• PCC Question(s)

  • General discussion about fallen trolley and interurban lines in North America, past and present.
General discussion about fallen trolley and interurban lines in North America, past and present.

Moderator: Aa3rt

  by MaineCoonCat
 
What was the maximum speed capability of a PCC?

Did they employ a governor other than just the gearing (or that bolt underneath the speed control pedal), and if so, any idea how it worked?

Thanks!

Moderator's Note: deleted duplicate thread, 11:35 PM CST
  by mtuandrew
 
I seem to remember that Twin City Rapid Transit's PCCs could hit 55 mph, though it was probably rare that they saw that speed. Not sure whether it was limited by gearing either, but it seems silly to have a city streetcar geared to go faster than 55.
  by polybalt
 
PCC streetcars did not have governors. The motors and gear ratio were designed for a balancing speed of about 42mph on level track. I understand the Pittsburgh interurban versions has additional field shunting added to the motors to get into the upper 40's. The balancing speed is the speed at which the tractive effort (which decreases as speed increases) just balances the train resistance (which increases with speed) at 600 volts on level track . Of course on downhill grades, of if the voltage was higher, the cars would go faster.

PCC cars were designed to run on the street with mixed traffic. They were geared low to get very fast acceleration at low speeds. Depending on passenger loads, they would accelerate at 4.5 miles-per-hour-per-second up to maybe 8 mph. This acceleration rate is too high for comfort of standing passengers. Modern transit cars limit initial acceleration to 3.2mphps, but have a substantially higher horsepower to weight ratio. Modern cars are governed, partly because the theoretical balancing speed is much higher than the rpm limitations on the motors.
  by typesix
 
The maximum safe speed is 50 mph, after that, there's no guarantee that the motors won't start flying apart.
  by walt
 
True ( city version) PCC cars did not need a very fast top speed because, as indicated by others, they were designed to operate in mixed city traffic. The primary advantage over older equipment was in their rate of acceleration and braking, which allowed for generally faster operation, even though top speed was not really a factor. Some of the interurban versions, many of which were not true PCC cars, primarily because they were geared for a higher top speed ( basically PCC bodies with non PCC electrical and mechanical components), did reach 55 or 60 MPH top speeds, but the true city version PCC's strained to reach 35 MPH. One interesting note- the 1946 all electric units built originally for Kansas City, but which spent most of their lives in Philadelphia or Toronto, had something akin to an "overdrive" which could be engaged using an unusual manuver with the throttle pedal, and which caused the cars to run faster than usual. I don't remember exactly what the manuver was, or what the actual top speed was, but it is said that these were the fastest of the "standard" PCC's.
  by mtuandrew
 
walt wrote:True ( city version) PCC cars did not need a very fast top speed because, as indicated by others, they were designed to operate in mixed city traffic. The primary advantage over older equipment was in their rate of acceleration and braking, which allowed for generally faster operation, even though top speed was not really a factor. Some of the interurban versions, many of which were not true PCC cars, primarily because they were geared for a higher top speed ( basically PCC bodies with non PCC electrical and mechanical components), did reach 55 or 60 MPH top speeds, but the true city version PCC's strained to reach 35 MPH. One interesting note- the 1946 all electric units built originally for Kansas City, but which spent most of their lives in Philadelphia or Toronto, had something akin to an "overdrive" which could be engaged using an unusual manuver with the throttle pedal, and which caused the cars to run faster than usual. I don't remember exactly what the manuver was, or what the actual top speed was, but it is said that these were the fastest of the "standard" PCC's.
I don't know if the Brilliners had a higher top speed, but some of the Brill Bullets, and some of the very late St. Louis Car Company offerings like the North Shore's Electroliners (which would have been somewhat influenced by PCCs), could travel at well over freeway speeds. As for the "overdrive", it sounds like a field shunt of some sort installed on the Kansas City cars, but I couldn't tell you more about it.

Returning to PCCs, what about those of the Pittsburgh Railways' Interurban line? I would have guessed they would be able to move faster than 50 mph.


Moderator's Note: Even though some PCCs still run in regular service, they're 60 years old and counting, and have been rebuilt to non-factory conditions long ago. Therefore, I'm moving this thread to General Discussion: Fallen Trolley and Interurban Lines, as papabarn asked his questions in the past tense anyway.
  by walt
 
mtuandrew wrote: I don't know if the Brilliners had a higher top speed, but some of the Brill Bullets, and some of the very late St. Louis Car Company offerings like the North Shore's Electroliners (which would have been somewhat influenced by PCCs), could travel at well over freeway speeds.
.[/i]
The Red Arrow Brilliners and that company's 1949 St. Louis "PCC type" interurbans had the four of the same 75 HP motors ( which is one of the many reasons why the St Louis cars are not "true" PCC cars). I would suspect that the city version Brilliners were not much faster than the "true" PCC's. The "standard" PCC motor, whether GE or Westinghouse built was a 55 HP motor, and each car had four of them.

The Bullet Cars and the Electroliner- Liberty Liners were different animals altogether. The Bullet Cars had four 100 HP motors, and I believe the Liners were even more powerful. Both types had top speeds of over 90 MPH. PCC cars, and the Red Arrow Brilliners and St.Louis Cars didn't come close to the Bullets and Liners with regard to their top speeds. ( The closest Red Arrow cars to the Bullets in that regard were the 1932 80- series Brill Lightweight Cars which had a top speed of 70 MPH)
  by PCC Guy
 
We work on PCC cars every day in boston. They are War time PCC from 1946. They generally travel between 25 to 30 mph. 30+ down hill. There is no governor. Just how fast the motors will go with 600 volts and no resistance.
  by Gerry6309
 
PCC Guy wrote:We work on PCC cars every day in boston. They are War time PCC from 1946. They generally travel between 25 to 30 mph. 30+ down hill. There is no governor. Just how fast the motors will go with 600 volts and no resistance.
Field Shunts are disabled on these cars. With the shunts in they will travel at the same speed as any other PCC. Track conditions in the 1960s led to the disabling of the shunts on all Boston PCCs. Although the Mattapan Line has better track, there is no interest in higher speed.