Combines Rasp bars and concave function explination

[tbran]

First of all, seeds are tough. The good lord made them that way so they could last a winter before the moisture caused them to sprout. (of course this year it has been so wet and warm, they got fooled and sprouted Dec. 1st!) In a controlled threshing action that exist in a combine the grain is injested and low inpact immediatlely happens from the cylinder bars. The reason little grain damage results is the low speed of impact. We have said many times, cylinder speed causes crackage of grain more than clearance. Same as driving a nail, if not struck hard enough it will never penetrate. This is the real key though , if you have ever seen a video of a cylinder threshing corn you would see that 90 % of the corn is threshed by compaction of corn on corn. The cylinder bars compress the crop, the concave retards the movement so as to back up the crop and let the incoming crop push it across the grate. On an open grate the kernals can fall through , on a closed grate such as a K,F,G the crop has to hop over the channel bars to exit. The same action occurs when filler bars are installed in a N,R series grate, more aggresive action occurs. The reason the majority of cobs are not crushed is due to a cylinder clearance equal to or slightly greater than the diameter of the cob. Thus the cobs roll out. We here in Tn take great care in preserving whole cobs so as to lessen the toilet paper bill at Wal-Mart. White cobs bring a premium.......

 

[ahbecalm]

I can understand the use of 68" pitch bars in the thresh area to move material toward the seperator area more quickly. I bought the F2 concave bars and installed acording to the picture and description. However, I have a short P3. The last time we had the rotor out I looked at the number 6 helical bar. At 300 rpm I think centrfigal force causes material to engage the helicals like auger flighting. (Rule of thumb 8 mph causes mud to fly off tires, a 25" rotor at 300 rpm has a tip speed of 22 mph.) The number 6 helical bar in a 1990 R50 looks to me like a 45" pitch and directs material from the thresher grate to the discharge area bypassing the seperator grate. Yes I removed every other wire from both grates. This machine had 2 bu_a corn loss since we got it 6 years ago. We've tried most if not all things listed here. The ratio of diameter to length is diferent between a short P3 and a long P3. The R50 has about a 45" pitch, the sales literature for the R55 says 40" pitch. I'm thinking a 30"-34" pitch over the seperator area would direct material to the seperator grate. Insalling the concave rasp bars did not reduce rotor loss, but did increase kernal sized cob bits in the hopper. My older brother looks behind a 2 year old JD and is disgusted by our losses. With new accelerator rolls this year I have near 0 shoe loss. Can the processor be correctedIJ I have all foreward bars, 4 into the discharge, 4 shortened paddles. The pitch of the bars is the one thing I haven't touched yet. NDDAN mentioned a diferent bar kit being available, but harvest interupted that exchange of messages. Any information is appreciated. I don't think I'll be using your advice on white cobs.

 

[ewbeye]

If a person safely watches a combine cylinder running with guards removed, while say your doing a cleaning or inspection of it, you think it is some colossal, whirling thing compared to the small size of an ear of corn or soybean plants. But its not and Tbran said it right that it compacts corn on corn. Once the cylinder is steadily fed crop [ear corn, wheat heads, or soybean plants] it builds a constant flow of material that somewhat slightly piles-up before it goes between the cylinder and concaves. Most threshing is done near the buildup area just before the cylinder_concave's narrow clearance, in that its grain threshing grain. That is why most leading edged concaves wear down first or the quickest. The cylinder is big for several reason: 1. Its mass [weight] is important. Kind of like a flywheel on a baler. Besides initiating the threshing action, it also has to keep the crop material moving constantly. 2. Its circumference denotes its gentleness in relation to its surrounding concave area. With that in mind, it may initially hit the material, but then there is ample room for smaller material to move "with it" as it turns. Harmony in motion. Most important - Its no better than its operator who maintains it, sets it, and feeds it. Good operators can efficiently feed a well set cylinder to maximize it's performance and get an excellent sample in the grain tank. And usually experienced operators can accomplish that given a wide range of crop conditions, except germinated seed as Tbran expressed - that just mother nature doing her thing.

