Robby Peartree Wrote:
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> Tom,
>
> Do you have any info on the % of boiler pressure
> factor I have seen it referred to a couple of
> things in modern writings but it seems to me that
> it refers to the pressure gradient you find in a
> locomotive to the cylinders and energy losses due
> to back pressure? The only time I saw GCR4960
> steam chest pressure match its boiler pressure we
> were stationary. When going around MP 48 at 8 mph
> we got 180 psi of steam chest at 12 psi of back
> pressure. While I realize 4960 will not put out
> the same numbers with its new nozzles but I have
> not seen it operate with the new exhaust.
>
> Robby Peartree


Hi Robby...I don't have any modern figures. I believe that the old figure used was 75% when
figuring t.e. Sometimes the higher value of 85% was employed. Heisler did this in an effort
to help boost sales with its West Coast Special. Using 75%, they advertised a t.e. of
43,600 lbs., which is pretty impressive given that a 90-3 Shay was 40,400 lbs. When Heisler
used the 85% figure, t.e. was raised to a whopping 49,410 lbs. Heislers were often
considered to be "over-cylindered", which is a polite way of saying inadequete boiler
size or heating surface, but of the 3 that I spent time on, all three-truckers, none ever
had any trouble maintaining steam pressure.
BTW, package headed your way today in the mail.