Looking over an EMD cab unit the other day it appears that the carbody side panels (steel, not ply-metal) were "floating" with the battens actually holding them on. But, I know I've seen several EMD cab units that had all welded sides (no battens) applied as a retrofit. So I was wondering about the advantages and disadvantages of these two styles? It would certainly seem that the all welded would sure be an improvement both from a ease of fabrication and making/keeping the unit weather tight.

Anybody have any thoughts?

ETA

Yes, the side panels on E's, F's, and "cowl" type EMD's (up to at least the FP45 models, I haven't had a close enough look at anything newer) float, held on by the batten strips.

The lower, fluted, portion of a E5 is a bit of an exception to this rule, with the fluting being secured by screws to an inner sheet metal side panel, which is screwed directly to the frame members. Even so, the fluting itself has horizontal slots for the screws, to allow some float in at least one axis.

As to your question of which style is better, in my opinion,if the locomotive was going to be stationary all its life, I'd say the welded sides would be much better.

But...
... a locomotive is not a stationary object, and its frame will bend or "work" slightly as it travels over track irregularities. The floating panels can move slightly to allow this working, without bending or wrinkling the skin. Welded sides lack this flexibility.

Jeff

But after years of flexing and rusting the floating panels tend to bow out as can be seen on Orange Empire's FP45 in this picture taken year ago.

http://railfan44.rrpicturearchives.net/ ... id=2334981

Many of the units without battens especially ex-Amtrak E units are not welded steel but rather 3/8" thick fiberglass panels. When running this was very evident by the amount of shake on the panel. Steel doesn't "quiver" like fiberglas.
The bulge in original panels is due to the material used not the way it is mounted. I have not seen the inside of a FP45 so I have no idea if EMD used the same type of panel as they put on the E units and F units.

Actually the floating panel arrangement is superior, as the frame of the loco tends to distort over time due to the weight of the equipment and the application of buff forces to couplers.

DPK