AFAIK, the only three-cylinder compound built for use in the USA was the 4-10-2 Baldwin demonstrator #60000, which now resides in the Franklin Institute in Philadelphia.
The center cylinder was/is high-pressure, the two outer cylinders low-pressure. The two outer cranks were 90 degrees apart with left-hand lead; the center crank was 135 degrees from both of the outer cranks. Since Alco had the license for the English Gresley valve gear for operating the valve of the center cylinder of a locomotive whose cranks were 120 degrees apart, Baldwin had to resort to a different method.
EdKing
Thanks Ed. I obviously had it "backwards" since I have never been around any compound locomotives, except the N&W "Y" class. All the three cylinder locomotives I saw in Germany were NOT compound, and had really great sounding exhausts, especially under heavy load & full throttle.
Thanks again for setting me straight.
