Tractive Force

[SpinyMouse]

OK, I'm sitting here watching the steady rain turn the world even muddier than it already was and my brain starts to wander...

We call these machines "tractors" because they exert traction. They pull. Pretty obvious. But, just how much traction do they exert?

So, I take that LK3054xs that I wish I had. I set the throttle to about 1650 rpm, because that's the peak of the torque curve for the engine. Put the lever in low range and the transmission in first gear. Then I let up on the clutch and slowly trundle forward. The tractor takes up the slack and starts pulling on a huge spring hooked up behind. At this point, magic happens and the tires grip perfectly with zero loss of traction. While the tires are gripping perfectly, the load gradually increases as the spring stretches.

How much force, in pounds (or Newtons for you metric minded engineers out there) can the tractor exert on this load before the engine stalls?

How about in real terms with tires that lose their grip? How many pounds of pull can you deliver in the real world? Can you expect to stall the engine before the tires slip? Or vice versa?

An exact answer isn't critical, but an "on the order of..." answer would be interesting.

 

[BigAl]

Holy Cow !
I think all that rain is water logging your brain ! /forums/images/graemlins/grin.gif Maybe you and Henro should get together on some of these questions .
I loved doing math in the 8th grade it was the best six years of my life ,but you guy's are making my brain get a cramp ! /forums/images/graemlins/crazy.gif
Big Al

 

[gone]

I think your leaving out to much data for any rocket sience guy to ansewer. but i'll bet in low first at 1650 it'll burn the tires off before it will stall. that to me is enough tractive force to keep most pepole happy for the machine gave it all it had to give, the tires are what will let you down. /forums/images/graemlins/smile.gif

 

[Dewave]

Spiny, in my nicest way of saying this, "You need some real world experience! Only with real world experience could you begin to understand all the outside variables that may come into play. Not saying it couldn't be done, I'm just saying it would be easier for you to understand. You'll see! /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif

 

[lablovers]

I probably could answer this if I new how far tractor a would travel in 20 minutes traveling at 1 mph while tractor b was traveling in the opposite direction @ 1650 rpm.
If you can give me these two variable, I think I can figure the cost of diesel in Seattle. /forums/images/graemlins/smirk.gif

 

[RobS]

If you assumed no tire slip you could calculate the tractive force from the tire diameter, gear ratios and engine torque. In the real world though, tire slip is the limiting factor and it's not easy to figure. Simplistically, it's the coefficient of friction between the tire (rubber) and the earth but that doesn't take into account the tread. Ag tire treads are designed specifically for traction in soft soils.

Interesting topic. Maybe someone with some tire design knowledge can chime in /forums/images/graemlins/smile.gif

 

[Egon]

Ahh- just get some springs, strain gauges and go the emperical route.

Maybe post resulte for PHD thesis.

Egon

 

[sl3uth]

Sounds like you need to get hooked up with those tractor pull guys. The "sled" they use puts more pressure on the tires as the weight increases...so you can actually see when the tractor will stall out.

BTW, I have nearly stalled my tractor when using my sub-soiler. The one I have is more hooked, so it creates both downward and rearward resistance.

Sam

 

[grainger12002]

This discussion is giving me a little outward force...........Spiny,you have way too much time on your hands.............................. /forums/images/graemlins/smirk.gif /forums/images/graemlins/smirk.gif