11.24.2012

smooth moves

Recently I was helping my dad wire up a 2-track staging yard for his O-16.5, Welsh inspired portable layout. Dad already had the yard built and attached, so I just packed up my VOM and other electrically necessary tools for the job. The wiring itself was easy.

The staging yard is a removable shelf that attaches to the back of the quarry section of the layout. Trains enter and leave the sceniced portion through a hole in the backdrop.

The intent is to be able to park a couple of short trains off scene, and selectively power one track or the other. The layout is controlled with a Stapleton walkaround DC throttle so a simple on-off-on toggle did the trick in the new yard. A flying lead equipped with Anderson PowerPole connectors brought power from the quarry section.

The entrance to the yard was via a curve ladi across the edge joint and, due to some dimensional assumptions, there was a short slope from the backdrop down into the yard tracks. The included 18" radius section lead directly into the point end of a Peco insulfrog turnout.

And this is where the trouble all started.

One section of rail at the frog end of the "previously enjoyed and slightly shortened" Peco turnout had an intermittent electrical connection. In addition, the points are powered from their adjacent stock rails via small wipers attached to the base of the point rails. As a loco was moving across the turnout, slight shifting of the components made the electrical contact fail unpredictably causing jerky motion or stalling.

I was performing my functional tests with an HO P2K SW 4-axle diesel that (normally) runs beautifully. However, dad only uses 0-4-2 Bachmann and Peco/Branchline locos on the layout. When placed in service they wouldn't make it across the turnout without constant poking and prodding. A bigger issue turned out to be the track geometry itself. The short slope at the backdrop caused the cab end 2-wheel truck on the Bachmann locos to drop down and leave the track entirely, and the curve leading into the shortened point-end of the turnout caused the loco wheels to pick the point tips and derail.


While the equalised chassis of the Peco/Branchlines 0-4-2 engine managed the distance better than the rigid frame Bachmann "Anglacised" On30 Porters, the consistency of operation was not sufficiently high. Something had to be done.

After much filing and adjusting, Dad & I came to the decision to alter the brackets holding the yard shelf to eliminate the slope. He then tore up the track to improve the flow by inserting a short straight section just before the points. The turnout itself will be replaced by a live-frog version so that the short wheelbase locos can enjoy fewer interruptions in electrical pickup.


I'm still waiting to hear if the planned corrections have eliminated all of the problems. The physical distance between our homes makes it difficult to collaborate effectively.

Lessons:

  • avoid sharp transitions in vertical and horizontal planes
  • avoid curves leading into point end of turnout
  • use guard rails where necessary
  • ensure close fitting joints on curves

No comments: