This thread has gotten real interesting and I always enjoy these types of debates
I agree with most of what spyderlk said and even some of what Jasg said.
After following this thread for a few days, here is my understanding of what everyone is trying to say.
Jasg: I think you are trying to emphasize that a tractor CANNOT flip backwards if hooked to the drawbar. I'll agree with this because it is true that the rears will break traction before a flip can happen, BUT...the fronts can come up a foot or so, as explained in one of the links with the remote controlled tractors. Which leads me to Spyderlk's position.
Spyderlk: Correct me if I am wrong but I don't think he's arguing the flipping of the tractor, rather the comment made about hooking to the drawbar putting downward force on the front end.
My understanding of this is that a drawbar, below the axle line, and a straight pull rearward, does indeed help to counteract the axle torque, but not stop it completely. It's about leverage, the drawbar is only about a foot below the CL of the axle. The tires are contacting the ground about 2' or more below the axle cl. The wheels have more mechanical advantage than the drawbar, therefor the possibility is still present to raise the front of the tractor. How far it raises is dependent on several other variables like length of drawbar, weight over front, traction, etc. In all reality, everyone knows that a tractor will break traction first, if hitched properly, but it DOES NOT add more weight to the front end, even if pulling in a straight line.
My conclusion is that traction, or lack of, is the only thing that keeps the front planted, not the hitch adding weight.
For sake of argument, take traction out of the equation. Say that the tires absolutly could not slip no matter what (like frozen, or poured in concrete), hook tractor to something with the drawbar, and put scales under front tires and see what happens. (This is just a hypothetical situation, I hope no one is dumb enought to do this)
After reading your post, and re-reading my original commet I see where I went wrong with my choice of words. I don't say or mean by my post that it would add weight to the front, but counter act the force of the axle by enough so the front would not come off the ground and be worth while for traction. In other words if you want to talk weight lets say you have 5000 lbs on the front axle the force from the rear axle is 6000 or 7000 lbs in the opposite directions, the drawbar or 3 point hitch will counter this enough (pull down on the front) so it will not rise. I did put in my comments when properly set up, this would mean connected and weighted properly. I did not mean the axle would increase under load to 6000 or 7000 lbs.
Any one who has used older tractors (vintage 1930's and 40's) that were not set up this way would have an idea of what I mean. Some of the old farmalls and even the Allis Chalmers with the 2 point system and drawbars connected to the back of the axle. The front wheels when disking or dragging would be very light on the ground or even spend a lot of time in the air.
