My opinion on this is that any type of harvester chassis would not be strong enough. Just not made for that kind of weight. This refers not only to the frame itself, but also the drive train. Have you ever tried to get a loaded combine rolling through a soft field in road gear? Combine hydrostats just don't have the stuff to get it done.
Many have argued that this would not be worthwhile expenditure because you only use it during harvest. I tend to think that it might be economically feasible if you could derive some extra benefit from it. Where would be if we never bought equipment that could only be used during harvest? Should we still be running pull type combines?
If you have a short trip from field to bin, I can definitely see having a "field-worthy" truck to haul directly from combine to pit/pile. If you could eliminate the truck trip from the equation you would save tremendously in terms of time, number of drivers, fuel, etc.
Has anyone ever done any estimating as to how much fuel gets spent pumping grain out of a cart and into a truck? A large farm could save thousands every year simply by letting grain go the way it wants to: down!
I would want a camera looking into the bin if I were the driver. They're so cheap nowadays there's almost no excuse.
350 bu * 60 lb/bu = 21000 lb
40' Macdon FD70 Flexdraper = about 6000 lb (5841 lb., to be exact)
So that's 27,000 lb. total
350 bu * 60 lb/bu = 21000 lb
Claas 16r30 cornhead = about 12000 lb (I think)
For a total of 33000 lb.
Compare that to 650 bu * 60 lb/bu = 39000 lb.
750 bu * 60 lb/bu = 45000 lb.
1000 bu * 60 lb/bu = 60000 lb.
So, if we started with a chassis from a Lexion 595R, we would be 6000 lb short of a 650 bu cart, 12000 lb. (or 200 bu.) short of a 750 bu. cart, and 27000 lb. (450 bu.) short of a 1000 bu. cart. I realize this neglects all the normal combine bits you would be able to ditch, but I don't think that weight would be altogether different from the cart components you would have to add.
Most guys have mentioned older model combines for these conversions, presumably for money reasons. As you can see, a combine designed for a 22' header and a 200 bu. bin would be seriously short in the weight capacity department. Plus, the weight distribution would be all wrong. Adding the equivalent of another grain tank or two in the rear of the combine would almost certainly threaten the rear axle.
If someone wants to go do this, more power to them. I'm not saying it CAN'T be done. In fact, it has been done. I have even seen one personally, some time ago. I'm just giving the reason I personally would start with something else. As I am inherently lazy, I would probably go pick a vehicle that more closely resembles what I want when I am done.
Harvester chassis not strong enough??? So you can haul 350 bu + on a combine and hang a 40' header on the front but the frame wouldn't be strong enough to remove all that stuff and put a 650bu grain cart on it?