I have a number of these Bachmann 4-8-2 Mountain locomotives, the C&O ones with the flying pumps and vandy tenders,...one of my favorite designs.
They suffer from the 'derail prone' pilot truck syndrome, and I am looking for solutions,
I was looking at the drawings that came with the locos, and a question came to mind. Am I reading the drawing correctly,... that there was at one time some sort of spring-metal part to push down on that pilot truck.....part # H114X-MTB44 in this dwg?
HO Spectrum Mountain loco.jpg
https://d28lcup14p4e72.cloudfront.net/259338/8603894/HO%20Spectrum%20Mountain%20loco.jpg(https://d28lcup14p4e72.cloudfront.net/259338/8603894/HO%20Spectrum%20Mountain%20loco.jpg)
While I can't speak of this locomotive in particular, similar springs on the pilot truck were used by Mantua/Tyco for the same purpose.
These Mountains are also among my favorite locomotives, for looks and pulling power.
Sooo... the front truck--I adjusted the wheel gages on my trucks--they were slighlty off.
Also, I added very, very small amounts of lead to the top of the truck... just glued it on top. That solved all my derailing problems.
Another thing to check is the loco's balance. The center of gravity should align between the middle of the drivers.
Can't speak to the spring you showed. Not near my locos at the moment.
Regards,
Jonathan
Your engines don't have that Spring?
That looks like the same spring as used on the decapod.
https://estore.bachmanntrains.com/index.php?main_page=product_info&cPath=68_158&products_id=9182