Combine harvesters are marvelous machines and they have many interesting features. For example, have you ever noticed that pretty much every combine harvester in the world has its grain auger on the left? Japanese or American, old or new, large or small – all grain harvesters empty their bunkers to the left. Why?

Gleaner R50. (Manufacturer’s pic.)

Combine harvesters normally do their job in a clockwise direction. This means that they keep turning right and right and righ, reducing the size of the field in a huge spiral. In this way the left side of the combine harvester is facing the portion of the field that’s already been harvested. This means that a tractor or a truck can pull up by the left side of the combine without damaging crops.

However, if the grain auger was on the right side, the combine harvester would simply do its job in an anti-clockwise direction – this would be the only change that would be needed. So it is really strange that all combine harvesters, regarldess of their country of origin, extend their grain augers to the left.

Grain auger – always on the left side. (Gleaner)

I asked this question several farmers, agricultural machinery industry representatives and historians. And all of them said something similar – “Good question… It’s always been that way.” However, representatives from the American agricultural equipment manufacturer AGCO and Dr. Oliver Dougla, curator of The Museum of English Rural Life, offered some interesting insights that helped greatly in researching this topic. Huge thanks to them.

Grain auger always on the left

A modern combine harvester is a powerful, highly computerised agricultural machine. But in order to figure out why grain augers are always on its left side, we need to look deep into the history of the combine harvester.

A couple of hunders years ago crop harvesting was a multi-step process. Harvest crop needed to be reaped (cut), collected and transported to some place for threshing. This was a laborous task, which desperately needed at least some degree of automation.

Reaper machine at the 19th century. (Stein der Weisen, Wikimedia)

A horse-pulled reaper with a scissor-type cutting mechanism was designed by a Scotish inventor Patrick Bell in 1826. In 1835 Hiram Moore, an American inventor, created the world’s first combine harvester – a machine pulled by at least 20 horses or mules that COMBINED reaping and threshing functions. In 1911, the US company Holt introduced the world’s first true self-propelled combine harvester, but it was a slow, overly compex and unreliable machine, which did not really catch on. In 1915 International Harvester began producing a horse-drawn combine harvester, but even at that point separate reaping and threshing machines were more popular as they were cheaper, significantly less complex, and didn’t require that many horses.

In 1923, two advanced self-propelled combine harvesters were introduced in different parts of the world. One was developed by the Australian company Sunshine, the other – by Gleaner from Kansas in the US. However, soon the development of combine harvesters pretty much came to a halt as the world was hit by an economic crisis and then the Second World War. After the biggest military conflict in human history simmered down, farmers were still using pulled harvesting machines, but horses were replaced by tractors.

More than 20 mules pulling a CASE combine harvester. (Zechariah Judy, Wikimedia (CC BY 2.0)

In 1947, the American Lyleas Yost invented the screw mechanism for discharging harvested grain. And that mechanism is the real subject of this article. It was a pipe with an Archimedes’ screw inside – we came to call it a grain auger. Before Yost’s invention, the grain in combine harvesters was poured directly into bags, even though this was a painfully laborious task. Some machines managed to unload the grain outside to a truck or tractor-trailer using a simple conveyor belt or gravity. But Yost’s grain auger changed everything and became the beginning of the Hesston Manufacturing company. And you’ve guessed – all of their grain augers were meant to be mounted on the left.

In 1947, when Yost invented the grain auger, most combine harvesters were still not self-propelled. To prevent the tractor from crushing the crop, the combine harvester was usually offset to its right. There were some machines that were offset to the left and there were some that could be adjusted to work on either side of the tractor. There were even harvesters that were mounted on the tractor itself. However, most of these harvesting machines were offset to the right side of the tractor.

Tractor pulling a Gleaner combine harvester. This kind of configuration, where the harvester is on the left of the tractor, was not too common. (Gleaner)

Because most people are right-handed, most tools are sort of right-handed. And this includes agricultural implements. It is easier for right-handed people to observe the right side, and when turning the horse-drawn machines to the right, more work is done by the stronger right hand. A large number of horse-drawn implements were right-handed in this way, requiring to work the field in a clockwise direction.

It may be funny, but the history of horse-drawn farming had a huge influence on the tractor era. The first tractors pulled implements that were originally made for horses. As they were made for horses and most people are right handed, these implements were made to work in a clockwise direction. If we skipped a few steps in this evolutionary sequence of combine harvesters, the grain auger invented by Lyle Yost had to be fitted on the left because most people are right-handed. And it’s true – horse-drawn implements were right-handed, first tractors worked with machines made for horses, and in 1947 there was no better place for a grain auger to be fitted.

From the middle of the 20th century this became the standard for a combine harvester design. (Gleaner)

In the middle of the 20th century, self-propelled harvesters finally took over and pulled-type machines slowly became obsolete. Modern combine harvesters had the opportunity to break away from those old design ideas, but no manufacturer wanted to ignore the standard because farmers would not like it.

Why not on both sides?

The farmers we talked to did not know why the grain auger is always on the left, but a few of them said that there are situations where an auger on the right would be useful. One farmer even said that sometimes he wishes he had an ability to dump the grain in front of the combine harvester. This would allow him to pull up face-first by a tractor or even drive inside of a grain shed.

A solid standard design allows using several different combines in the same field. It also helps operators to get used to a stable work environment. (Gleaner)

However, manufacturers are in no hurry to create different grain auger mechanisms. Farmers are used to the current standard and diverting from it would bring more complexity, cost and very small benefits.


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