A combine is
used to separate the kernels of grain from the straw and chaff. Combines may be
either self-propelled or pull type.
The combine has
many abilities and operations that it must perform. A combine must pick up
swaths of grain. To do this, a special pick-up assembly is used. A conveyor
brings the grain in and moves it to a cylinder. A combine must also thresh and
separate the grain from the stem. Once the seeds are separated from the straw at
the cylinder, they go into a sieve. Then, a combine must also clean
and store what has been harvested. Seeds and chaff are cleaned using a sieve.
The sieve shakes and stirs them in order to get them clean. You can imagine that it is
something like cleaning berries using a colander, shaking and
stirring them underwater. Only with grain, air is sometimes used instead of
water. The relatively clean seed is later taken to a grain tank. The
machine temporarily stores the grain and puts the straw back on the field.
combining, the machine is equipped with its own reel and cutter bar. These tools
cut the grain and put it onto a rotating auger. This auger draws the cut grain
toward the centre, where it is taken into the machine.
There are many
other special features that a combine might have to help with the complicated
process of harvesting. In certain combines, further separation is performed
using things such as straw walkers and sieves. Even the most basic combining,
however, is a complex process.