<div dir="ltr">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.<div><br></div><div>SO</div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Tue, Sep 3, 2019 at 7:56 AM Jim Becker <<a href="mailto:mr.jebecker@gmail.com">mr.jebecker@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div dir="ltr">
<div style="font-size:12pt;font-family:Calibri;color:rgb(0,0,0)">
<div>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).</div>
<div> </div>
<div>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.</div>
<div> </div>
<div>Jim Becker</div>
<div style="font-size:small;text-decoration:none;font-family:Calibri;font-weight:normal;color:rgb(0,0,0);font-style:normal;display:inline">
<div style="font:10pt tahoma">
<div><font size="3" face="Calibri"></font> </div>
<div style="background:rgb(245,245,245)">
<div><b>From:</b> <a title="moscowengnr@outlook.com">Dennis Johnson</a> </div>
<div><b>Sent:</b> Monday, September 02, 2019 5:46 PM</div>
<div><b>To:</b> <a title="at@lists.antique-tractor.com">Antique Tractor Email
Discussion Group</a> </div>
<div><b>Subject:</b> Re: [AT] weighted tires or not???</div></div></div>
<div> </div></div>
<div style="font-size:small;text-decoration:none;font-family:Calibri;font-weight:normal;color:rgb(0,0,0);font-style:normal;display:inline">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.
<div>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.</div>
<div> </div>
<div>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. </div>
<div> </div>
<div>Dennis</div>
<div><br><br>
<div id="gmail-m_-5025098376517213717AppleMailSignature" dir="ltr">Sent from my iPad</div>
<div dir="ltr"><br>On Sep 2, 2019, at 5:22 PM, Howard Pletcher
<<a>hrpletch@gmail.com</a>> wrote:<br><br></div>
<blockquote type="cite">
<div dir="ltr">
<div dir="ltr">
<div class="gmail_default" style="font-family:tahoma,sans-serif">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.</div>
<div class="gmail_default" style="font-family:tahoma,sans-serif"> </div>
<div class="gmail_default" style="font-family:tahoma,sans-serif">Howard</div></div>
<div> </div>
<div class="gmail_quote">
<div class="gmail_attr" dir="ltr">On Mon, Sep 2, 2019 at 5:54 PM Dennis Johnson
<<a>moscowengnr@outlook.com</a>> wrote:<br></div>
<blockquote class="gmail_quote" style="padding-left:1ex;border-left:1px solid rgb(204,204,204);margin:0px 0px 0px 0.8ex">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.<br>Adding low
mounted implements or weights would change this.<br><br>Dennis<br><br>Sent
from my iPad<br><br>> On Sep 2, 2019, at 2:37 PM, John Hall <<a>jtchall@nc.rr.com</a>> wrote:<br>> <br>> 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?<br>> <br>> John Hall<br>> <br>>
_______________________________________________<br>> AT mailing
list<br>> <a>AT@lists.antique-tractor.com</a><br>> <a href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" rel="noreferrer" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a><br>_______________________________________________<br>AT
mailing list<br><a>AT@lists.antique-tractor.com</a><br><a href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" rel="noreferrer" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a><br></blockquote></div></div></blockquote>
<blockquote type="cite">
<div dir="ltr"><span>_______________________________________________</span><br><span>AT
mailing
list</span><br><span><a>AT@lists.antique-tractor.com</a></span><br><span><a href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a></span><br></div></blockquote></div>
<p>
</p><hr>
_______________________________________________<br>AT mailing
list<br><a href="mailto:AT@lists.antique-tractor.com" target="_blank">AT@lists.antique-tractor.com</a><br><a href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a><br><p></p></div></div></div></div>
_______________________________________________<br>
AT mailing list<br>
<a href="mailto:AT@lists.antique-tractor.com" target="_blank">AT@lists.antique-tractor.com</a><br>
<a href="http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com" rel="noreferrer" target="_blank">http://lists.antique-tractor.com/listinfo.cgi/at-antique-tractor.com</a><br>
</blockquote></div>