Re: Question for Steam super-nerds

The Caprotti valve gear was tried out in the U.S. in the 1930s, but apparently was not adaptable to American practice of the period. A possibly apocryphal story concerning its inventor, Sr. Caprotti: He visited the U.S. to try to determine why his valve gear kept failing on American locomotives, while it seemed to work well on engine in Europe. He was taken out somewhere around Reading, Pa. to view a passing Reading 2-10-2 fitted with his valve gear. As the engine (they were the largest 2-10-2s ever built) thundered by, trailing a long string of freight, Sr. Carprotti was heard to exclaim, "American locomotives don't pull wagons, they pull houses!"
The Reading found that the gear worked pretty well on a 10-wheeler in passenger service, but failed in the rigors of heavy freight service. I suspect that was the problem in general.
As for the Pennsylvania's poppet valve gear-equipped T-1 4-4-4-4 locomotives, the Pennsy opted to equip their engines with gear-driven Franklin Rotary Cam poppet valve gear, against the recommendations of Franklin's engineers, who thought the chain-driven model would be more durable. The gearbox was located between the drivers inside the frames, very difficult to access and worse to maintain. In removing the cover of the gearbox, it was nearly impossible to keep cinders and other road dirt from falling into the gears. A single T-1 was later outfitted with Walschaerts gear and performed superbly. But the E-7s were already on the way and the experiement was not extended.