The Universal Current Controller (UCC) Switch
From page 18 of the 1923 Lionel catalog showing the "Twin Motor" 42:
"Universal Current Controller (Patent Applied For) A Unique device is affixed to these locomotives so that by simply moving a lever the windings of the motors are changed to series (which is the best winding when they are operated on the reduced direct current) or to multiple (which is the best connection when operated on reduced alternating current or on dry or storage batteries)."
I've wondered about this mysterious device ever since I first read about it. Being primarily interested in classic period standard gauge, I did not have a 42 loco in my collection until recently. I've been unable to find a wiring diagram for the twin motor 42, so I decided to search for a 42 with the original wiring intact including the Universal Current Controller (UCC). I wanted to answer questions in my own mind as to exactly how the UCC was wired and what the it did, and to prepare a wiring diagram of the loco.
The first twin motor 42 I located was missing the switch and wiring. However, I soon found one that appeared to have almost all of its original wiring and the UCC switch intact.
The loco was a bit rusty and the 80+ year old wiring was severely cracked and crumbling. But this loco was a great candidate for my wiring and research project.
For several days I worked on disassembly. As I removed the old wiring I began to prepare a wiring diagram to aid me in re-wiring the loco later on. Part of my time was spent removing rust and cleaning the cab, wheels and motors. Finally, I was ready to start re-wiring and re-building the loco.
As I re-wired each motor they were tested individually to insure that they functioned. I did encounter one glitch. The second motor blew out its commutator during the test run. So I had to wait a few days until a good friend helped me out by installing a new commutator on that motor's armature. Once I got the armature back I re-assembled the motor, tested it, and then I began the process of re-assembling the motors into the loco and the two switches. The twin motor 42 has both a reverse switch and the UCC switch. Both switches have four screw terminals.
It was a thrill to place this old refurbished loco on my layout and see it glide down the main line with sparks flying and the sweet smell of ozone in the air, with its side rods and cast iron wheels sparkling and flashing once again after so many years of neglect. The only change I had to make to my wiring diagram was to reverse the connection of the brush wires to one of the motors to get both motors working in tandem.
As for the UCC switch, I have it set in the AC position. I'm not an electrical engineer, but in looking at the wiring diagram it does appear to me that setting the UCC switch in the AC position feeds current to the field coils of both motors in parallel. Setting the UCC switch to the DC position feeds current to these field coils in series. What effect this has in terms of current draw I do not know. Why this setup is preferable remains a mystery to me. Perhaps someone reading this article can shed some light on the subject.
Here is the wiring diagram for the twin motor 42:
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