Drawbar pull capability

[rScotty]

I believe they are an excellent measure of pulling power IF they are conducted properly

Of course they are.
The Nebraska tractor drawbar pull tests are standardized and recognized around the world.
Anyone interested can read about their current testing and the history of tractor testing at:

Nebraska Tractor Test Laboratory | Nebraska

tractortestlab.unl.edu

rScotty

 

[Hay Dude]

Of course they are.
The Nebraska tractor drawbar pull tests are standardized and recognized around the world.
Anyone interested can read about their current testing and the history of tractor testing at:

Nebraska Tractor Test Laboratory | Nebraska

tractortestlab.unl.edu

rScotty

Right, so my point is I see too many focused on engine HP. Drawbar HP is the combination of engine power, weight & traction.
Much more important and realistic measure of a tractor’s power, yet few know or discuss it when purchasing.

Also, if all you do is PTO work, PTO HP may be more important.

 

[WinterDeere]

Also, if all you do is PTO work, PTO HP may be more important.

I think it's just a reflection of the numbers of homesteaders with CUT's, versus farmers pulling ground-engaging implements. This forum, and indeed the tractor market, is filled with a higher count of people buying CUT's for running things like brush hogs and snowblowers. So, of course the conversation often seems dominated by engine or PTO horsepower, over drawbar.

 

[Hermio]

Has anyone hooked up a pull gauge to their drawbar to find out the actual pull?


A TBN owned pull scale sent out to trusted people and tested in a standardized way would make a pretty neat spreadsheet on here for future generations.

I have not done so. But my Mahindra 5035HST managed to break a new tow strap supposedly rated at 20,000 lb breaking strength. Since my tractor weighs a bit over 10,000 lb as equipped, I am skeptical that the tow strap matched its claimed rating. My tractor has not broken a 40,000 lb strap, and it has not broken 3/8" grade 70 chain (working load 6600 lb, I think) or 5/16 log choker chain (6000 lb working load). I do not know the claimed breaking strength of the choker chain. I did manage to break 3/8" proof coil chain, which has a minimum breaking strength of 10,800 lb. Grade 70 3/8" chain has a breaking strength of over 26000 lb.

 

[dcarman]

Has anyone hooked up a pull gauge to their drawbar to find out the actual pull?


A TBN owned pull scale sent out to trusted people and tested in a standardized way would make a pretty neat spreadsheet on here for future generations.

Too many variables. Weight is the greatest of them. The weight of the tractor and the location of that weight make a huge difference in the traction which then equates to pulling power. The more horsepower you have the more weight you need.
You need the majority of the weight on the rear traction wheels. Once you start pulling heavy and there is enough traction weight on the rear wheels the weight of the front comes into play as the P (power) factor tries to lift the front of the tractor. These things make a dramatic difference in the pulling ability/power of any tractor.
The next greatest variable then becomes the traction tires. The greater pounds per square inch on the ground the greater the traction (with the proper tires, turf tires are not traction tires). From the factory tractors can be equipped with different tires and weight which change these dynamics,hence it's pulling power.

 

[sportscarclinic]

^^This^^ Glad someone finally recognized that weight is a, if not the, key factor.

 

[MHarryE]

The University of Nebraska Tractor Test Laboratory (NTTL) is the officially designated tractor testing station for the United States and tests tractors according to the Organization for Economic Co-operation and Development (OECD) codes OECD codes. Tractors are tested in the country of manufacture. Twenty-nine countries adhere to the tractor test codes (including non-OECD members: China, India, the Russian Federation, and Serbia) with active tractor test stations in approximately 25 of those countries. Reciprocity agreements with the codes require that once an OECD test report is officially approved, it must be accepted by all participating countries.

PTO horsepower, if measured correctly, is the best comparison. Tire type, manufacturer, ground surface, tractor weight on tires, drawbar height, and additional factors affect drawbar pull.

 

[LouNY]

For normal use hp, tires and weight are very important.
For the maximum pull hp and tire speed start coming into play.
low hp and good rubber;

A lot more hp and cut tires with very little tread;

 

[WinterDeere]

I have not done so. But my Mahindra 5035HST managed to break a new tow strap supposedly rated at 20,000 lb breaking strength. Since my tractor weighs a bit over 10,000 lb as equipped, I am skeptical that the tow strap matched its claimed rating. My tractor has not broken a 40,000 lb strap, and it has not broken 3/8" grade 70 chain (working load 6600 lb, I think) or 5/16 log choker chain (6000 lb working load). I do not know the claimed breaking strength of the choker chain. I did manage to break 3/8" proof coil chain, which has a minimum breaking strength of 10,800 lb. Grade 70 3/8" chain has a breaking strength of over 26000 lb.

I think the working load limit of most chain is set around 1/3rd of breaking strength, so those chains would probably have a breaking strength roughly similar to the strap.

Also, I think some strap manufacturers list their "breaking strength" as the webbing alone, ignoring the weak points that are where the webbing bends tightly around a hook at either end. I say this because I've noticed the same rating listed on the same straps, in both hook end and loop end. The stitching could also be a weak area, but I suspect most good brands put enough overlap there to ensure the stitching at least exceeds the strap strength.

Did your strap fail in the middle or where it goes thru the hook? If in the middle, was there prior damage in that area?

 

[PakProtector]

Pull is going to be a force. How fast you can pull is going to be a power. Have no idea what mu in dirt is, but figure max at something like .5, so a 25,000 lb machine can pull 12.5k pounds.

Douglas