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Model Railroading > Double articulating a Tenshodo Big Boy question

Date: 06/09/24 15:09
Double articulating a Tenshodo Big Boy question
Author: ATSFSuperCap

Hello TOers.    I am just wondering if any modeler out there has attempted to rebuild a brass articulated steam engine so that both the front and rear engines can swing under the boiler like a modern plastic model does, like an Athearn Genesis Big 
Boy.     I have smaller brass articualteds like a Rio Grande L-131 and even Tendshodo UP Challengers and they are fine on my layout.   However the Tendshodo Big Boy with a longer boiler really sticks out on curves and is scary close to say a passenger car on the outter curve.   It looks pretty bad also.   I do have a Trix Big Boy which is double articulated ie;  each engine pivots under the boiler it does look nicer on curves and will not sid swipe a passenger train on the outter curve.

My layout is double track ATSF New Mexico style with minimub 36.5" radius curves on the mainline.    The Tenshodo engine will clear a passenger car by about 1/8".   I am a very accomplished modeler so rebuilding the brass engine is within my capabilities but I am curious how another modeler might have done this, on any brass articulated.    

Richard Harris.

Date: 06/09/24 18:22
Re: Double articulating a Tenshodo Big Boy question
Author: bigmc83

I briefly owned one of these, and like most brass steamers, the motor and frame assembly on the rear are rigid and integrated. I believe the rear mech fastens under the cab with two screws and I’m sure another hinge point between the two mechanisms. I don’t think this is an easy modification and you’ll probably hurt the resale value if you care. I think Athearn and the other makers achieve this by center mounting the motor and having the mechs driven from each driveshaft….similar to a diesel drivetrain.
The one I had was my dad’s, and the main reason he preferred it to the plastic ones was because it articulated prototypically.
If you really want to, then you need to figure out how to just mount the frame at the hinge point of the two mechs. You’ll have to move the motor to the center as the rear mech won’t swivel if the motor is still back by the firebox.

Good luck

Posted from iPhone

Edited 1 time(s). Last edit at 06/09/24 18:26 by bigmc83.

Date: 06/09/24 19:52
Re: Double articulating a Tenshodo Big Boy question
Author: ATSFSuperCap

Hi Sean;   I do have two Genesis Challengers and one blew the sound board I had it apart and was amazed to see, as you said, it is set up just like a diesel!    I have replaced them with Tenshodo brass Challengers as I cannot stand steam engines with non sprung drivers and never mind traction tires.    They run rough down the track and do not pull for crap without the traction tire, and with the tire every jerk in the mechanism is transferred to the train.   What amazes me is how perfectly smooth the Trix Big Boy is and it has rigid drivers but you cannot tell.   The rear engine is mounted as you say at the back to the rear plate of the cab and at the cylinders to the boiler.    I have the experience and tools to make it pivot I thought I would see if anyone had done it and what their ideas were.    Thank you for your response.


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