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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Remember that a DC motor has a straight
line output curve on a horsepower diagram. For a given RPM there is
a fixed torque output at a certain voltage. ( Horsepower equals torque
times rpm.) Basically at zero RPM you have very high torque and at max
rpm you have virtually no torque. To change this curve- really the slope
of the straight line, the internal windings have to be changed. Gearing
is a way to match the motor output to the load, in other words, change the
torque output at the gearbox output. Thus, the slower locomotive with the
higher gear ratio should be able to pull more cars assuming that the wheel adhesion
does not come into play. Speed control via gearing change is not really
the right way to look at the issue. Output torque is.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>For two models of the same production
batch to run differently, there are some ‘quality’ issues within
one of the models that increases its frictional losses as compared to the other
model. It could be alignment of shafts, binding somewhere in the
mechanism, brush to commutator issues, friction or binding within the trucks or
wheel sets (is the wheel spacing correct?). <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The point of all of this is that when one
observes a change between two models one needs to compare the gear ratios and also
see if the motor was changed to determine what might be done to correct the
issue.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Digital controls pulse the voltage to the
motor (Pulse width modulation) via the semiconductors to bring the dissimilar
models into similar speeds, which makes the motor not run on the straight line
curve, but to one side of the curve.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Gary Rolih<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Cincinnati <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 color=navy face="Times New Roman"><span
style='font-size:12.0pt;color:navy'> </span></font><o:p></o:p></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
nw-modeling-list-bounces@nwhs.org [mailto:nw-modeling-list-bounces@nwhs.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b><st1:PersonName w:st="on">NW
Modeling List</st1:PersonName><br>
<b><span style='font-weight:bold'>Sent:</span></b> Sunday, June 07, 2009 6:10
PM<br>
<b><span style='font-weight:bold'>To:</span></b> <st1:PersonName w:st="on">NW
Modeling List</st1:PersonName><br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: P2K GP30 speed?</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>It has been my experience that in many cases two identical
locomotives from the same run often operate at different speeds. Not
using DCC, my solution has always been to put the faster locomotive behind the
slower. That way the faster one is slowed down by doing most of the
pulling of the train.</span></font><o:p></o:p></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Dick Dunford</span></font><o:p></o:p></p>
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<p class=MsoNormal><st1:place w:st="on"><st1:City w:st="on"><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'>Blacksburg</span></font></st1:City><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <st1:State
w:st="on">VA</st1:State></span></font></st1:place><o:p></o:p></p>
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>----- Original Message ----- <o:p></o:p></span></font></p>
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<p class=MsoNormal style='background:#E4E4E4'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>From:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:nw-modeling-list@nwhs.org" title="nw-modeling-list@nwhs.org">NW
Modeling List</a> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>To:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:nw-modeling-list@nwhs.org" title="nw-modeling-list@nwhs.org">NW
Modeling</a> <o:p></o:p></span></font></p>
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<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Sent:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> Friday, June 05,
2009 7:55 PM<o:p></o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Subject:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> P2K GP30 speed?<o:p></o:p></span></font></p>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hi Listers,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
I was able to run some new engines on a friend’s layout this
afternoon. For the first time I ran my new Athearn N&W SD45’s.
They ran great! I tried a new N&W P2K GP30 and the 45’s
just dragged it along. It appears to run about half speed of the
Athearn's. I didn’t have any of my older Athearn's or PPW or Atlas
to compare it to. So my question is that the P2K’s will only run
with other P2K’s?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks in advance,<o:p></o:p></span></font></p>
<p class=MsoNormal><b><i><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial;font-weight:bold;font-style:italic'>John Hecker</span></font></i></b><font
face=Arial><span style='font-family:Arial'> <o:p></o:p></span></font></p>
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face="Times New Roman"><span style='font-size:12.0pt'>
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<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>________________________________________<br>
NW-Modeling-List@nwhs.org<br>
To change your subscription go to<br>
http://list.nwhs.org/mailman/options/nw-modeling-list<br>
Browse the NW-Modeling-List archives at<br>
http://list.nwhs.org/pipermail/nw-modeling-list/<o:p></o:p></span></font></p>
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