speed and weight

Jerry He · Jan 17, 2015

Question; If a tractor can spin out at 6 mph at 9000 ibs, then all things being the same. Can this same tractor spin out at 9 mph and 6000 lbs using the same horsepower.

535353m · Jan 17, 2015

Interesting question,may not be an exact flip flop like that with the same numbers,but am thinking that my tractor does those speeds,but never pulls 9000. I believe the speed will affect performance more than the weight at the slower pace.It may very well be close though.In my experience,adding a thousand lbs. is almost always a gear lower,if the lighter class used 95 % of tractor's power.Most tractor's gears are 35-40 % apart,making it difficult to go just a little faster.A Case 400 is the only tractor I know with very close ratios.

Indiana Ken · Jan 17, 2015

(quoted from post at 11:39:52 01/17/15) Question; If a tractor can spin out at 6 mph at 9000 ibs, then all things being the same. Can this same tractor spin out at 9 mph and 6000 lbs using the same horsepower.

HP = (FxD)/T

And

S = D/T

Substituting we have:

HP = FxS

Where F is force (horizontal pull at the draw bar) and S is speed.

Therefore, using this simple math model, pulling 9000 lbs @ 6 MPH would require the same HP as pulling 6000 lbs at 9 MPH. In the real world there would be other factors that would influence the result to some extent.

Note, in this case the weight of the tractor is either 9000 lbs or 6000 lbs; the drawbar pull is the rear wheel weight x the coefficient of friction with the track. To keep it simple we just assume the coefficient is the same for both weight classes in which case every thing remains proportional.

535353m · Jan 28, 2015

we missed the point that the sled gets increasingly heavier and much harder to pull as you continue down the track,so at what point is the load the same,distance will be different each pull at different weights.I do not believe the graph of power to speed ratio is linear,it most likely is a steep slope.Power required to go X fast is not two times at 2x?????????? I learned about exponential in high school,makes a huge difference.

speed and weight

Jerry He

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535353m

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Indiana Ken

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535353m

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