Class Lamps and Smokebox Heat

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one_inch_railroad
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Class Lamps and Smokebox Heat

Post by one_inch_railroad »

A friend of mine is planning on adding some working class lamps to his locomotive. He is planning on putting LEDs in them. He is worried about the amount of heat because there attached to the smokebox. Is there something that can be done to help insulate the class lamps from the heat of the smokebox?
Tim B Guenther
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Re: Class Lamps and Smokebox Heat

Post by Tim B Guenther »

It might not be a problem. I have an LED and a battery inside the head light mounted to the smokebox of my Shay. It has operated for two seasons without a problem.
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Greg_Lewis
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Re: Class Lamps and Smokebox Heat

Post by Greg_Lewis »

I agree with Tim. Many years ago I took an IR thermometer to a number of running engine's smokeboxes and as I recall I rarely found any surface temp above about 375°F. And that temp is not going to transfer through the lamp mounting to the internals of the lamp.
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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gwrdriver
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Re: Class Lamps and Smokebox Heat

Post by gwrdriver »

Greg,
Interesting. What were your conditions? Fuel, smoke box size & material, etc? I've been wondering what kind of smoke box surface temperatures I could expect on my engine, which is 6" diam Sched40 steel, reduce slightly in thickness, propane fired.
GWRdriver
Nashville TN
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Greg_Lewis
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Re: Class Lamps and Smokebox Heat

Post by Greg_Lewis »

Hey GW.... here's the complete report. Be sure to read the intro and footnotes. Also be sure to look carefully at the raw data and the differences in readings.

viewtopic.php?f=8&t=16207&p=16207&hilit ... res#p16207
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
jscarmozza
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Re: Class Lamps and Smokebox Heat

Post by jscarmozza »

Attached is a photo of my 1" Atlantic's working classification lights and headlight. I made 20 ga. steel mounting brackets to stand the lights off from the smoke box and used 18 ga. high temp (insulation) wire with shrink wrap for the conductors. I packed the resistors for the classification light's LEDs in the headlight and painted everything with liquid tape to avoid short circuits because I grounded to the body do to space limitations. The lights have been working fine for about 2 years, heat doesn't seem to be a problem. What I would suggest is to match the colors of the lights, my headlight lamp is a 6v. incandescent which is yellow in color, while the classification light lamps are LEDs and blush white in color.
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Dick_Morris
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Re: Class Lamps and Smokebox Heat

Post by Dick_Morris »

Stainless steel is a lousy conductor of heat compared to other metals (16% of brass, 12% of aluminum, 35% of carbon steel). Using it for stand-offs or brackets would decrease heat transfer somewhat.
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Greg_Lewis
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Re: Class Lamps and Smokebox Heat

Post by Greg_Lewis »

Don't over-think this. Make up the lamps and put them on. If the LEDs fail, replace them with grain of rice bulbs. These guys have incandescent bulbs down to .055 in diameter. https://cir-kitconcepts.com/shop/index. ... Path=13_42
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
Mike Walsh
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Re: Class Lamps and Smokebox Heat

Post by Mike Walsh »

Your plastic lenses would probably melt before the LEDs...
BillF
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Re: Class Lamps and Smokebox Heat

Post by BillF »

I would worry more about melting the electronics-grade solder used to connect the LEDs (unless you have some appropriate crimp-on connectors). That temperature is usually right around 370F. One potentially clever scheme might be to incorporate one of the many finned black-anodized heat sinks, made for electronic components, into the body of the lamp. (I'm thinking about the ones where the fins are co-axial disks separated by a small air space.) The black color often makes it hard to see the fins unless you look very closely at the part.

- Bill F
KarlKobel
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Re: Class Lamps and Smokebox Heat

Post by KarlKobel »

Mine are mounted on small blocks (the supplied 'brackets' were too weak).
I don't think there is much of an issue with conducted heat, only radiated heat.
Mine have been installed for three years of running without failure of the electronics or the supplied plastic lenses.
The electronics is 4 LEDs, two white, two green, a current regulator, and a hall effect switch.

Karl - www.karlkobel.com
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Greg_Lewis
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Re: Class Lamps and Smokebox Heat

Post by Greg_Lewis »

Karl:
What is a hall effect switch and what does it do for you?
Greg Lewis, Prop.
Eyeball Engineering — Home of the dull toolbit.
Our motto: "That looks about right."
Celebrating 35 years of turning perfectly good metal into bits of useless scrap.
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