2023 Inductee Louis Keller: A Persistent Problem Solver

Founded in partnership with the United States Patent and Trademark Office in 1973, the National Inventors Hall of Fame^® has inducted more than 600 visionary inventors over the past 50 years. Each of our Inductees is a U.S. patent holder who has made an indelible impact on our society and in our lives. Some of these inventors have launched entirely new industries through their inventions, like 2023 Inductees Louis Keller and Cyril Keller, who created the world’s first compact loader – which became the Bobcat^® skid-steer loader. Read on to learn more about Louis Keller and find out how he and his brother launched the compact equipment industry with their ingenuity and resourcefulness.

Making a Mark in Minnesota

Born in Tenney, Minnesota, on May 9, 1923, Louis Keller had no formal schooling beyond the eighth grade. During World War II, he served in the U.S. Army as a staff sergeant stationed at the Army Air Corps base in Manila, Philippines. He received five decorations for his service. Though Keller had originally planned to go into farming upon returning to the United States, he instead started a business and found himself on an innovative path that would shape the agriculture and construction industries.

In 1947, Keller established Keller Welding in Rothsay, Minnesota. A few years after his brother Cyril joined the business in 1953, the Kellers were approached by a local farmer with a specific need. Eddie Velo was looking for a machine that could clean manure from his two-story turkey barn because he’d had difficulty finding farmhands who were willing to do the job manually. The machine would need to be able to maneuver in tight spaces and be light enough to operate on the second floor. The Keller brothers were determined to deliver a solution.

Over the course of just six weeks, they created the first small, lightweight, three-wheel front-end loader in their machine shop in 1957. They used mechanical parts from local junkyards and bars from the old Rothsay jail for the manure fork teeth. The loader, which they called the Keller Self-Propelled Loader, had a bucket in the front, which was operated using hydraulic foot pedals, a motor in the back, two front tires and a rear pivoting caster wheel that enabled sharp turns.

The Kellers’ patented clutch system, operated by using two hand levers, made it possible to put one side of the loader into forward and the other side into reverse, without the use of a transmission gearshift or a steering wheel. The loader could turn completely around in a circle the size of its own length, with one front wheel moving forward and the other moving in reverse, pivoting around the caster wheel.

The Keller brothers demonstrated their invention at the 1958 Minnesota State Fair, at a booth run by Melroe Manufacturing Company, a farm equipment company. Melroe was later awarded exclusive manufacturing rights to the Kellers’ loader on a royalty basis. The Kellers then sold their business, became Melroe employees and continued to develop their invention.

Initiating a Global Impact

In 1960, the first four-wheel skid-steer loader was introduced as the M400. Having a second axle made the M400 a four-wheel-drive vehicle, as well as the first machine that required the wheels to skid for directional control, or skid steer.

The M440 entered the market in 1962 and offered enhanced maneuverability and bucket control. This was the first model to bear the Bobcat name, which is now universally recognized.

In addition to the skid-steer loader, Louis Keller also patented steel over-the-tire tracks for wheeled vehicles that were manufactured and sold by Loegering Manufacturing in Casselton, North Dakota. Loegering has since been sold to ASV, which continues to sell the tracks worldwide.

In 1969, Clark Equipment Co. purchased Melroe’s agricultural products business for about $36 million. Ingersoll-Rand took over Clark in 1995 and in 2007 sold Bobcat for $4.9 billion to South Korea’s Doosan Group.

More than 1 million Bobcat skid-steer loaders have been sold worldwide and are used at construction sites, farms, railyards and seaports. Joe Keller, son of Louis Keller, summarized the impact of the compact equipment industry launched by his father and uncle when he said, “The tractor replaced the horse and oxen. The Bobcat replaced the pitchfork and wheelbarrow.”

In 2004, the American Society of Agricultural and Biological Engineers named the Kellers’ skid-steer loader a Historic Landmark. In recognition of their impact, the Keller brothers were inducted into the Association of Equipment Manufacturers Hall of Fame in 1999 and the Minnesota Inventors Hall of Fame in 2004.

Louis Keller earned six U.S. patents for his inventions. At the time of his passing in 2010 at the age of 87, he was the father of 10 children, a grandfather to 52 and a great-grandfather to 77.

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