Steam & Excursion > Basic steam question

Hello all;
Talking with a friend and we had a question. On steam like the 3751, UP Challenger or Daylight, how do they get electrical power? Does it come from a steam generator on the locomotive itself or some other source. I should know this but can't seem to recall. Must be the 'old age' thing. Thanks for all responses!

Comes from the dynamo.

Yes. Small steam turbines (Dynamotors) provide 32VDC. In the case of the Daylight, there are three Dynamos: one powers the Mars Light & radio (12VDC), one powers the head light and cab lights (32VDC) and the third powers the lights under the skirts (the third Dynamo originally was for the electro-pneumatic train brakes).

The UP 844 and 3985 now carry twin Dynamos in order to provide additional power since the latest style solid state cab signal/ ATC was added.

Usually on the top of the boiler just ahead of the cab was
the steam operated dynamo..that's why most photos show a feather
of steam emitted just ahead of the roof or the cab...

Typically there is a small steam powered turbo generator located on top of the boiler. Generally it's just referred to as the turbo. Location varied by make, model and road. 32 volts DC was common. There were generally no batteries on steam engines. I'm sure others will have much more detailed information.

Tom

Now there's something I've always wondered about. Why not batteries? I guess (am I answering my own question?) when steam was in regular service battery technology was not very advanced, but in the case of restored locomotives, the big ones at least, why not a bank of deep cycles? More trouble than its worth?

Cheers, Dave

Hillcrest Wrote:
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> Now there's something I've always wondered about.
> Why not batteries?

My question: Why batteries? Suppose I'm a steam era Master Mechanic - Convince me.

Is there an advantage? Sooner or later, they're going to need charging and/or replacing. Who's gonna do it? At what cost? Are there waste disposal issues? Could they make it 31 days between monthly inspections? They are unproductive weight to be hauled around. Would they generate one more pound of tractive effort? When would you need electricity without the turbo available, anyway?

Here's what you should be looking for.

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If you are standing near the steam engine you can hear a high pitched whine and that's the turbo. Two of the major mfgs. were Sunbeam & Pyle-National. My hearing is shot after all those years in the cab of a locomotive but I can still hear that.

And if you stand there long enough you can hear the thump-thump of the air compressor. (Except for the old SP ab forward mallets. Their compressor exhaust sounded like a small gun going off every time they would cycle.)

Nudge

Hillcrest Wrote:
-------------------------------------------------------
> Now there's something I've always wondered about.
> Why not batteries? I guess (am I answering my own
> question?) when steam was in regular service
> battery technology was not very advanced, but in
> the case of restored locomotives, the big ones at
> least, why not a bank of deep cycles? More trouble
> than its worth?
>
> Cheers, Dave

Because a steam locomotive does not need an electric starter motor to start up (raise steam); and once it has steam up, the turbogenerator runs continuously, so it also provides electricity continuously. Therefore, batteries are unnecessary.

Roger Lewis (airbrakegeezer)

Actually, on the CC&C Ry. 15 at the Chehalis Centralia Railroad & Museum there is a 12 volt car battery on the engine, we use it for power for the radio when the dynamo is off between trips to "save on wear and tear." There is also a converter from 32 volts to 12 volts to charge battery when the dynamo is on. There is also a 120 to 32 volt converter on the engine so it can be plugged in to use cab lights when the engine is cold and working in the cab, and there is one 120 volt plug in on the engine for use of drop lights in the firebox or power tools.

4449 from on top of the tender and you can see the 3 dynamos in the open space in the skyline casing to the left just ahead of the cab.

C.C.Chas.

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Yikes Guys! I'm not completely new...I'm not sayin' eliminate the dynamo (charging system),I was just thinking about a way to hold a constant voltage for some of the state-of -the-art electronics available, or a way to light things up when steam isn't up enough to make it all spin...I like a turbogenerator as much as the next guy but...well, I guess the battery backup is more trouble than its worth...

Cheers, Dave

I have actually heard from sources within the industry, that running your radio straight from the dynamo to a 32VDC to 12VDC converter will eventually ruin the internal bearings and is becoming a common repair in shops. Running the radio through a 12VDC battery is actually a very smart thing to do. Its something we are currently exploring for use on the 2472.


Jeff

You would need a large battery bank for just a few hours of lights and accessories, and then there's the added danger of having lots of lead acid around on a machine that already is a rolling pressure vessel. :)

The turbo generator operates continuously. They were made by Pyle and others as catalog items. It's a very small version of the generators you see at dams. Here is a cutaway on the right: http://books.google.com/books?id=YjsOAQAAIAAJ&pg=PA206&dq=pyle+national+generator&hl=en&ei=7BYbTKveJ9Xungen_qy1Cw&sa=X&oi=book_result&ct=result&resnum=8&ved=0CE8Q6AEwBw#v=onepage&q=pyle%20national%20generator&f=false

It is a brushed motor in reverse, essentially.

Mike Massee
Tehachapi, CA
Photography, Railroading and more..

Thanks to all for your wonderful and informative responses. Appreciate it!

Jeff mentioned:
I have actually heard from sources within the industry, that running your radio straight from the dynamo to a 32VDC to 12VDC
converter ill eventually ruin the internal bearings and is becoming a common repair in shops.

That's odd. Why would that be?

I didn't realize radios had bearings...

CDTX Wrote:
-------------------------------------------------------
> I have actually heard from sources within the
> industry, that running your radio straight from
> the dynamo to a 32VDC to 12VDC converter will
> eventually ruin the internal bearings and is
> becoming a common repair in shops. Running the
> radio through a 12VDC battery is actually a very
> smart thing to do. Its something we are currently
> exploring for use on the 2472.
>
>
> Jeff

We use a 12 auto battery (mounted under the cab on the Engineer's side) on 4449, which is continuously charged when ever the 12VDC Mars Light Dyno is running. The battery is necessary because when keying the radio to talk, the power inrush to the Dyno is so great that the voltage suddenly drops and the radio quits. That battery simply "smooths" the current flow, plus the radio can be used briefly when the Mars Dyno is shut off.

The railroad radios that we use don't have bearings either, nor does the battery!

The dynamo bearings guys. work with me here. What Jack just explained is exactly what it is thats wearing down the bearings, the excessive load. Got questions? Call Bernie Watts (spelling?).

Jeff



Edited 1 time(s). Last edit at 06/18/10 09:22 by CDTX.