JOHN Lazar - What Steve B actually said was the main rotor drive on IH's Axial flow combines are via a BIG Honkin' V-belt, able to bring a 300+ HP diesel to it's knees. No v-belts on the old corn binders, maybe leather belts, but mostly spur gears and cast iron link chains.
I forget who all worked on them, but flexible steel belt continuously variable speed transmissions have been available in small cars & SUV's for several years now, operate on the Salsbury principle like used on snowmobiles, etc. Not a rubber V-belt like the cheap off-topic lawn tractors use.
Had to laugh at Bill "QQ" J.'s comment, reminded me of a comment another person made to me on another forum that the little 7 & 8 HP lawn tractors acted as powerful under really low or no loads as a 16, 17, & 20+ HP tractors. Just another situation where someone with NO experience with tractors or equipment formed an incorrect assumption based off their totally inaccurate "butt dyno". I mean really, in the case of full size ag tractors, if a 30-35 HP tractor could do everything a 70-150 HP tractor could do, why would anyone buy the larger tractor?