## Locomotive current demands

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• To All: We have made some observations here, with the combined ownership of some 40 z scale locomotives (4 of us), and I wonder if anyone else has noticed it?
Message 1 of 13 , Jul 3, 1999
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To All:

We have made some observations here, with the combined ownership of some 40 z
scale locomotives (4 of us), and I wonder if anyone else has noticed it?

In an effort to determine the safe operating range for our locomotives (some
locos where getting really hot), we ran across the following test:

a. Put the loco on a short test track against a soft bumper at one end
b. Turn the power up until the loco spins its wheels (only do this for a
second)
c. Note the current draw from the powerpack (in milliamps)

What we found is:

Marklin locos draw from 300 to 400 milliamps at 6 volts
Marklin locos in bad need of cleaning/oiling draw 400-500 milliamps at 6 volts
and - they run hot....VERY hot
and - when oiled properly, they drop back to 300/400 milliamps

MicroTrains F7's draw 400-500 milliamps at 6 volts
but MT's are heaver locos, bigger motors, and pull twice as many cars
sorry, we didn't have one in bad shape to identify its overcurrent points

What we are looking for it a go/no-go test at shows BEFORE we put a loco out
there and burn it up.

Since motor current demands are affected by load (number of cars/wagons)
there is no clear definition of what a "standard" load might be. We "think"
wheel slip represent the maximum load condition on a loco. We "think" it
represents that point where any more cars/wagons cannot be pulled by that
particular loco. In any case, it would be the same point for a given loco
every time.

Bill Kronenberger
Houston, Texas
• ... Actually, maximum load isn t when the wheels spin. To explain this I ll have to give a crash course about friction. There are two types of friction. I do
Message 2 of 13 , Jul 3, 1999
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>From: BJKRONEN@...
>
>Since motor current demands are affected by load (number of cars/wagons)
>there is no clear definition of what a "standard" load might be. We "think"
>wheel slip represent the maximum load condition on a loco. We "think" it
>represents that point where any more cars/wagons cannot be pulled by that
>particular loco. In any case, it would be the same point for a given loco
>every time.
>
>

Actually, maximum load isn't when the wheels spin. To explain this I'll
have to give a crash course about friction.

There are two types of friction. I do not know their English names, but
I'll try to explain anyway.
One friction is the "gliding friction". It is the resistance an object
gives while *moved* over a surface.
The other friction is the "threshold friction". This is the resistance an
object gives when it is stationary and you *try* to move it.
The "threshold friction" is always higher that the "gliding friction",
often much higher.

This is easily illustrated with car tyres. Once the wheels lock, we have
much less braking power. This is the princible behing anti-lock breaks;
they keep the wheels at just about locking, that is where friction is
greatest.

Another way to easily test this is to put an un-powered loco on a long
piece of rail, then lift one end of the rail. You can lift it quite high
before it slips, but once it is moving you don't need much angle at all to
keep it moving.
Friction is actually measured as this angle - or rather, these two angles.
The other angle, for "glide friction", is the angle where the loco stops
again.

So, when you meassure a spinning loco, it is only encountering "gliding
friction". Before a moving, loaded train starts spinning, it must be
subjected to a load that makes it pass the "threshold friction".

And after this lenghly lecture, do I have a way to measure current demand
at maximum load? No. None other than to put weights on a freight car till
just before the loco slips.

I hope this helped more than confused.

/Jacob
• ... You ve had better luck that we have. I have not one, but two, Marklin steamers that striped their worm gear to pieces, due to the assumption they were
Message 3 of 13 , Jul 5, 1999
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Steve:

> I do admit though that Z locos get quite hot when run over longish periods.
> Having said that, this I assume is catered for in their design as I've
> never had one stop or burn out due to overheating.

You've had better luck that we have. I have not one, but two, Marklin
steamers that striped their worm gear to pieces, due to the "assumption"
they were properly lubricated from the factory. They were both brand new.
How dumb can I get? And it only took a few minutes of running to do it.

A lot of z locomotives which have been stored for many years (and the oil
turned to concrete) have overheated and burned up. Locos with bad brushes
can eat the commutators in the motors. Grime in the gearbox can be just as
fatal. All of these conditions tend to cause the locos to draw more than
normal current.

There are some really nice folks in Florida, who spend 30 hours a week
digging junk out of locos (for others). I would bet that they would be the
first to agree that 10 year old oil is as bad as, or worse, than no oil at
all.

I'd be the first to agree, that with PROPER maintenance, Marklin and
MicroTrains locomotives will last forever. The concern we have for ourselves
(and our guest runners), is that someone will put a poorly
lubricated/maintained loco on the track, and watch it die before their eyes.
Or make the same "assumption" I did.

