[AT] weighted tires or not???

Tue Sep 3 07:32:15 PDT 2019

There are literally hundreds of factors involved in tractor stability. I
believe that the most frequent cause of roll-overs is dropping a wheel in a
hole or off of a ditch bank. Next is hitting an unseen object. My sister's
husband rolled one by hitting a stump in tall grass. He wouldn't normally
have hit it with the rear wheel first since the small tractor was wide
front but he was in mid turn and the front wheel missed it. He was also an
"inexperienced operator". That term, "inexperienced operator" is a giant
factor in tractor accidents of all kinds. I constantly see my non-farming
neighbors doing all sorts of really scary things.
One factor I have looked at is what is commonly called "offset" tractors.
My Farmall Cub is one as is a Farmall A or Super A. Ford sold a number of
offsets in the later 1950's.
Another variation is a centered tractor but where the operator sits off to
one side. Allis WC, WD and WD-45 are in that class as is the Farmall B.
Some 12 year old kid isn't much of a factor on those but some of us
"FATG's" can be a big factor.  :-)
A similar factor can be how high the operator sits on the tractor. My Ford
8N's and Ferguson TO-20 sit the operator very low astride the transmission.
Others like my old Case VAC and a Farmall C / Super C sit you up high with
your feet on a platform above the transmission and your butt up at chair
height above that.
High clearance tractors can be a whole other scary thing on rough ground
with some at nosebleed levels.
Another factor is ground that can set up a rocking motion. A rock or hole
is usually a one time thing but I can recall back in the old days when we
cultivated several times and threw a lot of dirt in the rows to cover
weeds. Then we would later be disking the same field diagonal for wheat and
it was possible to get a tractor rocking pretty hard.

Here is a factor that has come up in the background in these discussions.
Ford was mentioned as a roll-over tractor... Frankly I personally have
never seen or heard of one rolling in my life except for the old Fordsons
back flipping. Don't get me wrong, I'm not saying it isn't so, I just
haven't seen any. Maybe people just sit them back up and keep quiet about
it. There is a sort of a "Ford factor"... There simply were more Ford N
series tractors made and sold in North America than any other tractor,
period. Not only were there more of them but as a light tractor with three
point hitch they are highly versatile and near ideal for small acreages.
You can also walk in most farm stores and buy equipment and accessories for
them. As a result large numbers of them have fallen into the hands of the
above mentioned "inexperienced operators". Even on the farm they were
considered to be pretty safe and often ended up with very young operators.
I recall a lot of discussion years ago among farmers about the starter
safety interlock that kept it from being started in gear. It sticks in my
head that the interlock was Harry Ferguson's idea.

These are mostly pretty small factors but sometimes a small factor is the
difference.

I have been extremely lucky over a lot of years. ANY of us can slip up at
any moment... I try to increase my level of caution along with my birthdays
but there are no guarantees.

.

On Tue, Sep 3, 2019 at 8:19 AM Stephen Offiler <soffiler at gmail.com> wrote:

> In 3-dimensional space, the CG of a tractor is likely to be very close to
> the center in terms of left-right; closer to the rear in terms of
> front-back; and some height from the ground.  When you add ballast to the
> tires it does not change that left-right CG location (assuming you add
> ballast equally to both rears), and moves CG even farther to the rear and
> closer to the ground.  It is intuitively clear that a tractor on the verge
> of a side rollover will be aided by weight added to the uphill side.  But
> from a free body diagram perspective, the difference comes from the changes
> in CG rearward and downward.
>
> SO
>
>
> On Tue, Sep 3, 2019 at 7:56 AM Jim Becker <mr.jebecker at gmail.com> wrote:
>
>> The added 500# on the high side has more effect than the 500# on the low
>> side.  It is farther away horizontally from the bottom of the low side rear
>> tire (or the magic triangle/trapezoid) and thus has more leverage.  As far
>> as it “having a greater effect than any change in CG”, it is the same
>> thing.  Looking at the 500# by itself is just selecting one component of
>> the CG to look at (a valid way to look at it).
>>
>> Adding fluid to the tires definitely lowers the CG.  How much depends on
>> a bunch of factors, including how tall the tires are, how high the CG is to
>> begin with and the relative weight of the fluid vs. the weight of the
>> tractor.  The taller the tractor, the more effect it has.  When we first
>> started using mechanical grape pickers (1960s), many of them were built on
>> a very high clearance tractor (6 feet+ under the axles).  The things were
>> plenty heavy enough as delivered, but everyone loaded the tires to help the
>> stability.
>>
>> Jim Becker
>>
>> *From:* Dennis Johnson
>> *Sent:* Monday, September 02, 2019 5:46 PM
>> *To:* Antique Tractor Email Discussion Group
>> *Subject:* Re: [AT] weighted tires or not???
>>
>> Static rollover happens when the CG moves outside of the pivot point
>> which is the bottom of the downside tire (or tires of pivot is against
>> stop). As long as the CG is “inside” of the down side rear tire the vehicle
>> will not roll. As soon as the CG moves outside of the pilot point the unit
>> will rollover.
>> Dynamic rollover when turning at speed changes things because it adds
>> centrifugal force to help shove the CG sideways and make the unit roll
>> sooner.
>>
>> With weighted tires, the downside tire has an extra 500# outside of the
>> pivot point trying to tip it, in addition to the 500# or the upside tire
>> holding it back.
>>
>> Dennis
>>
>>
>> Sent from my iPad
>>
>> On Sep 2, 2019, at 5:22 PM, Howard Pletcher <hrpletch at gmail.com> wrote:
>>
>> Wouldn't the extra 500# or so holding the high side down have a greater
>> effect than any change in CG?  It seems it would be more stable.
>>
>> Howard
>>
>> On Mon, Sep 2, 2019 at 5:54 PM Dennis Johnson <moscowengnr at outlook.com>
>> wrote:
>>
>>> The weighted tires would lower the center of gravity slightly. Assuming
>>> the tires were 100% full the CG of the added fluid would be on the axle CG.
>>> If less than 100%, then the CG would be slightly lower. The CG of most
>>> tractors will be slightly above the axle center. Tractors with offset final
>>> drives would have CG a little higher than those with the final drive in
>>> line with the engine crankshaft. Combining the CG of the tires and tractor
>>> would lower the overall CG a little bit, making the tractor more stable.
>>> Adding low mounted implements or weights would change this.
>>>
>>> Dennis
>>>
>>> Sent from my iPad
>>>
>>> > On Sep 2, 2019, at 2:37 PM, John Hall <jtchall at nc.rr.com> wrote:
>>> >
>>> > All this talk about wide front vs. narrow front got me wondering about
>>> something else. Are tractors with fluid filled rears more stable on hills
>>> or in quick maneuvering on uneven ground? The reason I ask is that I
>>> replaced the tires on a IH utility tractor we have had since new (1972
>>> 454). It has over 8,000 hrs and we have always had weighted tires on it.
>>> Well I didn't have time to fill the tires with fluid before I began using
>>> it this spring. So far I am liking the less weight for treading on wet
>>> spots in fields. I recently reduced the air pressure (it was at 25, I
>>> dropped it to 20) because it was shaking me to death while spraying a
>>> field. The only time the loss of weight has been an issue is moving one
>>> load of hay--it was digging pretty bad. We do all of our bushogging with
>>> this tractor so there are quite a few banks and hillsides to get into.
>>> Wonder if it would be more stable with the fluid in?
>>> >
>>> > John Hall
>>> >
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-- 
-- 

Francis Robinson
aka "farmer"
Central Indiana USA
robinson46176 at gmail.com
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