Ready Your Combine for Harvest

September 21, 2016 03:01 PM
combine soybeans

Calibration Synchronizes Combine Components With Cab Displays

What you see on the cornerpost display in a combine cab isn’t necessarily what’s going on inside the combine. The numbers detailing concave, chaffer and sieve settings might be inaccurate compared with the actual settings of those critical combine components.

Before you start the calibration process, check for free movement of all adjustable components, especially if they’re adjusted from the cab. Clean out the previous year’s crop debris and make sure the chaffer, sieve, concave and cleaning fan actuators move freely through their full range of motions, then calibrate according to the owner’s manual. 

 Lack of attention to chaffer calibrations and  misalignment of a door on the straw chopper led to  severe damage to the chaffer’s louvers. 

Concaves, chaffers, sieves and other components that can be opened and closed by remote control from the cab use potentiometers to calculate their actual position. Those sensors register low voltage when a component is completely shut. Voltage increases incrementally as the component opens. The numbers displayed on the console in the cab rise and fall proportionately as the voltage increases and decreases. 

For example, the systems are closed when the display shows 0 and opened appropriately when 15, 20 or other numbers show on the display.

In addition to zeroing out before heading to the field, periodically check chaffers and sieves during harvest to maintain accuracy.

“Sometimes guys tinker with adjusting their concave or rotor speed from the cab and temporarily put a lot of broken cobs through the combine and over the chaffer,” says Kelly Kravig, marketing manager, Case IH. “Those broken cobs get jammed in the chaffer louvers. Then, when they need to close their chaffer, the cobs hold open some of the louvers even though the cab display shows a tighter setting.”

Attempting to force a chaffer to close when cobs are creating a jam can spring the adjusting mechanism and cause inaccurate numbers to display on the cab console. A chaffer with an actuating mechanism that has been tweaked could show 14 on the cab display but produce a dirty grain sample because it’s actually open to 20 in the machine.

In addition to calibrating a concave’s clearance sensor, make sure the concave is level with the rotor, says AGCO’s Caleb Schleder.

“If the threshing surfaces and the surface of the concave aren’t parallel it can decrease threshing efficiency,” he explains. “Even if you start the season with the concave level, all it takes is one big slug of crop to knock the concave out of alignment.”

A combine’s grain loss monitors also require recalibration before and during harvest. 

“Grain loss monitors will accurately sense and report even small changes in grain loss from the rotor or chaffer if they’re calibrated for crop and conditions,” Kravig explains. “But they aren’t preset from the factory, and they won’t automatically recalibrate when crops or conditions change.”

Checking for grain loss behind a combine is the key to calibrating grain loss monitors, says Jeff Gray, product coordinator, Claas Lexion.

“I drop the [straw] chopper, harvest for a ways in average crop at average speed, then study what’s in the windrow behind the combine,” he says. “Dropping the chopper puts all the losses in one spot and really tells you what the combine is doing. Once you’re happy with what you see in the windrow, then you can recalibrate the grain loss monitor and accurately keep track of what the combine is doing from the cab.”

A Pre-Harvest Checklist for Combines

Find the owner’s manual. It’s not a sin if you forget various aspects of combine operation and adjustment from year to year; no one needs to know you had to look in the manual to remember how to do something. If you need a new manual, stop in at your local dealership. New manuals for older combines start at around $80; manuals for late-model combines can cost hundreds of dollars. But that’s cheaper than a couple hours of a mechanic’s time fixing or adjusting something you could have done yourself.

Update software. Modern combines can have more than 30 computers on board. Just like with smartphones and personal computers, software updates improve performance and reduce “buggy” behavior. Contact your local dealership to determine what software is available for download.

Update/configure GPS-related programming. Software related to autosteer, yield monitors and other GPS-based systems requires separate attention. Licenses must be renewed. Calibrations and parameters must be updated or confirmed—especially if the display screen in the combine cab was used for planting or spraying. It’s necessary to meticulously switch every setting and value so they are relevant to harvest operations. 

Check the stuff your grandpa never heard of. Modern combines have “accelerator beaters,” “discharge beaters,” “cob doors” and other components often overlooked when adjusting newer combines. Make certain those systems work, and alter their speed, position or setting to match whatever crop you’re harvesting.