Hence, the desire to compare notes with others to see if a check of current
demands can be used as a "quick check" before its too late.

Regards

Bill Kronenberger
Houston
• I have to agree with Bill on this one. I have purchased four or five Märklin steamers off the shelves of hobby stores. They were sold as new but from my
Message 4 of 13 , Jul 5, 1999
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I have to agree with Bill on this one. I have purchased four or five
M�rklin steamers off the shelves of hobby stores. They were sold as new but
from my examination of them, they had all been sitting around for anywhere
from 5 to 9 years!

As you can imagine, the lubrication had evaporated and the resin that was
left made burning out a motor practically a sure bet. In fact, I found out
the hard way with the first one that I bought. Fortunately for me, M�rklin
USA replaced the motor under warranty.

Subsequently, I cleaned out the old muck and lubricated the engines before
putting them into service on the Val Ease Central. The locos on my layout
run continuously for 2-3 hours at a time so they do tend to get hot.
However, with proper cleaning and lubrication they have given me solid
performance over the years. They will be running some more at the National
Train Show, July 23-25 in Saint Paul. (Am I repeating myself enough yet?)

P.S. I have also added weight to all my motive power, except the MT's in
the belief that every little bit helps. To hedge my bets, I also use Relco
high frequency AC track cleaning units on the layout.

P.P.S. Thank you Simon for adding the SAR of Hong Kong to our list of
Countries. That brings the total to 11!

Cheers,
Jeffrey

>
>I'd be the first to agree, that with PROPER maintenance, Marklin and
>MicroTrains locomotives will last forever. The concern we have for
>ourselves
>(and our guest runners), is that someone will put a poorly
>lubricated/maintained loco on the track, and watch it die before their
>eyes.
>Or make the same "assumption" I did.
• Hi All: During the summer, I raised this topic and got about as much interest in it as watching the grass grow. But that was the off-season for trains, and
Message 5 of 13 , Dec 31, 1999
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Hi All:

During the summer, I raised this topic and got about as much interest in it
as watching the grass grow. But that was the off-season for trains, and the
list did not have the 100 plus members it does now.

I still feel the topic is of value, especially to those who only infrequently
run their locomotives. Or worse, run them and watch the motors burn up in a
few minutes.

I'll try the issue one more time. While we have become believer's in it down
here, I would really be interested to see if our findings compare with anyone
else's.

Bill Kronenberger
Houston

-=-=-=-=-=-=-=- Summer Rerun Follows -=-=-=-=-=-=-=-

To All:

We have made some observations here, with the combined ownership of some 40 z
scale locomotives (4 of us), and I wonder if anyone else has noticed it?

In an effort to determine the safe operating range for our locomotives (some
locos where getting really hot), we ran across the following test:

a. Put the loco on a short test track against a soft bumper at one end
b. Turn the power up until the loco spins its wheels (only do this for a
second)
c. Note the current draw from the powerpack (in milliamps)

What we found is:

Marklin locos draw from 300 to 400 milliamps at 6 volts
Marklin locos in bad need of cleaning/oiling draw 400-500 milliamps at 6 volts
and - they run hot....VERY hot
and - when oiled properly, they drop back to 300/400 milliamps

MicroTrains F7's draw 400-500 milliamps at 6 volts
sorry, we didn't have one in bad shape to identify its overcurrent points

What we are looking for it a go/no-go test at shows BEFORE we put a loco out
there and burn it up.

Since motor current demands are affected by load (number of cars/wagons)
there is no clear definition of what a "standard" load might be. We "think"
wheel slip represents the maximum load condition on a loco. We "think" it
represents that point where any more cars/wagons cannot be pulled by that
particular loco. In any case, it would be the same point for a given loco
every time.

Bill Kronenberger
Houston, Texas
• well so far I have a whopping ONE loco and i don t wanna mess with it too much. I also don t have a volt meter aside from touching my tongue to the trackto see
Message 6 of 13 , Dec 31, 1999
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well so far I have a whopping ONE loco and i don't wanna mess with it
too much. I also don't have a volt meter aside from touching my tongue
to the trackto see if I get a jolt like with 9volts. I suppose I'm not
quite clear on what we're checking here though.

