Don't Blame Your Combine for Every Harvest Hitch

September 7, 2016 10:00 AM
Don't Blame Your Combine for Every Harvest Hitch

If your combine is leaving beans in the field, throwing grain out the back or acting puny when going up hills while unloading on the go, don’t start kicking the tires in frustration. There’s only so much a combine can do, so knowing how to work as a team with the machine to maximize performance will alleviate harvest headaches.

  • There’s a mechanical limit to how close a cutterbar can cut soybeans. “Most cutterbars and skid shoe assemblies are at least 1½" thick; to cut closer than 2" is tough,” says Jeff Gray, senior product specialist, Claas Lexion. That means it’s impossible to get every pod when harvesting varieties that set pods at ground level.

Soybean varieties that branch near the ground cause similar harvest losses. Branches that develop at ground level create a thickened stem joint that might not cut cleanly, especially with cutterbars that use 1½" knife sections rather than 3".

Soybeans that branch below cutting height also leave “stringers”—single, slender stems—waving in the field behind combines. Stringers result when main stems deflect as they’re cut, bending low branches so the cutterbar glides over them rather than cuts them.

There is no solution at harvest for soybeans with  low pods or branches. Cut as low as possible, then make note to either avoid that variety next spring or plant at a higher population to create a heavier crop canopy. Thicker canopies reduce sunlight penetration and discourage low-branching.

  • Don’t always blame sieve settings for dirty corn samples in the grain tank. Narrow cornhead deck plate clearances, high gathering chain speeds and slow ground speeds can feed excess leaves and trash into the combine. Excess trash traps grain as the material travels across the sieves and carries that grain out the back of the combine.

The less trash a combine takes in at the front, the better the grain sample in the grain tank. Adjust deck plate settings, gathering chain speeds and ground speed with a goal of seeing nothing but ears of corn entering the feederhouse.

  • While it is possible to “blow” grain out the back of a combine with high cleaning fan speeds, it’s more common to lose grain off the sieves because of low cleaning fan speed. Without enough cleaning fan volume to “float” crop residues across the sieves, the mat of residue carries trapped grain out the back of the combine. More air is generally better than less air when harvesting corn or soybeans.
  • Lugging combine engines until the low engine speed warning light comes on reduces threshing capacity and grain-cleaning quality. If you lug the engine below 2,000 rpm, you dramatically decrease cleaning fan speed, shake speed of the sieves, rotor speed and chopper speed.

Ease up on the hydro handle long before the low engine rpm warning light comes on because the entire threshing and separating process degrades rapidly as engine rpms fall below optimum.

  • Few combines have enough horsepower to suit their owners. While a combine might have 400 hp available on the end rows, as soon as it pulls into a crop, at least 100 hp goes to power the cornhead. A 12-row cornhead can pull as much as 200 hp.

Heavy residues passing through a straw chopper can draw more than 100 hp. Grain tank extensions not only increase the weight of the combine but also horsepower demands as the grain tank’s fountain auger labors to push grain through once the end of that auger is buried.

Engaging the machine’s unloading auger to unload on the go also causes a horsepower deficit for
many combines. 

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