Tire Ballast safety issue?

[b249]

I agree w/ Don. Perhaps a rops limit has been / could be exceeded. I havn't paid much atttention to tractors w/ cabs; do they all have rops units? If not the weight would probably exeed the capability of the the cab to withstand crush.

I also agree w/ Ed in that a unit w/ a cab and no ballast would have a higher c.g. than one w/ tire ballast.

Another possibility could be that a tractor with a cab and tire ballast (in addition to any potential load) could exceed the weight rating of the tires themselves. As an examle; I was investigating a stake truck fire the other day where the truck was loaded w/ softener salt. The rig appeared to be overloaded based upon the overdeflection of the tires so I had it weighed. The truck was with-in limits for axle wieghts but it exceeded the maximum weight rating of the tires on the vehicle. I plan on checking out my tractor tire sidewalls today to see if there is any info there.

b249

 

[patrickg]

BYUBILL, I too had hope that the folks at Kubota USA would "fess up" when I sent my email query. No response yet. Maybe you will "get lucky" and get a quick but correct answer. So far the top "guess" is concern for the strength of the cab in its ROPS role in case of a mishap. I included that in my latest query but they may choose to not reveal their reason(s).

Patrick

 

[gerard]

My vote is for exceeding the weight limit of the tires as previously mentioned. With the ballast, a cab, AND a load on the 3 point it seems plausible you could exceed the tire specs. (Looks like two votes for exceeding tire specs!)

 

[patrickg]

Gerard, I musta missed the other tire spec comment. There was an axle spec comment but like wheel weights, liquid tire ballast doesn't add weight to the axle load. Wouldn't you think if it were a tire strength issue that they would tell you what rating of tire was required? Or maybe they would tell you that with tire fill in excess of xx% you must derate the 3PH loading by the amount of fill in excess of xx%. Safe 3PH ratings are way in excess of the weight of liquid ballast so if it is a tire strength issue the tires must be nearly overloaded as you approach max 3PH loading. Again, why not just tell the operator to derate his 3PH by the weight of fill?

Sorry but I think the ROPS strength is a more likely answer, maybe totally wrong, but more plausible.

Patrick

 

[b249]

<blockquote><font size=1>In reply to:</font><hr>

Wouldn't you think if it were a tire strength issue that they would tell you what rating of tire was required?

<hr></blockquote>

Not really. In my example above the truck axle was rated for 24,000 lbs but the rear tires were only rated for 16,000 lbs. The guy who ordered the truck claims to have ordered it for hauling 24,000.

That being said (and not yet looking at my tractor tires) ROPs strength would appear to be a more plausable concern (as patrick said), but the tire issue should probably not be dismissed entirely.

b249

 

[Soundguy]

I don't know what size of tractor we are talking about.. but most of the smaller compacts can do around 1000 lbs on the 3ph.. so... how is 80-200 lbs of tire ballast going to be a big deal....

If so.. 3pt hitch is useless on that tractor, ulless you are -dragging- something.

Soundguy

 

[dmccarty]

Patrick,

You might want to look up your tires on the manufactuer's website and
see what they say about the tire. I know my truck tires are listed at the
manufactuer's site and it has lots of load/inflation information...

But you would think if the tire load was the problem they could point
you to a different brand of tire that would support the load. Sounds
like the ROPS but that is a scary excuse in my book....

Later...
Dan

 

[patrickg]

B249, This seems to be one of those things that make me go HMMMMM... I think we all agree that the weight of the liquid ballast tire fill doesn't add to the axle load B_U_T it isn't that straight forward at first glance how it figures into max tire or wheel load. Hmmmm, I say HMMMM, Doesn't it seem that some of the fill weight would be pressing directly down on the part of the tire that is the footprint and would not therefore be "stressing" the tire or wheel? Some of the remaining fill weight would have to be contained by the tires ability to withstand internal pressure, as if it were inflation pressure. It seems that this second part would vary with the depth of fill until at the top of the liquid at the liquid/gas interface there would be no additional stress on the tire.

Of course there is one of the guiding principles of hydraulics: the pressure everywhere in a liquid is the same (except for acounting for pressure due to depth (head). This is a bit hazy still, I haven't taken a more time to think about it than it took to type this.

Anyone got a clear understanding of this they would share????

Luckily it will probably turn out to be the ROPS angle. I still haven't a reply from Kubota. They can get mighty quiet sometimes.

Patrick

 

[patrickg]

Soundguy, Right on brother. I made that same basic comment to another fellow in an earlier post. I said something to the effect of, if that were true I should remove the 3PH since it was only an ornament and not usable.

The tractor in question is a Kubota Grand L4610HSTC. Someone at Kubota probably has a valid reason to have the manual tell you clearly and explicity to not use liquid ballast if you have a cab. Wish they would share it. If not in the manual to at least reply to my email query.

I'd bet a dollar against a doughnut (over time that is becoming an even money bet rather than the original "long odds") that it is a ROPS strength/safety issue. The cab on the L4610 is quite a "green house", mostly seamless glass with almost "no visible means of support." If that is true then it probably isn't a problem until you turn it over. Then your estate could sue them. When I find out and if it is a ROPS strength/safety issue I will comply and not use ballast or wheel weights but will opt for a 3PH cast concrete ballast or a HD carryall to haul external ballast.

Patrick

 

[EdKing]

<font color=blue>will opt for a 3PH cast concrete ballast</font color=blue>

Maybe I'm way off base here, but it seems to me that the weight on the 3ph would add to the load the ROPS would be carrying. Maybe the ROPS will take the weight of the tractor plus the heaviest implement the manual recomends, but not the extra weight of the tire ballest. If this is the case, I would be very careful on choosing implements for the tractor. Get one a little too heavy and the ROPS could fail in a rollover. I wonder if they take into account the weight of the operator ? The weight of a tool box full of tools ? I think I would be pretty leary of getting a model with a cab, you might be beter off getting one with a normal ROPS and possibly fabricating your own cab. The whole deal sounds a little shakey to me.