Western Railroad Discussion > SD90MAC-H, et al question

OK, I know the logic (or lack thereof) in the SD, 90 and AC parts of the model designation. But clue me in on the M and -H parts, as well as any others I may have missed....

thanx in advance

The H referrs to the series engine in the locomotive. The H engine is the Four cycle engine from GMLG. The G series was the letter designation for the 710 series engine.

The M is the letter designation for the North American Comfort Cab. This letter seems to get dropped if the cab is an isolated cab (indicated by the seam across the side and top of the nose.

I hope this helps.


Frank D. kenw wrote:
>
> OK, I know the logic (or lack thereof) in the SD, 90 and AC
> parts of the model designation. But clue me in on the M and -H
> parts, as well as any others I may have missed....
>
> thanx in advance

M is emd'd designation for a wide cab or saftey cab as in SD60M
The H is for the 6000 h.p. power plant, I believe there is a long model number for it that simply begins with the letter 'H'. When they first came out with this locomotive, they didn't have all the bugs worked out of the 6000 hp 'H' engine, so they put in 4300 h.p. engines into the SD90's body. designation therefore is SD90MAC-43. The grand plan at the start was to eventially convert the 43's into true SD90's when mass production of the 'H' engine was available. That is no longer the plan however as the railroad's have soured on this model because of all the problems with them.

To get 3 of them together is quite the feat, I am from Salt Lake and we tryed to get them when they were new. For one they didn't stay on the piont long, and I personally only was able to shoot 3 together once. 8551, 8552, 8526. I would mind just seeing one now that the are all based in the southeast part of the system 8522-8562. We do see an occasional one with the normal cab here. 8500-8521.
A question for those down in texas. are 8500 ever on the poin or in multeples.

pic was taken in Spring, Tx (Houston), 5-11-2001. I thought 3 together was a real treat, too.

kenw wrote:
>
> OK, I know the logic (or lack thereof) in the SD, 90 and AC
> parts of the model designation. But clue me in on the M and -H
> parts, as well as any others I may have missed....
>
> thanx in advance

"M" is a holdover from the early days of wide cab units in the United States. Standard cab EMD units of various makes carried a "Normal" designation. I.E. GP-60, SD-60 etc. Wide cabs were givin the moniker "M". SD-60M, GP-60M etc. This has lead to some clever marketing by railroads as more options were ordered. BN like calling their new SD-60 units with AC traction control "Big Macs" (SD-60 M (Wide cab) AC (AC traction control. EMD tried using "I" to denote the Isolated cab units but it screwed up the "MAC" part

GE uses the suffix "W" for the same reason. Dash 8-40C is a Spartan cab Dash 8-40CW is a wide cab. (Where "Dash" came from is a mystery to me.)

-H is used to indicate the locomotive is equiped with the "H" series engine from EMD. (6000 hp)

BTW, you Do Not have a picture of an SD-90 MAC. You have a picture of an SD-90U.

The U is supposed to denote the change to the crew entry area and the front door. (This does NOT allow the use of one window size between units as sometimes reported)

Most think the U stands for "UGLY"

Hope this helps. Everyone else feel free to jump in and correct me wont be the first time today I'm wrong.

Gary

Well,

The "M" designation for the SD90MAC means that it is just a plain 90MAC......most likely a SD90/43MAC, which has not been upgraded to a true 6000 hp model.....it only has the 90MAC body style. The SD90MAC-H is used to designate the true 6000 hp models....those that were delivered after EMD worked all the bugs out of the 6000 hp prime mover. The spotting features of the SD90MAC-H are the following:

1. they have a hump between the radiator section and the filter intake area...this hump sticks up to allow room for the bigger 6000 hp engine.

2. or.....more easily, they can be identified by the Phase II cabs like the ones you posted photos of at the begining of the thread.

Hope this helps.

-Ryan

For me, the most obvious spotting feature between the SD9043ACs "convertibles" and the true SD90MACs is the roof line over the engine access doors midway along the hood. On SD9043ACs, the roof and sides meet in a perfect right angle, while on SD90MACs there's a very visible "bevel" or notch. I sometimes think of the SD90MACs as "bevel tops".

Nice photo Ken! :)

I'd like to get all four of Canadian Pacific's MAC-H's together at once. I have only caught them in pairs.

Wayne
Sudbury, Ontario.

