EMD switcher radiator cores


For my sw1500 kitbash project, I have drummed up some 3d models of the radiator cores commonly seen on the later generation EMD end cab switchers. The Atlas rendition as produced is woefully lacking in even simple accuracy but certainly in detail. I have several versions drawn as there appear to be several combinations of cores utilized on the prototypes, depending on any number of factors. I will get these printed, and possibly try to cast them in resin ultimately. The goal is to have the core “fin” area of the assembly hollowed out, with the top face replaced with a piece of finely etched metal screen, which is intended to let the sound out. This screen will play the same role as the speaker fabric that Bob proposes to use on his switchers, but I hope the metal will more readily accept paint and weathering without losing the properties that make it appropriate for use.

I’m curious whether the earlier iterations of EMD switchers like the sw8/9 that Atlas depicts use the same radiator cores? It’s easy to discern the cores on the later switchers, but I’ve never found a picture from the right perspective to see down into the radiator area on the earlier models.

I also have 3d cad for the radiator fan area, which shares many features with the earlier EMD switchers.

If any of this is applicable to Bob’s switcher project, I’d be happy to share.



Jim -

Thanks for the offer. I don’t know all the dimensions of what would fit in an Atlas off the top of my head. The first drawing, showing 3 cores, might work.

The SW8/9/1200 had a 3 segment core on each side, the top surface resting 7" below the protective screen. The cores were mounted at the same angle as the top of the hood.

I managed to take a few detail shots of an SW8 being cut up in Loveland. Click on the photos for a larger size.

With permission I climbed aboard a wrecked SW9 at the Colorado Railroad Museum. It turns out that the unit was stripped prior to donation.

Finally, you might find something helpful here:
Link to gallery with more SW photos


One more thing. Working with real woven screen can be a challenge, especially at diagonal corners. The mesh can fall apart.

It turns out that Alliance Model Works makes several sizes of square and diamond etched brass mesh that might prove useful. I have a sample of TW017, which is a 1mm spacing diamond mesh which I may use for the SW9 top screen.

McMaster-Carr carries various mesh sizes in woven brass. The catalog details the percentage of open area. Brass might be easier to form and can be soldered in spots that would not be visible.

McMaster-Carr woven brass woven wire cloth


Thanks for the reply. I have seen plenty of great photos on your Smugmug site, but I think I missed the particular album you linked to above. I’ve only seen the photos that you included in your album on the Atlas switcher. And I too took a look at the ex-Coors unit at the Golden museum, although I didn’t get up on it. But I could open the doors from the ground and could see that the guts had been stripped out. Also, as you noted, the grille on the front of that loco is of a later design.

I’m of the impression that the design of EMD cores is consistent at least for switchers and hood units through the first incarnation of the sd70’s. Based on your photos and other data I’ve found on the web, the same cores are used from the early switchers through the later units, just in varying combinations of lengths depending on cooling load requirements. The only other distinction might be in the depth of the core cross-section on larger units, but I need to verify if this is true. If nothing else, the similariities can be seen in the photos of gp7 2233. Those cores of essentially the same as found in the sw8 photos.

Regarding screen material, both to represent the core and as safety grilles over the cores and fan, I am planning on a combination of Plano product and custom etch. I was going to try and work up some custom etch artwork for the core surface, but I think first I will test some Plano roofwalk sheet material intended for scratchbuilding projects. I have custom etch artwork already done for the front and top grilles, but I need to get that produced yet.

I’ve read about your quest for the proper woven screen with both the proper open area, aspect ratio, and diamond pattern. Fortunately, the later models like the sw1500 had moved to welded grilles as found on the Golden Museum switcher.

There appear to be many similarities between the early and late switcher radiator sections, at least for the guts. The grilles changed, as well as the position of the cores with respect to the hood itself, but the cores, shutters, fan plenum, and fan blade all seem the same. It would be nice to be able to leverage the cad development for my sw1500 model to other late and early models as well.

I’m about to send some cad out for test prints, after which I’ll be able to test if my engineering works with the Atlas shell and the Plano roof walk material. Once I get everything dialed in, I’ll be happy to get you a 3-core version to test out.