Traditionally, three reasons have been given for the transition from “compound” to “simple” articulated locomotives: (1) high-pressure joints were developed. (2) maintenance of intercepting valves was difficult. (3) the diameter of the low-pressure cylinder exceeded the maximum allowable width of the locomotive.
However, the advantage of high efficiency of “compound” is enormous. Modern steam turbines for generating electricity have three stages. I can’t help but feel that another fundamental reason is being overlooked.