BN7149 wrote:

> The spotting features of the SD90MAC-H are the following:
[snip]
> 2. or.....more easily, they can be identified by the Phase II
> cabs like the ones you posted photos of at the begining of the
> thread.

This only works for the later SD90MAC-H's. UP's first order,
8500-8521, have "normal" widenose cabs like the 8000-series
SD9043MAC's. The bevelled hood top has remained a consistent
spotting feature difference, though. What I'd like to know
is *why* the hood is bevelled on the 6000hp locomotives and
not the 4300hp locomotives. It was a nice favor to us rivet
counters, but that's surely not why they did it.

SD-44R wrote:

> GE uses the suffix "W" for the same reason. Dash 8-40C is a
> Spartan cab Dash 8-40CW is a wide cab. (Where "Dash" came from
> is a mystery to me.)

It's a hold over from before GE "reversed" their nomenclature.
For locomotives like the C30-7, B23-7, and C36-7, the designation
would be pronounced, for instance, "see thirty six dash seven."
The locomotives were part of the "Dash 7" series. For reasons
unknown, not long after the introduction of the Dash 8's, GE flipped
the designations around to put the series up front. It's less than
obvious how to pronounce -8 40C, so they threw in the word "Dash:"
Dash 8-40C.

By the way, I once was able to get close enough to a GE Super 7,
one of those rebuilt Dash 7's in Dash 8 carbodies without the
microprocessors, to get a peek at the builder's plate.
"Super 7-30C," it said.

> BTW, you Do Not have a picture of an SD-90 MAC. You have a
> picture of an SD-90U.
>
> The U is supposed to denote the change to the crew entry area
> and the front door. (This does NOT allow the use of one window
> size between units as sometimes reported)

That's a new one on me. Is SD-90U a UP moniker or something EMD
came up with?

Evan_Werkema wrote:
>
> > BTW, you Do Not have a picture of an SD-90 MAC. You have a
> > picture of an SD-90U.
> >
> > The U is supposed to denote the change to the crew entry area
> > and the front door. (This does NOT allow the use of one window
> > size between units as sometimes reported)
>
> That's a new one on me. Is SD-90U a UP moniker or something
> EMD
> came up with?

I don't think it's either UP or EMD. I think the SD90U designation is something a railfan came up with to denote the Phase II carbody. I would think the "U" refers to the poor aesthetic qualities of the Phase IIs.

>>BTW, you Do Not have a picture of an SD-90 MAC. You have a picture of an SD-90U.

The U is supposed to denote the change to the crew entry area and the front door. (This does NOT allow the use of one window size between units as sometimes reported)

Most think the U stands for "UGLY"<<

No, that is incorrect. The true 6000hp units have never been called or classed as SD90U. The units in question are indeed SD90MAC-H's, which is what EMD calls them. UP classes them as SD90AC.

Bryan

redneckrailfan wrote:
> No, that is incorrect. The true 6000hp units have never been
> called or classed as SD90U. The units in question are indeed
> SD90MAC-H's, which is what EMD calls them. UP classes them as
> SD90AC.
>

The caption that ran in Trains or a similar magazine with a photo of one of these beasts when first released stated they were called SD-90U's for the reasons I stated previously.

This struck me funny since myself and several friends have often refered to the 3 window SD-60M's as SD-60U's for the same reason...They're UGLY. We thought it ironic EMD had chose that moniker.

Now, Could the caption in Trains be wrong? Sure. Could I have qouted it wrong. Sure. Don't think so and I'm checking but for now...Sure. The only real way to be sure is get a look at the builders plate or paperwork for the unbit

Are they ugly as sin....Yes.

Gary

sorry so many of you dislike the looks of these engines. I rather like it. so much for opinions....

by the way, UP calls them plain-old SD90MAC on the cab side.

I thinking some railfan disgrunted maybe came up with the U as for ugly. I think those MACs look cool with the phase 11 nose

Has anybody else noticed that the back end of the long hood is shaped differently on at least the phase 2 90MAC's, and maybe all H-engined units? Compared to the original convertibles, the end of the long hood is much more pointed appearing whereas on the convertibles the flat center portion is much wider. I'd like to see good photo comparisons to see if my memory is correct on this or not, and whether the difference is a part of the Phase 2 body or the H engine difference.

....

...