Foundations of Construction: Ingenious compact skid-steer loader invented in 1958

Bobcat original
“Turkey farmer Eddie Velo operates the original skid-steer loader that Cy and Louis Keller built for his barn cleaning needs,” Bobcat Blog, November 8, 2020. Retrieved from

By Susanna McLeod

Special to Ontario Construction News

Resembling an adorable life-size toy, the Bobcat® skid-steer loader scrapes, lifts, loads and hauls. Used at industrial and agricultural workplaces, the multifaceted compact machine is especially useful on construction sites. But the skid-steer wasn’t built with construction in mind. In 1956, a commercial turkey farmer visited the blacksmith shop of brothers Cyril and Louis Keller at Rothsay, Minnesota. It was the spark that ignited the Bobcat.

The farmer needed a custom machine to speed up cleaning enormous two-storey barns.     Describing a machine that could be “nimble—able to navigate around poles set eight feet apart,” Ed Velo asked that “it had to be able to turn, scrape, and dump with a bucket or fork,” wrote Marty Padgett in Bobcat: Fifty Years of Opportunity 1958-2008 (Motorbooks/MBI Publishing 2007). Reliability was essential to replace the shovel and wheelbarrow.

Brainstorming processes, the Kellers tossed aside steering to turn wheels. “The key, they decided, was to move one side of the machine back and one side forward, so the machine would pivot on its centre,” Padgett said. “A set of pulleys and belts would manage the machine’s power.”

Combing through junkyards to fill their project parts list, the men found car wheels, a caster wheel, and levers to control the machine. Locating rods for forks, they later installed a bucket. The Kellers also acquired a 5-horsepower engine with a rope starter system. Sitting right at the controls in front of the motor in 1957, Velo was delighted with the small self-propelled three-wheeled loader.

Featuring a 132-cm bucket in front of two standard car tires, the rotating caster wheel was located at the rear. Using foot pedals, the operator hydraulically raised and lowered the bucket, and “the nine-ft.-long (2.7m) machine was steered using two levers operating the power-transfer belts,” said Construction Equipment Guide (CEG), Southeast Edition #8, April 6, 2020. Making adjustments, the inventors replaced the pulleys and belts with a clutch-drive transmission.

The Kellers next built and sold six machines, inspiring the interest of potential customers. They recognized the business opportunity but needed a fortune to establish a factory.

Meeting Les Melroe in 1958, the Kellers were invited to demonstrate their invention at Melroe Manufacturing Company’s booth at the Minnesota State Fair. Fairgoers lined up, marvelling at the new compact skid-steer. The Kellers handed out a thousand pamphlets and “Les had stuck a pair of Melroe decals on the machine, making the beginning of a partnership with the Kellers.”

Applying for a patent in December 1958, six years later Cyril and Louis Keller were awarded US Patent No. 3,151,503 for their “transmission system.” Moving to Gwinner, North Dakota, the brothers joined Melroe; Louis Keller oversaw modifications and developments while Cyril Keller went on sales rounds. The brothers also agreed to a royalty arrangement with Melroe for use of their patented clutch-drive.

“The company sold 25 Melroe loaders the first year and, more importantly, placed the loader in dealerships across the region,” said CEG. “The Kellers collected and shared a $15 royalty from each machine sold, a formula that remained unchanged over the years even as the sales price of the skid steer loaders climbed.”

Problems emerged when the rear caster wheel had trouble maneuvering in soft soil. A redesign was necessary. Louis Keller eliminated the caster wheel and added two drive wheels at the back. Keller determined that “a 70-30 weight distribution would let the front or rear set of wheels skid sideways in a turn.”

Sales soared for the efficient compact loader. After introducing the red-coloured M400 skid-steer loader in 1959, Melroe remodelled the machine and launched the “Melroe Bobcat” in 1962. The new Bobcat’s paint was changed to white and red.

The Keller brothers overflowed with ideas. Leaving the company, Louis Keller developed an even smaller skid-steer loader to fit through spaces less than one-metre-wide. Not interested at first, Melroe executives soon changed direction. Sending the small machine to an Arizona convention, “in two days, the mini-Bob, later dubbed the M371, attracted 950 orders,” said CEG. Keller began designing attachments for the Bobcat, as well.

Manufacturing farm equipment was Melroe’s core business but by 1967 the Bobcat made up 65 per cent of sales. The next year, Melroe Manufacturing Company was purchased by Clark Equipment Company. “Clark had tried and failed to build its own skid-steer loader, so buying Melroe is a logical alternate choice,” said Doosan Bobcat.

After undergoing several acquisitions, Bobcat became part of multinational conglomerate Doosan Infracore North America in 2007. The company was renamed Doosan Bobcat, and it continues to innovate Bobcat machines.

Among several honours for their compact skid-steer loader invention, the Keller brothers will be inducted into the National Inventors Hall of Fame in 2023. Louis Keller died in 2010 and Cyril Keller in 2020.  From turkey barn clean-up to construction essential, the Kellers designed an ingenious machine.

© 2023 Susanna McLeod. McLeod is a Kingston-based freelance writer who specializes in Canadian History


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