Disc Blades Spurred Steel Processes

Let's Talk Rusty Iron

| October 2009

  • The author's 1946 Minneapolis-Moline ZTS and Roderick Lean disc harrow
    The author's 1946 Minneapolis-Moline ZTS and Roderick Lean disc harrow.
    Sam Moore
  • The 1869 patent drawing for Frederick Nishwitz's revolving harrow
    The 1869 patent drawing for Frederick Nishwitz's revolving harrow.
  • Ad for the Sandoval Rolling Coulter dating to 1911
    Ad for the Sandoval Rolling Coulter dating to 1911.
  • An early Japanese disc harrow
    An early Japanese disc harrow.
    Sam Moore
  • A disc blade made by the Galesburg Coulter-Disc Co. showing the firm's logo
    A disc blade made by the Galesburg Coulter-Disc Co. showing the firm's logo.

  • The author's 1946 Minneapolis-Moline ZTS and Roderick Lean disc harrow
  • The 1869 patent drawing for Frederick Nishwitz's revolving harrow
  • Ad for the Sandoval Rolling Coulter dating to 1911
  • An early Japanese disc harrow
  • A disc blade made by the Galesburg Coulter-Disc Co. showing the firm's logo

Not long ago, someone asked about the early history of disc harrows and, particularly, disc blades.

I’d never thought much about it but, upon reflection, it was obvious that disc harrow blades, along with rolling coulter blades, could hardly have been hammered out of wrought iron on a blacksmith’s anvil, nor could they have been cast from pig iron, the two most popular materials for making early implement parts. These circular blades had to be sharp enough to cut through trash and soil, which meant they had to be thin, and they had to be tough so they could withstand rocks, roots and other obstructions in the field. In other words, they had to be made from steel — and pretty good steel at that.

Making steel affordable

In the early to mid-1800s, the problem faced by inventors and manufacturers of disc harrows and rolling coulters (and many other products) was the scarcity of such steel and, consequently, its high cost. An American, William Kelly (in about 1850), and an Englishman, Henry Bessemer (in 1856), discovered independently of each other a steel making process. The process (named for Bessemer because Kelly went broke in the panic of 1857) entailed making steel by blowing a steady blast of air through molten iron. The oxygen in that air caused the impurities in the iron (such as silicon, manganese and carbon) to burst into flame and burn away, leaving steel behind. By controlling the amount of carbon burned away, different grades of steel could be produced, although that wasn’t discovered until later.

In the 1860s, American steel makers produced less than 17,000 tons of steel per year. By 1880, after the Bessemer and other processes were developed, U.S. production was 10 times that, and continued to grow at an average of more than one million tons every year. Steel became plentiful and cheap, a factor that contributed greatly to the Industrial Revolution and to the fortunes of farm equipment manufacturers as well.

Evolution of the disc

Rolling coulters for plows seem to have been introduced in about 1840 and the few early patents I’ve found specify that the blade should be made of “steel saw plate” or “thin steel.” The dished blades found on disc harrows are tougher to pin down, but seem to have appeared toward the end of the Civil War. In his 1894 book, American Agricultural Implements, Robert Ardrey claims the Japanese used a tillage implement “from time immemorial” that had a row of straight, undished discs in a framework, but in those days Japan didn’t export its technology as the country does today.

The earliest U.S. patent I have found for a disc harrow, or at least a machine with a series of discs side-by-side on a shaft, was patented in 1866 by Silas A. Moody of San Francisco, who called it a “sod-cutter.” Moody’s invention consisted of a row of “circular wheels or knives with sharp edges” placed on a horizontal axle. A frame for attaching the pole and a rear platform with a seat for the driver completed the thing. There was no provision for angling the gang of discs, nor were they dished (concave). Moody made no mention of what material the disc blades should be made of, although another inventor who patented a similar machine a year later specified that they be cast (presumably from steel) “on a chill, so as to better withstand the wear and tear to which they are subjected.”

Frederick Nishwitz, Brooklyn, N.Y., patented a revolving harrow in 1869 that had two heavy beams connected at the front in a V-shape. Under each beam was mounted a row of individual brackets, each supporting a dished disc at its lower end. The angle of the beams was adjustable, as well as the angle of each disc on the beam. Nishwitz is generally credited with inventing the forerunner to the modern disc harrow. Again, no material was specified for the discs.

Seizing a market

As might be expected, a demand from plow, harrow and grain drill manufacturers for steel coulters and discs soon developed. In 1883, a steel man from Pittsburgh turned up in the little town of Sandoval, Ill., with a plan to build a factory to make agricultural discs. He bought, on credit, most of the factory building materials from a local lumberyard owned in part by Stephen Ingersoll. The steel man went broke and gave up on his project and Ingersoll ended up owning the disc factory. So in 1884, with a work force of fewer than 20 men, Sandoval Mfg. Co. began turning out blades for plow coulters.

Ingersoll went on the road to sell his discs to the implement makers, but it was an uphill battle because he was competing with the much larger Bethlehem and Crucible steel companies who were also in the business. Ingersoll persevered, however, produced a good product, and soon began to get more and more orders. Along the way, he added dished blades for disc harrows and grain drills to the straight blades for plow coulters the firm had been making.

Needing to expand the plant and also get closer to customers, Ingersoll moved the factory in 1905 to Galesburg, Ill., and renamed the enterprise Galesburg Coulter-Disc Co. By 1920, the firm had grown nearly 1,300 percent from its first days in Galesburg. In addition to coulters and discs, the company was also making automotive clutch discs for Borg & Beck.

Perfecting a design

By 1920, there were many tractors on American farms and they pulled implements at faster speeds than horses had. As a result, disc blades were failing rapidly and implement manufacturers were complaining to their blade suppliers. Stephen Ingersoll’s son Roy eyed one of the beat-up discs that had been returned to the factory, bent, twisted and with torn edges. After much thought and many experiments, Roy developed a heat-treating process that made the discs tough enough to hold their shape and stay sharp under severe use.

The new disc blades were so good that sales increased dramatically. Bethlehem Steel tried to develop a similar process, but finally gave up in 1925 and got out of the disc blade business, although Crucible Steel, with its LaBelle and Fieldmaster Slow-Tempered disc blades, remained a strong competitor.

8/20/2012 5:29:01 AM

Wonder if there was a connection to the steel in saw blades, especially circular saws. One bragging point for one manufacture was that a fine handsaw could be bent back on itself without breaking or taking a set. Certainly this was expensive steel anyway and all manufacturers, even if they made their own steel, bragged about using English steel in their best handsaws. The railroads were reluctant to use steel until quite late, preferring wrought iron instead. It was an Interesting world back then.


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