NIntroduction
A combine harvester is a machine that combines harvesting, threshing, and cleaning in one. It helps turn crops in the field into clean grain. Knowing the parts and functions of a combine harvester is important because it helps you understand and choose the right one for your needs. Next, I’ll explain more about this. Keep reading if you’re interested!
wheat harvester
Parts of combine harvester and their function
Combine harvesters can be divided into two types based on how crops are fed into the machine: full-feed and half-feed. And the main difference is that in a full-feed combine, the entire crop goes into the threshing unit during harvesting. In a half-feed combine, only the heads of the crops enter the threshing unit. Because of this, the parts of the two types of harvesters are also different.
Header
The header of a full-feed combine harvester includes a divider, reel, cutting unit, and auger. In a half-feed combine harvester, there is no reel.
The crop divider is usually installed at the front of the machine. It has a cone-shaped tip that straightens and separates the crops into the cutting area and the non-cutting area as the machine moves forward, making harvesting more efficient.
The reel is a polygonal wheel with multiple flexible tines that bend to handle crops of different heights. Its job is to push the crops toward the cutting unit. After the cutting unit cuts the crops, the tines guide the crops to the header auger.The cutting unit of a combine harvester is usually made up of multiple blades. These blades move back and forth to cut the crop stems.
The auger system has a rotating spiral inside a closed tube or trough. It efficiently moves crops from the header to the central transfer system.
Middle Transfer System
The middle transfer system of a combine harvester, also called the feeder house, has three types: chain rake, belt rake, and rotary. Each type has a different structure and crop transfer speed.
Chain rake system: Uses a rectangular transfer trough and a looped chain with rakes. It transfers crops at 3–5 meters per second.
Belt rake system: Made of looped rakes and transfers crops at 2–4 meters per second.
Rotary system: Features a conveyor belt and several rotating wheels with blades or gears, moving crops at 10–15 meters per second.
The middle transfer system varies depending on the machine. Choosing the right transfer system ensures the harvested crops are fed evenly and continuously into the threshing unit, keeping the combine harvester running smoothly.
Threshing Unit
The core of the threshing unit is the threshing drum and concave sieve. Inside the drum, there are several threshing elements, like spike rods or teeth, that separate the grain from the crop stems through impact and friction. In a half-feed combine harvester, there is an extra conveyor chain. This chain turns the upright crop stalks into a horizontal position and feeds the heads of the crops into the drum for threshing.
Although most modern combine harvesters use spike-tooth drums, some still use a double-drum threshing system or axial-flow threshing system. The double-drum system has two sets of drums with concaves, one in the front and one in the back. The two drums have different structures and specifications. The front drum removes most of the grain from the crop, while the rear drum helps remove the remaining hard-to-separate grains from the stems.
The axial-flow threshing system is different from the three types I mentioned earlier. In the spike-tooth, spike-roll, and double-drum systems, the crop heads move along the tangential direction of the drum’s circumference. However, in the axial-flow system, the crop heads move around the drum’s circumference and, with the help of guide plates, also move along the drum’s axis. This method causes less damage to the grain.
Separation Unit
The separation unit in a combine harvester separates the crop stems from the grain. The most commonly used separation unit is the bar-type separator, which consists of a stalk wheel and a bar. The bar consists of vertically aligned boxes that move alternately up and down, forward and backward. And this creates a step-like motion that continuously throws the grain, allowing it to fall through the sieve holes, while tossing the stems out of the combine.
Cleaning Unit
But it’s not just the grain that passes through the sieve; small impurities, like broken stems, also go through. That’s where the cleaning unit comes in. It blows away the impurities to ensure you end up with a clean grain.
The cleaning unit includes parts like a sieve box, a drive mechanism, a fan, and fish-scale screens. The sieve box has a shaking plate, an upper sieve, and a lower sieve. The fish-scale screens separate the grain from the impurities, blocking larger particles. The grain passes through and falls into the collection bin.
At this stage, the fan works with the sieve box. By adjusting the airflow, you can blow away lighter impurities from the grain, ensuring the grain stays clean.
Grain Tank
Manufacturers usually make the grain tank from metal, making it strong and durable. After cleaning the grain, an elevator funnel lifts it into the tank. The tank temporarily stores the grain, preventing it from spilling or getting damaged, and facilitates unloading the grain.
Straw Handling System
Combine harvesters are equipped with a straw handling system to effectively handle and transport the straw. Depending on how they process the straw, the system may include a straw collector, a straw baler, or a straw chopping and spreading unit.
The straw collector is hung at the back of the machine. Its main job is to collect the straw discharged by the separation unit. Once the collector is full, the gate opens to release the straw. Some combine harvesters use a baler instead of a straw collector to bundle the straw for easier loading and transport. If you want to use the straw as fertilizer for the soil, it’s best to choose a combine harvester with a straw chopping and spreading unit.
Mobility System
And another important part of a self-propelled combine harvester is the mobility system. It usually comes in three types: wheeled, tracked, and semi-tracked. The common wheeled mobility system has two large drive wheels and two smaller guide wheels at the back. This type works well on harder ground. If you plan to work in wet areas or mainly harvest rice, it’s better to choose a tracked or semi-tracked system. These types are less likely to get stuck in the soil.
Conclusion
I believe after reading this article, you now have a better understanding of combine harvesters, these precise machines. Based on what I’ve shared, you can choose the right type of combine harvester. If you have any more questions, feel free to contact us at ANON. As experienced agricultural experts, we can offer you the best advice and high-quality machines!
FAQ
How many acres can a combine harvest in a day?
Do you want to get the answer to how many acres of corn can combine harvests per hour? In short, the newer models of combines can cover a maximum of 200 acres, even during hot and dry days. An average combine will be covering 150 acres in a day.
What are the principles of combine harvesting?
A combine harvester executes four main tasks: reaping (cutting crops), threshing (separating grains from plants), gathering (collecting the grains together), and winnowing (cleaning the grain by separating out chaff). These functions streamline the harvesting process.
How fast can a combine harvester go?
In short, field observations recorded that the combine harvester operated at normal working speeds ranging from 7.54 km/hr to 11.77 km/hr during field tests, with an average of 9.59 km/hr. They noted the average grain losses at 49.80 kg per acre, which accounted for 2.49% of the total grain production in one acre.
