Combines Understanding Rotor loss

This comes from the loss sensor signal being divided by the ground speed signal. When you slow down quickly, the loss probably doesn't go up significantly in either area, but you are simply dividing the loss number by a smaller number (speed) which makes the meter peg. In some of the later machines I think the monitor automatically switches to a straight loss mode, rather than a loss per acre mode, when the ground speed gets really low. The bottom line is that losses should alway be considered at steady ground speed that is consistent with normal operation. Rapid changes in ground speed are beyond what the meter is capable of reporting accurately.

Similar to the air situation in the shoe the amount of material in the rotor cage is critical for good threshing and separation. Rotor speed is a critical factor too.

Remember when you shelled corn on the cob out of a cribIJ Your father keep telling you "KEEP IT FUll" because when the sheller went a little empty the cobs came out with corn on them. Jack

No I don't because the only corn I've ever touched is in the garden.

Is that rightIJ I didn't realize the grain loss monitors in my machine were that sophisticated. Just as I'm writing this I've realized something that I've always wondered about. When I would come to the end of a swath (windrow) and not slow down as I turned around for the next one the monitors would stay put. But if I stopped suddenly in the middle of a swath the monitors would peg.It being linked to ground speed explains it. Thanks. I've learned something new today.

It's odd that you metion the corn cob example.One thing I have always noticed about my Ih is the fact that when you turn on the ends in corn you will almost always thorw some out grain out the rotor. I always figured that it was from the rotor not having enough crop in it. so your comparasion is very valid at least to me. Um as a side note does anybody know how to cure the above problemIJ Will

James, You are exactly correct. Keeping your ground speed the same as you run out of crop in the header is the best way to tell if your loss is speed dependent or related to how full the rotor is. I would guess that if everyone would simply run this experiment, the perception that the rotor has to be full to thresh properly would probably start to die off. I think most of us are just getting tricked by the way the monitor works. I ran the machine for years without understanding what was going on, but we don't have corn. I did some checking and the 2188 monitor switches from ground speed mode to time mode at 0.5 mph. So, when you slow down the needle will climb until you get below 0.5 mph. Below that, it will quit dividing the signal by speed and will divide it by time. Of course, it's all achedemic because there is no provision to calibrate the time mode independently. The book says that time mode is primarily used to check sensor operation, rather than measure field loss. Probably more than you ever wanted to know about the topic! I'm not sure if the monitor in the older machines is the same, but I suspect it is. Mike

Farm Kid 2 I have wonder why they link performance (loss) meter to the speed, it seem to me that I would not wont any more loss a higher speed then at lower speed but the monitor allows for more loss at higher speed, is that right. I dont understand why it is designed this way; I would rather have a switch to turn that function off. Dee

I agree that it would be nice to select between Time mode and Speed mode. Then a person could read the amount of loss directly, and factor in the groundspeed themselves. However, that would probably be even more complicated than what most people would want to mess with. By dividing the loss by the ground speed, they are able to approximate the percentage of the crop being lost out the back of the machine. I think this is what most people are interested in.

I think that if they separated Time mode and Speed mode, you would end up with a monitor that is trying to be more accurate than it was ever meant to be. After all, all you have to do is adjust the sensitivity knob and the needle will go from showing no loss to excessive loss.