How Does A Combine Work
How Does a Combine Work?
If you’ve driven around Lancaster County in the fall, you may have seen machines out in the fields, harvesting the corn, wheat, and other grain products. These machines, which are big and rather box-shaped, are called combines (pronounced COMM-bynes). Combines are a revolutionary machine first invented in 1834 by Hiram Moore, in the United States. Early models were pulled by horses, and eventually tractors, before evolving into the self-propelled machines we use today.
The Harvesting Process
In order to understand what a combine does, you first need to know the three steps of harvesting a field. The first step is called “reaping,” which means cutting the crops down. This was originally done by hand with a scythe, until Cyrus McCormick perfected his father’s mechanized reaper. Though not the first machine to simply the reaping process, McCormick’s design revolutionized the industry with its specialized parts.
The second step in harvesting is called “threshing.” This is the process of separating the edible part of the grain from the inedible chaff that surrounds it. This was originally done by beating the grain on the threshing floor, though later it was done by shaking the crops in a large bin so the chaff could fall through to a lower container. The threshing process was originally the most time-consuming part of the harvest—it took one hour to thresh just a bushel of wheat. A Scotsman named Andrew Meikle invented a threshing machine in 1786 that mechanized the process.
The last step in the harvest process is known as “winnowing.” While threshing caused the grain to separate from its surround chaff, the two were still all mixed together on the threshing floor. Farmers still have to winnow the grain or throw it all up in the air, allowing the lighter chaff to float away while the heavier grain fell right to the ground, where it could be collected. Sometimes a winnowing fan was used to aid the process. This process is still used in some countries today, or in places with a very small field, where a large combine would not be useful.
The combine is so-named because it combines all of the harvesting steps into one giant machine! As the combine is driven through the fields, it cuts the grain, separates the edible grains from the inedible chaff, stores the good stuff inside, and blows the chaff and other waste out behind it.
Mechanics of the Combine
So how does a combine actually work? As the machine moves along the field, the header cuts the crop. There are different kinds of headers for different crops—for example, the corn header has large spikes that fit between the rows of corn, while the wheat header has a revolving reel with teeth on it. The headers draw the crop into the row of teeth, which are usually along the bottom of the header. The crop is then drawn into the belly of the machine through the use of an auger and conveyor belts. They land in the threshing drum, which shakes the grain away from the chaff and straw (unwanted waste). The straw continues out of the drum onto straw walkers, which gradually move to the back of the combine, shaking out any pieces of grain that got missed in the threshing. The straw shoots out the back of the combine, back into the field, where it may be gathered into straw bales and used as fodder or bedding for animals.
Meanwhile, the grain falls through sieves to further separate the grain from smaller chaff pieces. Sometimes, larger pieces are carried back to the threshing drum to go through the process again. When the finest pieces of grain have reached the lowest levels of the combine (sometimes going through two or three sieves in the process), they are carried by conveyor belt to the grain bin, which is usually at the top of the combine. When the grain bin is full, a truck comes alongside the combine, and the grain is spat out of the top into the truck bed, where it is then carried to the storage silos. The combine continues on down the field, harvesting everything in its path.
Here’s an animated gif that shows the basics of how a combine works. Keep in mind that each brand does things a little differently, but this will give you a good sense of how the crops flow through the combine.
Did you know?
The first mechanized combine required twenty horses to pull it! For this reason, combines weren’t widely used until the early twentieth century.
Modern combines are the most complicated machines to be produced on the assembly line. They require over 17,000 parts—in comparison, standard automobiles are made up of 6,000 parts.
Combines are painted using a process called “electrostatic painting.” This process charges the metal pieces of the combine’s body with a positive charge, while the paint is given a negative charge. When the combine is dipped into the vat of paint, the charges react to each other, and the paint bonds with the combine tightly and completely. The combine is lifted out of the vat so it can drip dry and then baked in an oven at 363 degrees Fahrenheit. The result is a hard, rust-resistant finish, which is necessary for the combine to withstand all types of conditions and bad weather, including blistering sunshine and moisture from rain.
In 1953, the first self-propelled combine harvester was created by Claas and named “Hercules.” It could harvest up to 5 tons of wheat in one day!
Newer combines are equipped with “side-hill leveling,” which allows the machine to tilt on a hill while the inside processes stay level. This helps the process remain efficient and also helps with the center of gravity of the machine, in hopes of preventing a rollover.