SP&S E7 #750 Completed Kitbash

[peteski]

I totally took your remarks as helpful and with a sense of humor, Peteski!  Not to worry.
About that tire, I suppose a more accurate statement is that in a 3 axle truck, I usually find
that two of the wheels make good contact most of the time and the other one doesn't.
I support all three could be perfectly aligned so they contact equally, but it doesn't seem likely.

With   my tire, the trick was to get it set just right so it makes some contact, but not enough
to lift the others off the rail.  The first time, I didn't  quite get it right.  It stuck out too much
and the other two rocked on it like a see-saw. The pickup was terrible and the engine sputtered
all over the place.  So I cut another .005" into the grooves and tried again, with much success.
It  could run around my entire layout at creep speed with narry a sputter or stall.

The "scale speed" motor would supposedly have more windings of thinner wire so it would turn slower
and produce more torque.

Sounds like you did all that could be done for the traction tire to be optimally installed.  I wonder if the new Kato wheelsets would have given you more traction without the tires. They use different plating on those.

As far as the motor goes, I thin you are correct. But to me more windings with finer wire means lower current. The to me translates to weaker magnetic force generated (and less torque). So the motor might spin slower then Kato motor at some given voltage, but it also produces less torque (which is very important for smooth running).  I have no way to measure this, so I can't say whether this is true.

I realize that more turns in a winding will produce stronger magnetic field, but since the current will be lower, that will pretty much cancel the benefit of more windings (since magnetic field also depends on the current passing through the windings).  I could be wrong - I'm again thinking out loud without any proof.

To me it seems that "slow speed" motors while giving an appearance of a better choice (since they run slower at full throttle), aren't actually better than Kato motors. Now the gear ratio OTOH would be the elephant in the room. Higher gear ratio would increase the torque ant the wheels.

[mmagliaro]

The whole thing about more/thinner windings vs fewer heavier windings and how that translates to torque
confuses me too.

What you say about fewer windings = lower resistance = more current make sense to me.
And you would intuitively think that since it draws more current, it must be producing more torque, but
I do not think that is true.  I just don't understand enough about motors and magnetic fields.

I do know this:
A typical coreless motor, which has ultrafine wire in its windings and draws VERY little current,
can produce a lot more torque than a conventional motor drawing a lot more current, so there's a lot
more to this whole torque output equation than just the resistance, current, and thickness of the windings.

[peteski]

The whole thing about more/thinner windings vs fewer heavier windings and how that translates to torque
confuses me too.

What you say about fewer windings = lower resistance = more current make sense to me.
And you would intuitively think that since it draws more current, it must be producing more torque, but
I do not think that is true.  I just don't understand enough about motors and magnetic fields.

I do know this:
A typical coreless motor, which has ultrafine wire in its windings and draws VERY little current,
can produce a lot more torque than a conventional motor drawing a lot more current, so there's a lot
more to this whole torque output equation than just the resistance, current, and thickness of the windings.

Same here (lack of knowledge about motor design). I wish that I had a way to measure motor torque as that would answer my question. I still think that the slow speed motor benefit is only in the eyes of the modeler (lower top speed but not more low speed torque).

Coreless motors can be explained (in my mind).  First, they use rare-earth magnets with much stronger magnetic flux than standard ceramic magnets used in conventional motors. Then the rotor cage has a larger diameter than a rotor in an equivalent diameter body conventional motor. That larger diameter rotor produces more torque (even with with less current) in a very strong magnetic field of the rare-earth magnet.  Plus, with no cogging (which results in pulsating torque), the coreless motor is a winner.

[jmlaboda]

You got a beautiful model there!!!  It wore more paint schemes than any other unit, sometimes being repainted in just a few years time, yet no engine wore that paint any better!!!  Look forward to seeing it done!!!

[victor miranda]

motors and windings and current and controls
wow all we need is tony and lou.
simple motor guidelines.

more current will give you more torque... this has limits.
more wraps... mostly gets efficiency .... this has limits

generally more wraps of thicker wire gets you more torque at a given voltage...
the current should stay the same because the static resistance stays the same.

so if you have a motor that performs as you like at 2 volts,
to get a similar performance at 4 volts you add enough wraps
to allow a similar amount of current as the 2 volt version.

you may want to use watts for this, not just current... I did say I was trying for simple

What is frustrating is that you may not get the overall motor performance you want.
Because while the above is straightforward for a static motor,
things are very interesting once the rotor is moving.

one of the reasons small motors tend to have lower voltages
is because the magnetic wire has to get smaller to effectivly control current
in the space confines of a small rotor...
the price of that wire ramps up the prices of the motors.

[nkalanaga]

Max:  I doubt that you could align all three axles to make perfect contact, simply because our track isn't perfect.  Even if the axles are in line, any uneven spots in the rails will leave at least one wheel out of touch.

[mmagliaro]

Max:  I doubt that you could align all three axles to make perfect contact, simply because our track isn't perfect.  Even if the axles are in line, any uneven spots in the rails will leave at least one wheel out of touch.

I agree.  The point is, I have apparently gotten it close enough to work.

