Yesterday, someone asked what radius meant. Yesterday, I also ran across a term ("ghost car") that I'd never heard. Both made me think we could use a go-to list to post definitions. The definitions can be be basics to help beginners understand the terminology, or obscure terms like Bob's "Gandy Dancers". Sooo....post 'em! I'd like to suggest posting your term at the beginning of your entry so a new person can scan down the list and find the item you thoughtfully provided. Thank you!
: Definition: A ghost car is a model railroad freight or passenger car that's equipped with a motor and driving trucks. This motorized car helps power very long model trains. When needed, a ghost car is placed somewhere near the middle of the train. If multiple ghost cars are used, they are distributed evenly throughout the train.
: A radius in geometry is the distance from the center of a circle to any point on the circle. For model train track, radius is a measure of how tight a curve is. Let's suppose you have a circular layout: no straight pieces. If you put a pin in the exact center of the circle and then measure out to the center of any piece of track, you have a measurement of the circle's radius and therefore the measure of the track's radius.
: Gauge is the distance between the tracks. Normal track gauge (on a real train) is 4' 8 1/2" between the rails. The model train you are looking at has wheels that are (side to side) a specific distance apart; that distance matches how far apart your rails are. Gauge is not the same thing as scale, but it's an indicator of the size of a model train.
: Scale implies that is it a scaled down version of the real thing. It starts with the car or engine's relationship to itself (1:1, or "one-to-one"). If it were half the size of the original car, the relationship would be "one inch on the real thing = 1/2" on the scaled-down version". This is written as 1:2. Scale is always based on a mathmatical relationship between the real thing and the model. O scale
(not gauge) is 1:48, so the O scale car is 1/48th the size of the original. Scale refers to size of the car or engine compared to the original; gauge refers to the distance between rails on a length of track.
: A section of track with movable rails to divert a train from one track to another. Also "switch," although technically the switch is only the moving parts of a turnout. "Turnout" also avoids confusion with electrical devices.
: The word "switch" is often used in place of "turnout" (defined above). It also refers to the mechanical part of a turnout, both on layouts and in real life. Finally, it also refers to electric switches. For clarity in conversation, most model railroaders try to use "turnout" to identify the track section described above. "Switch" is reserved for the electrical or mechanical device that controls the turnout.