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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'>Nigel: I didn’t want to get into
these details about DC motors because this stuff usually makes the average
modeler fall asleep. The guy trained in physics or engineering enjoys the
discussion and information, but to those not trained in the art it is information
that they can’t readily understand. Personally, I like it. <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'>Never the less, based on my engineering
experience, and you will probably agree with this, it is likely that the simple
dimensional, fit and alignment issues are causing the differences between the
two locomotive models. “Make it like the print!”, is something you
have probably said too. 90% of the time it is a dimensional 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'>Somewhere in one model is a binding
situation that is likely causing most of the trouble. <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 basic problem is the Chinese
production lines have poor or no quality control. While the motor
manufacturing line which uses some pretty definite hard tooling to product a
motor which tends to limit the range of variability between motors to a
rational Bell curve of performance ( Let’s not get off into this
assumption!), the hand assembly line for the model itself has very limited
control on quality. They build ‘em. And if they run, they get shipped.
Customer service will sort out the bad ones by shipping out a new one hot off
the production line to replace the bad one. <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><st1:City w:st="on"><st1:place w:st="on"><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Gary</span></font></st1:place></st1:City><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'><o:p> </o:p></span></font></p>
<div>
<div>
<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>
</div>
</div>
<div>
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face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<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> Monday, June 08, 2009 1:50
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>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'>Hi Gary;<o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'> <o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'>Your note seems to indicate that you are
assuming the motor is perfect. There are also variations motor to motor
such as:<o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'> <o:p></o:p></span></font></p>
<ul type=disc>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;mso-list:l0 level1 lfo1'><font size=3 color=black face=Arial><span
style='font-size:12.0pt;font-family:Arial'>the variability of the steel in
the laminations <o:p></o:p></span></font></li>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;mso-list:l0 level1 lfo1'><font size=3 color=black face=Arial><span
style='font-size:12.0pt;font-family:Arial'>the number of laminations -
being off ±1 is not uncommon on low end end motors due to thickness
variation of the lamination material.<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;mso-list:l0 level1 lfo1'><font size=3 color=black face=Arial><span
style='font-size:12.0pt;font-family:Arial'>variability in the magnet
material - high energy NdFeB magnets are typically ±5%; cheaper ferrite
magnets can be "tuned" resulting in tighter tolerances, but less
efficient motors.<o:p></o:p></span></font></li>
<li class=MsoNormal style='color:black;mso-margin-top-alt:auto;mso-margin-bottom-alt:
auto;mso-list:l0 level1 lfo1'><font size=3 color=black face=Arial><span
style='font-size:12.0pt;font-family:Arial'>geometric variability in the
magnets.<o:p></o:p></span></font></li>
</ul>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'>For low end motors like in our model
locomotives, three sigma limits of ±10% within a particular model of motor
should be expected.<o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'> <o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'>I worked on spindle motors and voice coil motors
in hard disk drives.<o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'> <o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'>Nigel<o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'><a href="http://www.linkedin.com/in/nigelmisso">http://www.linkedin.com/in/nigelmisso</a><o:p></o:p></span></font></p>
<p><font size=3 color=black face=Arial><span style='font-size:12.0pt;
font-family:Arial;color:black'><br>
----- Original Message -----<br>
From: "<st1:PersonName w:st="on">NW Modeling List</st1:PersonName>"
<nw-<st1:PersonName w:st="on">modeling-list@nwhs.org</st1:PersonName>><br>
To: "<st1:PersonName w:st="on">NW Modeling List</st1:PersonName>"
<nw-<st1:PersonName w:st="on">modeling-list@nwhs.org</st1:PersonName>><br>
Sent: Monday, June 8, 2009 9:46:16 AM GMT -08:00 US/Canada Pacific<br>
Subject: RE: P2K GP30 speed?<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'>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.</span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <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?). </span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <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.</span></font><font color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <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.</span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <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</span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><st1:City w:st="on"><st1:place w:st="on"><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'>Cincinnati</span></font></st1:place></st1:City><font size=2
color=navy face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:navy'> </span></font><font color=black><span style='color:black'><o:p></o:p></span></font></p>
<div>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <o:p></o:p></span></font></p>
</div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
color=black face="Times New Roman"><span style='font-size:12.0pt;color:black'>
<hr size=2 width="100%" align=center>
</span></font></div>
<p class=MsoNormal><b><font size=2 color=black face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma;color:black;font-weight:bold'>From:</span></font></b><font
size=2 color=black face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma;
color:black'> 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><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>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><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Dick Dunford</span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><st1:place w:st="on"><st1:City w:st="on"><font size=2
color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'>Blacksburg</span></font></st1:City><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> <st1:State
w:st="on">VA</st1:State></span></font></st1:place><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
<blockquote style='border:none;border-left:solid black 1.5pt;padding:0in 0in 0in 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>----- Original Message ----- </span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div style='font-color:black'>
<p class=MsoNormal style='background:#E4E4E4'><b><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black;
font-weight:bold'>From:</span></font></b><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'> <a
href="mailto:nw-modeling-list@nwhs.org" target="_blank"
title="nw-modeling-list@nwhs.org">NW Modeling List</a> </span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black;font-weight:bold'>To:</span></font></b><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'> <a href="mailto:nw-modeling-list@nwhs.org" target="_blank"
title="nw-modeling-list@nwhs.org">NW Modeling</a> </span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black;font-weight:bold'>Sent:</span></font></b><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'> Friday, June 05, 2009 7:55 PM</span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black;font-weight:bold'>Subject:</span></font></b><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'> P2K GP30 speed?</span></font><font color=black><span
style='color:black'><o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Hi Listers,</span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>
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?</span></font><font color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=black face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:black'>Thanks in advance,</span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
<p class=MsoNormal><b><i><font size=3 color=black face=Arial><span
style='font-size:12.0pt;font-family:Arial;color:black;font-weight:bold;
font-style:italic'>John Hecker</span></font></i></b><font color=black
face=Arial><span style='font-family:Arial;color:black'> </span></font><font
color=black><span style='color:black'><o:p></o:p></span></font></p>
<div class=MsoNormal align=center style='text-align:center'><font size=3
color=black face="Times New Roman"><span style='font-size:12.0pt;color:black'>
<hr size=2 width="100%" align=center>
</span></font></div>
<p class=MsoNormal><font size=3 color=black face="Times New Roman"><span
style='font-size:12.0pt;color:black'>________________________________________<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>
</blockquote>
<p class=MsoNormal><font size=3 color=black face=Arial><span style='font-size:
12.0pt;font-family:Arial;color:black'><br>
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