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Reminiscing About Roto-Thresh Combines

Western Roto-Thresh isn t exactly a household name among farmers anymore. In fact, it never really was. The Saskatoon-based combine manufacturer had a relatively short-lived existence during the 1970s, but it managed to become a pioneer with its innovative harvesting technology, nevertheless. Its machines used a large-diameter, longitudinally mounted, axial separating drum for the final threshing stage rather than straw walkers, which were the industry standard at the time.

The small Saskatchewan company faced an uphill battle when it came to winning market share; it had to compete with the major combine manufacturers and try to convince farmers to adopt an unconventional technology at the same time. Still, it did manage to sell a number of its machines, which had a box-like shape, much like today s rotary models.

Mervin Lloyd, who farms near Fiske, Sask., was one of those who saw merit in the Roto-Thresh concept. He liked the design and performance of the combines so much he bought two of them, and he spoke withGrainewsabout his recollections of using them on his family s farm. His uncle, who farmed nearby, also bought one.

I ordered it (the first Roto- Thresh) for delivery in 1975, but they didn t get it done until 1976, says Lloyd. After they quit manufacturing them, I bought a second one. (At that time) they were selling them rather reasonable. About $15,000, I think. That fire-sale price made the second combine a bargain, but buying another new machine from a company that was closing out meant he needed to stockpile some spare parts.

When they were shutting down, I went and bought a truckload of parts, he says. That on-farm store of replacement components allowed him to keep his Roto- Thresh combines going for many years after the company folded.

According to information supplied by the Western Development Museum, in the 1960s a pair of Manitoba farmers developed the basic centrifugal threshing design on which the Roto-Thresh was based. The Western Roto-Thresh company was formed in Saskatoon a few years later. Staff at the Department of Agricultural Engineering at the University of Saskatchewan also became involved with the company by participating in testing the performance of newly-built prototype combines. The first production machine built by the company was sold in April 1973 to a St. Denisarea farmer.

If you boiled the whole story down, their big drum was the way they advertised the combines separated grain, says Lloyd. But that was their weak point. He believes that to produce a future model with significantly more capacity would have been impractical, because it would have required an enormous separating drum. The production models already required a corrugated drum 66 inches in diameter and 108 inches long. Incorporating that under the sheet metal gave the body of the Roto-Thresh its distinctive boxy shape.

Although the primary threshing system relied on a conventional cylinder like other combines, the large drum replacing the straw walkers used centrifugal force to separate remaining kernels from the straw. A smalldiametre stripper auger inside it lifted the material away from the drum surface and created a pulsing action, which increased the separating force. Kernels then dropped down onto collection augers below the drum. Company literature claimed this method of separation allowed the Rotothresh to perform as well on hillsides as it did on flat land.

Lloyd remembers the combines were capable of putting a very clean sample of grain in the tank. He notes that was due to the unique design of the cleaning system, which used two aspirator fans to remove chaff at the front of the cleaning shoe. You had fans blowing air that exhausted on both sides, he says. That really cleaned it (dockage) out. That aspirator was the best part.

Even if the drum separator concept had development limitations, Lloyd credits the Roto-Thresh production machines with having one of the highest capacities of any combine on the market at that time. It would thresh grain at a high rate of speed, he says. As long as you were within your capacity limit, you could do really, really well with it.

According to a performance evaluation report on the Roto-Thresh published by PAMI (The Prairie Agricultural Machinery Institute), the combine they tested in 1977 managed to harvest 11.1 tonnes per hour at a ground speed of 5.8 km/h in a crop of Neepawa wheat. PAMI conducted tests on the Rotothresh design over two seasons, 1976 and 1977.

Lloyd also liked how thrifty the Caterpillar engine was when it came to fuel consumption. It would never burn more than three or 3-1/2 gallons per hour, he recalls. It had a 50 gallon tank and I never burned more than a tankful in a day, and I put in some 16-hour days. Although, the model PAMI tested with a later-model 3408 engine didn t perform nearly as well in that department, averaging about double the fuel consumption rate of Lloyd s machines.

Roto-Thresh combines also handled well, he recalls. It was a pleasure to drive. You were dead comfortable in that cab. The PAMI report agrees: The evaporative cooling system maintained an acceptable cab temperature in hot weather, it reads. Furthermore, The steering system was excellent for field operation.

The company continued with efforts to refine the combine s design after commercial production began. Lloyd was one of the farmers who allowed company engineers to use his farm to conduct tests on potential design changes. Before I bought a second one, they brought a machine out and tried a few experiments with it, he says.

The different threshing characteristics of these combines required some getting used to. Operators had to spend some time learning how to adjust them to ensure the machines performed up to their potential. There was a lot of learning and adjusting, trying different settings with it, says Lloyd.

In the end, though, the production run of Roto-Thresh combines was limited to only about 50 machines. The list price for one in 1977 was $51,900, according to the PAMI report. That included a 10-1/2-foot Melroe pickup, straw chopper and spare parts kit.

Using the Bank of Canada s online inflation calculator, that works out to about $187,400 in today s dollars. Investing that much money in a combine from a manufacturer without a dealer network and that used an unfamiliar design required a significant leap of faith from farmers. Small wonder not many were willing to make the jump.

ScottGarveyismachineryeditorforGrainews.Isthereanoldpieceofmachineryyou dlikefeaturedinGrainews?EmailScottatscott. [email protected]

About the author


Scott Garvey

Scott Garvey is a freelance writer and video producer. He is also the former machinery editor at Grainews.



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