Troubleshooting for Axial Combines

Here’s how to correct crop problems…on the fly.

By Denny Eilers

Crop conditions can affect the performance of your combine. Photo by Denny Eilers

Crop conditions can affect the performance of your combine. Photo by Denny Eilers

You have performed next to perfect preventive maintenance and fine-tuned your combine to bring in the new crop with minimum loss. But, when you hit the field, crop conditions are not always perfect.

So, with the help of AGCO’s service experts, we’ve prepared the following quick fixes for several common problems operators encounter in the field.

“These are suggestions to the most common adjustments to help achieve the best performance, best grain quality and lowest grain losses,” explains Bryan B. Compton, product marketing manager at AGCO Parts division. Compton also points out that on 9005 Series combines, sieve and chaffer adjustments can easily be made in the cab on the C2000 Virtual Terminal, or from the control box on the left rear side of the combine.

For even more help in adjusting your machine “on the go,” the AGCO service department has prepared a two-page quick guide (ask for guide number 79033465). It’s available from your dealer and can be used in the field and during initial set-up.

Problem #1: Wet Corn

Assume concave wire spacing is set for corn, perforated overlaps are installed on left side and concaves are leveled and calibrated.

What Could Happen: Rotor Loss – Most common cause of rotor loss is plugging of the concaves and/or separator grate.

Quick Fixes:

  • Concaves must be closed enough so space between concave wires is kept clean. Operating the rotor at faster speed helps.
  • Closing concave and speeding rotor too much increases cob breakup and loads cleaning shoe*. This can move rotor loss to shoe loss and doesn’t solve the larger problem. (*Your dealer can help. The cleaning shoe overloads in heavy crop conditions and/or on hillsides, so contact your dealer about the cleaning shoe performance kit offered by AGCO.)
  • If corn easily threshes from cob, it’s crucial to move crop material to the exit of the rotor as quickly as possible. Remove the 2 reverse bars, knives and paddles over concave.

What Could Happen: Shoe Loss – If loss is coming from shoe, inspect chaffer. If cobs seem to be broken up, then shoe is being overloaded and cause is evident.

Quick Fixes:

  • Slow rotor and/or open concave so more whole cobs exit machine, keeping them off the shoe and sending them through the chopper.
  • Reduce load on shoe by reversing bars, knives and removing paddles.
  • Set cleaning fan for max rpm as more air flow will elevate some material and allow more grain to fall through chaffer.

Problem #2: Green-Stem Soybeans

What Could Happen: Most common problem is rotor loss.

Quick Fixes:

  • Speed up rotor and/or reduce concave clearance.
  • Make adjustments in small increments; otherwise rotor loss can be transferred to shoe loss.

Problem #3: Grain Not Completely Threshed

Possible Cause: Noted in grain sample, and is often caused by non-aggressive threshing.

Quick Fixes:

  • Set concave wire spacing correctly for proper threshing.
  • Rotor may be turning too slow, speed up in 50 rpm increments.
  • Clearance may be too wide between concave and rotor, close in small increments.
  • Hard to thresh crop may require adding concave blanks under front concaves. Start with one and add others as necessary.

Problem #4: Excess Cracked Grain

Possible Cause: Usually results from over-threshing the crop.

Quick Fixes:

  • Rotor may be turning too fast. Slow down in 50 rpm increments.
  • Clearance may be too small between concave and rotor. Open in small increments.
  • Check for excess tailings to rotor. Adjust cleaning shoe to reduce tailings, speed up cleaning fan and/or open sieve in very small increments.

Problem #5: Excess Foreign Matter in Bin

Possible Cause: Material other than grain (MOG) can often be reduced with simple adjustments.

Quick Fixes

  • Close sieve in very small increments, but be careful as this may also plug tailing return.
  • Then, speed up cleaning fan in 50 rpm increments and follow by closing chaffer in small increments.
  • The rotor can often over-thresh the crop; slow down in 50 rpm increments.
  • You can also reduce over-threshing by removing knives and paddles over the concave and replacing the 2 reverse cylinder bars with forward cylinder bars.

Problem #6: Dry Crop

Assume combine has correct concaves and overlap on left side is solid, not perforated.

What Could Happen: When crop is dry, over-threshing can occur due to excess shoe loss.

Quick Fixes:

  • Make sure concaves are level with rotor, and calibration for electric actuator and in-cab reading is correct.
  • Remove rotor knives and paddles over the concaves. Then, remove 2 reverse bars over the concave and replace with forward bars, or leave blank. Removing these lets the crop exit the rotor faster and reduces volume of material released on the shoe.
  • Check distribution on grain pan. If more grain is on left side, speed up rotor and/or open concave. If more grain is on right side, slow rotor and/or close concave clearance.
  • If grain pan is still overloaded on left side, install concave blanks—one at a time—to even out crop distribution.

Problem #7: Hard Threshing Wheat

What Could Happen: Usually results in rotor loss. Determine where loss is coming from. With straw chopper rolled back, rotor loss can be seen to the right of the right rear steering tire.

Quick Fixes:

  • The rotor and concaves must be set to be more aggressive, by adjusting them closer in small increments.
  • Make sure overlap is solid, not perforated.
  • Make sure the two reverse bars are installed per factory location.
  • Speed rotor in 50 rpm increments and/or close concaves in small increments.
  • Install rotor blanks, one at a time, starting at front of concave to force grain out of the head.

Problem: #8: Tailings Elevator Overload

Possible Cause: Can plug when combine is set to allow too much tailing material to the rotor.

Quick Fixes:

  • Open the sieve and/or slow the fan. (Caution: slowing fan too much can overload cleaning shoe.)
  • Close chaffer openings.
  • Remove the 2 reverse bars, rotor knives and paddles over the concave.
  • Slow rotor in 50 rpm increments and open concave clearance in very small increments.

Preventive Maintenance Tip:

An Easy Way to Re-lubricate: “We see a lot of combine operators shut the machine off when harvest is done, then not start it until next year. This lets the hot lubricants drain from the wearing parts and expose them. To prevent this, after you stop the combine for the season, let it sit for a day and cool off. Then start it and run everything for a couple of minutes to re-lubricate the wearing parts. This will help protect them during the off-season and save on repairs. Also, re-starting will help clean crop residue out of the machine to keep mice and other pests from nesting during the off-season.”

Wayne Burrett
Shop Foreman, Reiser Implement
Waukon, Iowa

For More Info

See our checklist for combine maintenance before, during and after harvest in “Keep Up The Good Work.” Also, read more about how AGCO’s preventive maintenance program PM360 can save you money and time.