Common Denominators

02:08AM Aug 27, 2014

Check these five combine areas to improve threshing

Making adjustments to five components common on all of the major combine brands can significantly improve harvest performance.

The angle of the feederhouse "face plate" is relevant in corn, but it’s critical for optimum soybean harvest.
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Slow down straw choppers when harvesting corn, and adjust deflectors and doors to the proper position to prevent damage to sieves by flying cobs.

"The angle of the face plate on the feederhouse determines cutterbar angle [on soybean platforms], and cutterbar angle determines the quality of cut," says Amos Greene, a Case IH service technician at Vetter Equipment in Nevada, Iowa. "Too steep of an angle makes the platform into a rock picker. If the cutterbar is heeled-back, it doesn’t cut close and leaves the bottom pods on the cut-off stems."

On corn heads, face plate angle influences the ability of the head to pick up down corn. "Chopping heads," with spinning blades beneath the row units, benefit if the face plate angle positions the cutting units so they’re tipped slightly forward.

The feederhouse face plate angle depends on the size of front tires, rear tires and other variables. Greene recommends lowering flex-type soybean platforms until the cutterbar is in the middle of its flex range, then visually inspecting to see if the front of the cutterbar is tilted slightly downward. The skid shoes behind the cutterbar should be parallel to the ground with even pressure from front to rear.

Some adjustments, such as the height of the feederhouse conveyor chain drum, are easier to make when the header isn’t attached to the combine. This is convenient, since combine manufacturers uniformly recommend different feederhouse drum heights for corn and small grains.
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Dull, worn straw chopper knives do a poor job cutting and distributing crop residue causing stripes that inhibit emergence and growth of next year’s crops

"The feederhouse drum should be set in the lowest position for small grain and soybeans," Greene says. "It should be raised for corn. If you leave it raised while harvesting beans, the feederhouse conveyor chain doesn’t pull in beans as well. Crop will build up in front of the feederhouse before it finally pulls in a bunch all at once."

Bunch feeding at the feederhouse creates problems throughout the machine. Inconsistent crop flow temporarily overloads the concave, then the sieves, resulting in bursts of "dirty" grain in the grain tank and unthreshed grain out the back of the machine.

"It’s a little hassle to change the feederhouse drum between corn and beans," Greene says. "On Case IH combines there’s a middle setting, and some guys put it there and leave it for all crops. But that’s a compromise. If you want optimum threshing performance, you need to set the drum up for corn and down for beans."

A matter of speed. At the opposite end of the combine, straw choppers and straw spreaders are another commonly misadjusted component on combines. Those systems are universally sped up for beans and small grains and slowed down for corn.

"Some customers leave their straw spreaders on high speed when they harvest corn, which causes problems with cobs getting tossed forward and getting caught in the grooves of [drive belt] pulleys and damaging the belts that run on those pulleys," says Tim Holt, a New Holland service manager at Casady Brothers Implement in  Webster City, Iowa. "We’ve installed shields made out of old belting to keep cobs out of the pulleys, but it’s better to just slow down the spreader."

Proper adjustment of straw chopper speed and straw chopper cutting action influences both this year’s harvest performance and next year’s crop.

"Dull chopper knives are a drag on horsepower," says Jeff Gray, product coordinator, for Claas Lexion combines. "Plus, dull knives don’t cut and distribute residue as well as sharp knives, so next year’s crop has to deal with erratic soil temperatures due to uneven residue."

Grain loss monitors don’t influence the mechanical performance of a combine, but they dramatically improve the ability of operators to optimize combine performance. The best way to calibrate a grain loss monitor is to turn it off, says Larry Wendt, AGCO service technician at Marzolf Implement in Spring Valley, Minn.

"Turn it off or ignore it until you can check the job it’s doing at the head and behind the combine," he says. "Once you have the concave, rotor, sieves and fan set to do a good job, set the grain loss monitor to tell you if something changes and you need to readjust." 

Tweak Your Brand

All modern combines have the potential to vacuum fields almost clean and deliver top quality grain to the bin. But each brand has unique design characteristics that benefit from careful calibration or adjustment by operators.

"Older Gleaners have a spring-loaded rock door, and you don’t want that door set so tight that it won’t open if a rock goes over it," says Larry Wendt, service technician at Marzolf Implement, Spring Valley, Minn. "On the other hand, big corn heads can put so much material through [the feederhouse] that the sheer volume forces the door open. There’s a spring on each end of the door, and I turn the adjusting nuts one full turn at a time. It’s easy to get it too tight or too loose. I start with the recommended spring length in the owner’s manual, then run crop through it to see if it needs to be a little looser or tighter."

Claas Lexion. "It’s important to change the pre-separation grates between corn and soybeans," says Jeff Gray, product coordinator, Claas Lexion combines. "The hardest part is cleaning out the rock trap, which you should be doing once a day, anyway. It takes about 15 minutes and helps the whole machine do a better job."

Gray also encourages adjusting de-awning plates when switching between corn and soybeans.

"In corn, you’ll keep them open, but in small grains and soybeans you can close them to improve threshing performance," he says. "It’s just a lever on the outside of the machine."

Case IH. "You can adjust the clean grain elevator speed on Case IH combines," says Amos Greene, service tech at Vetter Equipment, Nevada, Iowa. "You definitely want it on high speed for corn. It doesn’t have to be slow for soybeans, but you’ll get less grain damage."

The covers on the unloading augers in the grain tanks on Case IH combines can be adjusted. When harvesting wet corn, lower those covers and unload a little slower instead of digging corn out of the unloading auger after the unloading drive shear bolt breaks, Greene recommends.

John Deere. When setting feed accelerator and straw chopper speed on John Deere combines, it’s important to remember soybeans are considered "small grains" by company engineers. 

A decal on the pivoting door just in front of the straw chopper indicates the "corn" and "small grain (soybeans)" positions. Failure to pivot the door from the small grain position when harvesting corn allows the straw chopper to fling corn cobs forward across the upper sieve, bending the louvers and restricting crop flow.

New Holland. The sensor for an electronically-triggered stone trap door must be calibrated.

"When a rock strikes the sounding board, it electronically triggers the stone door to open," explains Tim Holt, service manager at Casady Brothers Implement, in Webster City, Iowa. "If the linkage doesn’t move freely, the door can trigger but fail to open. Before harvest season, push the red button in the cab for three seconds to force open the door. Check the linkage under the feederhouse to make sure everything is moving freely."