Tractor drawbar pull

[Minerva]

Is it possible for a tractor that weighs 3000 pounds to pull more than 3000 pounds? Of course people say yes but they're talking about a heavier ROLLING load.

Say if you wrap a chain around a large tree and put a scale in the middle and pull away. Is there an easy way to determine what the max pull is before the wheels spin? Let's assume the tractor has four wheel drive and can deliver power to all four wheels equally.

It would seem to me that the reading what peak and then drop as the wheels started spinning. Also the surface would play into the max significantly!

 

[Demon-Xanth]

It really does depend all on the traction you can get. Most tractors can easily out power the dirt they're on. A Cat D9 with a weight of about 54 tons can drawbar pull 72.

Edit:
From a review I was able to find, a Kubota BX23 tractor was able to pull 750LBs in 2WD, 1420 in 4WD, 1760 in 2WD w/ 600LBs of ballast, 1920 in 4WD with 600LBs of ballast, and it has an operating weight of 1520.

So in this case, a dozer can easily. And it's very conceivable for a tractor to.

 

[exdeath]

If you are talking about tracked vehicles, than sure, easily. The pressure and friction forces exerted on the traction surface per square inch is very small due to the track surface area. Friction in and of itself does not depend on surface area, but traction drive of a vehicle isn't just friction, but also pressure stresses on the medium (dirt compaction, asphalt deformation, etc).

A 70 ton Abrams tank can idle across a surface that a 2000 lb car could not. The tank is actually lighter per square inch of supporting medium than the car (pressure / stress).

Traction is similar, in that the more of the surface you grip in total, the less pressure there is on the traction medium (eg: dirt, asphalt) and the less it is distorted, thus the more traction you can effectively apply before things start spinning.

The scale you are talking about would be effectively measuring the static and then kinetic friction between the traction surfaces.

 

[CurseTheSky]

I don't know why, but this thread reminded me of this video: http://www.youtube.com/watch?v=qBF6iZfguF0.