"Allen Hazen" wrote:
"Thanks for the weight. D-77 is the version ??? used on Dash-2 models ??? Things (this seems to be an almost universal law of engineering) get heavier over time, so one of the earlier versions might have weighed a bit less. Or the weight I saw quoted didn't include the shipping skid."
Been enjoying this discussion a good deal, I worked in the coil shop of a large remanufacturer of traction motors for just over 21 years. (Now a division of GETS) While we were primarily an EMD rebuild facility when I was there, we did do some GE coils also.
To the best of my knowledge, your assumption is correct for the version of the EMD motor. For the most part all EMD motors from the D-47 through the D-78 are basically the same, at least as far as the coils were concerned. Only major differences that I was ever aware of was bearings or armature insulation, both of which were constanty under revison/improvement, bearings more so than insulation. Both EMD and GE settled on polyimide based wire enamel and polyimide film with fiberglass tape outer insulation for armatures prior to my employment starting in 1979. It was simply far superior to the old mica insulation of the earlier model series.
The D-78 used essentially the same armature as the D87A, and the major difference in those from the D-77 was copper size for the conductors and the conductors were transposed within the cell section of the core iron to help control eddy currents and reduce heat.
GE field and aramture coils were substantially larger that EMD. An EMD main field weighed around 102 pounds without pole iron, a GE 752 E series main weighed about 125 pounds if I recall correctly, and that is without the pole piece. The A series (AF, AG) weigh even more. As a side note, "back in the day" when there were a number of us "young bucks" in the shop in the late 1970"s, one of our favorite tests of manhood was to see who could lift a bad order 752 main potted on its pole piece the the highest...well over 200 pounds. Today that practice would earn you some swift discipline, and we all wonder why we have bad backs!