AC versions of diesels are typically a little larger than the DC versions in some way. The AC4400 has a massive AC box on the left side behind the cab, while the regular DASH 9 has a box of half the size in the same place.
From what I can tell in those prototype specs, it’s the AC version that’s longer (DC specs on the left, AC on the right), but only by about 6".
(From Wikipedia) The EMD MP15AC is a 1,500 hp (1,120 kW) diesel switcher/road-switcher locomotive built by General Motors’ Electro-Motive Division between August 1975 and August 1984. 246 examples were built, including 25 for export to Mexico, and four built in Canada. The MP15AC was a development of the earlier MP15DC model, but replaced the earlier model’s DC generator with an alternator producing AC power which is converted to DC for the traction motors with a silicon rectifier. The MP15AC is 1.5 ft (457 mm) longer than an MP15DC, the extra space being needed for the rectifier equipment. [Edit: Learn more here.]
Looks like the dimensions are being referenced from two different sources. Darth, I think you are using the dimensions shown on the link, and Jeffery is (I think) quoting Wikipedia.
One or the other might be incorrect. So, the only thing we can probably agree with right now is that the AC is longer than the DC. Now assuming that the models have been accurately dimensioned down from the prototype, maybe the OP can measure them and tell us how much difference in length they actually are.
A little more information: the October 1978 issue of Model Railroader had an article by David Engles discussing the MP15/MP15AC and a drawing by Alan Cerny showing the MP15. In the article it states that the over coupler face length of the MP15 was 48’ 8". It also states that the MP15AC had 6" more space between its trucks to allow a larger fuel tank. These dimensions seem to correspond to those shown on the sketck at http://www.thedieselshop.us/Data%20EMD%20MP15.HTML.
Looking at the pic of my old and new toys the difference is the full width of the front steps of the AC… which I’d guess would conform with the 18". The AC also has a longer tank than the DC.
As I said above, there seems to be a difference between the sources. However, the OP posted later something about the difference he is seeing was at the full width at the front steps. If this is really what he sees, then the length differences are not relevent to the answer.
The original poster had noted the locos were different lengths. He wasn’t talking about the fuel tank being a different size or the steps being a different width…
That’s a moot point now since it was pointed out that the difference in distance between the bolsters was because of the larger tank. He asked what the length of the loco was (not the extra length between the bolsters) and I told him the correct length was a foot and a half longer than the DC.
Here’s another site with drawings made to 1/25th scale. I suppose we could print them out and measure them up if we were really interested. As far as the actual length goes, as I posted above it was my opinion that the AC was longer than the DC, and that was all we could conclude from the references at that point.
Concerning what the length actually is, as they say around here at the Eagle’s football stadium, I’ve got no dogs in that fight.
And Jeffery, it wasn’t my intent to argue with you. If I wanted to start an arguement, I would have said something like “the MP15DC is the better locomotive”. And then you could have said “No, the MP15AC is a better locomotive because you don’t have all the toggle switches that you have to throw to get it to run around the railroad.” And then we could both sit back and watch the fray, LOL!
Actually I don’t much care about either one as I don’t have either of them in my collection. Only diesel switchers (besides road switchers) I have are the SW1000 (Athearn) and the SW900 (Proto 2000).
Could we have a friendly cease fire please? As soon as I get the chance I will takes some photos of the locos with a tape measure next to them. Even if we can’t get the “official” data we will then have a definite reference for the differences between the models. – All I’ll need then is someone I can e mail the pics to to get them posted…
I got a rather nice Conrail SD35 at the same time [:P]