 

[PETE]

Thanks for the info fellers, especially the premium paid for white cob down south. I myself prefer button weed leaves but they are in short supply during the winter months. Fortunately about the time that button weed leaves become scarce pine cones are in abundance which not only clean but leaves you with a nice pine scent that lingers long after you are done. Here's hoping everything comes out alright, Pete Hinrichsen

 

[Tom_Russell]

Good topic, Pete, but what is button weedIJ Ive heard the term before but have not heard what it is.

 

[Gpurrs]

Velvetleaf,softest wipe in the feild.

 

[Harvester]

2 possible suggestions: how much trash is coming into the combine at the cornheadIJ Particularly with an R50_52, you need to minimize trash (husks and stalk) being ingested by the machine in order to maximize processor efficiency. Otherwise, no matter what you do to hyperize, you won't see any improvement. You don't have a lot of time to separate in a 50 or 52, so starting with the corn head to pick only ears and as little husk as possible will probably have the greatest effect. Second, and I know I will be scorn and perhaps banished from the site forever for saying it, try reinstalling 2 reverse bars in the separator section of rotor. Reverse bars were designed for a reason and have merit, especially in an R52, and I have always found them necessary to give the corn more time to separate in the 68" rotor vs. an 88" in a 62 and up. Yes, they will take some power, but you'll also see your rotor loss go down to an acceptable level, given the fact you've now also pulled wires in the right places (separator grate). A third idea is borrowed from the MF rotor and incorporates a series of rotor knives placed around the rotor in the separator area to increase agitation beyond what a rasp bar alone can do. On a Sunnybrook enclosed rotor, fitting these rotor knives would be a relatively simple job.

 

[Tom_Russell]

Thanks. Thats a new one on me or its a local thing.

 

[Illinois_Gleaner]

You have never heard of Button weedIJ Or do you mean you have never had to wipe with oneIJ And it is a local thing when you have to use it.lOl Illinois Gleaner

 

[NDDan]

We are learning as we go. Reason for steep pitch in some of the thresher area is to prevent material that has allready been threshed from dumping back on feeder concave area. In doing this it reduces feed chain problems and prevents totally overloading left side of concave in some crops and conditions. I think there is a much better chance of doing more seperation at concave if not loaded excesively on the one side. I studied drawing of R50 and or R52 helicals and see no way material can make it to discharge without traveling across seperator grate. You must remember that material will basically not move over without the help of helicals. Them small rotors were sent out without the top two helicals on seperator side. We have them installed on everyone but you can see where that would slow flow to discharge if you removed them. Did you plug the exposed holes from removed wires in both halfs of thresher concave and seperator grateIJ Do your helicals follow the same pitch all the way threwIJ Does the first helical that starts at gearbox wall drop straw back onto feed chain about 8" from seperator grateIJ Tring to figure out if someone installed something other than stock pitch helicalsIJ We have never used anything other than chromed standard pitch in the small P3s except a short piece of steep pitch to hook first helical from gearbox to the helical filler over top left corner of feeder. There were never any alternate pitch available for small P3s. I would double or triple check rasp bar clearance to concave at all four corners plus midway threw and do what you need to to get it true. I also wonder what kind of power that machine has for you told me in an email that you ran with as many as 10 reverse bars for a season with no help on loss. You also said soybeans were pooring out. Makes me very confused unless concave is way out of wack or maybe someone installed a full set of steep pitch helicals in that small P3. When we put a full set of steep pitch helicals plus a couple extra in the large P3s it very close to duplicates the time material would stay in the small P3s. Only difference is a wider path until it dumps into the same size discharge area. Don't forget removing the top helicals on seperator side will do the same thing as shallower pitch helicals. Hopefully that's enough food for thought and maybe you can check her out again and pinpoint the problem. Good luck