[PRCo] Re: PCC__Speeds

[Jim Holland]

Good Morning!


>> From: Jim Holland <PghPCC at pacbell.net>

>> 1.>-- You say that changing from 50% to 67%
>> field-shunting yields faster  *acceleration.*   
>> This would just be the *Rate--of--Change*  in speed,
>> not the ultimate speed  --  is this correct??

> Pepa Kalousek wrote:
 
> No, this also causes the balancing (ultimate) speed
> somewhat higher.

	Thanks!    Gives a better understanding of this statement from
pgs.145-146 of  *The__Book* (in the process of learning!)::

	"""The first Westinghouse controller, used on PRCo PCC 100 in
1936, differed from the original pilot unit in that it had 99
instead of 66 points, with all of the accelerating resistance
being cut out by the 75th.    Field Shunting was progressively
inserted at points 78, 79, 81, and 82 to boost the balancing
speed of the car from 25 to 42 mph."""


	Would this be a good description of field shunting:  Diverting
power from the armature to the field?    This would then result
in a stronger magnetic field that would allow for the same
current to the armature to produce a higher speed.


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Waiting for a bus is as thrilling as fishing,
    with the similar tantalisation that something,
        sometime, somehow, will turn up. 
            George Courtauld

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James B. Holland

• Holland  Electric  Railway  Operation....... 
  "O"--Scale St.-Petersburg Trams Company (SPTC)
	Trolleycars and "O"--Scale  Parts
		including Q-Car
	mailto:pghpcc at pacbell.net

• Pennsylvania Trolley Museum
	http://www.pa-trolley.org/
• Pittsburgh  Railways  Company  (PRCo),
	1930  --  1950
• N.M.R.A.  Life member #2190;
	http://www.nmra.org

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