Answers to Go with Susan Smith

Q. We often travel north to Minneapolis to visit family. The grain elevators surely stand out on our drive. How tall are they? How do they work?

A . According to the online Feb. 5, 2018 issue of “IowaAgLiteracy,” those prairie towers are often between 70 and 120 feet tall. This website also offers a diagram of the internal works of the grain elevator.

Let’s turn to the “World of Invention” for more information: “The shipping and handling of grain from farm to market was once a very awkward, inefficient process. Grain had to be moved about in sacks, and for longer journeys, it had to be transferred into difficult-to-handle barrels to protect it from the elements.

“American Oliver Evans patented a fully automated grain mill in 1785 that used an elevator consisting of an endless chain of buckets. This system was used to move the grain both at the storage elevator and at the mill.

“Mill operators did not accept Evans’ elevator until after 1843, when another American, Joseph Dart, added steam power to it. Since the grain was delivered to large storage bins classified by type and quality, the grain inspectors no longer had to spend time examining every barrel.

“In 1848, the first storage elevator was built in Chicago. Soon, other elevators were located at major transfer centers in the Great Lakes area and along rivers and rail lines. With the increased efficiency of grain transfer and transport, farmers could locate further from centers of population. Globally, more farming was done in regions, or belts, especially suited to grain production, such as the Great Plains, Argentina and the Ukraine.

“Today there are four types of grain elevators, but the bucket elevator remains the most common type. It is capable of lifting grain to heights of three hundred feet at rates of two thousand tons per hour. The buckets move by either chain or conveyor belt.

“Similar to the bucket type is the continuous chain elevator. Paddles mounted on a chain move the grain forward inside a long steel tube either horizontally or vertically.

“The pneumatic elevator literally vacuums grain from the holds of ships to dockside facilities. By using a flexible intake hose, changes in water level or the ship’s own level as its load weight changes can be accommodated without adjusting the equipment.

“Another type is the Archimedean screw, or, auger elevator. Named for the Greek mathematician who designed it, the large rotating screw mechanism pushes the grain through a shaft horizontally or at angles up to eighty degrees.

“The grain and grain dust inside an elevator are highly combustible, resulting in constant danger of explosions and fire. Care also much be taken to prevent spoilage and reduce invasion from pests. A forcedair treatment was developed in the 1950s in the United States to keep stored grain aerated, reducing moisture accumulation and the need to fumigate for pests.”