[PRCo] Re: Fineview___PCCs

[Boris Cefer]

From: "Fred Schneider" <fschnei at supernet.com>
Subject: [PRCo] Re: Fineview___PCCs


> If you are suggesting Tony DeSensi at Arden ... he was a parts replacer
who
> could get a car moving.

But he should know particular parts and how the assembly works. When
electric brake actuators are adjusted at shops (heavy maintenance), they use
a dynamometer to adjust them at 55 kilogram pull. Don't know exact value in
lbs required by WABCo specification.

> Regarding variable rate drum brakes:  drums were generally used only in
> conjunction with extended dynamic brakes in North America, which extended
the
> dynamic brake capability down to about 1 mph or about 1.5 feet per second.
> Given a normal braking rate of around 4 miles per hour per second, the car
is
> going to stop in about 4/10ths of one second after the drums come on,
which is
> faster than any operator could adjust the pedal depression to change a
braking
> rate.  Regardless of such reality, General Electric did build variable
rate drum
> brakes which, to me, seems somewhat lame.

I don't know much about GE, but Westinghouse equipped PRCo 1700s had their
drum brake control circuits designed so as to obtain 3 different braking
rates. Wiring diagram shows it clearly. And we had the same arrangement on
earlier equipment.

> I was not aware that anyone had variable track brakes.  The general
principal
> here is that you simply don't use them in normal service because they
cause
> excessive rail wear, particularly at stops.  A good operator simply
doesn't push
> the pedal more than half way down.  We also don't want the passengers to
be
> alarmed by hearing the emergency buzzer.  And when you need them in an
> emergency, graduation of the braking rate is the last thing you think
about ...
> at that point you want the car to stop yesterday.   But given the the
propensity
> of  car owners to dream up something that distinguishes their cars from
everyone
> else's, I don't doubt that it happened.  I recall questioning a control
engineer
> from General Electric  about all the various control and motor designs for
> PCCs.  I was bewildered.  His answer was simple.  GE wanted to make money
and if
> the customer didn't like the off the shelf product, they would change it
to get
> the money.
>
> Make sense?

GE policy? Why not. But again - I don't know GE. Westinghouse 1700s had 4
(F-O-U-R) rates of track brake actuating. Gives sense to you?

> Boris Cefer wrote:
>
> > Wasn't the problem of all-electrics in lack of drum brake adjustment?
Maybe
> > no. The soft adjustment of standard all-electric drum brake would
provide
> > very long stopping distance on steeper downgrade and the shoes would
suffer
> > heavy wear.
> >
> > Maintenance specification we use here for drum brake says that each car
must
> > be tested by removing of drum brake fuse and pressing power pedal to
reach
> > starting current of 290 Amps - drum brakes must hold the car (on dead
level
> > track). 290 Amps cause approximately the same traction effort as 9.5 %
> > downgrade. Sometimes we experience drums which are sufficient to hold
the
> > car at 350 Amps, which would be about 11.5 % downgrade, but this is with
new
> > brake shoes and freshly adjusted brake. I think there is no considerable
> > difference between WAB brake and our CKD product, as for the braking
> > capability.
> >
> > But if you find any drawing and cpecification for WAB drum brake and
> > actuator at Arden (that would need some work - consign it to limbo), I
can
> > easily made a calculation and answer the question of maximum grade which
> > allows drum brake operation.
> > Or you can ask Tony, I think he has some experience with 1700s. I am
curious
> > what he knows about drum brakes.
> >
> > B
> >
> > ----- Original Message -----
> > From: "Fred Schneider" <fschnei at supernet.com>
> > To: <pittsburgh-railways at dementia.org>
> > Sent: Thursday, March 11, 2004 11:32 PM
> > Subject: [PRCo] Re: Fineview___PCCs
> >
> > > The 1600s did not have spring applied drums ... they had air brakes.
It
> > was my
> > > understanding (correct or incorrect) that the cars used on Fineview
were
> > set up
> > > for higher brake pressure.  Extended dynamic braking would not have
been
> > > significant because the cars would stop automatically ... they faced
> > forward
> > > uphill.  The problem was holding the cars on a hill.  I can assure you
> > that
> > > all-electrics would not hold on Henderson Street without also using
track
> > brake
> > > shoes.
> > >
> > > Boris Cefer wrote:
> > >
> > > > I know about 1689, 1690, 1695 and 1697. What else?
> > > >
> > > > But my opinion is that it had nothing to do with dynamics. The
problem
> > was
> > > > in drums which were not sufficient to hold the car on a steep grade
or
> > make
> > > > a rapid stop.
> > > >
> > > > Boris
> > > >
> > > > ----- Original Message -----
> > > > From: "John Swindler" <j_swindler at hotmail.com>
> > > > To: <pittsburgh-railways at dementia.org>
> > > > Sent: Thursday, March 11, 2004 10:37 PM
> > > > Subject: [PRCo] Re: Fineview___PCCs
> > > >
> > > > >
> > > > > Correct Jim.  Not gospal - just something once heard - or read.
And
> > the
> > > > > recollection is that it wasn't the entire 1680s.  Had to do
something
> > with
> > > > > extended braking - which sounds like something for Fred the third
to
> > clear
> > > > > up.
> > > > >
> > > > > Wish I'd paid more attention back then.
> > > > >
> > > > > John