BJKRONEN@... wrote:
>
> From: BJKRONEN@...
>
> Hi All:
>
> During the summer, I raised this topic and got about as much interest in it
> as watching the grass grow. But that was the off-season for trains, and the
> list did not have the 100 plus members it does now.
>
> I still feel the topic is of value, especially to those who only infrequently
> run their locomotives. Or worse, run them and watch the motors burn up in a
> few minutes.
>
> I'll try the issue one more time. While we have become believer's in it down
> here, I would really be interested to see if our findings compare with anyone
> else's.
>
> Bill Kronenberger
> Houston
>
> -=-=-=-=-=-=-=- Summer Rerun Follows -=-=-=-=-=-=-=-
>
> To All:
>
> We have made some observations here, with the combined ownership of some 40 z
> scale locomotives (4 of us), and I wonder if anyone else has noticed it?
>
> In an effort to determine the safe operating range for our locomotives (some
> locos where getting really hot), we ran across the following test:
>
> a. Put the loco on a short test track against a soft bumper at one end
> b. Turn the power up until the loco spins its wheels (only do this for a
> second)
> c. Note the current draw from the powerpack (in milliamps)
>
> What we found is:
>
> Marklin locos draw from 300 to 400 milliamps at 6 volts
> Marklin locos in bad need of cleaning/oiling draw 400-500 milliamps at 6 volts
> and - they run hot....VERY hot
> and - when oiled properly, they drop back to 300/400 milliamps
>
> MicroTrains F7's draw 400-500 milliamps at 6 volts
> sorry, we didn't have one in bad shape to identify its overcurrent points
>
> What we are looking for it a go/no-go test at shows BEFORE we put a loco out
> there and burn it up.
>
> Since motor current demands are affected by load (number of cars/wagons)
> there is no clear definition of what a "standard" load might be. We "think"
> wheel slip represents the maximum load condition on a loco. We "think" it
> represents that point where any more cars/wagons cannot be pulled by that
> particular loco. In any case, it would be the same point for a given loco
> every time.
>
> Comments please? A better way? Are we on a fool's path?
>
> Bill Kronenberger
> Houston, Texas
>
> > CraZy 'bout Zee!

--
Jeff Masiello - Level I Technician - Customer Services
masiello@... - 301 847 5082 (fax)
24-hour Support Line - 301 847 5200 or (800) 581-8711
• Answering a question with a question... What do you use to measure current??? I know that it is a milliammeter or ammeter, but do you recommend and
Message 7 of 13 , Dec 31, 1999
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Answering a question with a question...

What do you use to measure current???

I know that it is a milliammeter or ammeter, but do you recommend and
manufacturer / model number, etc???

Is there something that I can get at Radio Shack or elsewhere for a
reasonable price to use at home???

Bim B

BJKRONEN@... wrote:
>
> From: BJKRONEN@...
>
> Hi All:
>
> During the summer, I raised this topic and got about as much interest in it
> as watching the grass grow. But that was the off-season for trains, and the
> list did not have the 100 plus members it does now.
>
> I still feel the topic is of value, especially to those who only infrequently
> run their locomotives. Or worse, run them and watch the motors burn up in a
> few minutes.
>
> I'll try the issue one more time. While we have become believer's in it down
> here, I would really be interested to see if our findings compare with anyone
> else's.
>
> Bill Kronenberger
> Houston
>
> -=-=-=-=-=-=-=- Summer Rerun Follows -=-=-=-=-=-=-=-
>
> To All:
>
> We have made some observations here, with the combined ownership of some 40 z
> scale locomotives (4 of us), and I wonder if anyone else has noticed it?
>
> In an effort to determine the safe operating range for our locomotives (some
> locos where getting really hot), we ran across the following test:
>
> a. Put the loco on a short test track against a soft bumper at one end
> b. Turn the power up until the loco spins its wheels (only do this for a
> second)
> c. Note the current draw from the powerpack (in milliamps)
>
> What we found is:
>
> Marklin locos draw from 300 to 400 milliamps at 6 volts
> Marklin locos in bad need of cleaning/oiling draw 400-500 milliamps at 6 volts
> and - they run hot....VERY hot
> and - when oiled properly, they drop back to 300/400 milliamps
>
> MicroTrains F7's draw 400-500 milliamps at 6 volts
> sorry, we didn't have one in bad shape to identify its overcurrent points
>
> What we are looking for it a go/no-go test at shows BEFORE we put a loco out
> there and burn it up.
>
> Since motor current demands are affected by load (number of cars/wagons)
> there is no clear definition of what a "standard" load might be. We "think"
> wheel slip represents the maximum load condition on a loco. We "think" it
> represents that point where any more cars/wagons cannot be pulled by that
> particular loco. In any case, it would be the same point for a given loco
> every time.
>
> Comments please? A better way? Are we on a fool's path?
>
> Bill Kronenberger
> Houston, Texas
>
> > CraZy 'bout Zee!
• Hi Bill, I ll be able to give you a reading on a MT F7, actually, 4 F7 s, shortly as I just finished installing a DC Voltmeter and Ampmeter in an enclosure for
Message 8 of 13 , Dec 31, 1999
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Hi Bill,

I'll be able to give you a reading on a MT F7, actually, 4 F7's, shortly as
I just finished installing a DC Voltmeter and Ampmeter in an enclosure for
the VEC controls. Normally I wouldn't have bothered but it is the last
requirement for the Electrical certificate.

