I noticed an odd problem with my Polar Express. When running with a revised CW80 transformer, the train will run at a set speed for about 15 minutes or so before beginning to slow down. If I don't increase power, the engine will eventually stall in a curve. When I do increase power, after about 10 more minutes, the train will suddenly speed up and I will have to reduce power to bring it back to a normal speed. After noticing this, I switched over to my old Type R Lionel transformer and the problem went away. The train runs normally without the odd slow-down and even seems to go through curves more smoothly. I'm *guessing* that the CW's sine-wave pattern has something to do with this, but why does the engine eventually speed up again after running for a while?
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