Re: 464

The tractive effort has always been the same. When the Vauclain compound cylinders were originally replaced by slide valve cylinders, the cylinder size was calculated to retain the same tractive effort. Originally all of the engines were equipped with slide valves and were still saturated engines. The second rebuilding of most of the engines was when most of the engines equipped with piston valves were superheated. Superheating does not work well with slide valves and their lubrication because the superheated steam is dryer. After this rebuilding, only 450, 451, 457 and 460 were left saturated with slide valves. 462 was given piston valves, but never superheated.