Ballast/Counterweight

[patrickg]

John, My Kubota loader (LA852) manual mentions ballast in tires, wheel weights, and 3PH implements but not in a very complete manner. It has a matrix that lists 6' box scraper, rotary tiller, and backhoe and gives the weights respectively as 990 lbs, 530 lbs, and (blank). Liquid ballast for rear tires is listed as 450 lbs through 495 lbs depending on what strength CaCl solution is used to fill to 75% full. I don't want to use liquid ballast in tires, yet if ever as I will likely go foam filled.

sIDE NOTE: It says use no liquid in front tires or weights on front wheels!!!

There is a note listed...

Note: When mounting a heavy rear implement, liquid in the tire may not be required.

OK, based on that what would you do? I will perform the experiment to empirically determine the 3PH weight required to handle the FEL at max capacity and then add a safety margin (in addition to the operator).

One small point, John, on which I dissagree with yor post. The required weight in the rear would only be equal to the weight in the front if the lever arms are equal. GlueGuy and other pilot fellas are hip to weight and ballance calculations where the moment (product of weight and distance from datum) is the operative value not just weight. Consider a teeter totter. A 200 lb guy would ballance a 100 lb guy if the 200 lb guy was only half as far from the fulcrum as the 100 lb guy. Say 10 ft and 5 ft. 10x100 = 5x200

Tractor ballasting works like that too.

As a part of the empirical method I could determine the location of the center of gravity of the tractor and then simple measurements would finish the job. That is for puting 1800 lbs in the loader bucket what weight under the 3PH would balance that? Measure the distance from bucket to CG. Multiply 1800 times that distance and divide by distance from CG to 3PH. That gives weight required for ballance. Less weight than that would still work because the tractor can pick up some weight without tipping over on its nose with no counter ballancing. Hence my previously stated empirical approach: 1800 lbs or so in bucket and see what weight on 3PH is needed to keep tractor from nosing over. Add a safety factor but stay under max 3PH load.

Kubota could have been a bit more complete in this section of the manual!

Patrick

 

[Bird]

Patrickg, I ain't sayin' there's anything wrong with your calculations; only that they're more complicated than they need to be./w3tcompact/icons/wink.gif John Miller's are quite adequate and much simpler./w3tcompact/icons/laugh.gif You scientific types tend to go over us old country boy's heads sometimes./w3tcompact/icons/wink.gif/w3tcompact/icons/laugh.gif

 

[patrickg]

Bird you ole pot stirrer, Which part of John's version do you like? 1. The part where he says consult the manual but my manual is woefully inadequate as I indicated or 2. The part where he assumes the lever arms are equal but frequently aren't in my limited experience. On my tractor and many others I have seen the FEL sticks out a bunch farther than the 3PH does. If you don't think that distance makes a difference then I would like to show you some cheap sandy beach property in Arizona. You might like it, since the distance to the ocean won't be important to you.

If you don't like the calculatin' part, didya like the practical try it version??

I have always said, "rather than argue about the number of angels dancing on the head of a pin, get a loupe and count'em!"


Patrick (insert appropriate emoticons here)

 

[Bird]

Patrickg, I liked the <font color=blue>to normally realize the full lift capacity of the loader bucket, you will have an equal amount of weight in the rear of the tractor</font color=blue> part of his post./w3tcompact/icons/laugh.gif

 

[patrickg]

Bird, I see, it is a very simple unambiguous statement that is unfortunately not well suported by reality. Wish it were that simple, but I don't think it is except and unless your tractor has a 3PH as far from the CG as the FEL bucket center of load is from the CG. Most tractors don't look like that. Employing that method and "getting away with it" is similar to crossing the street without checking for traffic. You might get away with it but that doesn't make it smart.

Another possibility is that within the limited experience of the involved the tractor's stability (CG, wheelbase, etc contributes much of the needed counter balance and the operator has not exceeded the envelope of "conditional" stability. Still I would not risk the liability of recommending that as a safe practice, in general. It isn't.

Patrick

 

[Bird]

You're makin' it too complicated, Patrickg, if both back wheels don't stay on the ground, put sumpin' else on the back end of the tractor 'till they do; that's all./w3tcompact/icons/laugh.gif

 

[patrickg]

Bird, One of my favorite Einstein quotes is, "everthing should be made as simple as possible but no simpler." Once you "oversimplify" a problem its solution doesn't yield a useful insight into the original problem.

I quess we just dissagree where that division is. One assumes that your "add weight till the back wheels stay on the ground" method starts on level ground standing still. Then when stopping with a load in the air on the FEL or pallet forks you fall on your nose for lack of ballast. Add more weight and try again if you and tractor not injured. Now try stopping while going down an incline and if you fall on your nose again add more weight. etc etc. Some engineering problems are so difficult that this iterative try-it-and-see-what-happens approach is "THE WAY" but I think tractor ballasting is something that can be figured fairly well without all the evolutionary trials that risk the operator and or machine.

I prefer to try to think through the problem with the tools at hand, just arithmetic, not even algebra or calculus. In addition to applying arithmetic to the static situation I like to try to think aout the dynamics a bit as well and add a bit of a fudge factor. I bet you put a lot more thought into things that relate to safety than you are claiming. Perhaps you do it virtually subconsciously from years of practical experience and don't even realize how complex your approach/thought processes really are.

It only costs a little time and thinking and can prevent operator and equipment damage. It isn't like I want high fidelity real-time simulation and modeling on a bunch of super computers. We've discussed it at greater length than the time I have spent and will spend analyzing the problem. So if it only takes a few minutes time, one time, and can help prevent accident and injury I don't think it is such a terrible waste of time.

Patrick

 

[TWINKLE_TOES]

Patrick,
<font color=blue>unless your tractor has a 3PH as far from the CG as the FEL bucket center of load is from the CG. Most tractors don't look like that. </font color=blue>

The rotation is about the front axles. The three point has a longer moment arm than the loader with respect to the point of rotation. Most tractors do look like this.

<font color=blue>to normally realize the full lift capacity of the loader bucket, you will have an equal amount of weight in the rear of the tractor </font color=blue>
Sounds pretty conservative to me. Without real data on the CG. the weight distribution about the CG. etc. I would take John's approach well ahead of an engineering analysis with no actual data.
May not optimise the weight you may carry around but sounds more conservitive (safer) than <font color=blue>"I like to be conservative and not carry around too much weight if it isn't needed."</font color=blue>

Al

 

[Egon]

Patrick:
Have you included the varying weight of the fuel tank and the effect of the fuel sloshing around?
That empirical [ can't spell ] method souds real good. Also check the weight of material you are using as it can vary according to the type of aggragate for concrete or the type soil or gravel used.
Egon

 

[glennmac]

I would think it would be difficult to find an elegant 3ph counterbalance solution for a loader that can lift as much as the 852. I suggest you overcome your tire filling reluctance. That is the obvious solution. I see no downside to tire filling unless you are finish mowing or driving a lot on soft ground. Unless you have a lot of money to blow on all foam, you could go Rimguard in the rears and foam in the fronts.

As to rear counterweight, I believe that whatever you have hanging back there ought to serve some useful purpose other than being just a counterweight. That's why I dont care for weight blocks.

I use a Walco 3ph dump box. You can carry things in or on it, and it dumps. For ballast, I use 70 lb. sand tubes. You can put in as many as you want to adjust ballast. The dump box comes in two sizes, but does take up space. Not as much as a shredder, however.