July 12, 2009

Curve Radius Test Video

I was able to spend some time testing my new 4-4-0 locomotive, the USMRR Whiton. This locomotive did not run as well as the other two I had. As I observed it, I noticed that it was derailing the front truck on the tight curves in this part of the layout. The derailing was occurring from interference with the pilot truck and the pilot above it. I added some shims (0.045 inches) and stretched out the spring on the mounting bolt. This raised the pilot slightly and removed the interference. That seems to have fixed the problem. I am hoping that a back EMF decoder may resolve the slowing down problem on the curve.

I made the video using an iPhone 3GS. The location of the tiny lens on this camera allows for a really low "worms eye" view of the action


  1. There did seem to be a little hesitation as the loco entered the curve? Was that just a video artifact?


  2. No, the loco does slow a bit as it enters the curve. I am currently using a DC power pack. I am hoping a back-emf decoder might smooth out the performance. I also cleaned the track after I made the video and that helped too.

  3. AnonymousJuly 13, 2009

    That is an interesting idea to shim the pilot to raise the steam cylinder relative to the wheels, because that is what impinges on my SMR Atlantic. I have increased my min. radius to 30" and the Atlantic runs well in general. Because it is 'tender driven', rarely the drivers will slide rather than turn. I think this will resolve with run in.

  4. Yes. It was the pilot truck side frames that were hitting the cylinder and frame. My Whiton was also sliding every now and then. I oiled all the rubbing surfaces and that seemed to help. But since I added the shims that problem seems to have gone away. I wonder if the slight weight transfer to the driver wheels helped?

  5. Glad to see progress has resumed...

  6. Gary GoodmanJuly 16, 2009

    Glad to see you are back. You had mentioned that Your Winton was somewhat louder than other locos you have ,did you find the cause of that?
    I have a Texas engine that does seem to be noisy
    but had nothing to compare it to.It has only been test run , so it may just need broke in.
    My progress on my railroad has been only that of buying things for it, this site is a moral builder for me, Thanks for having it on the web. Gary

  7. Brian and Gary,

    Thanks for the positive feedback. I'm glad you are enjoying the site. As for engine noise, all three of mine seem a bit on the noisy side. Hopefully sound decoders will help muffle the none prototypical sounds.