Adjusting a combine is like balancing a tire. True, running a combine is far more complicated than just adding a weight to ensure smooth tire rotation. Keeping a harvester at peak capacity -- so it gleans all the grain from residue and produces a clean sample free of broken kernels -- requires some fine tuning. Harvest speed must be in sync with the operation of the header or platform, threshing area, separator, and cleaning shoe.
Still, the tire analogy applies, because adjusting a combine is a true balancing act. Making a change in one area of the combine operation can throw another area out of kilter.
For example, a poorly set head can cause an uneven flow of crop into the cylinder or rotors. This, in turn, causes part of the crop to be underthreshed, resulting in cobs with kernels still attached riding out over the separator into the cleaning shoe.
“If you see the cobs and kernels in the cleaning shoe or on the ground, you mistakenly increase threshing speed to remove those kernels,” says combine expert Graeme Quick. “Instead of making the needed adjustment at the head, now you are overthreshing the entire crop. This results in broken cobs with kernels still attached as well as damaged grain coming off the chaffer sieve.”
To make matters more complicated, combine adjustment is challenged by advances in crop breeding, which are turning those tried-and-true homespun adjustments that served you well in the past on their head.
Today’s hybrids feature corn shanks that rarely drop ears in the field. Tenacious shanks can make it harder for a header’s deck plates to strip ears from stalks, resulting in more butt shelling, for example. Green soybean syndrome delivers a mixture of both dry and green pods, which challenges threshing adjustments.
To guide you with the balancing act of combine performance, Successful Farming magazine’s Combine Doctors, Earl Knuth of Barker Equipment (a John Deere dealership based in Indianola, Iowa) and Graeme Quick (a retired Iowa State University engineer and one of the leading authorities on combine operation in the world), present this short course on key adjustments that will keep you speeding across fields this fall.
Finding the sweet spot
While there is no single path to discovering the operating sweet spot in a combine, there are some absolute rules you must follow to fine-tune a harvester for peak performance, advise Quick and Knuth. The first of these binding rules is to live with your operator’s manual. “It should be worn from use,” says Knuth. “The manual reveals the crucial first baseline adjustments and gives a wide variety of tips on fine-tuning settings.”
Besides employing the manual, other key commandments in Quick and Knuth’s harvesting bible include: