I don't know about you, but one of the things I really wanted to have when I built the train room was a stand alone test track.
It comes in handy to run locomotives off the layout, and it's closer to my tools for repairs and adjustments.
It's a rather simple affair, where I set a piece of flex track on a strip of cork, hooked up to a cheapie power pack.
Having a power pack on the work area is helpful as well, in that you can test accessories and lighting equipment for the layout.
So here's some pics of a P1K Erie Built B Unit I cleaned the wheels and checked the coupler height on.
The Test Track:
Here's the B Unit getting one truck cleaned at a time. I put solvent on the paper towel and ran the unit , spinning the wheels on the solution. It left black "skid marks" just like at the drag strip!
And here's the Kadee Coupler Gauge sitting on the track. NOTE:
DO NOT USE THE GAUGE WITH THE POWER ON!!!!!!!! (Did I use enough exclamation marks?

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Oh, and one more bonus- the test track doubles as a place to park your rolling stock and display them when not in use!
