I rolled my tractor

tjkadar · Sep 9, 2005

Even a 2WD tractor with only rear brakes has some front wheel assistance when stopping. The friction (traction, if you will) of the front tires on the ground will aid in stopping the tractor. Granted, this might be a miniscule amount, but it is still there.

It doesn't really matter what vehicle you are stopping. The basic physics of braking doesn't change simply because you are stopping a car, truck, tractor, or motorcycle. The dynamics might be larger or smaller, but the same rules of physics still apply.

I'll admit it, Keith Code did a much, much better job explaining the traction theory then I can. He can take a complex idea or theory, break it down into its basic parts, and then make someone feel as if they really do understand it. I wish my Physics professors had the same talents. /forums/images/graemlins/grin.gif

Now how about aerodynamic braking? Would a tractor with a FEL stop quicker then a tractor without - all other things being equal? /forums/images/graemlins/confused.gif

Tim_in_IA · Sep 9, 2005

I think we need a 3pt mounted emergency parachute! This of course should be connected to the draft control in some anti-opposing force. /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif

tjkadar · Sep 9, 2005

Awesome idea! With a little work, maybe the parachute could be used in some manner to prevent tractors from rolling over too! But would it be an option on CUTs with no draft control?

Caveat: The above was a very lame attempt to try and bring the subject back to the original topic. /forums/images/graemlins/crazy.gif

KentT · Sep 9, 2005

( Awesome idea! With a little work, maybe the parachute could be used in some manner to prevent tractors from rolling over too! But would it be an option on CUTs with no draft control?

Caveat: The above was a very lame attempt to try and bring the subject back to the original topic. /forums/images/graemlins/crazy.gif )

How about a giant, inflatable airbag instead? That could work in rollovers, and the "balloon effect" could serve as brakes -- of course when it deployed, it'd be like a rocket booster... /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif

RedRocker · Sep 9, 2005

Ejection seat, just watch out for the sunshade.

trlong · Sep 10, 2005

Where this thread has gone has been interesting, thoughtful, and informative. However, the "physics" of stopping vs. braking has pretty much hijacked the thread. I believe (and some one correct me if I'm wrong), the original problem had nothing to do with tire condition, "road" condition, coefficient of friction between tires and surface (sorry, I expanded on that), or much of anything besides...

( I stomped on the breaks the tractor did not slow down. )

My interpretation of that, and subsequent statements was that the problem had nothing to do with traction but, that the wheels' d(rotation)/dt /forums/images/graemlins/grin.gifwas not a negative number /forums/images/graemlins/shocked.gif.

My experience with that function,

f(stomp on the brake) = 0

when releasing the "parking brake" on an incline without 1st placing the HST in gear, has brought me to the same conclusion as SoundGuy. The "parking brake" is pretty much just that, a Parking Brake. Never trust it to do much for you, regardless of traction. Just make sure you're in gear before you release it and don't rely on it on an incline.

As said, I kinda like the RB dropped (or BH with stabilizers down), the FEL dug in, and the wheels turned hard when stopped on an incline. Not great on the lawn but provides a pretty decent coefficient of friction. QED

'Nuff pontificating on physics? /forums/images/graemlins/smirk.gif

Tom

Soundguy · Sep 10, 2005

( a machine with ONLY rear brakes would use them for 100% of it's stopping power, since it only has rear brakes to work with )

Yep..

Soundguy

Soundguy · Sep 10, 2005

( Even a 2WD tractor with only rear brakes has some front wheel assistance when stopping. The friction (traction, if you will) of the front tires on the ground will aid in stopping the tractor. Granted, this might be a miniscule amount, but it is still there.
)

That's a red herring argument.. lets stick to the tangibles. and leave the 'epsilon' constant forces of bearing drag and wind resistance out, and focus on dynamic braking.

A 2wd vehicle with rear brakes only.. 100% of the dynamic braking comes from the only brakes present.. the rear in this case.

Lets forget about tail winds, gradient, and what grade of axle grease you are using... ( if your bearings drag so much that your tractor will stop rolling on a grade.. then the preload is too high or the lube is insuficient.. or the bearing is already shelled! /forums/images/graemlins/shocked.gif )

Soundguy

Junkman · Sep 10, 2005

I just finished doing the brakes on the wifes car... all four wheels... pads and rotors. Just like last summer when I did them last, the rears were down to the rivets and the fronts still had lining material on them. I replace all rotors and pads that time also. If the rears do less braking than the fronts, then why are the rears wearing out so quickly? I have my ideas as to why, but will hold onto them for a while and want to see what your opinions are....
The car is a 1997 Ford Explorer with 4 wheel drive, automatic with 6 cylinder engine... and a female driver 100% of the time. /forums/images/graemlins/frown.gif

ronjhall · Sep 10, 2005

I'll take a guess at this one. When pushing on the brake pedal the rear brakes always energize first. If someone is riding the brake pedal, rear brakes drag and wear out. /forums/images/graemlins/tongue.gif