Calibrate the corn head or small grain platform’s automatic header height control system to the combine. Check to see if the header automatically raises, lowers and tilts to help it follow the ground’s surface. Combines are supposed to “remember” header calibrations from year to year, but it’s good insurance to recalibrate each unit to the combine before harvest. 

Once heads are calibrated to the combine, find a large open grassy area and drive the machine around with the separator and header running to make sure everything “floats” as designed.

Check autosteer operation. Take the machine out on the gravel road, set an A-B line, and see if the machine will follow the line. 

If you recently traded corn heads or small grain platforms, experiment with loading the heads on your trailer. Switching from a conventional platform to a draper-style head or a “chopping” corn head, might require major adjustments or new head trailers.

Check fire extinguishers. Make sure all powder-filled extinguishers have a full charge. Make sure water-filled fire extinguishers are filled with water and properly pressurized with air.

The Secrets of Setting Sieves to Optimize Combine Performance

Dirty grain samples are often the result of operators misunderstanding the relationship between the chaffer, sieve and cleaning fan.

“A lot of operators run their chaffers open too wide, to try and guarantee they don’t lose any grain out the back, or they don’t run their cleaning fan fast enough,” says Jeff Gray, product coordinator, Claas Lexion. “Running the chaffer too wide can overload the lower sieve. You end up running a greater amount of tailings, and rethreshing a lot material that doesn’t need to be rethreshed.”

 This operator never visually checked his chaffer  settings, adjusting them only from the cab, and ran a  lot of grain on the ground because debris on a foggy  morning plugged the chaffer.

“As for cleaning fan speed, air is the lubricant that lifts and floats crop material across the sieves,” Gray explains. “Without enough air, the shaking motion of the sieves will actually pack the material into a dense mat. The grain gets trapped in that mat and carried out the back of the combine.” 

When harvesting corn, optimum chaffer settings are generally at least five millimeters less than the diameter of smaller cobs in the field. 

“Allow the machine to clean out, then stop it and check the chaffer,” says Kelly Kravig, marketing manager, Case IH. “If whole cobs are stuck in the chaffer, it’s set too wide. If there are broken pieces of cob stuck, the concave is too tight and it’s breaking the cobs into pieces. You need to completely clean the chaffer so it can close and reset the concave to eliminate pieces of cobs. Then set the chaffer so whole cobs move across it instead of through it.”

In soybeans, the chaffer should be open just enough to allow unthreshed pods to fall onto the lower sieve. The lower sieve should be closed enough to catch and shuffle those pods to the return system for rethreshing, while allowing free grain to fall through. 

Don’t expect the chaffer and sieve to compensate for faulty settings in the front of the combine. Excessive quantities of unthreshed pods working through the chaffer and sieve indicate problems with rotor/cylinder speed or concave settings. 

Abruptly stopping a combine with a full load of crop inside (a kill-stall)is a good way to analyze the machine’s internal performance, says Caleb Schleder, tactical marketing manager, AGCO. 

“[After a kill-stall] you want to see little or no grain in the MOG [material other than grain] that’s laying on the rear of the sieves,” he says. “Any grain in the material on the rear foot or so of the chaffer is probably going out the back of the combine, so you need to open that chaffer, or increase fan speed, to try and get that grain down through the chaffer sooner.”

Kill-stalls also allow operators to check the side-to-side distribution of crop material across sieves.

“Air follows the path of least resistance, so you want crop material distributed evenly from side to side across the sieves,” Schleder says. “If it’s thicker on one side, all the air will go through the thin side, you won’t get good separation on the heavy side and you’ll put grain out the back on that side.”

Kravig says optimizing the performance of the chaffer, sieve and cleaning fan is a logical process.

“Just set the chaffer to clean out the big pieces, the sieve to separate the grain from the smaller pieces, and run the fan fast enough to keep everything floating so the grain can separate out,” he says.

Back to news


Spell Check

No comments have been posted to this News Article

Corn College TV Education Series


Get nearly 8 hours of educational video with Farm Journal's top agronomists. Produced in the field and neatly organized by topic, from spring prep to post-harvest. Order now!


Market Data provided by
Brought to you by Beyer