how does a corn harvester work? it can separate
corn from the cobs, and chop up the husks and stems.
how can it be so smart? i’ve searched all over the net
and can’t find an answer.
A harvester is actually called a “combine harvester” because it combines two other farm implements – the picker and sheller.
The picker grabs the corn (same thing for soybeans, cotton and many other crops) and pulls it in. It also separates the ear from the stalk. The stalk is then chopped and blown out the back.
The ear then goes through a series of blades (think of an old fashioned pencil sharpener with the spiraling cutting edge). The blades first remove the leafy covering, and then shave the kernels off the cob. The kernels go through a series of screens to filter out the general crud, which, along with the cobs, goes through a chopper and out the back.
You’re right, the whole thing is complex, and constant adjustments are necessary. Set the blades too close and you’ll mash up the kernels and likely jam the unit. Set them too far apart and you won’t clean the cob successfully and probably get a lot of foreign matter in the crop.
also, the corn has to be dry enough (growers shoot for about 13%, anything over about 18% is asking for trouble) or it turns into creamed corn.
thanks for the response -
anywhere i can find drawings or photos?
You may want to start by Googling the two big U.S. manufacturers, John Deere and Case-IH. AGCO and Caterpillar also sell combines.
You’d probably be more interested in the various combine boards (yes, they have them) but I can’t remember any right now. Try Googling “ancient iron” That’s primarily an old tractor group, but they may have some info about old combines or pickers.
So you can’t use a combine for popcorn. How is corn destined or the popper harvested and de-cobbed what is it’s moisture content?
When corn is ready for picking, the husks are dried and folded back so that the ear is more or less hanging out in the open. The picker consists of one or more slots in the machine which straddle the row of corn. There are link-belt chains on each side of the slot that pull the ear from the stalk with the husk usually being simply blown away. The chains then move the ear into the rest of the machine. In the harvesting process no one worries much about the trash such as vestigal husk and stalk that gets taken up. Corn and other grains that are used for human food are further cleaned by a modern version of winnowing. The grain falls past an opening through which air is blown. The lighter material is simply blown away and the grain falls into whatever recepticle is provided.
More and more, in the midwest at least, corn is being converted to silage by being chopped up; stalks, husks, cobs, kernals and all, and put into a silo.
Don’t forget the old motto, “If at first you don’t suck seed, try drier grain.”
I’ve visited my buddy’s family farm in the middle of Kansas, and this is exactly what they do. This gives them cattle feed for the bare farmer cost, because they grew it themselves. IIRC, they often throw in alfalfa and “milo”, a type of sorghum.
Chop it all up, auger it to the top of the silo so it drops down on top of the last stuff, and let it start fermenting. Cattle have quite a system for breaking down roughage, but I guess the idea is to get it started for them a bit. I think they also like the taste a bit more.
From that same friend mentioned above:
“The comment, “The ear then goes through a series of blades” is a bit misleading, though. Knives imply cutting. In traditional combines, the blades are called ‘cylinder bars.’ They are about as sharp as my finger and actually grind the grain off of the ear.”
Depending on the moisture content. A lot of people in my area harvest when corn is still fairly wet. Putting that in a silo could lead to spontaneous combustion, so it’s more common to put the silage in bunkers on the ground (sometimes covered with a tarp) or in HUGE plastic tubes (think long gigantic trash bag).
Popcorn is dry when it is picked so a mechanical combined picker-sheller would work. You might be thinking of sweet corn which is picked while the kernals are still not fully mature. Sweet corn, in fact, never does mature into the full sized kernals like feed corn. When it dries, the kernals shrink up and are separated from each other, not touching.
I’ve got to admit I have never worked with sweet corn on a commercial scale so I don’t know how it is harvested. For home use it is picked by hand.