Traction old vs new - it's not always hp - interesting video

[aczlan]

Pulling upwards only applies if the angle of the vector is increased during the pull. There was no change in the angle of the chain during the event and therefore no impact on the traction of the JD. If the steamer changed angle at the hitch during the pull then it would matter but the pull remained the same throughout and therefore its net effect is zero.

On the contrary, the angle of the chain changed several times (see from 2:05 on for some examples).
If the relative hitch height doesn't matter, why does most every tractor pull rulebook list a max hitch height (see: https://www.google.com/search?q=tractor+pull+hitch+height for some examples)? Its so someone doesn't get an unfair advantage by having a higher hitch point (transferring more weight to the rear end).

Would it have made a difference in this case? No, the steamer had too much of a weight advantage.

Aaron Z

 

[TerryR]

2. Torque is THE only thing that matters in engine output. Remember that horsepower is derived form an equation with Torque as an input variable. Remember that HP=Torque*RPM/5252.

But engine output has nothing to do with the outcome in this case. The JD had plenty of power to spin it's wheels. The outcome was decided by traction, not by engine output.

Pulling upwards only applies if the angle of the vector is increased during the pull. There was no change in the angle of the chain during the event and therefore no impact on the traction of the JD.

That is simply not correct. Nothing has to change during the event for the angle to matter. Assuming the connection was unrestricted at each tractor, as would be the case with a chain connecting them, the vector of the force connecting them was along the chain. That vector can be resolved into a vertical and a horizontal component. The vertical component was lifting the JD and pulling down on the steam tractor. The upward force on the JD offsets some of it's weight and reduces its traction.

That probably didn't matter in the end because the much heavier steam tractor simply had more traction, but was a handicap for the JD nonetheless.

Terry

 

[RaydaKub]

On the contrary, the angle of the chain changed several times (see from 2:05 on for some examples).

Would it have made a difference in this case? No, the steamer had too much of a weight advantage.

Aaron Z

I'm with Aaron on this one. Heck just the trench he dug affected the angle.

 

[TerryR]

Change in the angle isn't the point. When they started the hitch point on the steamer was higher than the one on the JD, so as soon as either of them applied power the chain is creating a lifting force on the JD. When the angle changes that force is increased or reduced, depending on the direction of the change. But as long as the chain is higher on the steamer end it is applying lifting force to the JD, reducing its traction. The change in angle isn't what creates the lifting force, it's the angle itself.

Terry

 

[adventure bob]

The JDs traction was the same at the beginning of the pull as the end. The steamer never did anything statistically significant to lift the JD that would change or reduce the traction. Your misunderstanding of physics leads you to the belief that the JD is being pulled "up" somehow, reducing its traction. The fact that it buries in indicates that the total vector of the system is to the left of screen and DOWN, not up. Same as a sled pull: the reason pull vehicle sinks as it runs out of forward velocity is the impact of the downward component of the sleds total vector on the system. This steamer, due to its weight has a monstrous downward component to its vector and the result on the system of steamer, chain, JD.
My Ram 2500 diesel will out pull 500 HP Dakota all day long regardless of chain angle.

 

[bcp]

And the steep angle of pull is not lifting the rear of the car.

 

[adventure bob]

So the uninformed answer is thatif the chain was level the JD had a chance? Is that really where going with this? The chain is irrelevant in this. Lower, higher, even, the JD would have gotten beat. Its a weight and torque thing, you wouldn't understand.

 

[bpbolde]

I never knew a Deere could make such a good trencher! All about the synthesis of torque and traction. Without one, the other is meaningless. It's like hooking a semi to a race car. Cool vid!

 

[bcp]

So the uninformed answer is thatif the chain was level the JD had a chance? Is that really where going with this? The chain is irrelevant in this. Lower, higher, even, the JD would have gotten beat. Its a weight and torque thing, you wouldn't understand.

I do understand. The JD would have been beat even if the chain sloped the other way. The chain angle was irrelevant to the outcome, but was not "fair." What if the chain angle was so steep that the JD rear wheels lifted off the ground, just like the car did? Would that have had no reduction of the JD's traction due to the pull angle?

Bruce

 

[wade23454]

So the uninformed answer is thatif the chain was level the JD had a chance? Is that really where going with this? The chain is irrelevant in this. Lower, higher, even, the JD would have gotten beat. Its a weight and torque thing, you wouldn't understand.

I could design a hitch for the john deere that would allow it to drag the steamer down the road. I might need to add some front end weights to the john deere and reenforce the rear axle, but the mounting point is not irrelevant.