Good afternoon to any interested readers,
As stated in my previous post just below, my two (2) Davenport Gas Mechanical Engines (DGME) were operating at a slow, reliable speed on my test track (less than 5 smph). Operating them on my layout was a different story, both only running several inches before stalling and stopping, requiring a nudge to get them moving again for a few more inches. Why? Back at the test track again, they ran smoothly.
Trying to keep this short, my test track is a 3-foot section of flex track, no joints, curves, turnouts, scenery and cleaned before every test session. The layout had all of these. Apparently my track laying skill on the layout was not quite as good as it should have been. Testing as I built, my Shay and Porter engines operated reliably, overcoming my unknown errors. The recently acquired DGMEs are fussier. "Close enough for government work" is not acceptable.
After several days of thinking, then going over my layout track again with the NMRA gauge, and making necessary adjustments/corrections, I have reached the following conclusions. The Shay (15.8 oz.) and Porter (5.8 oz.) have more mass, weight, larger wheels, higher axle clearance; hence, slightly more forgiving. The DGMEs (5.5 oz.) have smaller wheels, lower axle clearance, lower and wider front and rear running boards and less weight/mass; hence, less tolerant.
The running boards showed me scenery that was too close/too high at the track which "snagged" the engine. I use a brush to weather my rail and ties. Evidently some of the simulated track spikes on the tie plates received enough paint to eliminate Peco's designed clearance for the spikes, causing a bumpy ride or complete stall by the smaller wheels.
In conclusion, my DGMEs run a lot better on my layout track. So, if you have similar problems, I advise to check your track before tearing down your engine or sending it back to the factory to cure a problem that might not be there.
Old Pilot