Pulling a trailer with your tractor

Localmotion · Nov 23, 2011

LD1 said:
Because they have MUCH larger rear tires than fronts. SO unless we are taling about a machine with the SAME sized tires front and rear (large articulating ag, JCB backhoe, Skid Steer, to name a few) the same principals apply as a 2wd.

I'm sorry to be so blunt - but that arguement makes no sense at all. The traction offered by the front wheels will still exceed the extra traction on the back...

If you don't believe me, get two identical tractors and chain them together - one with the chain attached to the draw bar and one with it attached to the top link bracket.

Put them both in 4wd and pull - we did this many years ago at college, to challenge exactly what you say in your last statement. Your theory may well have sound phyics behind it, but tractor designers know what they are doing. The position of the draw bar is such that it is the optimum traction on a 4wd tractor...

Redneck in training · Nov 23, 2011

Tractors for pull contests are two wheel drive (at least those I saw).
The geometry of the hook up is critical for success. They place the point high and back. The height above the contact of the rear wheels with ground is the arm that makes the tractor lift front wheels and transfers all the weight on the rear tires. Since as the tractor rotates up the hook up point get lower thus shortening the arm that rotated the tractor upward. Therefore the tractors can operate in more or less stable manner with the front wheels up. As long as the traction is somewhat larger than the force trying to stop it the tractor will move. The tractor stops when they are equal. This approach works because the traction in given condition is known and more or less constant. If the traction would, unexpectedly, increase the tractor could flip backward or in opposite case would not lift the front wheels.

Based on above the key is "known traction". Since that is usually unknow in farm environment we shoudl hook up out equipment for the worst scenario and use common sense at the first place.
1.) Hook up low and behind the tractor in example to pull bar.
2.) If 3ph is used make sure that you have enough tongue weight to prevent the hitch rising.
3.) If parked outside in freezing condition make first move in reverse.

LD1 · Nov 23, 2011

Localmotion said:
I'm sorry to be so blunt - but that arguement makes no sense at all.

Makes perfect sense when you think about it.

Localmotion said:
The traction offered by the front wheels will still exceed the extra traction on the back...

...

Impossible. 100lbs of weight over a MUCH larger pair of tires so going to have more traction than 100lbs over a smaller pair of tires.....Unless you are running turfs on the back and ags on the front.

Localmotion said:
If you don't believe me, get two identical tractors and chain them together - one with the chain attached to the draw bar and one with it attached to the top link bracket.

Put them both in 4wd and pull - we did this many years ago at college, to challenge exactly what you say in your last statement. Your theory may well have sound phyics behind it, but tractor designers know what they are doing. The position of the draw bar is such that it is the optimum traction on a 4wd tractor...

I call bull. (sorry to be so blunt)

It may have indeed resulted in a stale mate, I can believe that. BUT...It takes more than just a little more traction for one tractor to out-pull another. It takes a LOT. In other words, think about how much force it takes JUST to pull said tractor while in neutral. THAT is how much more it takes in traction.

IE, tractor takes 500lbs of force JUST to roll in neutral. IF THAT tractor is capable of pulling with 2000lb force, another tractor would NOT pull it if it was able to generate 2200lbs. It would need 2500+.

Similar example (allthough different), I have pulled a TON of logs with my tractor. And I can assure you that hooking to the 3PH and raising (transfering weight to the rear) will pull WAY more than hooking to the drawbar.

BUT, just to be clear I understand where you are comming from, Let me ask you this.....

Say we have a tractor. IT is 4000lbs with 1500lbs on the front axle and 2500 on the rear.

Example 1: straight Drawbar pull. under load we have 1500lb front and 2500lb rear.

Example 2: 3PH chained high. This not only ads weight in the form of lessinging it from whatever it is pulling, but also transfers weight off the front.
So lets say we are able to transfer 500lbs off the front, and add 800lbs from the downforce of the load. Now we have 1000lb/F-3800lb/R

Which is going to pull more???

And even if we negate the 800lbs that the load adds (which is impossibe, because if no weight is added, there can be no transfer from the front). But just hypothetically, 1000lb/F-3000lb/R

You think that wont outpull example 1 of 1500lb/2500lb on a 4wd? If you actually think that, you are nuts.

Lets Take it even farther.

Lets put ALL the 4000lbs over ONE axle. :thumbsup: So....

Will 4000lbs over a pair of 7x16 tires outpull 4000lbs over a set of 11.2x24's????