The original XBR-2 Bi-Rotor combine sold for $22,000 at Mark Underwood’s estate auction near Burr Oak, Kansas, on October 29, 2018. Peridot, Inc., a manufacturing and product-development firm in Hoagland, Indiana, bought the prototype. It was an experimental machine built around a different approach to threshing and separating grain—not a commercially launched combine.
What sold at the 2018 auction
The auction marked a closing chapter in the project led by Mark Underwood and his cousin Ralph Lagergren. Three potential buyers bid on the original XBR-2, and Peridot emerged as the buyer at $22,000, according to Successful Farming’s 2018 sale report.
Underwood and Lagergren first tested their Bi-Rotor concept by retrofitting an International 1480 combine. They later built the XBR-2 from the ground up. The auctioned machine was that purpose-built prototype, not the earlier converted combine.
How the Bi-Rotor system was designed
The design used two rotating threshing elements: an inner unit and an outer concave that moved more slowly. The inventors’ rationale was that the arrangement could improve threshing and separation while treating crops more gently than conventional systems. Those were design goals; the cited reports do not provide independent comparative test results proving better performance.
The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →#1 Best Overall
- VORACIOUS HARVESTER - The most impressive mechanism is the combine harvester. One such machine can replace a thousand people on the field. Knowing no fatigue, the harvester cuts threshes the ears, separates the straw from the grain, forms sheaves, and unloads the final product. And it doesn't stop moving.
- PROTOTYPE HISTORY - In 1835, in the United States, Hiram Moore built and patented the first combine harvester, which was capable of reaping, threshing, and winnowing cereal grain. Now millions of agricultural workers have been replaced by machines. Their diversity is very great. They can sow, nurture, fertilize, irrigate, protect, and eventually harvest almost all crops. All these machines are united by one broad term - "combines".
- UNIQUE DESIGN - "Voracious Harvester" is a DIY model of a combine harvester. A standard model of a cereal harvesting machine was taken as a prototype. The main parts that determine the appearance of the combine are the header and the bunker. In front of the hull, there is a cab, in which there are schematically marked combine harvester controls - a steering wheel and a dashboard.
- FEATURES and BENEFITS - The Voracious Harvester has four wheels in two sizes. Both pairs of wheels are hollow with imitation treads. The wheels rotate freely if you move the model with your hands and are connected to the winding mechanism. Thus, the model can move independently, simulating the work of a combine.
- SKILLFUL HANDS and SPATIAL PERCEPTION EXERCISE - Assembling the Voracious Harvester is a fun activity for enthusiasts. The model consists of more than one hundred sixty parts and is among the designers of medium difficulty. Some nodes will require the ingenuity and dexterity of the fingers for the successful assembly and functioning of the model. Amateur designers will first have to study how the components of a real combine are arranged, which will undoubtedly expand their horizons.
The XBR-2 also differed in several reported specifications. Successful Farming’s 2018 auction preview described the machine as having a 400-bushel grain tank and 100 moving parts, compared with 225 in typical machines of its day. That moving-part comparison is the publication’s historical comparison, not a current industry benchmark. The preview also said the combine used a conveyor unloading system rather than augers, intended to minimize crop damage. The prototype had a Caterpillar engine and track undercarriage. (Successful Farming, 2018)
Why the sale mattered to the developers’ story
Underwood and Lagergren formed Agri-Technology to develop and field-test the concept. In 1995, they sold 17 patents to Deere, according to the 2018 sale report. The report says some aspects of the technology became part of Deere technology; it does not say Deere commercialized the complete Bi-Rotor combine.
Rank #2
- HOBBY MODEL KIT – Unassembled model packed in an envelope with easy to follow instructions. Ideal for ages 14 and up
- HIGHLY DETAILED ETCHED MODEL – Display your 3D model once completed - collect and build them all
- FROM STEEL SHEETS TO 3D – Pop out the pieces and connect using tabs and holes. Includes illustrated instructions
- FARM TRACTOR – 2 Sheet Model with a moderate difficulty level. Once assembled, dimensions are 2.85x 1.76 x 1.76 inches.