My F7s can easily be considered well run in and probably in need of some
cleaning.

Wheel slip is my choice for the point of measurement.

I'll be in touch in the next couple of days with the results.

CheerZ,
Jeffrey MacHan
• ... There are two nightmares you can have with any model train in any scale: 1. Burn out the motor (with too high a voltage, or some types of pulse power) 2.
Message 9 of 13 , Dec 31, 1999
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Jeffrey and Bim:

>Jeffrey: I suppose I'm not quite clear on what we're checking here though.

There are two nightmares you can have with any model train in any scale:

1. Burn out the motor (with too high a voltage, or some types of pulse power)

2. Have a dysfunctional mechanism that gives you frustrating performance and
overloads the motor until it burns out, or tears up the gears.

The question at hand addresses the detection of # 2 before it is too late.
With all my 12% knowledge I claim to have, I calmly put a brand new Marklin
steamer on the tracks a year ago and watched it tear itself apart at a show.
Dumb. Dumber than dumb. I "assumed" a brand new loco was properly oiled. I
know better.

What are some of the things that we have found inside locos:
- - - - - - - - -
Dirt and grime
Excessive grease/oil - or - No oil at all
Oil that has turned into concrete from age
Strings, pieces of wire and springs
Ballast, pieces of scenery, rolling stock, or even parts of the loco itself
Unidentified gummy "stuff"
Misassembled gear stacks, idlers, worms
Brushes completely worn out
Brushes far too tight on the commutator (acts like a brake on the motor)
Screws
Bent shafts and gears
Animal hair
, etc., etc., etc.

No, we do not store our equipment rolling loose in the trunk (boot) of our
cars. While they have clean storage, they run on layouts. Layouts always
have some kind of loose "stuff" on them. There is no better track cleaning
device known than a loco itself. If its loose, the loco will pick it up and
digest it.

I have bought locos from others which appeared to have been stored outside in
a horse barn.

The amazing thing, is that locos will desperately try to run with all this
"stuff" inside of them. Or at least for a while. Until the motor or the
gears give up.

Anything on the list above, will try to prevent the motor from turning at its
normal speed. This will cause the motor to draw more current. That can be
seen on a meter, without a disassembly of the loco to check for all these
problems.

The idea is to see if a "benchmark" for normal current, at a specific
voltage, under repeatable load conditions can be established for a quick
check BEFORE someone puts a loco on the track.

> Bim: What do you use to measure current???

Most folks know that a volt meter measures electrical pressure expressed in
volts. In order to make that measurement one puts the meter in PARALLEL with
the power pack, the rails or the loco.

In order to measure current, one has to put a meter in SERIES with the power
pack. Since the polarity of the power back can be reversed, a "zero center"
meter is appropriate. That means a meter that at rest, will have its pointer
in the middle of the scale, and not off to the left side like most meters. A
meter with 1amp-zero-1amp offers a usable reading, but can survive a dead
short across the rails. Remember, any current (including a short) will pass
through the meter on the way to the rails in a series connection.

Likewise, a "zero center" voltmeter is quite appropriate too. Again, because
the power pack can reverse the polarity to the rails.

If interest develops, any one of several of us on the list can put together a
list of parts from common (cheap) resources that folks can buy and use, with
little or no electrical knowledge. A number of how-to books already have
this information.

But let's see if anyone agrees with the "normal" readings and the "test
procedure" before we advance to that step.

Who's next at the keyboard on this topic?

Bill Kronenberger
Houston
• ... [snip] ... Me! But I m not at all sure, that my question is relevant in the context. - What about the inner resistance of the ammeter? Is it a specific
Message 10 of 13 , Jan 1, 2000
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On Fri, 31 Dec 1999 22:52:42 EST, you wrote:

>From: BJKRONEN@...
>

Bill and group:

>Jeffrey and Bim:
>
>>Jeffrey: I suppose I'm not quite clear on what we're checking here though.

[snip]

>Who's next at the keyboard on this topic?

Me! But I'm not at all sure, that my question is relevant in the
context.

- What about the inner resistance of the ammeter?

