Combine Adjustments

Originally written February 1, 2006 | Last updated August 21, 2014

  1. Be sure the crop is ready to harvest. Test for grain moisture percentage

  2. The combine must be correctly adjusted and equipped for the crop to be harvested. Inspect rasp bars for chips, bends, or cracks. Replace as necessary. Start with initial settings for the crop from the operator's manual.

  3. To get the maximum efficiency without grain loss, the header must be operated efficiently. Use the proper size header for the machine and know the adjustments needed to achieve best results. Read the header operator's manual for specific adjustments.

  4. Operate at full throttle. All drives of the combine are based at governed engine speed.

  5. Keep an even, uniform flow of material moving through the combine. When the combine is running near empty or taking in bunches of crop material, increased grain losses and grain damage are likely.

  6. Select a ground speed that will not overload the combine or overrun the header's ability to do its job. Observe the engine overload monitor. When engine speed is reduced, cleaning system speed is reduced also.

  7. Use the correct cylinder/rotor speed and concave clearance to properly thresh and separate the crop being harvested. Excessive cylinder speed is the leading cause of grain damage - always use the lowest possible setting to achieve the best total threshing. Always try to eliminate unthreshed losses by adjusting concave clearance first rather than cylinder speed.

  8. The sieves must be open far enough to let all grain through. The chaffer sieve should allow all grain and unthreshed cobs/pods/heads through. The shoe sieve below should let only threshed grain through, so that the unthreshed portion goes to tailings and is returned to the rotor cage to be re-threshed. If the chaffer setting is too open, it overloads the shoe. If the shoe sieve is too tight, tailings will increase; if it is too open, the grain in the tank will be dirty. Set sieve to widest recommended setting and work back if required. 

  9. Wind blast through the sieves should be strong enough to remove all particles lighter than grain. Too little air from the fan causes shoe overload, high tailings and sloughing of the crop. Set fan to highest speed recommended and work down if required.

  10. Check all augers for wear because grain handling can increase seed damage also check grain cart). Proper rotor speed , concave clearance, fan setting and sieve adjustment will reduce the amount of tailings. Tailings should include only unthreshed particles. Above all else, perform only one adjustment at a time to minimize your time spent adjusting to optimum performance.

Read you operators manual thoroughly for detailed settings for you specific combine model. Attend combine clinics to learn fine-tuning methods from other combine operators. With proper adjustment, a quality crop can be harvested.


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