World Famous Bi-Rotor Combine Goes to Auction

Bi Rotor Combine

Auctions can be a great avenue to acquire one of a kind items, from collectibles to machinery. Monday, October 29, 2018, a machine that changed the course of modern farming in America will be for sale at auction.

The original Bi-Rotor Combine (XBR2), will be going to auction in Burr Oak, Kansas with Wolters Auction & Realty. The world lost one of its finest inventors, Mark Underwood, last summer, and the combine he brought to life will be up for sale at his estate auction. The auction will include other machinery that Underwood had on the farm, as well as the farmland itself.

Mark Underwood, along with his best friend and cousin Ralph Lagergren, first got the idea to build a better harvester in 1978. Over the next two decades, the duo built never before seen technology and filed patents around many of their inventions on the journey to build the Bi-Rotor Combine.

In 1989, Underwood and Lagergren built a team to make their vision a reality. They began lab tests at Kansas State University, testing their revolutionary bi rotor threshing system. The traditional stationary concave with a rotating cylinder tested with 72% separation in the threshing chamber. Underwood and Lagergren’s bi rotor, which consisted of a concave that rotated at a slower rate and in the same direction of the cylinder, could achieve 96% separation in the threshing chamber with minimal damage. This rotor only needed to be half the size of the traditional rotor, about four feet in width, and was retrofitted to a International Harvester 1480 for two years of field testing. This prototype is also up for auction, with original artist murals on the side panels.

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The artist’s murals convey the pioneering spirit of the new technology, honoring the American farmer’s dedication to continue forging ahead.

In 1993, the original Bi-Rotor Combine was built in approximately six months. The machine was taken all over the country to test harvest a variety of crops, from corn and soybeans to wheat and milo. The team that brought the combine to fruition signed the panels on the combine, as well as marked the dates of their test crops, which can still be seen today.

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The XBR2 had about half of the parts as a traditional combine harvester, minimizing the likelihood of breakdowns. The goal was to bring a combine to market that not only performed better, but was also cost effective to the farmer. At the combine’s official unveiling, people came from around the world to see the XBR2.

While the combine never ended up on the mass production line, Bi-Rotor Combine inventors sold 17 different patents to John Deere in the 90s.

Underwood continued to invent until he passed in the summer of 2017. The world lost a wonderful man with a brilliant mind, but his legacy will live on for the American farmer.

Attend the auction on Monday, October 29, 2018 at the Underwood Farm in Burr Oak, Kansas. Check out the full line up at Tractor Zoom, and head to Wolters Auction & Realty for more details and directions on how to get to the auction.

Kyle McMahon

Kyle McMahon

Owner at Tractor Zoom
Kyle McMahon is the founder of Tractor Zoom and leads the company as CEO. As a 3rd generation entrepreneur, Kyle grew up with hard work and curiosity ingrained in his demeanor. Kyle and his Tractor Zoom team are 2018 award winners in the John Pappajohn Entrepreneur Venture Competition.
Kyle McMahon