B6100 stability

Arkansas Hoople

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Kubota B6100
Jul 5, 2020
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I know this has been discussed but I couldn't find it. I have a B6100 that has always been tippy. The wheels are already spread wide. Would turf tires make it more stable than the 8" ag tires that are on it now? Do wheel weights or liquid in tires do much good on this narrow tractor. Thanks.
 

freewheel3

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I know this has been discussed but I couldn't find it. I have a B6100 that has always been tippy. The wheels are already spread wide. Would turf tires make it more stable than the 8" ag tires that are on it now? Do wheel weights or liquid in tires do much good on this narrow tractor. Thanks.
Yes, turf tires are wider than the ag tires and will give more stability but you will probably have to obtain different rims, as the turf tires don't fit the ag rims. If it's 4wd you will have to replace all 4 tires and rims to keep the correct ratio. There are a few different settings that you can set the rears at, I believe on the widest, the end of the axle is countersunk into the hub about 1/2".
And yes, wheel weights and / or fluid in the rears will help a bit as well.
 

Dave_eng

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A substantial weight carried low on the 3 pt hitch will make a big difference to your tractor's stability.

The front axle pivots and contributes nothing to roll over stability.

Filling a drum with concrete as ballast is not the best as much of the weight is too high above the ground.

Wheel weights and liquid tire ballast, while a help, also carry a lot of the weight at axle height which canot help roll stability.

Tire ballast and wheel weights improve loader lifting perfromance but not roll over resistance.

Dave
 

freewheel3

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A substantial weight carried low on the 3 pt hitch will make a big difference to your tractor's stability.

The front axle pivots and contributes nothing to roll over stability.

Filling a drum with concrete as ballast is not the best as much of the weight is too high above the ground.

Wheel weights and liquid tire ballast, while a help, also carry a lot of the weight at axle height which canot help roll stability.

Tire ballast and wheel weights improve loader lifting perfromance but not roll over resistance.

Dave
I agree with everything you said except the last sentence. Because physics.
 
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Dave_eng

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I agree with everything you said except the last sentence. Because physics.
Please explain your logic. I am all ears and open minded when it comes to arguments based upon physics.

My thinking is that the tractor will roll sideways about the outer edge of the rear tire. In effect this becomes the pivot point and if doing a physics or engineering statics study on the matter, the wheel weights or tire ballast center of gravity of the downhill tire will start to move beyond the pivot point being the outer edge of the rear tire . Initially these weights will help but if the tractor has hit a hole or depression soon the center of gravity of these weights will be outside the pivot point of the downhill side tire and now will be contributing to the roll rather than inhibit it.

The uphill tire can provide some roll resistance but its height relative to the downhill tire works against it.


Dave
 

BigG

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Please explain your logic. I am all ears and open minded when it comes to arguments based upon physics.

My thinking is that the tractor will roll sideways about the outer edge of the rear tire. In effect this becomes the pivot point and if doing a physics or engineering statics study on the matter, the wheel weights or tire ballast center of gravity of the downhill tire will start to move beyond the pivot point being the outer edge of the rear tire . Initially these weights will help but if the tractor has hit a hole or depression soon the center of gravity of these weights will be outside the pivot point of the downhill side tire and now will be contributing to the roll rather than inhibit it.

The uphill tire can provide some roll resistance but its height relative to the downhill tire works against it.


Dave

Dave

I enjoy reading your answers and I have learned a great deal from them. The argument you present has me confused. Weights or load tires does add stability when you look at the whole system. If you are looking at the rear of the tractor and the right tire drops into a hole the weight at the top of the tire would shift to the right as you stated. Wouldn't the weight of the left tire that is extended to the left side of the pivot point and with this longer lever arm counter act the slight shift of the center of gravity of the right tire. Thus the overall effect is an improvement in the stability? Of course if the left wheel to rise high enough then it would carry the tractor over but the left tire would need to come very high for that to happen.

This video illustrates my thinking:

Near the end at the 7:20 mark there is a chart of his data.
 

freewheel3

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On level ground the cog is the center of the tractor. As one side raises, the cog shifts to the other side until it reaches the tipping point. Due to leverage a wheel weight on the uphill side will have more effect on keeping that tire on the ground than the counter effect of the other wheel weight on the other side that is closer to the cog.
 

North Idaho Wolfman

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I'm going to say if you still feel it's narrow at it widest setting of the rims and hubs, you've got something wrong, I have a b7100 that's set to the second to widest position and it's so wide it's ridiculous.

