Athearn Challenger and Life-Like 0-8-0: Same motor

[mmagliaro]

Thanks Max! I am cursed because the cogging is more apparent with the 3 pole motor. Oh well, I'm the guy that walks into a sports bar, and instantly sees that all 100 screens have the wrong aspect ratio ...

It annoys me, but not enough to want to swap out the motor in my 0-8-0.

Mark

Really?  In that video?  Man, tough room.  You're a better man than me.  When I would run and watch those two versions
run, I could honestly never see any difference, not in minimum speed, nor start-up smoothness, pulling power, nada.
But if you can see it, well, then more power to you.
Now, these days, I have a Mashima 5-pole with a 5:1 gearhead on it in my 0-8-0, and it can only top out
at about 18 mph, but that's wonderful for a switcher.  But that's not any sort of comparison on the poles.
I'm just overwhelming the chassis with so much torque from the gearhead that it can't help but run well.

[victor miranda]

my u-tube videos are rarely smooth so I don't try to guess.

in the case of that motor and that locomotive model
I do not think I would be considered objective, may be with good reason.

I happen to have a couple of the 0-8-0's that walthers sold.
one was a lowball bay bid that carried.

I have a few other locos I want to have pulling cars,
and since the 0-8-0 are operational, they sit on the back of the list.
I'll have to try shunting with one and see how that goes.

victor

[Mark5]

Really?  In that video?  Man, tough room.  You're a better man than me.  When I would run and watch those two versions
run, I could honestly never see any difference, not in minimum speed, nor start-up smoothness, pulling power, nada.
But if you can see it, well, then more power to you.
Now, these days, I have a Mashima 5-pole with a 5:1 gearhead on it in my 0-8-0, and it can only top out
at about 18 mph, but that's wonderful for a switcher.  But that's not any sort of comparison on the poles.
I'm just overwhelming the chassis with so much torque from the gearhead that it can't help but run well.

I might be seeing things. 

I'm a lil crazy I guess. I've yet to see a 3 pole that doesnt cog. But, I have to admit some of the new ones are pretty good. Its a huge step for me say that I'll leave a three pole motor in a loco.

Gearing definitely helps a lot. 

[peteski]

If someone can tell in a Youtube video whether there is a cogging 3-pole motor in a model, I am very impressed. Especially if the model is also equipped with flywheels (since flywheels, just like in internal combustion motors) smooth out any power pulsed on the rotating motor shaft.  I can't see any cogging on 3-pole motor locos even when seeing them in-person.   

Also considering the gear ratio between the rotating (an cogging) motor shaft and the loco's wheels is great enough that the each cogging step in the motors rotation (I think there are 6 per revolution in a 3-pole motor) would cause dozens of "hiccups" per a single revolution of the model's wheels. If cogging was that pronounced, the entire model would be shaking like a piece of Jello.

How do skewed-armature 3-pole motors behave (like the one being described in this thread)?  There are many of those out there (even Bachmann makes them).  Do they still cog visibly?

[Mark5]

How do skewed-armature 3-pole motors behave (like the one being described in this thread)?  There are many of those out there (even Bachmann makes them).  Do they still cog visibly?

I have a bunch of the skewed 3 poles (including some of the newest Bmanns). They all cog to my eye to some degree at slow speeds, though I admit that it is very subtle. I might be crazy though.

If you can't see the cogging, don't worry about it ... be happy.

Mark

[peteski]

I have a bunch of the skewed 3 poles (including some of the newest Bmanns). They all cog to my eye to some degree at slow speeds, though I admit that it is very subtle. I might be crazy though.

If you can't see the cogging, don't worry about it ... be happy.

Mark

I am quite happy that I can't see the cogging. 

I wonder is this in DC or DCC. If DC, are you using pure DC or pulse)?
I'm asking because either DCC or pulsed DC will cause a vibration of the armature due to the pulses used to power the motor. You can easily observe that on locos with exposed motor sides after you take the shell off. Running that way you can observe the armature's behavior.

This is visible at very slow speeds - you can clearly see the motor's armature swaying slightly as it is rotating very slowly.  But that is not really cogging. At the speed the armature is rotating, if pure DC was used the motor would simply be stalled.  The pulsing power is what allows the motor to run slower than its as-designed speed.

[Mark5]

Pete,

Motors in question observed in DC, pulse DC, and DCC.

Granted, under DCC, the Bachmann locos were using the factory Bachmann decoders, which may leave something to be desired.

Mark

[peteski]

Pete,

Motors in question observed in DC, pulse DC, and DCC.

Granted, under DCC, the Bachmann locos were using the factory Bachmann decoders, which may leave something to be desired.

Mark

At what speed do you mostly notice the cogging?  That is my last question - I promise.
Would  you be interested in a blind test whether you can tell if a model has a 5-pole or a 3-pole motor?  Just kidding here! 

