A combine harvester is an important machine on a modern grain farm. It allows a very large amount of grain to be harvested very quickly. A combine harvester is so called because it does both of the processes involved in harvesting the grain — cutting the crop and separating the grain from the plant. Before the combine harvester, one or both of these jobs was done by hand or by two separate machines.
The crops we grow in our fields, such as wheat, barley, and rye, are only partly edible. We can use the seeds at the top of each plant (known as the grain) to make products like bread and cereal, but the rest of the plant (the chaff) is inedible and has to be discarded. Before modern-day machines were developed, agricultural workers had to harvest crops by carrying out a series of laborious operations one after another. First they had to cut down the plants with a long-handled cutting tool such as a scythe. Next, they had to separate the edible grain from the inedible chaff by beating the cut stalks—an operation known as threshing. Finally, they had to clean any remaining debris away from the seeds to make them suitable for use in a mill. All this took a lot of time and a lot of people. Thankfully, modern combine harvesters do the whole job automatically: you simply drive them through a field of growing crops and they cut, thresh, and clean the grains all by themselves using rotating blades, wheels, sieves, and elevators. The grain collects in a tank inside the combine harvester (which is periodically emptied into tractors that drive alongside), while the chaff spurts from a big exit pipe at the back and falls back down onto the field.
The Parts Explained:
Header: Cereal crops are gathered in by the header at the front, which has a pair of sharp pincers called crop dividers at either end. Generally speaking, the wider the header, the faster and more efficiently a harvester can cut a field. Different headers are used for cutting different crops; the header is often hydraulically powered and can be raised, lowered, and angled in different ways from the cab. The header can be removed and towed behind the harvester lengthwise so it can fit down narrow farm lanes.
Reel: A slowly rotating wheel called the reel (or pickup reel) pushes the crops down toward the cutter. The reel has horizontal bars called bats and vertical teeth or tines to grip the plant stalks.
Cutter Bar: The cutter bar runs the entire length of the header underneath the reel. Its teeth (sometimes called mowing fingers) open and close repeatedly to cut off the crops at their base, a bit like a giant electric hedge cutter sweeping along at ground level.
Conveyor: Behind the cutter bar, the cut crops are fed toward the centre by spinning augurs (screws) and travel up a conveyor to the processing mechanism inside the main part of the combine.
Threshing Drum: A threshing drum beats the cut crops to break and shake the grains away from their stalks.
Grain Sieve: The grains fall through sieves into a collecting tank below.
Straw Walkers: The chaff (unwanted material) passes along conveyors called straw walkers toward the back of the machine. More grain falls through into the tank.
Unloaded: When the grain tank is full, a tractor with a trailer on the back pulls alongside the combine. The grain is carried up from the tank by an elevator (a series of augers) and shoots out of a side pipe (sometimes called the unloader) into the trailer.
Straw & Chaff Removed: The unwanted straw and chaff tumbles from the back of the machine. Some combines have a rotating spreader mechanism that throws the straw over a wide area. Usually, the straw is baled up by a baling machine and used for animal bedding.
Picture Credit : Google