I can post a picture if you need to see it wide.

I also have a B7100 with wide truck tires on it that are filled with ballast, it too is wide and very stable.
 

Dave_eng

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I watched the video.

A real world test would have to be done on a slope not a flat surface as the CG of the entire tractor moves off center down the slope.

Because the front axle pivots, the CG will move forward when a front wheel enters a dip which is the opposite of what you would want happening

I do not disagree with your points. However, to quote you:

"wheel weights and / or fluid in the rears will help a bit as well."

We have all seen people cutting on slopes using riding mowers and trying to sit on the uphill fender to prevent a roll over. I have seen these situations roll over when a dip in the ditch is encountered and the high operator ballast weight starts to move down the slope.

My point in my initial post was to try and make the point that wheel weights and ballast cannot stabilize the tractor to the same extend that a serious weight on the 3 pt hitch can. Wheel spacers can, on some machines that have a design where they work, make big improvements in stability

Messicks ballast chart shows a B6100 Ag tire can hold about 60# of ballast per tire.

The entire tractor weights around 1,000#

Its 3 pt hitch can lift around 40% of the total tractor weight or 400# and a properly made ballast will have this weight close to the ground and within the track of the rear tires.

The link to the prominent law suit, which was successful against John Deere who sold a tractor with no rear ballast but with a loader, will change the industry regardless of how you might view the legal argument.

John deere ballast

I spent many years in the accident investigation field and that experience has made me exceedingly cautious when offering advice where a safety concern exists. I suffer badly from PTSD decades later.

The operator of the B6100 is concerned for his safety because of possible roll over.

Perhaps all our focus should be on encouraging him to get a ROPS and wear a seat belt.

In any event, I enjoyed this dialogue, am never offended by opinions that are at odds with mine because none of us has all the answers.

Dave
 
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Arkansas Hoople

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Kubota B6100
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Yes, turf tires are wider than the ag tires and will give more stability but you will probably have to obtain different rims, as the turf tires don't fit the ag rims. If it's 4wd you will have to replace all 4 tires and rims to keep the correct ratio. There are a few different settings that you can set the rears at, I believe on the widest, the end of the axle is countersunk into the hub about 1/2".
And yes, wheel weights and / or fluid in the rears will help a bit as well.
[/

Thanks everyone for the good ideas. I am new to this forum and this has been a great help. I have lived with the roll over problem for years but since my son wants to use it in his orchard I am concerned with safely letting him have it. The B6100 is the toughest little tractor and the ONLY problem I have ever had with it is the feeling you are going to roll over when you hit a very small hole or when I try and brush hog the side of my driveway. I wonder why Kubota didn't address this. I am guessing their later tractors don't have this problem. Thanks again.


I know this has been discussed but I couldn't find it. I have a B6100 that has always been tippy. The wheels are already spread wide. Would turf tires make it more stable than the 8" ag tires that are on it now? Do wheel weights or liquid in tires do much good on this narrow tractor. Thanks.
 

GeoHorn

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In any event, loaded tires should be more stable than wheel weights, as in a loaded tire the weight is not distributed concentrically about the axle.... but below the axle.
In practical terms however, none of the demonstration in the video is directly applicable to operations, since motion (forward or reverse and/or turning) introduces momentum to the problem.
Bottom line: Keep carried loads low, slow, and wear your seatbelt. (Also, keep your beer-glass between your ankles for best COG.)
 

NHSleddog

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Physics is great. One of the reasons I love math is the black and white nature of it. (unless you are counting covid data - lol)

Adding ANY weight in ANY location below the center of gravity (COG) WILL aid in stability and roll over resistance. That is just simple math.

Take the base tractor and tip it over (doesn't matter the slope or angle). Measure the force needed to create the roll.

Now add 10 pounds, or ten thousand pounds, below the COG, it will take more force to tip it over. Again, simple math. More force needed to tip = more stability.

The force can be gravity, it does not have to be you pushing on it. On a slope, it is all about the center of gravity, weight below it adds stability. Unlike pushing on the ROPS, gravity is pulling straight down, so the numbers will slide, but the result will be the same.

In the case of the loaded tires, as long as more than 50+ % of the weight is below the COG it will have a positive effect on tip resistance. If the tip allows the ballast to "move" putting it 50+ % above the COG, it will have a negative effect. As my father the old engineer would always say - "do the math".
 
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