@O Gauge Jim posted:
Hi Rob, I am confused by your post. All the diagrams I have of proper connection of transformers shows the U terminal going to the number 2 lock on terminal which connects to the two outside rails. It shows the A or B terminals going to the number 1 lock on terminal which connects to the center rail. Jim
Generally speaking with classic transformers, in isolation, those designed to run a single train had the U terminal as the variable post. With transformers with multiple variable taps, the U terminal was the common ground.
Much of Lionel's documentation was focused on the simple layout, especially in their generic instruction sheets and it really didn't matter (inconsistencies can be found).
Yes, that instruction is a little misleading, but as bmoran points out, this works with a basic set. The problem comes in with common ground layouts, and accessories that use the common ground as a return to the transformer, unlike the lamps illustrated. If you used "U" as common, every time you used the direction switch the accessories would cut out.