Question, what is the running speed for a three truck shay, (8 mph?), (12mph?)< (16mph?)?
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I'd say 10 mph tops. I could be wrong but to me Shays on the Cass Scenic Railroad climb to Whittaker Station and to Bald Knob at a fast walk.
I think I read somewhere that 10 MPH was really fast for a Shay. And I think you are right about Cass.
I'm guessing that the WM Shay #6 was probably about as fast as any Shay out there, because it had the largest wheels, which I believe were about 40" in diameter. Wheel size is a critical factor in a steam loco's speed, most of the switchers had small wheels(48"-56"), freight locos had larger wheels and thus were faster, while the largest wheels were found on passenger locos (up to 80" in diameter). Add to that the fact that rod engines were directly driven (the crankshaft turned at the same RPM as the axles), while geared engines like Shays, Climaxes, and Heislers had reduction gearing so that their crankshafts turned much faster than their axles, which made them sound like they were going much faster than they actually were. Ten to fifteen miles an hour was pretty fast for a geared loco, especially since they were likely not very well balanced at that speed either.
Bill in FtL
You can squeeze about 12 mph out of a Shay if the wind is at your back. You'll sound like your going 60 and the ride is anything but smooth.
Rusty
Western Maryland Shay #6 runs 5/6 MPH up hill and up to 8 MPH down hill. Chuffs are 15 per one revolution. How do I know? I talked to the people that work on it.
...keep the rails polished...
How do they get 15 per on a three cylinder locomotive with the cranks 33.33 degrees apart? Or even a odd count for that matter...
Last time I counted (admittedly a long time ago), you get 12 per revolution, at least on J Neils #5.
Rusty
"How do they get 15 per on a three cylinder locomotive with the cranks 33.33 degrees apart? Or even a odd count for that matter...
Last time I counted (admittedly a long time ago), you get 12 per revolution, at least on J Neils #5."
The gear ratio from drive shaft to wheels was different from locomotive to locomotive (it could be ordered to customer specs). There would be about 6 chuffs per drive shaft revolution on a given locomotive. In the case of WM #6, the gear ratio is 2.45/1 (i.e. 2.45 drive shaft revolutions per 1 wheel revolution). When you do the math, you get 14.7 which is pretty much 15 chuffs per wheel revolution. In the engine you mentioned, if they are getting 12, the gear ratio is probably 2.0/1.
