.
How does a rotary combine work?
The rotary combine uses centrifugal force to drive the grain through the straw. The faster the cylinder spins, the higher the centrifugal force so it’s easy to increase the capacity. Such a design is more productive than conventional. Therefore, such models are more suitable for areas with high productivity.
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Other advantages of rotary combines are listed below:
- a small number of rotating mechanisms
- the processing process requires less labor
The disadvantages of rotary combines are as following:
- high price
- costly maintenance
- they are not as good in high moisture crops.
How does a hybrid combine work?
Hybrid harvesters are special agricultural techniques used to harvest grain and legumes. It combines the grinding devices of the previous two groups.
How to choose the right combine harvester?
In order not to avoid financial loss on the purchase of agricultural machinery, it is necessary to pay attention to the following criteria:
- the size of the planted area - for a small farm, a mini grain harvester is more appropriate. These small devices are several times cheaper than classic combines and are easier to repair and maintain. For medium and large plots of land, it is better to focus on modern grain harvesters of local or foreign production.
- productivity
- headband coverage
- losses during grain grinding - not more than 1%
- quality and purity of harvested seeds
- easily repairable and finding spare parts easily according to the model.
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