N scale brass Allegheny: weak motor?

[simsuper80]

simsuper80:  I hear you.  I repaired one of these for somebody once, and I do recall it being tricky to get back together.
It's been long enough that I cannot remember the details.
But Mark (spookshow)'s review page has a description of the process at the very bottom of his review page here:
http://www.spookshow.net/loco/key2666.html

I forgot to mention that when it is trying to pull a long train, it will get slower and slower until it comes to a stop, wheels not spinning, and throttle is up

[mmagliaro]

I forgot to mention that when it is trying to pull a long train, it will get slower and slower until it comes to a stop, wheels not spinning, and throttle is up

We still need more data for this.  It could be binding, which will cause motor heating, which can manifest itself as a motor that appears weaker and weaker until it cannot pull the train.  And if you do this more than a few times, then yeah, you will ruin the motor.    When this has happened, could you hear the motor still spinning inside?  It would have been obvious. 

[simsuper80]

We still need more data for this.  It could be binding, which will cause motor heating, which can manifest itself as a motor that appears weaker and weaker until it cannot pull the train.  And if you do this more than a few times, then yeah, you will ruin the motor.    When this has happened, could you hear the motor still spinning inside?  It would have been obvious.

https://www.dropbox.com/s/j63m2kldbuvq5c2/20220128_121738.mp4?dl=0

So this is with the boiler off. I am gradually grabbing the driving wheels to stop the motor and letting go. It doesn't take much to stop the wheels from spinning. I would think that doing this to a Kato 844 for example would be many times harder

[mmagliaro]

Okay, clearly from that video, the drive couplings aren't slipping.  When you grab the drivers, the motor stops.
So the couplings are eliminated from the problem.
 As for comparing it to a Kato 844, I don't have one of those, but I assume it has one of their coreless motors in it, and it's probably a lot more powerful than the motor from that vintage brass 2-6-6-6.

If you want more push when you put load on the drivers like that, then yes, you're going to need  more motor power.

So, what to do?  (and remember, even after we fix the motor, you've still got some sort of bind in the drivers that we have to fix)

I see two options:
1. It's possible that the old motor has badly clogged up commutator slots, which would rob it of power, make it heat up, and would
also make it get steadily hotter and weaker as it runs (as you described with a long train).  If you are game enough to disassemble the motor, the slots can be cleaned and then you can see if runs better.

2. Just bag it and buy a powerful coreless motor that can fit in there (or a Mashima, if you have one stashed away):
Can you measure the length and diameter of that motor?  It looks pretty big, so finding something suitable may not be too difficult.

By the way, I would bet that even a stock Atlas or Kato diesel motor would do well in there, but if I were going to all the trouble to
remotor this engine, I'd push right to the top and get a big Maxon or Faulhaber in there.

[simsuper80]

Okay, clearly from that video, the drive couplings aren't slipping.  When you grab the drivers, the motor stops.
So the couplings are eliminated from the problem.
 As for comparing it to a Kato 844, I don't have one of those, but I assume it has one of their coreless motors in it, and it's probably a lot more powerful than the motor from that vintage brass 2-6-6-6.

If you want more push when you put load on the drivers like that, then yes, you're going to need  more motor power.

So, what to do?  (and remember, even after we fix the motor, you've still got some sort of bind in the drivers that we have to fix)

I see two options:
1. It's possible that the old motor has badly clogged up commutator slots, which would rob it of power, make it heat up, and would
also make it get steadily hotter and weaker as it runs (as you described with a long train).  If you are game enough to disassemble the motor, the slots can be cleaned and then you can see if runs better.

2. Just bag it and buy a powerful coreless motor that can fit in there (or a Mashima, if you have one stashed away):
Can you measure the length and diameter of that motor?  It looks pretty big, so finding something suitable may not be too difficult.

By the way, I would bet that even a stock Atlas or Kato diesel motor would do well in there, but if I were going to all the trouble to
remotor this engine, I'd push right to the top and get a big Maxon or Faulhaber in there.

The problem is that I recently had it upgraded with dcc and sound. At this rate I would almost rather pay someone to replace the motor and re-wire everything to that new motor.

It's about 21mm long and 11mm wide

[mmagliaro]

You really only have to wire the decoder output to the new motor, so only 2 wires should be involved.
As far as fitting a new motor in there, that's up to you whether you can do it or not.   At those dimensions,
a 10x20mm can motor would fit nicely, and maybe a 10x24 if you have enough room out the back. 
Maxon RE10 motors come in a 24mm length, and there is a Mashima 1024 (and a 1020).  All of these still
pop up on eBay from time to time.

[peteski]

Motors factory installed in brass models usually have adequate power to spin the wheels of a loco if it is loaded beyond its pulling capacity.  Of course of the motor became defective (like clogged up commutator slots), that would degrade its performance.  I wonder how heavily was this loco used in the past?

I also wonder if the mechanism itself has a bind in it, causing strain on the motor.

[Kentuckian]

The problem is that I recently had it upgraded with dcc and sound. At this rate I would almost rather pay someone to replace the motor and re-wire everything to that new motor.

It's about 21mm long and 11mm wide

This may be the problem. Did it have the bind before you sent it off for DCC? Have you talked to the installer?

[simsuper80]

This may be the problem. Did it have the bind before you sent it off for DCC? Have you talked to the installer?

I'm not too sure, I never used it to pull anything before the dcc upgrade. But I did run it. It appeared to run ok both times

[mmagliaro]

From the video the OP posted, it obviously has a bind in it.  Whether that has always been there, is the cause of the loss of power, etc, who knows? 

Another thing we don't know is the current draw.  If it's high, that would indicate clogged commutator slots, and yes, maybe that happened because the drivers are binding, putting a lot of load on the motor, causing the brushes to break down.

I really only see one sensible way forward to fixing this thing right.   The drivetrain has to be taken apart, binds located, and motor comm slots cleaned.  Then reassemble it, see how it runs and what the current draw is.  If it's still a weak runner, then change out the motor.
And needless to say, you need to bypass the decoder while you're doing all this.  You can't tell anything about the real behavior of the mechanism and the motor while the decoder is in there.

We're talking a lot of work here, but you'll be chasing your tail forever otherwise.

[simsuper80]

From the video the OP posted, it obviously has a bind in it.  Whether that has always been there, is the cause of the loss of power, etc, who knows? 

Another thing we don't know is the current draw.  If it's high, that would indicate clogged commutator slots, and yes, maybe that happened because the drivers are binding, putting a lot of load on the motor, causing the brushes to break down.

I really only see one sensible way forward to fixing this thing right.   The drivetrain has to be taken apart, binds located, and motor comm slots cleaned.  Then reassemble it, see how it runs and what the current draw is.  If it's still a weak runner, then change out the motor.
And needless to say, you need to bypass the decoder while you're doing all this.  You can't tell anything about the real behavior of the mechanism and the motor while the decoder is in there.

We're talking a lot of work here, but you'll be chasing your tail forever otherwise.

Alright, thanks. I will probably just send in the locomotive back to the person who Installed the decoder. Much better than me trying to figure this out!

[SkipGear]

Knowing that it has a decoder in it, the problem may not only be the motor but the load the decoder is seeing is causing it to heat up and slow down. Too many variables to diagnose without having it in hand.