Pulling force of a BX23S

Tractor Dell · Dec 2, 2017

I was wondering if anyone knows what the pulling force of a BX23S (or similar tractor) is at the drawbar? With the FEL and BH on it, it is right about 2600 pounds in weight. I know it will depend on the type of terrain and things, as that will affect traction, but just a general idea. I have recently built a 5:1 pulley system and can increase it to a 15:1 in about 5 minutes. All I have to do is add 2 pulleys and a prusik knot. I was trying to make sure I don't overstress the parts of the pulley system.

If someone doesn't understand a 5:1 pulley system, in simple terms (not counting friction and things like that), if I pull the rope with 500 pounds of force, the object I am trying to move will have 2500 pounds of force. If my tractor can pull with 1000 pounds of force, it will put 5000 pounds of force on the object. At that point, I am probably at the limit of what my pulley system is designed for. Of course, I could break out my 10 ton pulleys, but they are heavy as heck! haha

I have looked all around the internet, but can't seem to find anything on this. Thanks!

Code54 · Dec 2, 2017

Im not much help but I have pulled my 2500lbs trailer up a slight gravel covered incline and have moved a 1000lbs steel box by sliding it on concrete with our BX 25 and it didn't have any issues.

bcp · Dec 2, 2017

Remember that drawbar pull is not the same as how much weight it will pull when the weight is on wheels or skids.

Here is a good start:

From:
Tractor drawbar pull - AnandTech Forums

"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."

Bruce

captronr · Dec 3, 2017

Not sure what you are trying to pull, but a couple of comments. I have a BX2200, which is almost identical to yours, minus the BH. Mine has turf tires, and no added fluid or weights.

When pulling a 5 ft box blade with rippers, my BX will typically lose traction before the motor slows down. When that becomes an issue, I pick up a bucket full of dirt. That tremendously increases the pulling power of the BX.

Recently I needed to pull out some small trees next to a paved driveway. Rather than use the BX which might have been able to do it, I used the GMC 4x4. That worked easily.

Ron.

4570Man · Dec 3, 2017

I'd guess with a level chain the pulling force would be pretty close to the weight. If you had a sharp downward angle in the chain you could do a lot more.

LD1 · Dec 4, 2017

Tires?

Typically a 4wd tractor, on level ground, with R1 tires will drawbar pull 90-100% of its weight.

So with your setup.....about 2500-2600# on dirt.

R4's would probably do equally as well on HARD dirt or pavement....but in loose or slightly soft stuff, they go downhill quick

Jerry/MT · Dec 4, 2017

Tractor Dell said:
I was wondering if anyone knows what the pulling force of a BX23S (or similar tractor) is at the drawbar? With the FEL and BH on it, it is right about 2600 pounds in weight. I know it will depend on the type of terrain and things, as that will affect traction, but just a general idea. I have recently built a 5:1 pulley system and can increase it to a 15:1 in about 5 minutes. All I have to do is add 2 pulleys and a prusik knot. I was trying to make sure I don't overstress the parts of the pulley system.

If someone doesn't understand a 5:1 pulley system, in simple terms (not counting friction and things like that), if I pull the rope with 500 pounds of force, the object I am trying to move will have 2500 pounds of force. If my tractor can pull with 1000 pounds of force, it will put 5000 pounds of force on the object. At that point, I am probably at the limit of what my pulley system is designed for. Of course, I could break out my 10 ton pulleys, but they are heavy as heck! haha

I have looked all around the internet, but can't seem to find anything on this. Thanks!

If you can find somedata like from the Nebraska Tractor Test Lab on drawbar power, you can calculate the drawbar force. It's simply Fd= HPdb/velocity, where Fd is the drawbar force and HPdb is the drawbar horsepower and Velocity is the velocity at which the drawbar horsepower was determined. As I recall that's in the Nebraska Test results.

Tractor Dell · Dec 4, 2017

Thanks all, for your input. I have R4 tires, and the last time I tried a 3:1 pulley system, the ground was a bit wet and I spun the wheels before I stump I was hooked onto even budged. I then got my 1 and 1/2 ton chain hoist and hooked it up to the stump and another tree and it came out without much issue. I was just surprised the tractor had that much issue. Guess the traction was more than an issue than the tractor itself. Thanks again

Tomtint · Dec 4, 2017

I had a BX22, it will pull just about anything you can put behind it. It will loose traction before anything else

Grandad4 · Dec 6, 2017

LD1 said:
Tires?

Typically a 4wd tractor, on level ground, with R1 tires will drawbar pull 90-100% of its weight.

So with your setup.....about 2500-2600# on dirt.

R4's would probably do equally as well on HARD dirt or pavement....but in loose or slightly soft stuff, they go downhill quick

That seems about right from what I've seen, too. So many variables though... ballast/no ballast, turf vs bar tires, type of surface, operator weight, etc, etc. If you have lugged tires (ags or industrials), you tractor will pull better going forward than backing up as any weight transfer will shift weight to the larger rear tires that have more traction than the fronts, and the tread pattern favors forward movement. Turfs have noticeably less grip vs bar tres, at least on my BX, altough they are reortedly better in snow.

