EMD "DD-series" official thread (covers all variations)

[Justin B]

UP's DDA35s 70,72,75-79,82,83 were equipped with GE753E traction motors, except for #84, which had D67 motors. The DD35 B units all had D67s.

Why?

[junction tower]

I believe they were salvaged from units traded in to EMD on the DD35 order.

[krobar]

What would the 753's come out of? Was this a typo, could they have been 752's?

[Steve F45]

Looking over pics and it just amazed me at the sheer size of this engine. I remember as a kid seeing it in a HO model and wanting it.

Do you think they'll ever build something like this ever again? How long was it in production and why did it stop beeing built?

[GOLDEN-ARM]

I heard the NYS&W might be planning a pair of DD-A90XMac's, for pusher service, on Sparta Mountain.............

[Allen Hazen]

"Ever" is a long time!
But I will be surprised (as well as delighted) if it happens in the next few years. Both EMD and GE can build 6000 hp units with a single 16-cylinder engine if asked, and for the moment U.S. railroads seem to prefer 4300 hp or 4400 hp units (with new 12-cyl engines if from GE or "classic" 16 cylinder if from EMD). So the dermand for a ?? 9000 hp ?? twin engine unit doesn't seem to be there.
But surprises happen.

[trainiac]

The problem with such as unit is that if something goes wrong and it's taken out of service, it's like taking two regular locomotives out of service. That proved to be the downfall of the big UP twin-engine units, which were withdrawn fairly rapidly. The DDA40X's lasted longer than the rest--they were the most reliable--but they still didn't reach 20 years of regular service.

[RailBus63]

I believe the same issue has led to a lack of follow-up sales for the 6,000 h.p. AC6000's and SD90MAC's. Railroads wanted to use two of these big bruisers to replace three or four lower-horsepower units, but the high-power units have been unreliable and there is too great a risk of having an underpowered or dead train clogging up the mainline if one unit goes down. I believe the 4400 h.p. units will be the new standard for years to come.

Jim

[inkyrail]

UP ran the hell out of them because they were so good. In the short time they were in service they were run as much as 2.2 million miles! They loaded up incredibly fast and were known to pull the other non-Centennial locomotives in a consist until they were able to put power to the ground.

http://utahrails.net/webpubs/up-dda40x.php

[Steve F45]

does anyone know of any video's of the guys running?

[GOLDEN-ARM]

Try this link, for Cenntenial videos.......... http://www.perryshobbies.com/video.html

[Steve F45]

GA, i was thinking more already on the net (home made). But thanks for hte link.

[QR National]

Here in Australia, the theory is they perfer 2 x 3000hp locos over 1 x 6000hp loco. a 12-710G3 is more fuel efficient than a 6000hp engine too.

[chicagorails]

they were not good on some curves, 8 drivers to replace 12 are not as powerful,one engine goes down whole unit not running,too much weight on some bridges, to name a few

[ExEMDLOCOTester]

they were not good on some curves, 8 drivers to replace 12 are not as powerful,one engine goes down whole unit not running,too much weight on some bridges, to name a few

The DDX's were delivered long before I started at EMD but the Locomotive testers had fond memories of the Beasts. UP wanted a 100 ft locomotive for the centennal but the Big Bay of EMD wouldn't handle anything longer than around 98 feet ( I don't remember the exact length). The other issues were the short radius's and light weight track on the property. From the stories of the old timers, the first couple of units spent a fair amount of time on the ground.