[PRCo] Re: Wheels__&__Shoes

[ktjosephson at earthlink.net]

Old WEPCO documents indicate that TMER&L believed that mixing shoes and
wheels was a problem because wheels tended to bounce and arc more often
shoes, causing the wire to peel. (See page 436, CERA Bulletin 112.) Cars
equipped with shoes would plane off the peelings,  supposedly weakening the
wire. This was based on their own findings during the 1920s when rebuilt
interurban cars were equipped with shoes and run in mixed service with
wheel-equipped city cars on some stretches of street trackage. Greasing the
wire seemed to help reduce wire wear.

I wonder if TMER&L's conclusion was based on one individual's personal
belief, or if a superintendent needed an excuse to slip an all-shoe fleet
proposal past the bean counters.

I am certainly not an expert, but I would think the condition and type of
wire (round or grooved), base spring tension on the cars, speed of
operation, road bed condition, etc. would affect the amount of bounce the
collector would have as it rode along the wire. This is indicated in the
book as well as blaming starting with a heavy load from a dead stop with
such a small area of contact on the wire ("high current density") for wire
wear.

I do not know if mixing shoes with wheels really caused problems, or if
these problems are only evident on heavily traveled sections of line.

Pittsburgh had lousy track for years and  used wheels long after most other
North American operators went to shoes.

Most operators found shoes to superior for all-around operation. As I noted
above, maybe the Milwaukee system had a large stock pile of wheels and
wanted to justify a large scale conversion to shoes. Corporate leaders are
more likely to let the worker bees make do with what's on hand unless
somebody can convince them that a major investment in change would be a
profitable benefit to the corporation.

But I would like to know why Pittsburgh did stick with wheels for as long as
it did. I know this was touched on in "Traction and Models" during the mid
1970s, but a definitive answer from PAT was never published in the article.

K.