Motors, torque, windings Scale Speed

[victor miranda]

these are the 4 numbers I found that seem to be scale speed.
445600
498100

540100
445600

you will likely need to move/remove flywheels to get the motor to the standard in your chassis.

e-bay is slightly cheaper in that Atlas charges for shipping.

victor

[rodsup9000]

  Thanks Victor,
 I'll check ebay then first.

[victor miranda]

Gray!

the black one are not scale speed

[mmagliaro]

Mine was 498100, and I did get it from eBay (but it was a new motor).

[victor miranda]

this is an evaluation report.

the rewrapped motor spent over 12 hours
pulling 10 cars at 6 SMHP without stopping...

it is not warm.
it was at 100ma and 3.1volts. 

I did not watch it like a hawk.
if it stalled, it restarted itself.

[victor miranda]

I have built another rewrapped motor...  ooof

not that that pain is done.  I am testing it.

prior to chassis install.

12 volts  no load current is 90 ma
without touching the throttle
the 12 volt stall current was 600 ma

my meter said .6 amps... 

so there is a start.

it does not start easily
and does run at 1.4volts ... forgot the current.

I will note it for later.

victor
 

[mmagliaro]

this is an evaluation report.

the rewrapped motor spent over 12 hours
pulling 10 cars at 6 SMHP without stopping...

it is not warm.
it was at 100ma and 3.1volts. 

I did not watch it like a hawk.
if it stalled, it restarted itself.

That's really good, Victor.  6 mph for 12 hours is a very rigorous test of whether the motor (and the chassis itself) can really run that slow.   Can you by any chance put it back at that speed, 3.1 volts, and then tack on another 10
cars and see how much it slows down?  That will really tell me how much reserve "oomph" that motor has.

6 mph is a lot to expect the motor to sustain with 10 additional cars. 
I would expect it to stop it you just slap on another 10 cars and leave the voltage
at 3.1v.   I might be more reasonable to run it at about 10 mph, with 10 cars, and then tack on 10 cars.

[victor miranda]

hi Max,

I can try....  Idon't think it can pull 20 of my cars around the loop...
it can do 15 and recall trying 20 recently to no movement.

I'll toss another 5 and collect the 45 smph consumption numbers and slow it to 5 to 7
I'll try to run your 15 car test later today. is an hour good?

in the news/update...
I have the, lets call it #3, rewrap in a chassis. (another atlas gp-9)

I didn't give it any rigorous  testing.  just a feel for what it does.
and some attempts to compare
so far the loco will not creep.  it does one slow speed or halts.
the motor alone exhibited that tendency.... one wonders
the slow speed? a little less than 4 smph. with that 10 car train.
uses 77ma 2.1v (161mW) to do it.

30 sec/ lap with train 110ma and 3.9v(429mW)

I am thinking there is a lot of performance to be found in good magnets.

victor




 

[mmagliaro]

Oh, okay.  At 20 cars, do the wheels slip?  So that is the grip limit of this particular loco?

I guess 15 would be okay.  It should be enough to detect a difference.

Either that or, if the problem is wheel slip, can you stack some lead weights on top of it so it can actually
pull 20 cars without slipping?  (You would of course have to remeasure at 10 cars first, to
account for the added weight, but then you could do 20).
I just think that we might need at least 10 more cars to really see if the motor has reserve
torque.   

[victor miranda]

I'll see what I can do.

it will be sometime tomorrow.

I have only a few f-things...  hunt a small brick, victor...
 
the coupler is the problem.... need brick with coupler...

the new motor is interesting.

victor

[victor miranda]

I put brass slabs on the walkways...

130ma and 3.5 volts
towing 20 cars at 17sec per foot.

lets see if it holds for an hour , 9:30 am start

at the end of the hour...

122ma 3.6v (439mW)
going at 14sec/foot.

not the least bit warm.

I'll slow it back to 17sec/foot
see if it sustains.

[mmagliaro]

17 sec/ft  is .0588 ft/sec = 6.4 SMPH

Can you run it at this exact voltage, 3.6, 3.1, whatever, with 10 cars, measure the speed, then tack on 10 cars,
keep the voltage the same, and measure the speed again?  That's really the head-to-head I'm after.
I want to see how much it dips with the added load.

I still think 6.4 may be too slow for this.  You may get it running 6.4 with 10 cars, then add 10 cars,
and it may stop if you don't increase the voltage.  If that happens, we can't tell anything.  If you have
to run it at more like 10, that would be more than fine.

[victor miranda]

Hi Max,
I think you are losing sight of what is being tested....

here is what I think you are requesting...

loco and 20 car train
118ma 3.5v and 18sec/foot(413mW)
.
I didn't touch the throttle I took 10 cars off the train.
train sped up to 12.7 sec/foot.
meters said 110ma and 3.5v (385mW)

k.
bacque to torque...

If you keep the rpm of the motor the same, the back emf (in volts...) stays the same
and the torque value is visible, in  direct proportion.

so... at 17-ish sec per foot
10 cars 100ma and 3.1volts 17sec/foot(310mW)
and
20 cars 118ma 3.5v and 18sec/foot(413mW)

we know the power in and the rpm is held steady
so the extra 100mW is a proportional torque value.

the motor is not warming up so we know the power is not in the form of heat.

[mmagliaro]

Thank you Victor.
No, I'm not losing sight.  But we are looking for more than one performance metric.

Knowing that an engine can handle more load, and can climb a hill, for example, pulling 20 cars
at a given speed are good signs.   A motor that can't develop enough torque at a given speed
won't be able to climb a hill at, say, 10 mph.  So that fact that your motor can do it is good.

But I am also after seeing how much the motor slows when more load is just thrown upon it.

We have two facts:

1.
12.7 vs 18 sec /ft equates to  8.58 and 6.08 scale mph
What this means is that if your 10 car train were chucking along at 8.5 mph, and the load on it suddenly
doubled, it would only slow down to 6 mph.   

2.
Your motor can actually run and pull the excess load (represented by the 20 car train)
at 6 mph with out stalling.

Performance like that is mighty fine, indeed, especially at such low speeds.

[victor miranda]

same test with rewrap #3
brass slabs moved from #1.

20 cars 98ma 3.2v (313mW) 16.5 sec/foot

did not touch throttle, blocked loco

pulled 10 cars off.

loco went to:
87ma 3.3v(287mW) 10sec/foot

of note is that the blocked loco did not stall, it kept the drivers spinning.

victor