Western Railroad Discussion > The A,B,C's of EMD prime movers.

While I understand what the "16-645E3" stands for in EMD naming convetions, I've always woundered what the numbers and letters that followed stood ment.

Example in "16-710G3B-EC", what does the "B-EC" stand for. what are the differnce from a "A" to "B" and "C"?

Thanks

The first EMC (since it was Electro Motive Corp at the time) designed engine to supersede the Winton 201A was the 567A. It had 8.5 X 10 bore and stroke giving 567 cid per hole. The initial version had a pneumatic-hydraulic governor. This was the engine in the early E's through the E6 and the FT's. A redesign was ready for the postwar market that Incorporated a greatly improved Woodward PG electro-hydraulic governor. For this engine, the designation became 567B, and this was the engine of the F3/F7/GP7/E7/E8 etc. By 1953 a major redesign of the engine with vastly different head and liner design was the 567C for the GP9, F9, and E9's. The horsepower race and unit replacement market led to turboed 567's which were a C engine in turboed version for the GP20 through the GP35. Horsepower kept going up and inter-coolers were added between the turbo and air box. These engines were designated 567D, D1, D2, D3, etc. The next step involved increasing bore to 9 1/16 to produce 645 cid per hole. This engine was designated 645E. For manufacturing purposes, the liner external dimensions remained the some so crankcases were pretty much unchanged from the 567C, RR's realized that they could put the new power assemblies in C crankcases. The next step was to lengthen the stroke to 11 and produce the 710G. Oh, not to neglect the F which was an E with engine top speed raised from 900 to 950 RPM. This engine was a problem and soured some longtime customers to begin EMD's slide from the top spot in the market. . . Joe S.

Oh excuse me by the way 710G3-BC gives some disignation for application of this particular 710 of which I have no knowlege. Perhaps an inquiry to EMD would produce the answer barring any proprietory restrictions. . . Joe S.

frontrangeflyer Wrote:
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> Oh excuse me by the 710G3-BC gives some
> disignation for application of this particular 710
> of which I have no knowlege. Perhaps an inquiry
> to EMD would produce the answer barring and
> proprietory restrictions. . . Joe S.

Its a bit more complicated with the early ones, the 567 (no letter) , the 567 "U" deck, and a couple of more early models preceeded the 567A which appeared during WW2. In the designation 567A the "A" indicates the crankcase variation, this is ongoing, you may note that the 645 did not reset this to "A" but rather continued on from where the 567 left off. Therefore the 645F represented a strengthening of the crankcase assembly to handle the greater power of the 645 engine as used in the 50 series locomotives. the number following the crankcase letter indicates either the presence of a turbocharger "3" for railroad applications, or an alternative use, "5" for marine engines, "8" for power generation (standby generators), drilling platform drill motors "9", etc. The following one or two letters indicates some further variation, the "EC" indicates EFI, "ES" indicates EFI with split cooling,"T2" indicates meets Tier 2 emissions. So a 16N-710G3B-ES, the most common engine in a SD70MAC, would indicate "16" 16 cylinders, "N" normal rotation (marine offers counter rotation), "710" the per cylinder displacement, "G" the 7th major crankcase variant, "3" turbocharged for railroad application, "B" second subvariant, "ES" EFI and Split Cooling radiator.
The use of the "1", "2" suffixes preceeded the modern nomenclature, there were also "AC", "BC" and "CR" early versions where "AC" means "A" block with "C" heads, and similarly with "BC". EMD had problems with water leaks in their early engines until the 567C debut. The 567CR was the first counter-rotating variant and a few made it into switcher production. It wouldn't surprise me if these were converted to standard at some time. Oddball crankshaft and camshaft.

Why would a rail application want an odd ball like this? What possible difference could rotation direction have on a locomotive?

Here is a really good article on the 567 engine and some thoughts about continuing to use them from a preservation viewpoint.

http://www.rypn.org/RyPN/articles/viewarticles.asp?filename=060228215551.txt

john1082 Wrote:
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> Why would a rail application want an odd ball like
> this? What possible difference could rotation
> direction have on a locomotive?

To get faster delivery, shortage of railroad parts, surplus of marine parts. Operationally it makes no difference, but for maintenance the camshaft and crankshaft must match,hence why I think they were probably later changed to standard. About half a dozen SW900s are the only confirmed cases, a few SW1200s are suspect, but block serial numbers are not confirmed on any of these.

I hope La Grange gave the buyer's a price break on this deal.

john1082 Wrote:
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> Why would a rail application want an odd ball like
> this? What possible difference could rotation
> direction have on a locomotive?


The opposite hand EMD engines (rotation) are largely a marine product. We sometimes use opposite hand roation engines in twin-screw tug to get the propellers turning opposite directions on each side of the boat. This is also done with a reverse/reduction gearbox as well, but not all gears can be set up to opposite-rotation, so sometimes the engine rotation is changed.

Bob

Marine use would make good sense as in a twin screw vessel you could cancel out the torque; aircraft with twin props are also configured this way.

But if I had a fleet of locomotives I'd want them all to turn the same way just to reduce the parts inventory.