No reverse, revisited

Classic Toy Trains Forum
1

I while ago, I posted a problem I was having with my 681. After cleaning the commutator, it suddenly refused to go in reverse.

I promised to post the solution whenever I found it, so here it is: I was studying the E-unit again today, after having just sprayed it with tuner cleaner for the thousandth time. All the fingers were still in alignment, and all the contact surfaces of the drum were still clean and shiny.

But this time, I noticed that one of the bronze fingers seemed slightly out of alignment. With a jeweler’s loupe, I looked more closely. I discovered that the metal just below the bend of the contact finger had become flexible. In fact, it was nearly falling off. Metal fatigue, from the look of it. It’s just short of breaking off, and yet when inspecting it, it appears perfectly healthy. But it doesn’t make proper contact with the drum any longer. Time for a replacement.

Just why this problem should have surfaced at exactly the time I cleaned the commutator remains a mystery. I guess coincidences do happen, although this sure seems a strange one.

I hope this helps someone else who might run into the same problem.

2

You can get a second life out of that finger if you want. The fingers are made with a right-angle bend at the end, then a semicircle. The semicircle wears in the middle where it touches the drum of course and half of it eventually falls off. If you flatten the 90-degree bend to about 45 degrees you can expose a different part of what is now a quarter-circle to the drum for the next 50 years.

3

Reminds me of the story of the Grand Ol’ Opry. During the renovations in the 70’s they planned to scrape all the old chewing gum off the bottom of the benches, but they discovered after their first attempts that the chewing gum was all that was holding the benches together! [(-D] Maybe your E-Unit was also being held together only by years of gunk build up! [(-D]

Becky

4

I just bought a rebuilt E unit, and the instructions say not to use WD-40 on the inside of it. Maybe the tuner cleaner could have been too strong and ate some metal away.

Lee F.