Some information that you could add for people to help you.

Do the pony truck wheels pop off on straights, curves, switches,  all?

If curves what Diameter are the Curves (O-36, O-54 etc)

Have you inspected the front pony truck to ensure it is moving freely?

Good chance it is the wheel gauge (distance between wheels).  One wheel may be dropping in an popping the other out. Take a good look from the front and a picture down at track level (set camera almost on the track (no power) and see where you are.  Also, there may not be enough spring pressure on the front wheels.

Dan

I had problems with 2 wheel pilot trucks derailing on two of my engines:  a Weaver 2-8-0 and a K-Line 2-8-2.  Both engines are die cast, as is the pilot truck assembly, and both were derailing their pilot trucks at facing point switches.  After checking for some sort of binding that might raise a wheel and finding none, I installed several of those little "stick on" type wheel weights used by tire shops to balance mag or aluminum wheels.  These weights are only a few ounces so I crowded two if them on the top of the pilot tuck frame and one on the bottom, making sure that there remained enough clearance between the truck, the pilot, the track and the steam chest.

Problem went away!  Both engines negotiate all switches and frogs on my layout and I have about 65 switches total.   Since then, I have also used those little wheel weights on several locos to add weight or better balance the engine,  Cheap fix and it works, permanently.

Paul Fischer

Just picked up a 2013 lionel legacy 4-12-2 I use 072 fastrack, front end tilts and front truck derails

Anybody out there with any thoughts

Thanks much

I have an older Lionel UP 2-8-0 and the instructions included a passage about issues with the front truck derailing.

They recommended installing a coil spring between the truck and the frame if you encountered derailing. I ordered a spring and installed it and the problem was solved...

Tom

Kevin Thompson posted:

Just picked up a 2013 lionel legacy 4-12-2 I use 072 fastrack, front end tilts and front truck derails

Anybody out there with any thoughts

Thanks much

A video showing what’s going on will get you better results than throwing darts in the dark and hoping somebody hits the dart board....Pat

Got it working, got into my parts, found a stiffer cone spring, then used a little sense and put a straight inside of the cone spring, creating a stiffer dual spring, works great now.

Odd that it worked through all my switches and on all my other curves, only the one curve gave me trouble and note that it's level both ways, mounted solid, and my triplex had no problem there.

Anyways thanks alot

Keep on rollin,

Kevin Thompson

Good job! Sometimes a little trial and error works out. 

Tom