[PRCo] Re: PCC Accelerator, WH Version

Sun Sep 2 09:34:03 EDT 2007

Instead of writing a new book, I decided to attach a few pages from a book 
which has been written. The description is related to postwar Philadelphia 
PCC car of all-electric type (no air) with Westinghouse equipment. The motor 
cut-out switch described at the end was optional and not all PCCs were 
equipped by it.

What Jim has said is basically correct, but I feel a need to make a few 
comments. First, the accelerating rate of 4.75 mphps, while contained in 
literature, was not usually used in regular service and many properties used 
to set the acceleration up to 4.5 mphps. Second, the max. service brake was 
usually set at 4 mphps.

I have a nice video of an accelerating PCC type car taken from a pit which 
shows also the accelerator movements, but how do I send it? It is a huge 
file.

Boris

----- Original Message ----- 
From: "Jim Holland" <PRCoPCC at P-R-Co.com>
To: "- 1714 PRCo__WP__JTC -" <pittsburgh-railways at lists.dementia.org>
Sent: Sunday, September 02, 2007 2:50 AM
Subject: [PRCo] PCC Accelerator, WH Version

> .
> I may have confused Robert Rockwell and Robert Simpson on the quote - My
> Apologies!~!
> .
> the photos sent to the list are in Noah's ArkIves at this URL::
> .
> http://lists.dementia.org/files/pittsburgh-railways/
> .
> but I have been unable to find a photo of a PCC accelerator where many
> of the photos are not appropriately identified is worse than the needle
> in the haystack  --  I am certain there is one on the list somewhere.
>  (And while this has been disgusted onlist before, someone new trying
> to find such a discussion in the archives is horrific since we are
> anything but good about subject line adherence!!!)     Attached is a
> Westinghouse accelerator which is also used for dynamic braking.     A
> pilot motor  *-reportedly-*  moves the accelerator through about
> 180-degrees to cut out resistance to the motors for acceleration and
> automatically spots the accelerator for dynamic braking when the power
> pedal is released.     I say the pilot reportedly advances the
> accelerator because this accelerator was inverted and placed in a glass
> top case in PCC 100 renumbered as M11 Instruction Car and I watched it
> revolve corresponding to how far the motorman depressed the power pedal
> --  half way on pedal and accelerator immediately went up half way.
> Every movement of pedal was followed by immediate movement of
> accelerator  --  one would expect the pilot motor to lag somewhat.
> .
> There are 99-points of resistance on this accelerator which is what
> makes the PCC so smooth.     The accelerator usually doesn't remain in
> one place so resistance ribbons are relatively light and would burn out
> easily if the accelerator did stick in one position.     Boris could
> give excellent description of operation if so inclined.
> .
> On Most but Not All PCCs the motorman had 3-pedals:::
> .
> .......Right - Power Pedal
> .
> .......Center - Brake.
> .
> .......Left - Deadman Pedal.
> .
> With the brake depressed about halfway the motorman can remove his foot
> from the deadman pedal which will hold the brake half-way - This Is 
> Park!~!
> .
> To move the PCC, the motorman places his foot over the brake, depresses
> the deadman which releases the brake, then moves his foot to the power
> pedal for acceleration.     Foot is always on deadman unless the car is
> placed in Park.
> .
> The maximum acceleration on the PCC was 4.75-mph/ps and this was a
> variable rate depending upon how far the power pedal is depressed -
> pilot motor mentioned above drives accelerator.
> .
> Maximum  """Service__Brake"""  is also 4.75-mph/ps variable to that
> point.     Pushing the brake further into emergency would provide up to
> 9.0-mph/ps braking.
> .
> The primary brake on a PCC is dynamic which is operable at all times
> regardless of state of 600-volts overhead  (but in an ImPerfect World,
> dynamics can fail for a variety of reasons) And Which faded at about
> 3.0-mph for Air-Electric PCCs  (friction brake, doors, windshield
> wipers, sanders operated by air pressure).     The dynamic was extended
> to 0.75-mph for All-Electric PCCs sans Air  (and a few Air-Electrics
> when built (PRCo 1601s) and not a few retrofitted for same)  after which
> a lockout relay allowed automatic application of the friction brake to
> complete the stop and hold the car once stopped.     While this friction
> brake was designed so the car could be stopped with Only The Friction
> Brake  """A_Few_Times"""  (when All Else Fails,)  this is Not the
> Intended purpose of the friction brake and using it as the sole brake
> will completely wear the brakes Very Fast - much less than a trip -
> witness the runaway of 1727 in Mt.Wash tunnel  (also disgusted here
> innumerable times!~!~!)     Magnetic Track brake came into play when
> emergency braking is engaged!
> .
> You might enjoy going through the photos at the archive - just copy and
> paste the url into an email if you have any questions.     Someone here
> will have some answers!~!~!
> .
> .
> .
> Jim__Holland 

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 655k (670800 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_001.jpg

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 685k (701717 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_002.jpg

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 674k (690473 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_003.jpg

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 681k (697698 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_004.jpg

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 660k (676272 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_005.jpg

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 665k (681134 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_006.jpg

-- Attached file removed by Ecartis and put at URL below --
-- Type: image/jpeg
-- Size: 348k (356426 bytes)
-- URL : http://lists.dementia.org/files/pittsburgh-railways/Philly%20PCC_007.jpg