Bruce,

I saw what appeared to be carbon (or graphite) brushes in use on the
Lake Compounce carousel.  You mentioned trolley wheels.  I've thought of
this, but wouldn't anything which rotates have some sort of bearing or
bushing at the point of rotation, which assumes a minute amount of space
in which electrical arcing would naturally occur, causing eventual
burning out of the components?  Isn't this why the more prevalent
methods were the brass fingers or replaceable carbon?

Bill Luca