Any pics of the new DD40AX posted anywhere yet?

[UPOzzie]

i have just seen some pics of the loco on the atlas forum . i have 2 ordered from my LHS here in Australia and am looking forward to getting them.

[igoldberg]

Anyone have a critique of the operating qualities of the new DDA49X?

[C855B]

On DC it seems to be moderately good, but not great. Getting a smooth low-speed startup takes a really gentle hand on the throttle, and the operating speed range at the low end is very narrow. It's a bit speedy at the top. Haven't reached pulling capacity because of coupler limitations at around 20 cars.

To tell the truth, though, I think the low-speed control issue is a factor of the decoder getting in the way of DC. I am very tempted to remove the decoder and wire it for straight DC. They (the Bachmann "they") were very, very smart (kudos!) in using a conventional decoder module with pigtails, and then wiring it to a generic power distribution board. Aside from the relative challenges in getting the shell off (DON'T be fooled by trying to remove the shell and walkways separately! - you will break things  ), this is a 10-minute job.

[r0bert]

Keep in mind that the DDA40's were geared for 90 mph+ operations pulling express reefers, not yard service.

[C855B]

Keep in mind that the DDA40's were geared for 90 mph+ operations pulling express reefers, not yard service.

Uhhhhhhhh... no. Three things to learn here.

First, there was never any location on the pre-merger UP where speeds over 79 were legal. This required a system known as "Automatic Train Stop", which UP didn't use. The 6900's may have been geared for high maximum speeds, but that gearing was primarily to improve operating efficiency in higher speed ranges.

Second, DDA40X's were rarely if ever used on the expedited PFE (reefer) trains of the day. Very little produce originated on UP lines, and the priority trains were typically joint run-through (no power change) operations with SP handling the origination in California. Other railroads were afraid of the DD's and wouldn't let them on the property, and while SP had three DD35's, they would not run them over Donner Pass, and would not let UP run theirs over Donner either. Of special concern was that the 100-foot-long Centennials would scrape the sides of curved tunnels and snowsheds. So the express produce trains of the day typically drew new C-C's.

Third, what they were was the power of choice for expedited intermodal service, usually with an SD40-2H sandwiched between two, but sometimes three of the "Big Jacks" were at the front. Intermodal in the '70s was mostly TOFC since COFC was just starting, and included trains such as the "VAN", a hotshot between Omaha and Los Angeles.

However, the TOFC use wasn't exclusive. While DDA40X's were not "wasted" on drag freights, coal service or slogging the taconite trains, they saw the majority of their service on any UP train that was end-to-end - between Omaha or North Platte and L.A or Portland. UP consistently over-powered their trains during the '60s and '70s, and the 6900's moved those trains along pretty smartly.

They were very, very impressive to experience in operation. My hat's off to Bachmann for taking the trouble to revisit this prototype and produce a worthy model of it that, if not 100% perfect, certainly captures the flavor.

[C855B]

In the above, replace "Omaha" with "Council Bluffs". Yeah, a rivet-count, but I thought that I should catch it first. 

Anyway, I'm going to back down a little bit about the "speedy" top-end of the DDA40X model on DC. I was testing it last night with a Kato SD40-2 "snoot" that I'm renumbering to be an 8000-class SD40-2H, and the Kato was nearly double the speed of the new Bachmann at any given throttle setting.

The test was a comic moment, fully in view of my wife, who then started to ask all sorts of questions I really didn't want to answer. I normally test speed matching on my test loop by putting each loco on opposite sides of the loop and see who catches-up first. The speed difference was so big that the Kato caught-up to the Centennial so quickly I couldn't kill the throttle fast enough, and WHAM!!!. I had to examine couplers for missing bits. 

The speed problem with the Kato is so bad it's looking like DCC is in my near future whether I like it or not.