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Current draw and brass locomotives

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Current draw and brass locomotives
Posted by tstage on Monday, July 20, 2020 2:19 AM

I have a couple of brass steam locomotives that I converted to DCC recently and I've been enjoying running them around my temporary layout (extended oval) to break them in.  One is an 0-6-0 switcher and the other, a 0-10-0.  Both have can motors.

I have my Power Cab set up so that it displays current.  When the 0-10-0 is running @ speed step 040, the motor draws anywhere from 0.03 to 0.25A.  However, when the 0-6-0 is on the track and I operate it @ speed step 025, its motor draws anywhere from 0.24 to 0.54A.  And, after the 0-6-0 has run for ~5 min or so, the cab - where the motor is located - is warm-ish to the touch.  Both locomotives are pulling identical loads: 4 tank cars and a brass caboose.

Is it common for brass locomotives to run warm when operating?  Or, could lubrication have some effect on the temperature?

I notice that if I push the 0-6-0 switcher to speed step 030, it has a tendency to surge and lag, which says to me that it needs some additional lubrication on the axles.  The current draw also increases, with spikes up to 0.75A.  At speed step 025, the 0-6-0 just cruises along with very little surge or lag.

I appreciate any insight from the electrical gurus.

Thanks,

Tom

https://tstage9.wixsite.com/nyc-modeling

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Posted by wvg_ca on Monday, July 20, 2020 6:02 AM

brass locos -shouldn't- draw more than plastic, and obviousle open frame motors draw more than can motors, and more axles spinning -should- draw more current than less axles ..

one place you -can- get more draw is the steel axle to brass frame on the loco, and in this case i would recommend a slightly 'thicker' oil to help retain it in the proper place ..as a brass frame is -usually- thinner than a plastic one ..

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Posted by SeeYou190 on Monday, July 20, 2020 7:33 AM

Tom, I have not run my brass steamers very much. I have been buying them after my last layout was torn down, and my next one is not built yet.

The one I ran a bit on the old layout was my old Tenshodo 0-8-0. It pulls 0.5-0.7 amps whener it is running. It has an open frame motor. It is also fairly noisy, but it runs reliable and smooth. This locomotive would get warm when it ran for a while, but never smoked, smelled, or got hot.

I have tested all my other brass locomotives as I buy them. The Key and Sunset USRA models are all made in Korea and have Canon Can Motors. These pull 0.2 to 0.3 amps. My United/PFM locomotives pull 0.6 to 0.7 amps with open frame motors.

My Oriental Powerhouse USRA Light locomotives pull right around 0.25 amps.

I hope this helps. Hopefully soon I will find out how cleaning, lubricating, and then breaking them in effects operating characteristics.

-Kevin

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Posted by rrinker on Monday, July 20, 2020 7:55 AM

 Numbers sound about right, tuning, cleaning, and fresh lube should help it. If they are open frame motors, the easiest way to improve performance without replacing them is to replace the magnets. 

 Also run it as slow as it will go and make sure there is no binding in the rods or other moving parts.

                                  --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by tstage on Monday, July 20, 2020 9:03 PM

As mentioned, both brass steamers came with can motors.  And the 0-6-0 does run very smoothly at low speed.  I'll see if a little lubing will help bring those numbers down some.  I looked at the metal gears when I was isolating the motor and they were fairly clean.

Would older can motors (ca. 1980 and older) be less efficient than newer can motors?  IIRC, the can motor in the 0-10-0 is 2-3 years older but it still draws 1/2 the current of the 0-6-0 can motor.

Tom

https://tstage9.wixsite.com/nyc-modeling

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Posted by wvg_ca on Monday, July 20, 2020 11:49 PM

the size of can has somewhat to do with draw, but unless they are -identical- [same part number], there is usually no way to determine amp draw at a certain speed .. draw will vary due to max speed, rated draw at rpm, and torque avalable, among other factors ..

there just no -easy- way to tell, manufacturers specs should give some idea though ..

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Posted by wrench567 on Thursday, July 23, 2020 9:38 AM

  Tom

  Another thing to consider is gear reduction. The 0-6-0 may be geared higher than the 0-10-0. That in itself would make the motor draw more amps. There are many variables to consider. Motor size, gear reduction, wheel diameter, and freewheeling of the chassis.

  For some strange reason my brass B6sb 0-6-0 has a motor almost twice the size of one of my brass 2-10-0 road locomotive. It draws just a tiny fraction of an amp more. The gear reduction is completely different. Setting CV 5 to 0 the 0-6-0 is a rocket. That is why it's set to 75.

  If you are comfortable disassembling valve gear. Remove the side rods on both sides and test run it just on the drive axle. Take note of how it runs at all speeds. Then put one side on and test again. Then the other if all is good.

 Take note of the position of the eccentric crank before disassembling it. I take pictures and keep the parts separate from left and right. Study prototype pictures. On one steamer I found the factory put the jointed side rods on the wrong end. After the swap around it seemed to run smoothly.

   Hunting from side to side is normal for a short all drivered locomotive. The prototype hardly ran much faster than 25 mph. The heavier and longer all driver engines not much faster. Fear of climbing over the rails on a 62 inch driver was a major concern. The smaller drivers not as much. Given a choice the crew would pick a 2-8-0 over a 0-10-0 for heavy switch duties.

    Pete.

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Posted by SeeYou190 on Friday, July 24, 2020 9:49 PM

wrench567
For some strange reason my brass B6sb 0-6-0 has a motor almost twice the size of one of my brass 2-10-0 road locomotive.

The motor in my Tenshodo 0-8-0 is huge, completely filling the cab. It is the largest motor in any of my models except for the Proto-Power West chassis that I have with a "Micro Motor", that thing is really huge!

-Kevin

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Posted by doctorwayne on Friday, July 24, 2020 11:04 PM

I've never concerned myself with the current draw of any of my locomotives.  Some have can motors, some open-frame motors and some open-frames with better magnets.  I run DC, and often doublehead locomotives and use pushers, too, due to the many curves and grades. 
I've also run a dozen-or-so locomotives at-a-time (without trains) for the amusement of my grandkids, as they enjoy chasing various ones around the layout.
As for my own operations, as long as the trains run reliably and can handle what I require them to pull, I don't care what they're drawing.  If there's ever a problem, I'm sure it will make itself known on my electric bill.

On the flip side, I have a friend who has mostly older brass and cast metal steam locomotives, and pretty-well all of them have unmodified open-frame motors.
Any of them run smoothly, even at a crawl, and at such speeds are drawing less than a tenth of an amp, even when pulling a train. 

Wayne

 

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Posted by ndbprr on Sunday, August 2, 2020 6:24 PM

As far as the heat brass is a metal and far more conductive of heat then plastic.  Take the boilers off and run them awhile.  I bet there is no difference in the motor temperatures

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Posted by Paul3 on Monday, August 3, 2020 11:53 PM

One thing to keep in mind with brass steam is that they may not be square.

Take a brass steamer and put it upsidedown in a cradle.  Run it using an ammeter.  Note the amperage.  Take off the bottom plate, and try shimming the journal boxes fore and after with small thin pieces of brass.  As you shim, keep an eye on the ammeter.  Every thing you do that makes the engine square will lessen the amperage while anything that makes the axle more crooked will increase amperage.

Continue this with all drivers.  At the end, you should end up with a better running engine that uses less amps.

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