Good question, Ralf. The Bi-Rotor features of concentric cage, rotating in the same direction as the rotor were our attempts to reduce the straw damage associated with Axial Flow, NH and N7 Gleaners of the early 1990s. I think we were able to show an improvement in discharged straw quality while also improving threshing and separation. JD seemed to agree in NE ten years ago. But the Bi-Rotor is not available on the market. What is the best option for good threshing and separation and straw quality from the combines currently offeredIJ I think the lexion is the best current production combine with the best flexibility. APS and the crosswise cylinder gives good feeding, early grain separation and nice right __ left __ right __ left __ threshing action and a parallel concave clearance, (most similar to our concentric bi-rotor concave theory). Everyone knows that convention JD combines turn out better straw quality than JD STS combines. So if you want best straw quality, use a lexion with strawwalkers that run 240 RPM and have the added separation of ISS or the new multi-finger agitator drum. Granted the lexions with rotors will be more aggressive on straw than the strawwalker versions, but even these have been tuned more and more to give good separation while minimizing straw and stalk damage. Improvements to the lexion rotor separation includes features like: 1) The three speed selections gave good adjustability to separation force. The lexion now includes a full variable speed option for best balance between separation and straw quality. 2) The raised rib grates provided better mat vibration than the earlier flat slotted grates while also reducing straw breakage and damage. 3) The paddle type rotors seem to add to the MOG agitation, and may be more aggressive than the early spiral flight separation rotors. But the related change to an eccentric rotor to housing position seems to be working out pretty well. If straw quality is your highest priority, then I would recommend a strawwalker machine. And I'd recommend a lexion over a JD because of the parallel concave, faster walkers and auxiliary agitation device. If high productivity is a greater priority and long straw quality is a secondary priority, then rotary separation becomes more important and should be included in the selection analysis. Bi-Rotor technology is not an available consideration or option at this time. If and when BR tech becomes available, then it will be an option to compare and consider. Base on my experience with the XBR2, it's apparent to me that being able to control both the rotor and rotary concave RPM (speed) creates opportunity to vary and balance these factors: Threshing aggressiveness vs gentleness, High vs low centrifugal force, Steep vs shallow vane angle, effective grate exposure size (small vs large). From what I've seen this past year, it will be tough to out perform the flexibility and adjustability of a lexion. But it is also my opinion, and always has been my opinion that the Bi-Rotor technology would have the best chance of matching or surpassing a lexion while also achieving some added level of simplicity. Add to this, features like the dual path grain handling system, multi-function VPS aspect, lateral distributor, overhead air intake, conveyor unloader, integrated transport system, joy stick steering, et al. There is a lot of opportunity for future improvements in grain harvesting. We'll see what happens over the next few years. Stay tuned and be careful with those 3_8 impact wrenches. Use a torque wrench on the JD rasp bars as recommended by the manufacturer. It is frustrating to the factory reps when farmers and you custom combine operators don't read or heed the manufacturers recommendations.
We'll see how these new lexions work out. Unfortunatly our closest dealer is a many hour trip away. The only exposure to them in this area is at a show. No one has one locally and I dont see it happening anytime soon unless a dealer shows up in the area. I'd be curious to see them in grass seed though. Grass is somewhat unique in that when its dry, horsepower is a waste cause the cleaning unit cant keep up. But if it gets rained on and the going is tough, I dont think there is an engine big enough to run the stuff through.