Motor behavior and driveline concepts - (a roundtable discussion?)

[DKS]

[mod mode] I have the sense here that it's down to semantics. I get what Victor is saying, but I can also see how Peteski might misinterpret it by taking every word very literally. I have the sense it could escalate out of hand if the wrangling over semantics is left unchecked. Be careful with words, especially those that might derail the topic. [/mod mode]

[SebastianLee]

Why not make yourself a better power source. 12V power bricks for laptops,monitors end HD cases can be found under $10. Shoot for under $20 you can get a nice 12V bench supply.  Add in a step down module and you'd be set.   Would be worth it if you do a lot of testing, and/or don't want to bother with a pile of wall warts.  There's 15V -18v power bricks if you really need 12 or more volts.   Or go crazy and use an ATX computer power supply.

[DKS]

FWIW, I have one of these: http://www.todc.com/Power_Supplies/Bench_Supplies/0-30V,_0-3A_Mini_Bench_Supply_9615_PS.asp

Provides just about any sort of DC power you may need for typical modeling applications.

[victor miranda]

dearest and most beloved peteski,
I only have words to communicate with you.
I can't make them mean any more or less than what they mean.
If I include them I will take responsablity for them.
If you want to imply them, I can't take ownership.

as you have also used something that skipgear said
in your response, you should read the part I address to him
and realize you are included.

ah, Skipgear, please believe me when I claim you as my dearest rival.
You do darn near everything better than me.
you once said I would make a great lawyer
(I don't think it was intended as a compliment.) and lawyers are good at symantics
as David mentioned.

I am going to attempt to clarify a post.
because I can see that what I made the mistake of thinking
what I wrote was self evident.

this thread has taken a digression because of my post summarizing
the thread up to that point.

here is perhaps what I should have posted:

over analyzing....

I'm hoping this opens up contribution of good opinion and knowledge on this stuff.

1. Why did it stop?

so far... (He who I think mentioned it first)
dirt in the brushes  (mentioned by skipgear)
loss of power supplied  (victor)
motor temp causing changes in resistance (PAL_Houston )
tuning the length of silicon tubing ( C855B )
increase in friction (darned near everyone, one way or another)
dirty track ( Iain )
 
2. So, what's with the higher current?

so far...
motor temp causing changes in resistance (PAL_Houston )
increase in friction (darned near everyone, one way or another)

3. What about that rubber tube drive?

so far...
might want to replace it with the motor to worm joint from the kato mike (victor)
tuning the length of silicon tubing ( C855B )


thems the answers to examine... good luck.


I think I will repeat something I said a little more carefully.

when a loco rolls slowly any electrical stall will stop the loco.
It is an electrical stall. no current flow.
any nudge will send the loco back into motion.
so I was stating it is a slow speed electrical stall.

I thought the post was clear and if you want to give me full credit
for "dirty track" you are also giving me full credit for all of those ideas.

not fair to the others or yourself.

victor

[SebastianLee]

FWIW, I have one of these: http://www.todc.com/Power_Supplies/Bench_Supplies/0-30V,_0-3A_Mini_Bench_Supply_9615_PS.asp

Provides just about any sort of DC power you may need for typical modeling applications.

But with your solution, you've got to work really hard to shock yourself 3-4 times with each use.  How will you ever learn to respect electricity

[mmagliaro]

Folks, I could certainly build myself a regulated supply, or buy one, and indeed, I even have them.

I should have pointed out that my saggy little controller, while something I threw together inside a plastic
food container years ago just for expediency, has turned out to be handy.  If things go wrong with
an unattended loco, it sags its output and doesn't overheat the motor.   

Sure, I could use a better supply.  I have 2 unused home-made solid state throttles sitting in a box.   I
could build a regulated source with a settable current limit easily enough.  I just haven't .

In this fluke of a case, it would not have helped anyway.  If people are thinking that the
engine may not have stalled if the supply kept it locked on 6v, that is highly unlikely.   The motor was not connected to the power
source anymore, for whatever reason: remember, the current draw was zero.  Stalled motors do not draw zero.
Only electrically disconnected motors do that.   

I think it is time to put this to bed, everyone.   

[peteski]

Victor,
DKS pretty much described me exactly.  I do take take technical discussions very literally.  That is just the way my brain works.  I also believe that is very beneficial (especially in technical writing) to be as accurate and literal as possible. That makes understanding a problem and providing a solution much easier.