I would bet that the rubber tire
compresses a little, and that's what makes it all work. 
It's not a stretch to believe that it compresses a few thousandths of an inch
with the engine's weight on it.  And if so, then the engine will ride on the two outer metal wheels, which will
provide pickup, and the rubber tire will still touch.   Think of it as a very simple "sprung driver".

[OldEastRR]

How many cars is the E8 pulling over how much of grade and what radius curve that it can't handle? I've had a stock KATO E8 pulling 16 KATO passenger cars up 2% grades and through 10.5"R curves (on a flat) with no trouble. I rate them as extremely heavy-duty haulers, up with the KATO PA and Walthers/LL DL109.

[rrjim1]

 
To me it seems that "slow speed" motors while giving an appearance of a better choice (since they run slower at full throttle), aren't actually better than Kato motors. Now the gear ratio OTOH would be the elephant in the room. Higher gear ratio would increase the torque ant the wheels.

The slower top speed of the Atlas scale speed motor is nothing more than a bonus for me. Not to be confused with what is called the Atlas slow speed motor, there not even close. It's the better low speed performance that I like. I have several Kato SD40s all with Atlas scale speed motors, and they will tighten up and pull a train out of one of my yards just perfect. I also own three Kato SD40-2s with the original Kato motors and they will not creep like the SD40s, they surge back and forth until there up to about 15-20 smph.
   

[strummer]

Me too!  If it were the later "broadstripe", I wouldn't have  done this.

When I was into TT scale,I painted an H.P. Products E-7 in the "broadstripe" scheme, and it looked really good....boy,that was a while ago!

Mark in Oregon

[peteski]

The slower top speed of the Atlas scale speed motor is nothing more than a bonus for me. Not to be confused with what is called the Atlas slow speed motor, there not even close. It's the better low speed performance that I like. I have several Kato SD40s all with Atlas scale speed motors, and they will tighten up and pull a train out of one of my yards just perfect. I also own three Kato SD40-2s with the original Kato motors and they will not creep like the SD40s, they surge back and forth until there up to about 15-20 smph.
   

Slow, Scale  whatever we call those - I thought there was only one (with people, or just me, calling them multiple names). Basically, the original (fast) and the slow/scale speed one.  Now you say that there are 3 types of Atlas motor?  Or just me using a bogus name?  If I used bogus name - sorry. Scale speed or slow speed to me meant the same thing.

So how exactly can you identify them in the first place?  Even Atlas staff admitted that the black or gray plastic is not a dead giveaway to the motor type.

[mmagliaro]

How many cars is the E8 pulling over how much of grade and what radius curve that it can't handle? I've had a stock KATO E8 pulling 16 KATO passenger cars up 2% grades and through 10.5"R curves (on a flat) with no trouble. I rate them as extremely heavy-duty haulers, up with the KATO PA and Walthers/LL DL109.

I thought they would be beasts for pullers too.  I was testing it with a freight train.  22 MT cars, 40' up a 1.7% grade,
18" radius curves, and it would completely slip out on the hill (just spin its wheels and not make any progress).

Radius wasn't the problem.  It would run over the curves fine, except that it would rock or lift a little to one side and lose contact.   The other thing to remember is that I did spread the wheels to correct the gauge to match the NMRA plate.
It wasn't losing contact on the curves until I did that, and I'm pretty sure that's because spreading the wheels
tightened the axles up between the plates.   We discussed that all earlier in the thread, about spreading wheels/drilling
the cones vs pressing the wheels further in on their axles.

[Nick Lorusso]

When delivered it pulled the Empire Builder, then the SP&S used it on the 5&6 which was just 4 passenger cars. when it switched to the #1&2 they teamed it up with a F3 or F7.

[rrjim1]

Slow, Scale  whatever we call those - I thought there was only one (with people, or just me, calling them multiple names). Basically, the original (fast) and the slow/scale speed one.  Now you say that there are 3 types of Atlas motor?  Or just me using a bogus name?  If I used bogus name - sorry. Scale speed or slow speed to me meant the same thing.

So how exactly can you identify them in the first place?  Even Atlas staff admitted that the black or gray plastic is not a dead giveaway to the motor type.

Atlas High Speed motor,  Atlas Slow Speed motor, Atlas Scale Speed motor.   The Atlas Slow speed motor has a sliver frame, black end bell.  The newest Atlas motor has went back to a black end bells, haven't checked one out yet, just seen it in pictures, so one might not be able to tell the difference by the looks, one would have to check the rpms. I have purchased about 40 gray end bell Atlas Scale Speed Motors and all have been Scale Speed Motors.

Fast Speed motor, higher starting speed, 30,000 +/- rpms at 12 volts dc.
Slow Speed Motor, lower starting speed, 29,000 +/- rpms at 12 volts dc.
Scale Speed Motor, real low starting speed, 13,000 +/- rpms at 12 volts dc.

Jim W.

[victor miranda]

you got the motors from Atlas?

the LL sw1200 has a silver metal part and a black endbell.
the seem the same size to me.

interesting....

victor