[PRCo] Re: Motor clarification

[roger]

Actually Fred a some of the territory that CL&E ran thru in Ohio was
undulating hill and dale but the cars rolled right thru this without much
effort for the roller coaster effect.
----- Original Message -----
From: "Fred Schneider" <fschnei at supernet.com>
To: <pittsburgh-railways at dementia.org>
Sent: Monday, March 10, 2003 8:50 AM
Subject: [PRCo] Motor clarification


> This responds to a query from Holland about PCC motors.  If that doesn't
interest
> you, delete now rather than be bored!
>
> To the contrary Jim.  Just because blown motors were a 1940 improvement
doesn't
> mean they lacked importance.  I find it significant that after merely four
years
> experience someone decided to force cool traction motors.  Probably Bill
> Rossell.   The basic laws of physics didn't change in 1940 or 1945; rather
> someone got tired of spending money rewinding traction motors and he saw
an easy
> out once there was no compressor to drive off the MG set.  .
>
> Maybe I was not clear before.  The advantage of a series wound DC motor is
> simple.  It creates the greatest torque at the slowest speeds. This gives
the car
> a lot of get up and go, and an ability to climb steep grades.   The
disadvantage
> is heat build up is also greatest under load at the slowest speeds.  And
if the
> fan is on the armature shaft, the heat dissipation is worst at the slowest
speeds
> because the fan is also turning slowly.   Now consider also that motor
vehicle
> traffic also increased in the late 1930s and drastically in the late
1940s.  As I
> write this I'm looking at a color picture of PRC 4823 followed by four
other cars
> in front of the Cathedral of Learning on Fifth Avenue in Oakland.  It was
a
> traffic jam of streetcars and motorists.  I remember riding through there
in the
> late afternoon with my mother .. we moved inches at a time.  That sort of
traffic
> is deadly to internally vented traction motors.  They just sit and bake,
and bake
> some more.
>
> With a 1600 or 1700, that wasn't a problem.  Air was forced through the
> propulsion motors at a constant rate of flow.  Didn't matter if the car
was
> moving at 40 mph or lugging along on resistance, and stopping, and moving
another
> twenty feet, and stopping again.  The motors were constantly being cooled.
>
> What happens if you don't cool them.  Remember the Lehigh Valley Transit's
> Liberty Bell Route?  They were plagued for the life of the Ten-hundreds
with
> burnt out motors.  Why, because motorman on the HL cars notched up too
rapidly
> and the accelerating limit relays on the PC equipped cars were set too
high just
> to make them accelerate on hills (without locking up).  These cars were
> engineered to run flat out across level western Ohio but not to run up and
down 5
> percent grades in eastern Pennsylvania with stops every half mile or so.
Out of
> 12 cars, I think about three or four were available for service on the
last day.
> The Indiana car (1030) was in the shop for motor work (it came out on the
> abandonment afternoon).  So what happened to all those "junk" motors?
Red Arrow
> bought all of the GE 706 motors for spares for the Bullet cars.  And once
they
> were no longer abused, they worked fine.
>
> fws
>
>
> Jim Holland wrote:
>
> > Good Morning!
> >
> > > Fred Schneider wrote:
> >
> > > I went back to the equipment chart in the PCC book ...
> > > the easiest way to determine blown motors is on
> > > GE cars because that apparatus supplier changed the
> > > motor number.  Their 1198 motors were internally fan
> > > vented, while the 1220 weries were blown motors.
> > > The first cars in Pittsburgh with GE 1220 motors were
> > > 1675-1699.  .
> > > If you have the first edition of PCC From Coast to Coast,
> > > there was a fold-out chart in the rear.  It did not appear
> > > in second edition (I think Mac was trying to save money).
> >
> >         Actually in  *PCC The Car That Fought Back.*
> >
> > > ...You'll find that the 1600 had 1432J, cars 1601-1975 had
> > > 1432HE and 1700-1775 had 1432K........
> > > How were the motors on the 1600s ventilated.......
> > > I apparently found evidence that the 1600s had a
> > > PC2 compressor,  which had to be driven off a pulley
> > > on the MG set.    This suggests that the other end
> > > drove a single fan to cool both the resistors and
> > > the motors, and to heat the car.
> >
> >         VERY  Interesting.    Apparently associated the move from
Truck-Level
> > air-intakes to Roof-Level air-intakes to Also mean Forced-Air (Blown)
> > Ventilation   ---   but after reviewing the charts as you suggested, I
> > Now see that All That Changed was the source of the air!
> > Truck-Level air source allowed for dirt stirred up by car movement to
> > be drawn into the motors so Air-Source was changed to roof level!
> >
> >         So the 1600--1799 cars were the Only PRCo Cars with Forced-Air
> > (Blown) Motor Ventilation  --  all other cars used Motor-Mounted Fans
> > for ventilation.
> >
> >         Cooling of motors must not have been a real problem since
> > Forced-Ventilation came along so late in the game.    Maybe this
> > development was held up by the war as well.
> >
> >         Thank You for taking the time to clarify this Information.
> >
> > > Please note that all-electric cars do not
> > > require standee windows.
> >
> >         Good Heavens   ---   A Given!    How did Windows get introduced
into
> > Electrical specifications?!?!(:->)
> >
> > A reminder (how often do you need the Reminders?!)
> >
> > Assignment__For__FWS3:::::::
> >
> >         Next time at PTM, please check the spare PCC trucks.
> > B2Bs have an obvious cradle welded to the tube frame for
> > holding the Rubber--Spring  bolster.
> >         **-PCC The Car That Fought Back-**  pg.128 shows
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