Pre-Harvest Combine Adjustments

September 21, 2023

Part 1

A combine-harvester that is optimally adjusted will improve its efficiency, reduce field losses and maximize the chances of obtaining a good quality harvest. In this first in a series of two blog posts, we offer our best tips for a successful harvest in 2022!

Key adjustments


  • Make sure the knives (blades) of the cutter bar are sharp and in good operating conditions;
  • Make sure the edges of the cross auger are sharp;
  • Lower the cutter bar for low-podded plants and dry conditions;
  • Auger clearance: 5/8 inch, or 15 mm above the platform;
  • Opt for a floating flex header and automatic reel height control to allow the header to shave the ground when harvesting soybeans avoiding the collection of soil;
  • Choose the slowest possible forward ground speed recommended by the manufacturer.

Threshing and seed separation

  • Adjust the reel spacing and reel cylinder speed to be about ~25% faster than the ground speed;
  • Add belts to the reel or use an air assist reel for faster loading of the platform/table;
  • Reduce the spacing between the reel, the cutter bar, the cross auger and the feeder house;
  • Adjust the concave.

Feeder house drum

  • Make sure the feeder house drum is properly adjusted to keep the flow as efficient as possible;
  • Slow its speed to between 0.5 and 1 mi/hr in the areas where harvesting might be risky;
  • It is crucial to make sure that the chains and bearings are properly lubricated and maintained at the recommended intervals. The belts must be tightened and checked regularly.

Cleaning and maintenance

  • Remove the perforated trapdoors under the elevators, the cross augers or the unloading augers;
  • Check the auger bearings for wear and tear to prevent droop and pinched beans;
  • Adjust fan speed by “Fine-Tuning” the airflow;
  • Open the chaffer (upper sieve) wide enough, say 5/8”, to prevent grain from being carried to the tailings system;
  • Open the lower sieve just a little, between 1/4” and 3/8”, to allow the clean grain to be carried to the tank rather than the tailings system.

What to do if the beans are small

  • Turn down the fan and reduce the spacing in the chaffer and sieve;
  • Reduce the spacing in the mulcher;
  • Increase the speed of the reel to (between) 10 and 25% more than the travel speed;
  • Reduce the space between the reel, the cutter bar, the auger and the feed house chain, to make sure the stalks go through the header and enter the feed house.

Be sure to read part 2: Tips on Identifying Threshing Losses.