I guess all new F-units in the 40’s and 50’s were delivered with diaphragrms.
Can anybody please tell me when they started to loose them; especially on the Santa Fe, UP, WP and SP ?
probably about the first time they were shopped or needed repair. i would say roughly 2-3 years after delivery. PRR dropped them pretty fast too.
I think the diaphragms began to disappear when the RR’s began operating the F units with other types, rather than as the classic A-B-B-A lashup. They weren’t needed then and were an extra maintainance chore, so they were removed.