EMD/UP DDA40X? 6900? Centennial? All of the above? (Questions about the DDA40Xs (aka Centennials, aka 6900s)

Model Railroader Prototype information for the modeler
1

Howdy folks, I’ve got a few questions.

What’s the real designation of the DDA40X locomotive type, I’ve seen them called “DD40AX” and “DDA40X” which one is it?

Also has anyone modeled the few units that were equipped with air raid sirens for grade crossing warning?

And has anyone modeled the sound effect too? I would guess that the sound would be the siren quickly spooling up and then holding a tone and then when it’s shut off it would slowly wind down, right?

Finally where can I find some pictures and maybe a video of the so equipped units?

Thanks in advance!

2

Ditto: My Go To site for the best U.P. information.

Utah Rails:

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

The diesel details page has tons of information.

http://utahrails.net/up/uprr-index.php

http://utahrails.net/articles/up-dd35.php

Double Diesels

Great site.

Good Luck,

Ed

3

to answer your firs question. The designation was DDA40X.

Ira

4

Thanks guys, I guys 3d printing would be the best option for it?

5

Athearn made one. Also can be found in Brass. Both would likely be cheaper than 3D print of that size.

http://www.athearn.com/Products/Default.aspx?ProdID=ATHG69553

You may have to search around a bit to find one.

Here’s two examples of the Overland one. You’ll have to learn how to paint though.

https://brasstrains.com/Classic/Trains?searchtext=DD40AX&showsold=True

Note they used a non-EMD designation on the model.

6

IT what?

3D print of the siren or the whole locomotive?

“Be specific — Choose Union Pacific”

That may be one of their slogans but it can be appropriate here.

Have Fun, Ed

7

Good point Ed,

I missed the whole siren part of the original post.

8

The siren itself.

9

It was a Federal Signal Thunderbolt 1003, modified (flattened projector or horn). They were tested on only two units 6918 and 6924.

UP_DDA40X_TB-1003 by Edmund, on Flickr

UP_6918_TB-1003 by Edmund, on Flickr

Regards, Ed

10

Ed ! You hit it right out of the park. Wow.

I knew a little about the DDA40X before but never knew of these horns. Very interesting. So, I took to YouTube to see what it might have sounded like. Found only federal signal thunderbolt tornado sirens.

I wonder what it sounded like ?

Does anyone know ?

Patrick

11

It looks like one of the “Horn Tweeters” that were popular in some of the high-end speakers of the '70s.

A few sound clips here:

https://en.wikipedia.org/wiki/Civil_defense_siren

Scroll down to Federal Signal Thunderbolt 1003

https://en.wikipedia.org/wiki/File:Federal_Signal_Thunderbolt_1003_video.ogv

Cheers, Ed

12

I figure it would sound like just a steady tone.

13

Or not.

One site I came across — and the roof mounting seems to back this up — is that there were two solenoids inside that horizontal enclosure shown in the above photo, that could vary the “choppers”.

One site demonstrates four different signals from the model 1003 Thunderbolt.

Maybe contact Don Strack at Utah Rails, he worked for UP, and ask him?

http://utahrails.net/contactme.php

What UP really should have done is mount one of these Chrysler 331 Hemi V-8 driven sirens onto a flat car ahead of the engines!

Cuda Ken sure would have liked that! He never does really “open 'er up” I like the sound of the engine almost as much as the siren.

https://en.wikipedia.org/wiki/Chrysler_Air-raid_Siren

Cheers, Ed

14

Just FYI. I worked the UP 1973-2003. The UP slogan at that time was “We can handle it.” There were still engines and freight cars with the older slogans. The U50 and U50C and DD35 still had the slogan “Dependable Transportation”.

15

Don’t forget Bachmann’s DD40AX…

http://shop.bachmanntrains.com/index.php?main_page=index&cPath=258_288_291

16

While we are on the subject, what are those pentagon-ish shaped things on the handrails of the DDA40X towards the back near the second engine housing? I just noticed today they have caps on them while looking at a photo of one… sand perhaps?

17

Ed, It’s Be specific — Ship Union Pacific.

Yes,that dates me to the era of brown 40’ boxcars.

18

[:$] [D)]

Better luck next time…

Ed

19

The items in question are the sand boxes for the rear truck.

20

The gaping hole in the Bachmann pilot makes me suggest don’t forget the Genesis version [:)]