DK50SE HST No Ballast Lifting

[deezler]

Every time these threads come up I just have to shake my head.

Sure, not everyone is a physicist or engineer, but this is a pretty basic concept that seems to allude most people.

There is no "point" at which weight on the 3-pt "starts" to unload the front axle. The effect of ballast in the rear tires is NOT negligible for loader capacity. it is all a continuum of mass distribution. Sure, more weight further back on the tractor is better at countering a heavy load on the front-loader. But there aren't rules about what works and what doesn't. It all has an effect.

Center of mass - Wikipedia, the free encyclopedia

 

[IslandTractor]

Every time these threads come up I just have to shake my head.

Sure, not everyone is a physicist or engineer, but this is a pretty basic concept that seems to allude most people.

There is no "point" at which weight on the 3-pt "starts" to unload the front axle. The effect of ballast in the rear tires is NOT negligible for loader capacity. it is all a continuum of mass distribution. Sure, more weight further back on the tractor is better at countering a heavy load on the front-loader. But there aren't rules about what works and what doesn't. It all has an effect.

Center of mass - Wikipedia, the free encyclopedia

The rear tire/wheel ballast is certainly very relevant to stability when using the loader. The debate here is not total ballast or stability so much as whether ballast aft of the rear axle takes pressure off the front axle when lifting.

 

[k0ua]

Please look at post #1 where the poster did actual scale measurements with ballast on the rear. This is a thread that references another thread where TX Jim doubted that putting any weight on the 3pt would "unload" the front axle. He proved himself wrong by doing actual measurements.

http://www.tractorbynet.com/forums/kubota-owning-operating/290328-ok-guys-today-weight-day.html

 

[IslandTractor]

Please look at post #1 where the poster did actual scale measurements with ballast on the rear. This is a thread that references another thread where TX Jim doubted that putting any weight on the 3pt would "unload" the front axle. He proved himself wrong by doing actual measurements.

http://www.tractorbynet.com/forums/kubota-owning-operating/290328-ok-guys-today-weight-day.html

Exactly.

 

[deezler]

Sorry I worded my last post badly. I did not mean to imply that weight behind the rear wheels was unable to reduce load on the front tires. I just meant it didn't begin to act at some random point, that it's all a sliding scale.

The entire equation is really quite simple by engineering standards. If you know total mass and it's relative distribution, you can calculate the center of mass. Then the distance from the C.O.M. to each axle determines the moment reaction to support said mass, i.e. the load on each axle.

 

[IslandTractor]

The entire equation is really quite simple by engineering standards. If you know total mass and it's relative distribution, you can calculate the center of mass. Then the distance from the C.O.M. to each axle determines the moment reaction to support said mass, i.e. the load on each axle.

That is the clearest explanation. Thanks.

 

[k0ua]

Here is a drawing that another member did to help explain the forces at work here.

 

[GManBart]

Let me try to explain it this way. I can lift the back end up with over 1200lbs of weight on the 3 point. I am guessing 1400 would be an equalizing point. That means I would have to hang 1500+ pounds off the back to even start removing weight off the front axle and I am guessing about a 4 to 1 ratio between the rear axle and weight center point to the rear axle and front center point at best, probably 6 to 1 without measuring so to take off 1000lbs off the front axle I would need 5400lbs. That is not going to happen. I'll use it for what it was designed for and it has been great for the first 350 hours. CJ

Nope, physics, and levers don't work that way. If you put 1 pound on the 3pt, it's taking weight off the front axle. Every pound you add to the 3pt is taking weight off the front axle, because it's gradually transferring it to the rear axle, and eventually, you could have zero on the front axle (if the tires lift).

In a practical sense, my loader can lift almost as much as yours (2,638lbs at pin), and with no rear ballast, I was able to just barely lift 1,300lbs (weighed as such). With that 1,300lbs turned into a 1,350lb counterweight, I can put my forks under something I can't lift at all (FEL hits relief) and the rears stay planted. That is clearly taking a lot weight off the front.

Most importantly, as you said, it should be used as designed, and Kioti specs 1,047lbs on the 3pt for FEL use. I don't think they did that by mistake....it's to protect the front axle, and keep you safe.

 

[rjwerth]

Until you lifted enough weight to lift the rear tires and your ballast off the ground then all the pressure is again on the front axle. all your ballast does is keep the rear on the ground. I do agree if you were to hang 3000lbs off the rear THEN it would be unloading the front but heck you could be riding wheelies around with that much weight!! Anyway I have 1100lbs on my three point and loaded tires, I can still lift the rear off the ground with the rollback but it seems to be just about right. 1500 would be better but I still need to haul this thing and my 1/2 ton fusses already!! CJ

And once you have done that, you have exceded the specs of the loader (and probably the whole tractor). Others have already given the official specs of what is needed to achieve the maximum lift capacity. Follow that and the front axle lives to see another job.

 

[Sysop]

I honestly don't see how everyone can set and argue simple physics.

When you lift something with the FEL, not only do you have the weight you are lifting on the front axle, but some weight also transfers from the rear of the tractor due to the FEL creating leverage on the front axle.

And the exact opposite is true as well...

When you lift something with the 3pt, not only do you have the weight you are lifting on the rear axle, but some weight also transfers from the front of the tractor due to the 3pt creating leverage on the rear axle.
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I honestly don't see how everyone can set and argue simple design facts.

Front axles aren't built as large and strong as rear axles.

THEREFORE;
When lifting things with the 3pt, there is not as much concern of breaking or wearing out the rear axle because they are made MUCH more stout than ANY front axle.

And the opposite does not hold true...

When lifting things with the FEL, there should be concern over breaking things or premature wear because they're made much smaller than the rear axle.
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Now with that being said, the best method to prevent wear and breakage of your machine is simply to ballast behind the rear axle you can counter some of the weight transfer effect when using the FEL, not totally but to a point. The point is not to "ballast out the back so no extra weight is put on the front loaded versus unloaded", it is to reduce the amount of transfer of the rear weight on to the front axle and keeping the rear axle supporting more weight than the front. To do that properly, with the geometry involved (3pt doesn't have as much leverage holding weight closer to the rear pivot point as the FEL does with the front pivot point) you need more weight on the 3pt than you will be putting on the FEL...

...and it's been said before, but perhaps it needs said again; adding weight to the rear tires themselves only provides extra weight for the FEL to transfer to the front. To properly use the pivot of the rear axle you must use 3pt ballast.

Anytime there are official specs to use, do so. Don't just think that because the back tires are still on the ground everything is ok... Balance is the key to life.