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<b>Hold it. Don't take it out of context.</b><b></b>
<p><b>The Picture Window cars had MCM control, the only PCC cars built
for domestic sale with cam control. The design was totally unrelated
to the commutator control marketed by GE on all the other cars.</b>
MCM was an evolutionary advance (or whatever) from the earlier PC (first
built circa 1917 for four of the IRT Steinway tunnel cars) and PCM (1928
for Chicago Sedans). Unlike the PC and PCM units which used air over
oil engines to rotate the came shafts to make and brake resistance, MCM
used an electric motor drive. Cam controls were, at least in the
1950s and later, the standard rapid transit car scheme until it was supplement
by and later virtually supplanted by solid state thrystor control schemes.
Interestingly, I worked all day today with another trainman at Arden who
created his own version of history ... hour by hour ... tidbit by tidbit.
One of his gems was that cam controls were a Westinghouse invention and
something that GE never used. I have never found any reference to
cam controls prior to the IRT application. However, the other four
IRT cars in that Steinway tunnel order had Westinghouse PK control, which
was simply a K-controller mounted under the car driven by a pneumatic head
in response to the commands from the platform controller. And what
was a K-controller? Simply another form of cam. One friend
described PK as a poor man's PC; it fell out of favor very early on but
some examples have survived at Seashore (Montreal was the biggest fan of
PK and Seashore actually took four ex Montreal PK controllers and put them
on two open cars in an interesting attempt to run MU open cars in a museum).
In general, however, Westinghouse still favored pneumatic unit switch control,
under an alphabet soup of HL, HB, AL, AB, VA, ABLFM, etc. for most remote
control applications until after WWII while GE used electric solenoid switches
for hand advance schemes under the term Type M or cams for automatic progression
controllers. The beauty of a cam is the lack of a need for complex
electrical interlocks for automatic progression schemes.
<br><b></b>
<p>Jim Holland wrote:
<blockquote TYPE=CITE>Greetings!
<p> A while back we had discussions
on the split of the electrical gear
<br>between these two suppliers and were wondering why this was done, esp
in
<br>Pgh a Westinghouse town. While this does not specifically answer
the
<br>question of 'why-the-split' it does reveal reasons as to 'why the cars
<br>were scrapped.'
<p> Again from the very last
para-giraffe on pg.34 *PCC From Coast to
<br>Coast* I quote:::::::
<p> "The confusion with which
the MBTA dealt with its PCC fleet is
<br>exemplified by the scrapping program begun in late 1976. Of the
12
<br>all-electrics eliminated, half had been overhauled under the federal
<br>rehabilitation program between 1973 and 1976. Some of those cars
had
<br>gone directly from overhaul at Everett to pre-scrap storage at
<br>Arborway. Also hard hit by the scrapper's torch were the Picture
Window
<br>cars, both groups being singled out because of their non-standard
<br>General Electric control systems."
<p> While I personally prefer
Westinghouse, I am still quick to point out
<br>that this GE scrapping was probably due more to expediency than
<br>inferiority - the only GE cars on the Boston system were the
<br>all-electrics (25-cars) and Picture Window cars (50-cars) out of a
total
<br>of 346 PCC cars. With just better than 20% of the fleet being
GE, they
<br>were more oddball and a nuisance and ultimately used as a *reason(?)
for
<br>fleet downsizing regardless of the fact that they were the newest
<br>vehicles on the property.
<p>James B. Holland
<p> Pittsburgh Railways
Company (PRCo), 1930 -- 1950
<br> To e-mail privately, please click here: <a href="mailto:pghpcc@pacbell.net">mailto:pghpcc@pacbell.net</a>
<br>N.M.R.A. Life member #2190; <a href="http://www.mcs.net:80/~weyand/nmra/">http://www.mcs.net:80/~weyand/nmra/</a></blockquote>
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