Lionel KW Transformer - Classic Toy Trains Magazine

As stated above the ‘U’ is common and should be connected to the outside rails

The ‘A’ and ‘B’ is variable 6-20 volts (to run the trains)
The ‘U’ and ‘D’ is fixed at 20 volts
The ‘U’ and ‘C’ is fixed at 6 volts
The ‘C’ and ‘D’ is fixed at 14 volts

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