I know that there are guys on this thread that have lots of experience, for sure. But I'd bet that not many have actually compared the different units (farm tractor vs conventionals) with a standard 100,000 lb axle scale ON THE JOBSITE. I have already done so. The immediate visual representation of the farm tractor's payload is misleading. Not only is there an enormous void left in the front of the pull-pan, but the dirt that is indeed there is typically riding in a "loose state" The conventional scraper's load is Jam-packed.... it's got to be. 200,000 lbs of push-cat and scraper tires have a tendency to do that.
No matter how you estimate it, the farm tractor, pulling his pull-type pans cannot match this. And no matter the type of farm tractor, no matter how many "tires" that you mount on the axle, no matter to a great extent, the horsepower of the farm tractor, you still don't end up with shear weight of the conventional twin-scraper/ push-cat arrangement.
I don't think that I stated anything erroneously and talk about weight and balance for a moment. External weights were always added to the front of a farm tractor to do (2) things: First and foremost, get equal loading to all (4) tires, then to add weight. When you apply huge drawbar weight to the farm tractor, the front axle becomes "light" and does very little to contribute to the forward vector. In a dynamic loading situation, the farm tractor is never truly balanced; it goes into the cut (empty) with tons of weight on the nose of the tractor, resulting in little effort from the rear axle, then, for only an instant, is it balanced, making both axles balanced; then it finishes its loading with more weight on the rear axle and less on the front. Point is that it is never perfect.
Now let's assume the push-cat/ twin-scraper arrangement. Both units remain perfectly in balance during the entire loading sequence, UNLESS the enexperienced push-cat operator lifts the rear of the twin-scraper with his blade, negating the drive effort of the scraper's rear axle. This not withstanding, the higher the push-cat's blade, when it contacts the scraper's push-block, the more tractive effort that the dozer realizes. It's simple statics; the more resistance the scraper offers, the "heavier" the dozer becomes (dynamically) It actually forces the steel tracks footprint into the ground. This is the principal of felling trees with a hyd excavator. Hit it higher and the excavator's dynamic footprint is enhanced. Tree falls over relatively easily; same phenomenon with a push-cat's blade.
BTW, I own (4) Reynolds LGP CS scrapers, (4) Prime pans, and (6) very old, original, (but welded immensely) 14 cy pans. I've pulled 'em with everything from Case 2870's, J.D. 8400's, J.D. 9400's, big Quad Tracs, and big round-tired Steigers. I am biased because I've owned 'em all, run 'em all, and evaluated 'em all. Farm tractors and lightweight pull pans are like the old gas-burning over the road haul trucks of yesteryear; they'll pull like the devil but they won't do it for long. Then you'll have to rebuild 'em. Dirt moving is a contact sport; and until electronics become less susceptible to the dust, vibration, and moisture of Real Dirt Work, new farm tractors will be cost prohibitive to big dirt work.
I see today, that there are company's out there building structurally-sound pull-pans for farm tractors, but check out what they are becoming... the good ones, I mean..............
big, heavy, mining-tire wearing, thick steel framed, large hyd cylindered, old-school appearing dirt pans.
Are pull-pan manufacturers going forward or backward?
Caterpillar, Terex, and the like had it right from the start. And I've found that late-model engines, because of EPA mandates, burn equivalent amounts of fuel, even with all of the new, electronic technology in injection systems.
Yep, I endorse "Old-School Iron"........... and the shorter the haul, the more disparity in load count. The old-school conventional Push-cats/ twin-scrapers will dominate by a large margin.
