SMALL AND simple. Those were the guide words for developing a new type of harvesting system for soybean growers in Brazil. The inventors — agricultural engineers Milford Hanna and Cezar Mesquita — knew simplicity and affordability were crucial components of any practical new design for the many small farmers in this South American country. The machine they created has not only met those criteria, but is also gentler on the crop than conventional combines are.

Lack of formal funding has made the new harvester a long time in the works, says the University of Nebraska's Hanna. The project really began back in the '70s, when Mesquita — a Brazilian native — was Hanna's graduate student. Although it took some 30 years for them to get from idea to working prototype, both engineers say they couldn't be happier with the result.

Fast fingers, flyin' beans

The heart of this novel design is based on two counter-rotating shafts mounted with unique plastic three-fingered discs that harvest only the beans and not the plant. “We originally thought the machine would be harvesting just the pod, but as it turns out, the fingers pop the beans right out of the pod, then the pod falls to the ground. So we're really just getting the beans,” Hanna explains. “That requires a lot less power than harvesting and threshing the whole bean plant.”

The four-row prototype harvester, now at work for its fourth season in Brazil, is powered by an old car engine, but Hanna estimates that it would take just a 40- to 50-hp engine to operate the machine. “In a typical combine, threshing accounts for 40% of the machine's energy consumption,” he notes. “In Cezar's research, he found that threshing the entire plant requires 10 times more energy than collecting just the pods.”

That's why the pair focused their new design on a higher level of harvesting, so to speak. Hanna says the harvester's threshing fingers, mounted just at pod height, strike the pod, and the beans come shooting out. The beans are projected upward, into a chamber lined with impact-resistant material. From there, a fan-produced airstream separates any remaining chaff and carries the beans into a storage hopper.

“There is nearly no damage to the beans with this machine,” Hanna says, noting that there was less than 1% broken beans in their field trials, whereas conventional combines typically have broken rates closer to 8 or 9%.

Versatile design

Although the engineers designed their machine primarily for use in countries where farming is still done on a smaller scale, the compact harvester also would fit a variety of niche markets in the United States. “It would be the perfect size for university and company test plots,” Hanna says. “It could also be easily modified to work with other crops, such as edible beans or rice.”

The harvester is self-propelled, but its design allows a pull-type or tractor-mounted version as well, according to the inventors, who are currently looking for a manufacturer. As for cost, Hanna says the new harvester should be affordable for small farm operations.

“It's just such a simple design and it works so well,” he adds. “Even though it has taken us a long time to get to here, it's really been a fun project.”

For more information, contact Hanna at 402/472-1634 or mhanna1@unl.edu.