@Mellow Hudson Mike, the opposite is true of open frame motors. They run measurably hotter on DC whereas in your case with DC can motors, the rectifier emits a negligible mount of heat barely perceptible to performance.
Okay, now I'm confused (again. )
The "Tracks Ahead" series did a video of the "Robinson Layout", featuring American Flyer S gauge. In that video, the narrater mentions that, by installing rectifiers in his engines, they will run "smoother and cooler" on DC.
Is that because the power source (transformers) are still supplying AC? Really, aren't most, if not all, "modern" engines, equipped with DC can motors, doing the same thing?
Mark in Oregon