The Westinghouse Cross Compound air compressors used on most modern steam locomotives in the 1910-1959 years did have two pistons, one a low pressure and the other a high pressure...just like a compound Mallet. They do exhaust their steam via various routes, but except for some locomotives, often all you hear is the pump, itself, making a loud boom and a click as the diverter mechanism allowed the used steam to enter the next cylinder. Some steamers, notably the Pennsy K4, had a pronounced but high pitched exhaust that sounded more like a double-air let-off.
"Tsshhh...tsheee, tsshee...tsshh..."
No chuffs. The exhaust orifice was maybe an inch in diameter.
steemtrayn The air pumps chuffed.
The air pumps chuffed.
True, but at speed or running on flat, level ground, they wouldn't be running, except at a very slow speed to make up for losses in the brake line. And what would you synchronize the chuffs to? Unless they had pistons actually moving in the air pump?
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Gary M. Collins gmcrailgNOSPAM@gmail.com
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"Common Sense, Ain't!" -- G. M. Collins
http://fhn.site90.net
Dave
Just be glad you don't have to press "2" for English.
http://www.youtube.com/watch?v=zQ_ALEdDUB8
http://www.youtube.com/watch?v=6hqFS1GZL4s
http://s73.photobucket.com/user/steemtrayn/media/MovingcoalontheDCM.mp4.html?sort=3&o=27
If they mention chuff in any official announcements or documents, somebody got lazy and didn't think it through, or just cut and pasted from previous steam locomotive announcements. I hope it's just a case of carelessness, but there can be no chuff, synched or unsynched, on a steam turbine locomotive of any description. I can't believe that BLI, which is the paragon of plastic Pennsy production in HO today, would possibly have made such a blunder.
BLI now works closely with the Pennsylvania Railroad Technical and Historical society on their PRR projects. i would guess that the society would want sound accuracy if their name is going to be associated with the project. I'm sure once the prototype is running, we will get a look at it on video.
I recently read BLI's announcement of their Pennsy S2 Turbine locomotive project which is scheduled for delivery in late 2014. The very nice picture of this loco was accompanied by the usual descriptive "boilerplate" mentioning that the loco will have a syncronized smoke mechanism. I'm assuming the smoke will be "syncronized" with cylinder chuffs at four chuffs per revolution. My concern is that the S2 didn't have a conventional cylinder/blastpipe arrangement. It had two rotary turbines, one for backing, mounted crossways in the middle of the engine and geared to the driving axle. The turbine was rotary, not reciprocating so it exhausted smoothly and steadily. To produce draft for the firetube boiler the blower worked all the time so smoke vented evenly from the stacks. The combination of the blower and steam exhaust produced a wooshing sound at speed, not the usual reciprocating drumbeat associated with most steamers. Pennsy men nicknamed the big turbine the "Swoosh" on account of it's singular sound signature. I'm wondering if the BLI people know this because to be authentic they will have to create a very different sound signature for this beast.