Is it a specific relationship between inner resistance of loco and
ammeter that will produce produce the readings mentioned? And does the
loco resistance vary with rotational speed - so that you will get
varying milli-amp readings depending on the point where wheel-spin
sets in (wheels and tracks not beeing 100% clean and friction/weight
relationship)?

I guess everyone will see immediately, that I do not know a lot about
these things! But....?

BTW: the lights on my locos only turns on at a voltage where the
current consumption makes the loco rather hot?? (Marklin locos)

regards Ole Rosted, Denmark
• To Bill B and the list. I don t remember seeing anything on whether or not the track should be level, and would it be possible to use wheel slip at a specific
Message 11 of 13 , Jan 1, 2000
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To Bill B and the list.
I don't remember seeing anything on whether or not the track should be
level, and would it be possible to use wheel slip at a specific angle?
I have my test track with a hinge on one end and a jack screw on the
other so I can see how a loco will do on a grade.
Have you or anybody tried using the "cheap" digital multimeters from
Is there any place (database) that we could put our data into, and all
get at? Somebody that has a web site to act as a server, but I don't
know about having external data input to a database on the net. Don't
want to burden the web site owner with having to manually input
everybodys inputs.
Ed Scullin
• ... We just kept it simple. Flat and level for the wheel slip current test. I d suggest computing grades may be more than some folks want to get involved
Message 12 of 13 , Jan 1, 2000
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Ed:

> I don't remember seeing anything on whether or not the track should be
> level, and would it be possible to use wheel slip at a specific angle?

We just kept it simple. Flat and level for the wheel slip current test. I'd
suggest computing grades may be more than some folks want to get involved
with.

> Have you or anybody tried using the "cheap" digital multimeters from

Yup, and its a problem. Digital meters sample the current a few times a
second and display the results. More you pay, more samples per second.
Problem is, there are a lot of variables and the digital meters tend to not
have a consistent reading, rather the numbers on the meter just bounce around
like you were playing roulette.

But good old analog meters tend not to do that, and the needle stabilizes on
a fixed point on the scale, so you can read it.

> Is there any place (database) that we could put our data into, and all
> get at?

What about the archives of the OneList itself? There are a number of folders

*** Jeffrey MacHan: How does that work, list owner? ****

Regards,
Bill Kronenberger
Houston
• Sorry if dredging up ancient history offends anyone ... ... though. ... pulse power) ... performance and ... late. A goal to which I aspire most vigorously!
Message 13 of 13 , May 13, 2006
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Sorry if dredging up ancient history offends anyone ...

--- In z_scale@yahoogroups.com, Dec 31, 1999, 9:52 pm,
BJKRONEN@... wrote:
>
> Jeffrey and Bim:
>
> >Jeffrey: I suppose I'm not quite clear on what we're checking here
though.
>
> There are two nightmares you can have with any model train in any scale:
>
> 1. Burn out the motor (with too high a voltage, or some types of
pulse power)
>
> 2. Have a dysfunctional mechanism that gives you frustrating
performance and
> overloads the motor until it burns out, or tears up the gears.
>
> The question at hand addresses the detection of # 2 before it is too
late.

A goal to which I aspire most vigorously!

> > Bim: What do you use to measure current???
>
> Most folks know that a volt meter measures electrical pressure
expressed in
> volts. In order to make that measurement one puts the meter in
PARALLEL with
> the power pack, the rails or the loco.
>
> In order to measure current, one has to put a meter in SERIES with
the power
> pack. Since the polarity of the power back can be reversed, a "zero
center"
> meter is appropriate. That means a meter that at rest, will have
its pointer
> in the middle of the scale, and not off to the left side like most
meters. A
> meter with 1amp-zero-1amp offers a usable reading, but can survive a
> short across the rails. Remember, any current (including a short)
will pass
> through the meter on the way to the rails in a series connection.
>
> Likewise, a "zero center" voltmeter is quite appropriate too.
Again, because
> the power pack can reverse the polarity to the rails.
>
> If interest develops, any one of several of us on the list can put
together a
> list of parts from common (cheap) resources that folks can buy and
use, with
> little or no electrical knowledge. A number of how-to books already
have
> this information.
>
> But let's see if anyone agrees with the "normal" readings and the "test
> procedure" before we advance to that step.
>
> Who's next at the keyboard on this topic?
>
> Bill Kronenberger
> Houston

What I would like to do is set up dual meters (Volts & Amps) for each
of my power packs, or integrate the meters into a Z Bend Track control
connecter. Where would I get the information as to parts & assembly
for this project?

John L. Battey in Roanoke, TX
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