From the middle 1960’s through the very early 1970’s all three major locomotive manufacturers in the U.S. produced massive twin prime mover diesel locomotives. The 6600 horsepower locomotives rode on the same DD trucks that were equipped on the DD-35’s.The final installment was the EMD huge DDA40X, delivering 47 units to the Union Pacific between 1969 and 1971. The UP would refer to these locomotives as Centennials, in honor of the 100 anniversary of the completion of the first transcontinental railroad.  Athearn-Genesis has announced that it will be releasing this locomotive in HO scale, both with and without sound.

EMD Union Pacific DDA40X (photo by Ken Whitehead)

New Athearn plot model of their DDA40X (photo from Athearn’s Facebook album)

A Brief Look at the Other Massive Locomotives of the 1960’s

DD35 A&B

EMD preceded the DDA40X with the DD-35, basically two GP35’s on one frame.  This locomotive was offered in both cab (DD-35a), and booster units (DD-35b). EMD sold 15 DD35a and 27 DD35b’s to the Union Pacific and 3 DD35b’s to the Southern Pacific. Their two prime movers produced 5000 horsepower and they rode on two 4 axle (DD) trucks, later used on the DDA40X. 

Union Pacific DD35 A (photo from worldrailfans.info)

Southern Pacific DD35b(from railpictures.net)

GE U50B & U50C

General Electric’s entry into the high horsepower race was their 5000 horsepower U50, offered in BB+BB (4 wheel trucks) or as CC (6 wheel trucks). Once again the two takers were the UP and SP, however, unlike EMD or ALCO no B version (cab-less) boosters were offered.

GE U50c Union Pacific (image by RPicturesArchives.net)

GE U50b Southern Pacific (image by RRPicturesArchives.net)

ALCO C-855 A&B

Like the DD35, the ALCO C-855 was offered in both cab and booster models, however unlike the U50’s and the DD35’s, Southern Pacific passed on these models. Introduced in 1964, only three locomotives were ever built, two cabs, and one booster. They were very short lived with all being scrapped in 1972.  

ALCO C-855 Cab UP (photo by David Rider)

ALCO C-855 Booster UP (photo by David Rider)