- NO GLUE OR SOLDER NEEDED – Parts can be easily clipped from the metal sheets. Tweezers are the recommended tool for bending and twisting the connection tabs
The project’s history is also chronicled in Craig Canine’s 1995 book Dream Reaper, identified in the auction preview as an account of the Bi-Rotor story. Its current retail availability has not been established.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What Peridot planned—and what happened afterward
After buying the prototype, Peridot president David Hockemeyer said the company planned to take it apart to understand the system and explore improvements using tools such as 3-D printing and computer-aided design. He estimated in 2018 that getting a market-ready version would take at least three to five years. That was a projection at the time, not confirmation that a product subsequently launched. Hockemeyer described the company’s aim as helping farmers work more efficiently while meeting their bottom lines. (Successful Farming, 2018)
Rank #3
- MECHANICAL 3D WOODEN PUZZLE: Detailed scale model of a Grain Harvesting Combine GH800 with grain header BARST 920 featuring 864 precision laser-cut wooden pieces that assemble into a realistic working replica with spring-powered mechanical drive.
- FUNCTIONAL MOVING PARTS: Spring-driven mechanism brings the harvester to life with realistic movement of the combine and grain unloading action, allowing you to see how actual harvesting equipment operates in intricate detail.
- IMPRESSIVE DISPLAY SIZE: Assembled model measures 20.75 inches long by 18.03 inches wide by 7.36 inches tall, creating a stunning steampunk-style kinetic sculpture perfect for home or office display.
- NO GLUE ASSEMBLY: All 864 wooden components fit together precisely without requiring glue, featuring easy-to-follow instructions for a satisfying 2-hour construction project suitable for adults and children 14 years and older.
- PREMIUM WOOD CONSTRUCTION: Crafted from high-quality wood materials with precise laser-cut details that accurately capture every feature of the Gomselmash combine harvester, making it an excellent gift for agriculture enthusiasts and model collectors.
A later follow-up reported that Davaus had the prototype harvesting corn and soybeans in Indiana, with a new Caterpillar engine and updated electrical and hydraulic systems. It said the machine had performed flawlessly. That account establishes reported field operation at the time of the follow-up, but not the XBR-2’s present status or commercial production. (Successful Farming follow-up)
The available reporting therefore traces the machine from a $22,000 auction purchase to a later reported revival in the field. It does not establish that the experimental combine became a product available to farmers.
Quick Recap
Best Value
- The most innovative modeling company in the industry. We engineer and produce a variety of kits from classic cars to giant space ships.
- Our die cast models are next level – when it comes to detail we are the best in the collectible business
- Racing is in our company DNA, our slot car brands and themes keep creativity racing around this retro hobby
- The newest hobby to our line up. Our detailed pieces bring your train layouts to life.
- South Bend, IN
Rank #4
- MECHANICAL CONSTRUCTION SET: UGEARS mechanical Combine 3D puzzle is absolutely unique and innovative toy for children, teens and adults. No analogue to date.
- UNUSUAL CRAFT: extraordinary kind of crafts that will suit anyone: beginners or modeling lovers. You don t need any additional tools. We made sure that everything needed was included in the kit.
- PREMIUM PLYWOOD: high quality eco friendly plywood, the best one for our customers. Non toxic, safe for children. Is produced according to all quality standards. We choose only the best for you.
- ENTERTAINING: an exciting construction set for adults and children. Want to take a break and take something off your hands or to spend an unusual time with your children by connecting with them through such a team task. Then this kit is perfect for you.
- SELF ASSEMBLY MOVING KIT: just press out all plywood boards and small details and start creating this masterpiece. It has a rubber engine and moves as the real prototype. And our step by step instruction will help you to start this combine.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
