# One of four Moguls lazy – why?



## pagosarr (Jan 5, 2008)

I have four LGB Moguls which are essentially identical expect for track time. One of them runs at a speed of about one-third of the other three. Does anyone have a guess as to why? 



I put each of the four on test rollers with a power supply set at 18 volts and then measured voltage and amperage under “load” with no tender. Also measured resistance of each one at the pickup shoes and powered drive wheels. Here are the results:
Loco A (LGB 23191 – track time about four hours)
V=15.2
A=0.6
R=24 M ohms

Loco B (LGB 2119 – track time about 10 hours)
V=14.8
A=0.7
R=8.52 M ohms

Loco C (LGB 21181 – track time about 15 hours)
V=14.4
A=0.75
R=11.5 M ohms

Loco D (LGB 23182 – track time about 50 hours)
V=15.2
A=0.6
R=17.8 M ohms

Loco A is decoder ready and has a flickering firebox. Loco D has a sound tender and a flickering firebox. All four were inspected for gear condition, lubrication (all re-lubricated) and quartering. I assume the higher resistance for Locos A and D are due to the additional electronics as compared to Locos B and C.

So Loco D is the slow one. Why? Old age in terms of track time - or ?

Any comments or suggestions would be welcome, Roger Bush


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## East Broad Top (Dec 29, 2007)

First thought would be to look at start voltage. Perhaps the "slow" one has a voltage dropping circuit so the motor doesn't start turning until the onboard electronics have sufficient voltage to run lights, sounds, etc. If that motor doesn't start turning until the track voltage reaches something like 6 or 7 volts, the other motors that don't have that kind of a circuit wuold already be turning. So at 18 volts, the "slow" loco would be turning at the same speed the others would be at 12 volts or so. 

Later, 

K


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## nkelsey (Jan 4, 2008)

One thought, as the slow loco has 50 hours of running time, is perhaps the bearings have worn, brushes on the motor, crank rods worn? Age does slow us all down!


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## krs (Feb 29, 2008)

First thought would be to look at start voltage. Perhaps the "slow" one has a voltage dropping circuit........ 

That is exactly right since this is the only one of the locos with sound. 

If you want to run the other ones in analogue at the same speed for the same voltage (speed) setting you need to add a "voltage dropping" circuit to them. 
LGB calls that EAV (Electronic start delay in German) on the older engines that include that circuit. 
You used to be able to buy an adjustable version but that seems to be no longer available: 
http://www.champex-linden.de/download_bedienungsanleitungen/cl60062_bda_englisch.pdf 

I guess the only option now is to build your own unless someone else knows of a source for a ready-built one. 

Knut


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## Dan Pierce (Jan 2, 2008)

Since the slow mogul was 1/3 of the speed, I would suspect a bad motor rather than the electronic differences. 

Out of quarter is a possibility, but usually would not account for this large difference. 

One way to tell is to remove the motor block (only takes 5 screws) and run it without any electronics by jumpering the motor block power pins. 
On the 4 wire block, inner pins are track power, outer pins are motor pins.


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## krs (Feb 29, 2008)

Since the slow mogul was 1/3 of the speed, I would suspect a bad motor rather than the electronic differences. 

I think we need to hear back from Roger now; all the possibilities are covered I believe. 
With that voltage dropping circuit at 6 or 7 volts, I could see the sound loco running at 1/3 the speed of the others depending on the speed where he made that observation. 
Also depends on the power pack used - the LGB ones I know of are not linear. 

Knut


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## DKRickman (Mar 25, 2008)

It seems to me that the logical thing would be to test the motors apart from the electronics. Swap drives, or power them directly with jumpers. That would answer whether the problem is in the tender (which I think is likely), the bearings or windings (Maybe, but I doubt it), or a combination of the two (possible). 

Of course, the question is has the speed changed over time? if it's getting slower, that argues for mechanical failure. If not, I'd say it's electronic.


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## pagosarr (Jan 5, 2008)

Well, Dan provided the method to rule out a bad motor. I applied power (BTW, power pack is Bridgewerks mini-mag 3-S) to the motor pins of Loco D and it ran markedly faster than when applying power to the track power pins. That observation then led me back to the test rollers and then discovered that the start voltage was indeed higher for Loco D than the "faster 3" but Loco D (the "lazy" one) still ran at only about 1/3 the speed of the others at full run voltage of about 15 volts (with power pack set at 18 volts). Therefore Loco D does indeed have a voltage dropping circuit so the motor doesn't start turning until the onboard electronics have sufficient voltage to run lights, sounds, etc., as suggested by K and Knut. 

Still it seems to me all four locos should run at about the same speed once they have reached full running voltage of about 15 volts. What am I missing? Does the voltage dropping circuitry in Loco D continue to draw voltage away from the motor even at full running speed?

(Loco D is properly quartered and has no tender attached when on the test rollers.) 

Many thanks to all, Roger Bush


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## krs (Feb 29, 2008)

Does the voltage dropping circuitry in Loco D continue to draw voltage away from the motor even at full running speed? 

Yes. 
Doesn't matter what the voltage on the rail is, the "D" loco motor will always see 6 volts or so (the dropping voltage) less than the others.


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## pagosarr (Jan 5, 2008)

Thank you, Knut. Mystery solved.


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