SD40-2

[Anonymous]

Greetings,

Anyone know why on the SD40-2 there is such large walkways in front and rear?

I always found this quite odd.

Any history and insight on this?

Thanks,

Mark in Texas

[dharmon]

Because it uses the same frame as an SD45-2. The smaller prime mover doesn't require as much space as the 45's. Hence the porches. Later units came with the "snoot" nose and the Tunnel motors used more of the frame for the displaced radiators so thier rear porch is smaller.

[nfmisso]

Mark;

A bit of additional information to dharmon's post. The SD45 sold far more units than the SD40, and EMD expected the Dash 2 line to continue that trend, so it made sense to commonize the chassis between the V16 (SD40-2) and V20 (SD45-2) models.

[Anonymous]

I'm a former railroader and I always wondered why EMD designed my favorite locomotive that way. A lot of the territory I worked on was single track. In other words, I spent half of my rr career stuck in sidings (the "hole") waiting for opposing trains to clear. These "porches" made nice places to take a snooze, a smoke , or eat lunch while waiting sometimes 6 hours. I sure do miss those old engines-NS ran them way past the service life of an average locomotive.

[Anonymous]

EMD also expected that engines would get larger in the future, so with a "standard " long frame they didn't have to worry about that for a while. I may be wrong but I believe that the SD-50's used this frame as well, and they were changed for the SD-60's.