Steve
If everything seems under control, you're not going fast enough!
Union Pacific used to run a train called "The Super Van" out of the Los Angeles area ports, up Cajon Pass, across the LA&SL through Utah and up onto the UP Overland Route. It was a high priority intermodal train. Its power was often a DDA40X on point and a few trailing SD40's with high speed gearing known as 'Fast Forties". This link shows a photo of two DDA40X's with an SD40 hauling the Super Van on a westbound trip: http://www.railpictures.net/photo/394337/
Here is a photo of a classic UP consist (along my favorite river). Two DD40's with a "Fast Forty" in between:
The DD40's were geared for a higher top speed than the typical UP road diesel (80 versus 65 mph). The Fast Forties were geared to match the DD40's. The DD40's COULD operated with the "regular" diesels, but they were more efficient when the gearing matched.
Ed
Uh theres pictures of the DD series units in MU with other DD units and smaller SD and GP series units.
Theres a picture out there of like four, yes FOUR, DDA40Xs and like three SD40/45s on the lead of a freight, the picture isn't the greatest, after the third unit in the consist its kindof a guessing game but my best guess was 3 or 4 Centennials and a few smaller units.
Hi,
Utah Rails is a good site to visit to see a great deal of U.P. and western road information:
http://utahrails.net/up/up-diesel-index.php
Scroll down a bit to "Diesel Articles" and browse away.
Good Luck, Ed
Apparently so, from image search. I guess they just added whatever together to get the HP needed in a situation.
https://www.bing.com/images/search?q=dd40ax&FORM=HDRSC2
Paul
Modeling HO with a transition era UP bent
Being the DD40X was two locomotives on one frame, did they ever MU it to another DD40X or MU it to a smaller locomotive?