Speaking of Air Brakes on 1600 B-2s and B-3s

[Jim Holland]

Greetings!

Fred Schneider wrote on Mon, 28 Feb 2000 16:23:46 -0500:

> There was a 1940-ish study by Transit Research Corp. comparing air brakes on
> a Pittsburgh 1200 with spring drums on a St. Louis 1500.  A conclusion was
> made that the springs could never possibly hold a car on Pittsburgh's hills.
> I can personally guarantee that the spring drums would not hold a Pittsburgh
> 1700 on Henderson Street (21 FINEVIEW) because I staged such a fantrip in
> 1958.  Track brakes were ineffective too.  The car coasted backward until
> the track shoes were canted upward at a 30 degree angle.

	This would be a physical impossibility!
	The two track brakes on each truck are bolted together through two
steel arms fore and aft located below the truck frame.  This can be seen
in the top left drawing of the B-3 plans on page 134 of *PCC The Car
That Fought Back.*  While this shows the configuration for B-3 trucks,
the same method of joining the two track brakes is used on B-2s as well;
otherwise, the track brakes would flop around in the breeze and be
totally ineffective!  There are snubbers/guides fore and aft of the
track brakes so the track brakes do not make contact with the wheels.
	The braces holding the track brakes together would have to be broken on
both sides for the track brakes to achieve any angle to the rail  -- 
and this on both trucks to allow all track brakes to be canted at
30-degrees.  But on a B-3 truck the drum-shaft brake actuator is in the
way preventing more than a couple degree rise!  And on a B-2B for the
city 17s, compression springs are used for mouting the track brakes. 
The plate that the spring rested on would prevent much of a rise of the
track brake as well.

	Additionally, if the track brake is energized, the whole brake grabs
the rail and slides along the rail as long as the car is moving--that is
how the track brake works--uphill--downhill--on the level!!!  There is
no reason for it to lift off the rail unless a considerable obstruction
is present - and it would be strange for such an obstruction to be
spaced exactly for the spacing of trucks on a PCC to make all track
brakes rise at an angle!  And the design of such an electromagnet does
not allow for one end to be de-energized, the only other possible
explanation for such a problem as one end gripping while the other is in
the air.

	While the drums on a 17 may not have been as effective as desired on
hills, I see no reason that a 17 could not be stopped on a Fineview hill
with drums and track brakes  --  and without a display as mentioned
above.  I rode a 17-interurban on a charter on Fineview and we made it. 
I don't remember any comments about brake problems.  And page 106 of
Volkmer's all color book on PRCo--WP--JTC shows 1708 stopped on
Henderson on 1959.04.26, a charter to cover the West End lines before
abandonment.

James B. Holland

        Pittsburgh  Railways  Company  (PRCo),   1940  --  1950
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