The PCC streetcar
A brief comment about the PCC streetcar
In 1929, the presidents of a number of major street railway companies formed the Electric Railway Presidents’ Conference Committee (ERPCC), whose job was to develop a new generation of streetcar that would help maintain the competitivity of street railway lines in the face of competition from cars and buses.
The resulting cars became known as the "PCC" type, an initialism taken from some of the the initials of the design committee's name, but it is sometimes said to stand for "Presidents' Conference Car", and is perhaps most commonly mistranslated as standing for "Presidents' Car Committee".
The new generation design was first actually used beginning in 1936, although serious introduction of the cars began in 1938.
In the US, the cars were primarily built by St. Louis Car Company and Pullman-Standard.
The cars incorporated several novel design features. Braking was primarily done on a dynamic basis (the car's traction motors acting as generators, the output from which was dissipated in large resistor grids on the car roof - or in winter to car heating grids), effective down to perhaps 1 mi/hr. For the later cars (perhaps post-1945), bringing the car to a final stop (and holding it in place) is done with drum brakes on the wheel shafts. They are spring applied and released with electromagnets while running, thus proving a fail-safe mode. These are augmented when needed with magnetic friction brakes operating on the track itself. Batteries in the car provide for the operation of these in the case of loss of power from the trolley wire.
In most cars, power control and braking are operated by foot pedals (unlike almost any other rail system), trying to give familiarity to retreaded bus drivers.
In the newer cars, the doors were also operated electrically. Thus, this design involved no use of compressed air (earning the cars the moniker "airless cars".) In the case of an emergency stop ("flooring" the brake pedal), they are put into the "free" state so that they can be opened manually if needed. (Earlier cars did have a compressed air system, used for the "second" brake, with shoes operating on the wheels, and to operate the doors.)
There was extensive use of rubber isolating elements to reduce operating noise.
Few cities converted all or even most of their streetcar fleets to the PCC type. In Cincinnati (at least during the time I spent summers there visiting my grandparents), only one line - Madisonville - used the PCC cars (which my mother called "streamliners"). I think PCC cars were later added to other lines.
A few lines of the municipal transit system in Cleveland used PCC cars. An independent rapid transit system, running from downtown Cleveland to the suburb of Shaker Heights, initially used PCC cars exclusively.
Here we see a former Cincinnati PCC car, now in service on the San Francisco Market Street Railway, with part of the crew who refurbished it. It has been repainted in the authentic Cincinnati Transit COmpany livery.
SFO Market Street PCC streetcar 1047 (Cincinnati heritage)
Photo from Market Street Railway
It is at this moment (2011.08.22 1046 CDT) on the Castro Street turnaround loop at the south end of the Market Street line (most of the cars have GPS and can be tracked on a live map!).
Best regards,
Doug