JWR · Dec 8, 2017

bcp said:
Remember that drawbar pull is not the same as how much weight it will pull when the weight is on wheels or skids.

Here is a good start:

From:
Tractor drawbar pull - AnandTech Forums

"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."

Bruce

Any car/truck/tractor wheeled & powered device can pull no more than it's own weight , I hasten to say with some specific exceptions. As a physics problem the 1:1 weight to pulling force ratio only happens when the coefficient of friction is perfect. As a practical matter the coef of friction is rarely as much as 1.0 so the tractor "can" pull something approaching its' own weight under best of circumstances. I assume through all this discussion that the tractor can, with gearing, pull more than it's own weight aside from traction issues. It should be noted that in some momentary circumstances with Ag tire lugs sticking down into ideal just-right-strength soil the coef of friction in effect goes above 1.0 In other words the cleats of the tire have penetrated the ground and are pulling against the ground along the direction of travel, NOT depending on friction. Like climbing a horizontal ladder.
All that out of the way, the review bcp found is probably a very good source of info. But be skeptical of what you read -- the quoted review says that the BX23 pulled 1920 lbs of force while weighing 1520 lbs !!?? No it did not, not unless it dug into the ground somehow while pulling in order to exceed 1.0 for a coef of friction or was loaded with some weight to make it heavier.
I did not take time to look, but Jerry in post # 7 mentions the Nebraska Test Lab. If anyone has authoritative data on what a tractor will pull it would be the Nebraska Lab. If they do have data, they will spell out exactly what the conditions are.
And finally, the 5:1 block and tackle that Tractor Dell has is irrelevant in terms of what a BX23 (or any other machine) "can pull." If you hook one end of a glorified block and tackle (who cares how many pulleys) to an immovable object (like a tree or other anchor of some sort) then any pulling source of force -- say a man walking along pulling on the rope or chain -- can produce as much pulling force as you choose based on the mechanical advantage he has via the force multiplier of the block and tackle. That is meaningless except that what the OP called a "5 pulley system" may well be an asset that he has and can apply in his circumstance. Has nothing to do with what a BX23 can or cannot produce in pulling force.

bcp · Dec 9, 2017

I read it as the BX pulled 1920 pounds with a weight of 1520 plus 600 pounds ballast. Hard to be sure with that little quote. I couldn't find the quoted review with a quick Google search.

Bruce

SDT · Dec 9, 2017

Jerry/MT said:
If you can find somedata like from the Nebraska Tractor Test Lab on drawbar power, you can calculate the drawbar force. It's simply Fd= HPdb/velocity, where Fd is the drawbar force and HPdb is the drawbar horsepower and Velocity is the velocity at which the drawbar horsepower was determined. As I recall that's in the Nebraska Test results.

Unless things have changed recently, Kubota does not submit machines for NE evaluation.

I've wondered if they will do so now that they are entering the higher HP market???

SDT

BrentB · Dec 9, 2017

Tractor Dell said:
I was wondering if anyone knows what the pulling force of a BX23S (or similar tractor) is at the drawbar?
...
I have looked all around the internet, but can't seem to find anything on this. Thanks!

According to Caterpillar Performance Handbook, the max coefficient of traction of rubber tires is:

0.9 on concrete
0.55 on dry loam
0.45 on wet clay loam
0.4 on wet sand
0.2 on dry sand
0.36 on loose not hard gravel road
0.2 on packed snow
0.12 on ice

Grandad4 · Dec 9, 2017

SDT said:
Unless things have changed recently, Kubota does not submit machines for NE evaluation.

I've wondered if they will do so now that they are entering the higher HP market???

SDT

The Kubota M5, M6 and M7 ag and utility tractors have been tested at the Nebraska lab (2016 and 2017); reports published. Looks like Nebraska lab is not doing much with "compact" tractors. At least no recent Kubota or Deere models tested. Makes some sense because the Nebraska evaluation seems mainly oriented toward ag field work, which is not what CUT's are designed for.

JWR · Dec 9, 2017

BrentB said:
According to Caterpillar Performance Handbook, the max coefficient of traction of rubber tires is:

0.9 on concrete
0.55 on dry loam
0.45 on wet clay loam
0.4 on wet sand
0.2 on dry sand
0.36 on loose not hard gravel road
0.2 on packed snow
0.12 on ice

That is great info. Never saw that in print before. Good find.

Understood that these things are NOT 3 decimal place accuracy and do not need to be, but this gives us a feel for the relative numbers from a serious commercial source. The coef can at least momentarily exceed 1.0 (like I described before with tread cleats getting down deep enough in just the right soil, etc.) The usual debate and interesting exception comes up in drag racing where the large "slicks" are made of super soft rubber compounds allowing the the rubber to get down in "behind" granular surfaces of the pavement. In effect raising the coef of friction above 1.0 for very short periods of time.