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Discussion Starter #1
Currently running 2 Lexion 760's in sunflowers and banging our heads against the wall trying to get our returns in check. No matter how we've set the combines we are filling our return elevator with sunnies that should be going into the clean grain.

Both machines have a TM6 top sieve and the standard frogmouth bottom, above a jetstream cleaning system. Started off with the initial Lexion settings and tried to fine tune from there.
APS open (10x40 keystock)
Cylinder down to 250-300 rpm
Concave 25-35mm
Rotors ~450 rpm (Both Doors closed)
Fan 1000-1300 rpm
Top Sieve 10-15 mm
Bottom 20 mm, wide open and still completely filling return

No matter what we've tried, it seems that clean grain is having a problem falling through the bottom sieve and is getting carried off the back into the returns. We've experimented with different fan speeds and haven't been able to see any improvement. It takes a good 15-20 seconds after stopping travelling forward for the return to empty out. Our ground speed is limited to less than 2mph with an 8 row head and filling the return to max capacity with clean grain. There is next to nothing for MOG moving through the returns.

The sunnies are tough, 11-14% moisture and running anywhere from 2200-3000lbs/acre. We ran a 580 and a 575 in years prior to this and never had a problem with excessive returns before.

We're parked for a few days because of snow, debating pulling the bottom sieve out of one machine and running to see where that gets us. Planning on blocking off one side of each of the 4 fan mills with cardboard on the other and leaving the bottom sieve in. Theory of keeping air velocity and lowering air volume to try and allow the sunnies to fall through before being carried off.

Has anyone else had this problem and found a solution? I've spoke with a few other Lexion owners in the Manitoba area who've encountered the same thing and haven't been able to remedy it.
 

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In our 750 seemed we had a lot also but our flowers weren't that good. We have a deep tooth on top so had that shut down to like 3 or 4 id have to check but id think youd want to crank your fan down a lot more try 800 and shut your top more. The guy also told maybe its common in flowers to get a lot of returns and that sometimes they have to open the return door as its mostly junk his words im not sure about that though.
 

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I have no experience with this crop but was wondering if you should try closing the top sieve more as long as losses do not increase.
 

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I don't have a lex but with the red ones I would keep the bottom sieve way open and do the cleaning on the top sieve . The other thing is that the sunnies don't need to be thrashed very much with the rotor as most will be thrashed out in the feeder house . So running the rotor slow and wide concaves with wide wires to get the seed out without all the chaff would help . You don't want to send the seed back into the rotor as this will give you more splits .I was also running an adjustable airfoil .
 

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I’m wondering if the fan is too high too. If you have a lot of seed falling through the very back of the top sieve it’s going to be returns as well.

Make sure the belts that drive the shoe are tight as well on the left side of the machine. The 2 you have to loosen off for the idler to slide and tighten up.

After that I’d be tempted to try a frog mouth in the bottom.
 

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We are running a 750 with TM6 sieves and we were having the same problem. Our mechanic made us a couple of plates to blank the returns and then we pulled the bottom sieve. In 2000+lb flowers it does a very good job of cleaning with just the top sieve. As we get into some lower yielding flowers it isn’t doing quite as nice a job, but still acceptable to us.
 

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I can only relate a distant memory using John Deere rotaries in tough Manitoba sunflowers.

I don’t like your idea of such a low cylinder speed. If they were that tough I would want at least a 400 RPM speed doing the trashing and no lower than 350 when it’s dry. It’s true there isn’t much MOG but if the damp pieces of pulp getting through separation and onto the chaffer are very sizeable the air can’t always support them off the chaffer surface. The pulp pieces tend to blow out easier when they are ground up small rather than recirculate in the returns.

Personally I would revert to more of a dead sieve cleaning method with the sieve set at about the width of your larger seeds across the edges and then setting your chaffer openings to about the length of the jumbo seeds. I suspect this would require the fan speed to be in the 650 to 800 RPM range to achieve the proper air jet velocity in the clean grain sieve openings.

You won’t be able to go 7MPH just because you can, because there will be more material arriving on the shoe than you have now. I would just set the wind to blow the blanks out the back and only save the seeds with meat in them. You can test this by cracking open the ones on the ground by bitting them.

Probably right now you have too much air velocity and open area in your clean grain collection system to allow all of the viable seeds to fall through. There is usually a high blank ratio of seeds this far north, and the best place for them is on the ground. IMO
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I had a very similar problem this season with swiss chard seed. I originally had Tm6 sieves in and I had the bottom wide open and the top down tight and the tailings was overflowing on me. I switched to my corn sieves, and put my deep tooth frogmouth top and bottoms in, and it did help a little, but much less than I thought it should. I also had the idea of pulling out the bottom sieve and blocking off the tailings with a cover plate. I think that the air was holding it all up and the bulk of the seed was falling through in the very back of the shoe and going into the tailings. in my case the clean grain was never very full at all. it is frustrating, I tried playing with the wind too, and if i went to low the shoe would stall out and losses would pick up. I ended up with a really tight top sieve and running the machine slow and basically driving by watching the tailings window. I was wondering if Claas makes a kit to block off the tailings for this scenario, seems like it might be needed in certain crops.
 

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There are filler plates available to block the returns. I would get in contact with your dealer.
In europe it is quite common to pull the bottom sieve and put in these plates especially in corn.
 

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Discussion Starter #10
We've gotten the oils off and now and seem to have found part of a solution to get some productivity out of the combines.

We switched the APS grates to a round bar and bought a rotor blanking kit from Agwest. One kit split between the 2 machines and we were able to blank off another 2 sections of the rotors and not see any rotor loss. Ordered another kit to blank off more but we were finished by the time they came in.

With the round bars in the APS we were able to run our cylinder around 400 rpm. Ideally it would've been better to run it slower, but even at 400 rpm we'd have problems feeding between the impeller and rotors. (Still running the factory Lexion impeller, these will be replaced through the winter with Sunny Brook. They made a world of a difference in our narrow body machines.)

Our fan speed varied from day to day, balancing act between filling the return and trying to keep our dockage down. Anywhere from 850 to 1000 rpm. We kept the bottom sieve wide open and the top around 10mm.

With these settings we were able to run 2.5-3 mph for the most part, our tailings being the limiting factor. Frustrating when your class 9 combine is reduced down to harvesting 7ac/hr at its best. I think the extra covers on the rotors made the biggest improvement and would think that adding one more set would allow us to dial the combines in better.
 
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