[Mark5]

At what speed do you mostly notice the cogging?  That is my last question - I promise.
Would  you be interested in a blind test whether you can tell if a model has a 5-pole or a 3-pole motor?  Just kidding here! 

The slower the more noticeable - so creeping is the answer I guess . Slow speed performance is super important to me - I spent a chunk of my childhood next to a large classification yard watching coal drags start.

Blindfold, lol! I would subject myself to seeing if I could tell the difference in person with Max's 0-8-0s, that would be a good test!

Mark

[peteski]

The slower the more noticeable - so creeping is the answer I guess . Slow speed performance is super important to me - I spent a chunk of my childhood next to a large classification yard watching coal drags start.

Blindfold, lol! I would subject myself to seeing if I could tell the difference in person with Max's 0-8-0s, that would be a good test!

Mark

LOL!  Not blindfold - just blind test.    The same model would be fitted with either 3 or 5 pole motor and you would be asked to observe it and be able to tell if it shows cogging or not.

[PGE_Modeller]

As for the motor's dimensions:

W: 10mm
H: 15mm
L: 19mm
Shaft diameter 1.5mm
Shaft length (dual shafts, same length on each end):  3.5mm

Thanks, Max.

Cheers,

[victor miranda]

a whirl...

the case for a three pole motor in an n-scale loco.
Much lower cost.

the case for a five pole motor in an n-scale loco.
loco could run at a slower speed.
the loco could run smoother at slower speed
the loco will have a lower top speed

Hi Mark and Peteski

when you two get to the test, please include me.

Peteski,
I figure you may want to try this yourself
try running a 5 pole motor awhile
shunt cars with it

do the same with a three pole powered loco

If you want to see the difference
use an atlas diesel like a gp-9
and a Kato GS-4

In my studies of today... I am more certain now than I ever have been
that for slow speed anything to happen the pick-up has to be certain.

so now I get to my point...

I tell three and five apart by how they start relative to how they stop.
5 usually starts close to the speed they stop
3 usually ramps up to a happy speed.

as you slow a 3 pole from the happy speed
it will often sustain a slower speed and then
in unreliable speed range the MOTOR will cog.

pulses and gears and flywheels will all add to the conga line.

Is it possible to get a three pole to fake everything a five can do?
I have not seen it yet.

so far, the best I have seen is the MP Pacific.
However....
it is a real jackrabbit even with that massive flywheel.

So one can set a 5 pole motor into a poor chassis and get no
improvement... but even a top notch chassis with a three pole shows
for being what it is.

If you had stopped me before I opened the gs4 and said
State the type of motor.
my answer would have been I am having a hard time believing Kato
used a three pole motor in this loco. right now I am praying that
I have a gear with some flash in it causing what I see.

so far the test is not a problem.
three pole is pretty easy to decide, five pole is harder to be certain.
In a poor chassis is no difference.

victor

[peteski]

as you slow a 3 pole from the happy speed
it will often sustain a slower speed and then
in unreliable speed range the MOTOR will cog.

pulses and gears and flywheels will all add to the conga line.

Flywheels add to cogging?  Really?  Flywheels are installed on output shafts of motors (steam, internal-combustion and electric) to smooth out any power pulses (be it from a reciprocating piston driving a crankshaft or from a cogging armature). Yet you say that they amplify the cogging effect of a 3-pole motor?

so far, the best I have seen is the MP Pacific.
However....
it is a real jackrabbit even with that massive flywheel.

Because  if  of inertia it will take some good torque to start a massive flywheel from a dead stop. That could be part of a problem with jackrabbit starts. Once the the is overcome, the motor will speed up. [Deleted poorly composed sentence] Once the motor (any motor, 3 or 5 pole) overcomes that flywheel inertia, the motor will smoothly speed up (this time the rotating flywheels inertia will actually smooth out any possible cogging).

This is my view of this, but I'm not a physicist.  I could be wrong...

[victor miranda]

Hi Peteski,

Am I the first person to tell you,
you are good at hearing what you want to hear...

'tis hard to imagine.

maybe tomorrow I'll feel like thinking up another way to say
what I am sure was not understood as I meant.

... is three divisible by 2 and a half?
... it there a square pi?
... what part of the gimbal is  the grye?

victor

[peteski]

Hi Peteski,

Am I the first person to tell you,
you are good at hearing what you want to hear...

Aren't we all? 

'tis hard to imagine.

maybe tomorrow I'll feel like thinking up another way to say
what I am sure was not understood as I meant.

... is three divisible by 2 and a half?
... it there a square pi?
... what part of the gimbal is  the grye?

victor

To me Victor is seemed pretty clear that you blamed a flywheel for being a contributing factor to cogging.  I wish someone besides me would evaluate your statement. It could be me who is misunderstanding things.