[PRCo] Pittsburgh Low Floor Gears

[Fred Schneider]

New Subject:

I discovered at PTM last Saturday an axle with two small wheels ...  
nominally 24 to 26 inches .... with a helical gear on the axle.  By  
question was,  "What did it come from?"

Answer was:  A Pittsburgh Low-Floor.

But the Helical Gear, I protested.

Bernie answered that all of our Pittsburgh Low Floor cars have  
helical gears.

Ah, but all of our (underline our) low-floor cars are high-speed  
cars.   And sadly we do not have all the car record cards.   Did the  
low-speed cars have spur gears?   And helical gears on the high speed  
cars?

If anyone out there has a clue, go right ahead and jump in.

The difference?  Spur gears have the teeth cut at right angles to the  
sides of the gear.  Phrased differently, the teeth are parallel to  
the axle.  As a spur gear wears, they get very noisy.    Helical  
gears have the teeth cut at an angle to the axle so that two or three  
teeth are engaged at the same time, thus reducing the noise.   It was  
often a later day improvement.   (You will see them illustrated in  
the first of the two PCC books.)   Philadelphia went for herringbone  
(double helical) gears on all the 5200s and 8000s that were  
modernized including the two at PTM.

I brought this up now because Jerry bought up the sound of a low- 
floor grinding in Donora.   All of those would have been low-speed  
cars.   PRC assigned all of the high speed double-end cars (ten of  
them) to Glenwood.

And if no one here answers, I'll try to remember to ask Ton DiSensi.