CaseIH 8120 vs JD9870

Case IH 8120 VS. JD9870:  Late Oct 09:  We were in the field today with a 8120 combine in South East South Dakota.  The corn was 31 percent moisture with a yield of 200 Bushels per acre.  We spent a little time setting up the machine for the wet corn conditions.  The 8120 had large wire concaves and skip wire grates.  It has 1 5/8 inch corn chaffer sieve and 1 5/8 inch shoe sieve.  We did put 4 straight bars on the rear of the rotor and kept the 8 spike bars on the rotor.  We moved the rear 4 vanes to the slow position.  When we were in the field, we did a kill stall to make sure the corn was loading evenly side to side on the active grain pan and the sieves.  (we had adjusted the concaves to the right about 10 mm to get the even loading.).    Ran 380 RPM rotor speed and about 18 to 20 mm on the concave setting.

The combine was running a 12 row chopping cornhead at a speed of 4.3 mph.  The 8120 was doing a excellent job!  In the same field there was a JD9870 running with a 12 row chopping cornhead.   The JD 9870 was set by the local dealer.  The JD operator said they were also driving 4.3 mph.  However, we double checked the speed with a handheld GPS and found speed reading was off.   They were only going 3.9 to 4.0 mph.  We double check the 8120 speed and found that it’s tach speed was correct.  It was interesting to note that the 9870 could not go any faster without trailing a yellow ribbon of corn out the right side.  The JD had the self leveling sieve bays, but the rotor was loading heavily on the right side.

I usually carry some 1 foot by 1 foot loss check screens with me.  I can run alongside the combine and throw them underneath and then evaluate the kernels loss behind the combine.  I have to admit that the 8120 combine was dialed in and doing a outstanding job with the wet corn!  In checking with the screens about 10 times, we could only average a 1/2 kernel loss at best (uniform spread).   We also did a loss check with the JD9870.  It always had 4 to 5 kernels (uniform spread) in the 1 foot screens (that did not include the broken and flour kernels also being thrown out).

I did some quick calculations and found that the JD was losing 2 bushels more per acre.  In making a round in a half mile field, that equates to 3.6 acres per round, or 7.2 bushels of additional loss.  7.2 bushels times $3.60 corn is $25.92.  On this day the JD9870 was losing $25.92 every round.  The sample in the tank also have a much greater amount of fines (which meant more drying cost to push air through to dry-extra cost there too.)

One nice thing about the Red combine is that it has adjustability.  The vanes can be adjusted, the concave position can be adjusted along with the pre-sieve.  It was really nice to have these features to really dial it in.