• series parallel transition

  • Discussion of Fairbanks-Morse locomotive products. Official web site can be found here: www.fairbanksmorse.com.
Discussion of Fairbanks-Morse locomotive products. Official web site can be found here: www.fairbanksmorse.com.

Moderator: pablo

  by DocJohn
This is partly a DCC sound model RR question. Both FM sound decoders I have (QSI and Soundtgraxx) do not go through a series to parallel transition as you hear from sound decoders that emulate a first generation EMD locomotive. Were the FM's different?
  by AVR Mark

I have never seen a FM locomotive, but I have read a lot about them. Depending on the model, the locomotives used either General Electric, Westinghouse, (or FM's own equipment on later switchers). From what I have read, Westinghouse electrical systems did not use transition. They operated at 980-1170 (or so) volts instead of 600 volts that was used on the General Electric electrical systems. After about 1954 all the FM locomotives (except the switchers) used General Electric electrical systems, since Westinghouse had left the locomotive traction business. There was a "transition period" when locomotives were built with either Westinghouse or GE equipment at the customer's choice.

  by DocJohn

Thank you for your reply. It explains the situation.


  by Typewriters
Ah... but the Train Master, and concurrent H-16-66 units which used Westinghouse electrical equipment, are those exceptions in the "Westinghouse-equipped universe" that actually DID utilize transition in addition to field shunting.

The Train Master used two different combinations of motor groups in parallel and series, and in addition had three values of field shunting. I do not have a manual at hand, but seem to remember three motors in series (the two groups in parallel) and two motors in series (three pairs in parallel) but am not certain.

Note that by the time the Train Master appeared, the problems with the Westinghouse main generators when operated at high voltages and high power outputs were already known, and also remember that the Train Master had to be able to operate at full rated engine power over a wide speed range in order to be effective as a product (as compared to the C-Line 2400 HP units which really only needed high engine output at lower speeds for acceleration and weren't intended to produce high tractive effort at low speed continuously.) Those are good reasons why actual electrical transition was employed on these six-axle heavy duty Fairbanks-Morse units.

Yes - there is an exception to every rule, it would seem!

-Will Davis
  by DocJohn
Will, thank you for your reply. I just listened again to the CD-ROMs from Daylight Sales which have five tracks of FM Trainmaster sounds from SP commuter service running south out of San Francisco. There are also sounds from an SP GP-9 doing the same thing. If Trainmasters were going through transitions, they were much faster than on other diesels of the time.


  by pennsy
Hi All,

While the Trainmasters were good engines, I always preferred the C liners. But then I always preferred streamliners to the bulking road switchers. Also, I have some C liners in my HO stable. Good running engines and really look good hauling a passenger consist.

Can you confirm something I read sometime ago ? Seems that FM engines fell out of favor because they really were designed for shipboard use, not RR engines. They had huge radiators that took in seawater and cooled the Diesel engines and so had a problem with RR engines that had self contained water or coolant supplies.

  by Typewriters
Well, the relation you make is true in one sense, in that in Naval applications the engines could be made to run cooler since you have an incredible heat sink available in the ocean water itself.

It is, however, largely irrelevant to compare Naval applications to railroad applications except in the simple sense that you can truly say that the engines were completely successful in their intended roles in shipboard use. (The submarine I served on for over four years had, as a standby power source, a six-cylinder 38D8-1/8 engine with which I was intimately familiar. Of course, the primary source of power was the reactor.)

Robert Aldag (a former F-M employee) has written extensively about the development of the engine and modifications thereto as regards locomotive application, and the relation you make is a partial quote of material he originally presented in one of the major railfan magazines, if I recall correctly. In that piece, he was relating the early piston failures of the engines when used extensively in long-haul service in the West, noting the comparatively high BMEP ratings and thus temperatures that the engines operated with in such service. The piston problems were apparently as much metallurgically driven as they were temperature driven, if those who are more engineering minded will allow that oversimplification, and were solved in time.

When you say "designed for shipboard use and not rail application" you are much closer to the mark. The nature of the construction of the engine, which, for example, made simple and quick inspection and replacement of pistons impossible when compared with the industry leaders, is commonly assumed to have been the locomotive program's undoing, which as Mr. Aldag has remarked bears some irony in the sense that it was solely the success (shipboard) of the engine itself that drove Fairbanks-Morse to develop a locomotive program centered around it in the first place.

(The Naval engines were offered in various numbers of cylinders, with further variation in power output per cylinder depending upon application and in many cases were actually producing less power per cylinder than the locomotive engines. The Naval engines also (especially in A-C generation) did not operate with rapidly and constantly changing speed and load. Thus, for the Naval engines, the regimen of teardown and inspection was often less frequent than it was for locomotive engines.)

Finally, there were many other factors that added to problems with F-M power, such as unfamiliarity to the shop workers (since the units were not common on most roads) and poor maintenance practices. In fact, and I've quoted from this before, I own a later F-M engine manual that has a list of "things not to do" or problems with actual maintenance practice which includes in its tone no small sense of bitterness. In this short section of this manual, it is perfectly obvious that F-M knew that railroad shop personnel were doing things in the field that led to often catastrophic failure of the engines (..."...the resetting of the shutdown point of a low oil pressure switch to a lower value, the increasing of the idle speed of an engine to keep the engine from shutting down because of low lube oil pressure will only bring disastrous results") and printed as much even though F-M knew that these things would continue. Even though these things were also probably being done to other makes of locomotive engine, those others being generally less expensive and difficult to maintain and more often available certainly helped F-M along the path to ending its locomotive production.

-Will Davis