I agree, the Classic Toy Trains forum is the right place for this inquiry!
I recently went through the second of my two pendulum reverse units, they’re very interesting devices.
The reverse unit itself has no brushes (I assume you meant the motor??). It has a set of 4 or 5 fingers, depending on whether it is for a steam or an electric locomotive, which move over a contact plate, to reverse the motor (and headlight, on electric outline models).
There is a steel, pivoting ‘flapper’ and a thin contact strip as well. In operation, as the motor powers up, the flapper will be drawn towards the motor field, breaking contact with the contact strip. The solenoid that throws the pendulum reverse is wired to this contact, such that initially it will get power when the track is energized, and then as the motor starts up, the flapper is pulled down, and the solenoid is de-energized. So the solenoid should only briefly get power, just long enough for it to throw the pendulum.
There are a number of issues that can cause these units to misbehave. They can perform very nicely, but require some TLC to get there.
Here are some pictures of the unit I recently worked on:
On the left is the contact plate, and pendulum with contact fingers. Immediately right of it is the solenoid. way over on the far right is the flapper, and above it (but not especially visible) is the contact strip (mounted to a piece of fibre board). Below the flapper is the brass ‘lockout’ lever for keeping the unit locked in one direction. It does so by forcing the flapper to remain down, even when the motor is not running.
Here is what the back of the contact plate looks like:
Note the two small contact patches set at 90 degrees off from the others. These are only for electric outline models, and are used to provide directional lighting.
Here is what the fingers look like- note that mine were badly worn, one of them all the way through. My solution was to make my own patches out of phosphor bronze sheet from K&S Metals.
Note the tiny finger at 90 degrees off from the others. Again, this is present for electric outline locomotives, and is for providing directional lighting.
Note that O gauge pendulum reverse units have the same parts, but use a differently shaped brass housing that is designed to mount onto an O gauge motor. The unit I have shown is for the Lionel ‘Super Motor’ and the standard gauge ‘Bild-a-Loco’ motor. Again, though, while the brass chassis is different, the O and Standard units use the same ‘internal organs’.
-El