Your "when a loco rolls slowly" phrase really confused me.   I did not know how that could be applied to a loco that had its wheels spinning in the air.  Well to be honest, I'm also a bit confused by your "electrical stall" phrase.  Using "electric open circuit" might have been clearer, as electricity doesn't actually "stall". It stops flowing. But again, these are semantics.

At this point we will never know where in Max's test the electrical open circuit occurred. It could have been the commutator or somewhere else in the circuit. But it certainly wasn't caused by the loco rolling (on the track).

As Max hinted, I'm putting this to rest.

[victor miranda]

Victor,
... snip
(on the track). unsnip.

the word 'track' is all you.  I didn't use the word track.

[Zox]

the word 'track' is all you.  I didn't use the word track.

You said "when a locomotive rolls." Normally, when something "rolls," that means it's physically changing location, not simply rotating its wheels while clamped in a bench rest. So at least one person  mistakenly assumed that the locomotive was going somewhere, which in the case of locomotives is generally done on tracks.

Hijinks ensued.

_{And yes, I know I'm going to regret getting in the middle of this. But I hate seeing people talk past each other.}

[DKS]

You said "when a locomotive rolls." Normally, when something "rolls," that means it's physically changing location, not simply rotating its wheels while clamped in a bench rest. So at least one person  mistakenly assumed that the locomotive was going somewhere, which in the case of locomotives is generally done on tracks.

Hijinks ensued.

_{And yes, I know I'm going to regret getting in the middle of this. But I hate seeing people talk past each other.}

Zox, please let's let this end here.

[LV LOU]

 So,there's this order of cloistered monks,somewhere high in the mountains of Scotland..Only one monk is allowed to speak at a specific night once a year.On one of these nights,the designated monk arises from his seat,and proclaims:"I think the soup is too salty"..And sits down..A year passes,not a word is said............On the next designated night,the newly chosen monk stands,clears his throat,looks the last monk that spoke straight in the eye,and declares:"I think the soup is just fine.."...Time rolls on,the next night arrives,two years past now..Brother Angelo stands,throws his napkin angrily on the table,and gruffly declares:"Knock it off!!I'm sick and tired of this constant bickering....!!!"
 
                                    I sincerely hope I got the semantics right.......

[up1950s]

Was the loco suspended right side up Max ? When it is , the driven wheel or wheels drop down as far as slop at the axles will allow it to go . As the wheels turn they may sink lower as they eat away any crap that they are normally not in contact with , including the bottom cover plate on its inside . On a worse case the wheel gear and the last gear in the drive train may lock up land to land ( peak of one gear to peak of the other gear ) instead of the normal mesh of land to groove . That land to land could have stalled the motor instead of skipping a tooth and falling back into mesh thus causing or risking increased amps , heat , deformed parts , magic blue smoke , and the risk of fire .
 
I always thought it risky to go and leave a loco running overnite . This idiot will get back under its rock now .

[mmagliaro]

Was the loco suspended right side up Max ? When it is , the driven wheel or wheels drop down as far as slop at the axles will allow it to go . As the wheels turn they may sink lower as they eat away any crap that they are normally not in contact with , including the bottom cover plate on its inside . On a worse case the wheel gear and the last gear in the drive train may lock up land to land ( peak of one gear to peak of the other gear ) instead of the normal mesh of land to groove . That land to land could have stalled the motor instead of skipping a tooth and falling back into mesh thus causing or risking increased amps , heat , deformed parts , magic blue smoke , and the risk of fire .
 
I always thought it risky to go and leave a loco running overnite . This idiot will get back under it's rock now .

Thank you for thinking of this in a new way!
It was running right-side-up, up on blocks at either end.  Since it was running with all the rods off, even if it skipped a tooth, I don't see how that would make the current increase.  Also, if it did jam mechanically in the idler gears as you describe (and yes, I understand your description perfectly), it would not
have started up again just by me nudging the motor armature.   It also would definitely have been drawing current in that state (not zero).

Good thought, though.

[up1950s]

Ok , how about this scenario . As the motor heats up the friction of the brushes in their holders increased to the point that the brush springs couldn't seat the brushes as the wore down . Eventually there wasn't brush continuity and the motor stopped and cooled . You then latter on come and give it a spin , and it frees the stuck brush or brushes . ( Also brush dust could have stuck a brush from advancing , till five finger Max's hand came along )

 

[pnolan48]

Have we reached the conclusion yet that no one really has any clue about this?

I have reached this conclusion: it was idiopathic.

Small things malfunction due to even smaller things.