trumptrain posted:Back in the 1960's I recall seeing 11 F units ( both A and B units ) on the B&O's old main line in Patapsco State Park. They were all up front of a long freight train heading toward Baltimore. I'm certain all the locomotives were not on line.
Correct. With the old/original MU control voltage design, the lead unit had to supply the control voltage throughout the train-line. Thus, not that many older units could be effectively MU'ed together. With the advent of the "LocalControl" voltage design, which came out on EMD units in the early 1960s, then any number of units could be MU'ed together, with no loss of control voltage throughout the train-line.
I remember being on the Santa Fe, in early 1967 working on SD45 traction motor flash-over issues, out of Amarillo, TX. The Santa Fe would be moving motive power from the LA Basin, back to Chicago for the Monday thru Thursday westbound rush of TOFC business, on Fridays with one or two VERY lightly loaded TOFC eastbound trains. One of those eastbound "motive power re-location" trains arrived at Clovis, NM, with 17 SD45 units and one SD40 unit on the rear! However, there were only about 10 or 12 TOFC loaded flatcars, and the standard Santa Fe caboose bringing up the rear. Since Clovis was a crew change point for all eastbound and westbound trains, I was talking with the Engineer & Fireman of the train I would be riding back to Amarillo on. I told the Engineer that I would climb on the very last unit and walk through the entire consist, in order to make sure everything was OK and all units were "on the line". We we still stopped, waiting for a clear signal when I finally arrived at the headend. The Engineer had taken my grip with him, so I was all ready to get comfortable in the third cab seat. To make small talk, the Engineer asked me how fast he could accelerate with this many powered locomotives (total of 64,200 horse power). I explained that, with the train brakes released, and by holding the independent brakes on, then wiping the throttle to #8, then quickly release/bale-off the independents,,,,,,we should reach about 60+ MPH within the station platform length! I explained that that is how new units are tested on the EMD in-plant grounds one mile long Test Track, i.e. the Locomotive Tester had a half mile to accelerate then a half mile to test the dynamic brake and get stopped.
The Engineer thought about that explanation for a few minutes then picked up the radio mic, and suggested to the Conductor and Rear Brakeman to get into their seats and put their seat-belts on, as he was going to "Try something leaving town on the green signal.". Sure enough, when the main line signal right in front of us went green, he whistled of, turned on the bell, and did just as I suggested. We attained 61MPH in the length of the station platforms! The Conductor even called on the radio and exclaimed, "WOW! That was wild!". With such a short train, and virtually no slack, when I saw the Conductor in Amarillo, he said it was a pretty smooth ride over all. We made the 102 miles between Clovis and Amarillo in about 110 minutes!
What with all the restrictions/limits on the number of powered axles, plus fuel conservation policies, such an operation with THAT many units could not be done today. But back then, the Santa Fe REALLY knew how to railroad and handle fast freight.
I would think that a large percentage were just in tow from Brunswick or another B&O shop location out west probably moving power around the system or on their way to a shop that does heavy locomotive repair.
