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So, I'm looking increase the entertainment value of my cabooses. I'm curious, how hard is it to add a smoke unit to a scale (MTH premier) caboose?  What sort of smoke units would be ideal? What other components would be needed? CV boards? Capacitors? Heat resistant materials?  Creative, constructive, and innovative ideas are all appreciated and highly valued! Been searching this forum for a while and I'm wondering if anyone has actually done it successfully. Cheers Railroaders!

Last edited by crzysnorider1218
Original Post

Hardest part?  Getting it apart.

I've installed several MTH HO smoke units in cabooses for folks.  I use a small DC-DC switching power supply with a bridge rectifier and filter cap to power the unit, some dropping diodes to run the fan at around 3 volts, and of course some brass tubing to mate the smoke unit to the existing chimney.

 

GRJ, at one time with MTH I seem to recall one needed to send in an old assembly to buy its replacement.   I'm not talking about individual components like wicks, heater resistors, fan motors, etc. but the entire assembly.  Also seems some assemblies can only be purchased by an MTH authorized service center or whatever?   Do either of these rules apply to smoke unit assemblies?

I must be thinking of another assembly item.  In poking around the MTH website, I don't see the asterisk symbol next to either the HO smoke unit or a PS2 smoke unit.   Both AA- numbers came up as order-able thru the MTH website parts ordering page. 

$45 and $50 respectively ...electronics not included...  shipping not included...  smoking is an expensive habit

mth smoke unit assemblies

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  • mth smoke unit assemblies

I like GRJ's approach of using an MTH fan-driven smoke unit.   7/32" brass tubing turned out to be a useful...as did heat-shrink tubing for alignment and better air-leak sealing.  Heat-shrink stays somewhat flexible for a minute or so after heating allowing alignment of the smoke-unit piping to the hole on the caboose roof to mate the chassis to the roof.  Using flexible piping method allows the smoke unit to be placed away from the walls for heat management (melting plastic).  

The arrow shows heat-shrink used as a coupler between two pieces of brass tube.  In addition to making for easy bends, I figure this reduces conductive heat transfer from the smoke unit up to the roof.

smoke unit elbow

In the measure-twice, cut-once department, I suggest thinking how to refill the smoke unit...ideally without having to open up caboose.  Think if all fluid drops will make it into the chamber and not leak onto the chassis.

ho smoke unit refill thru stack

And here's version 1.0 in action on a RailKing caboose using GRJ's suggested power levels of 5V to the heater element (about 3 Watts) and 4.5V to the fan motor.  I can't seem to get the video to embed so here's a youtube link:

https://youtu.be/Bq-44_9RAXo

 

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  • smoke unit refill thru stack
  • smoke unit elbow
Last edited by stan2004

That smoke unit happens to be an O-gauge model for small locomotives, but it obviously will work.  The benefit of the ran driven smoke unit, other than the fact you get reliable smoke, is that they don't get nearly as hot.  I haven't had to take any extraordinary measures to manage heat using one, unless the fan stops, I can't imagine it getting how enough to deform plastic, even right next to it.

BTW, the video doesn't work.

Last edited by gunrunnerjohn
gunrunnerjohn posted:

That smoke unit happens to be an O-gauge model for small locomotives, but it obviously will work.  The benefit of the ran driven smoke unit, other than the fact you get reliable smoke, is that they don't get nearly as hot.  I haven't had to take any extraordinary measures to manage heat using one, unless the fan stops, I can't imagine it getting how enough to deform plastic, even right next to it.

BTW, the video doesn't work.

You're right. It's from an O-gauge Alco S-2 switcher.  Here's a pic showing it (top) along with the HO smoke unit (bottom) from your posting: https://ogrforum.ogaugerr.com/t...oke-unit-for-o-guage

Small%20Smoke%20Units

I couldn't find a PDF exploded parts view for the S-2 on the MTH site but the smoke unit is AA-2100002, $40.  What's not clear is there's a brass cup / nozzle that must be ordered separately (if you want it).  The part number might be AA-2100008, $3.50 but there's no picture of it on the MTH parts ordering page and the dimensions they give don't exactly match what I have.   Anyway, I found it easy to heat-shrink over the brass cup to make a relatively air-tight seal.

smoke unit brass cup dimensions

I thought I knew how to post video, but I guess not.  I inserted a link to the youtube video in the original post.

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  • Small%20Smoke%20Units
  • smoke unit brass cup dimensions
Last edited by stan2004

the brass insert,  can be tapped  to 1/4-28 thread,   but  I  took it out  and  screw to hold boiler  goes into sm unit,  with a seal,  you can cut  the head of the screw off,   I have a lathe so  drilling thru screw no problem, 

if  anyone  wants anything like that  let me know,

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  • 20160125_102558: sm cup
  • 20160125_102724
Last edited by riki

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