I also wondered if the huge wheels on the drive shaft of the steam engine contributed to its advantage. I am not an engineer but maybe one could comment on that?
Lots of things to consider that contributed. Speed times Force over 5252-if I remember right.
Weight is the advantage. The steam tractor has traction. The farm tractor does not in this case.
Don't know the true dynamics, but the steam engine has 100% torque while sitting still - would have to break something to get it to back up. As long as it had traction, the newer tractor would have to drag it and probably had trouble with spinning tires.
Probably. As you watch the steam tractor pull the JD, you notice that the JD is digging into the soil much more than the steam tractor.
Since the combination of the two tractors isn't accelerating very much, one would conclude that the forces generated by each tractor are roughly equal.
In the case of the JD, the force is being generated over what looks like a smaller area and is sufficient to make the soil fail, which reduces the pulling force. If the JD was equipped with wheels identical to the steam tractor, one might expect that the greater horsepower would prevail, if the gear ratios were identical and the weight of the tractors was the same; which they probably aren't.
My smaller JD tractor has many plastic parts, to reduce manufacturing expense, and gets its weight from the frame of the tractor, the water-filled larger wheels, and some weights added to each wheel. It may be that the steam tractor is just inherently heavy because it's virtually all metal.
It isn’t a matter of horsepower or torque both of which are in favor of the newer tractor. It is simply a mater of traction. That is why the newer starts winning in most cases and then it reaches a point where it just starts digging itself into the ground like a power tiller. The steam tractor most likely outweighs the Deere by 2 or 3 times.