[PRCo] Re: Drum__Brakes_--_All-Electrics,__etc........

[Fred Schneider]

The 1200s were spring applied and air released and the operators  
didn't like them.   But theoretically they were fail safe.   Like the  
1700s, you didn't need to chock them in the yards.

But still the operative word is theoretical ... man has never yet  
built a spring that would not break.

Man has not built a spring which would not loose its tensile strength  
over time.

I suspect that Pittsburgh Railways might have been a tad negligent in  
replacing the brake springs on 1200s ... not an accusation but just a  
suspicion.  They were probably a whole lot better than any government  
agency.   Remember too that there were a lot of 1200s stored in  
Rankin in 1964 and many of those may not have been good to go.

So if you want to built a 1200 with spring applied drum brakes in  
1940 and then wonder why the same springs won't stop them in 1963....

Probably the same reason why your 1960 Chevy Impala wallows around  
today if you still have the original springs.  (I can just hear Ken J  
saying "Uh huh.")


On May 27, 2007, at 10:28 AM, Herb Brannon wrote:

> When mechanical 'things' (in this case a 1945 PCC streetcar, still  
> operating in 1975-76) get to a certain age, like humans, they start  
> to fall apart. Yes, it was the "Spirit of '76" car, and it had a  
> bad air leak. It would not have mattered if it would have had every  
> type of air applied brake known to mankind, it still would not have  
> stopped without any air pressure to apply the brakes. That brake  
> system (air applied/spring release), in my opinion, was one of the  
> more stupid systems devised. Couldn't at least one of the scores of  
> engineers working on the PCC project thought far enough to realize  
> that a spring applied/air released system would have been  
> safer ???? They thought enought to put a 'hand brake' on the car,  
> why not a "fail safe" braking system?
> Boris Cefer <westinghouse at iol.cz> wrote:  Are you sure, Herb? 1776  
> was formerly an interurban car with B-3 trucks and
> spring-applied drum brakes with air actuators (pressure-releasing).
>
> B
>
>
>
> Rise Up -- Go Cavs
>   Herb Brannon
>
>
>