EMD rebuilds with "Dash-2" electrics

DutchRailnut wrote:A dash 2 locomotive does not make transition, the traction motors are in permanent parralel,

That's funny, I've operated pleanty of SD40-2's that make transition, hell SD70's make transition.

difference is no traction motor transition, they change the pole pairs of the alternator, and that should hardly be felt unless electronics are set wrong.

Hardly be felt? I guess watching (and feeling) the loco drop it's load, from around 600-700 amps, down to 100-200, and the loco surge as it "reloads" COULD be called "hardly felt". Standing alongside the tracks, watching a train pass you, that might be entirely true..........

Or like when your climbing a hill and you can feel each of your trailing units go back through transition...or is every 40-2 I've operated 'set up wrong'? Dutch aren't you a passanger man??

Yes I run passenger engines but also have been electrician and supervisor in dieselshop before my job in transportation.
Why is that a problem ??

DutchRailnut wrote:Yes I run passenger engines but also have been electrician and supervisor in dieselshop before my job in transportation.
Why is that a problem ??

You guys shouldnt argue over such trivial matters, you guys are lucky! i don't work on a railroad,locomotives or anything rail related!,(medical problems) but reading this forum i think i have learned more in 3 weeks than i could ever have known, as corny as that sounds i love reading this forum! and thanks for replying to my sometimes stupid questions! seriously you guys are all right ! regards dash7

Are all Dash-2 the same when it comes to transition? I have a dim feeling I might have a dim memory that.... maybe 4-axle units were built with permanent parallel at a time when the available alternators weren't quite hefty enough to make that feasible for 6-axle? For that matter, even within a model there could be customer options: I have an almost equally dim (though this time a possible memory of where to look to check) feeling that the Santa Fe bought 3600 hp EMD units set up with permanent parallel because they used them mainly for high-speed freight, whereas some other railroads got them with transition because they planned to use them more often in sustained low-speed lugging. (But that might have been the original, 1966, 40-series and not5 the 1972 40-2 models.)

DutchRailnut wrote:Yes I run passenger engines but also have been electrician and supervisor in dieselshop before my job in transportation.
Why is that a problem ??

Well, I had thought you've worked nothing but passenger. What kinds of loco's did you work on?

CN_Hogger wrote:

DutchRailnut wrote:Yes I run passenger engines but also have been electrician and supervisor in dieselshop before my job in transportation.
Why is that a problem ??

Well, I had thought you've worked nothing but passenger. What kinds of loco's did you work on?

LIONEL-AMERICAN FLYER AND OTHER VARIOUS MODELS--

Instead of questioning my qualifications how about you guys trying to justify yours ??so far I only see useless atacks and no substance.

DutchRailnut wrote:Instead of questioning my qualifications how about you guys trying to justify yours ??so far I only see useless atacks and no substance.

I thought I asked a legitimate question. And how am I supposed to justify my qualifications?

How about just admiting that your were wrong and call it a day? If my memory serves me correct, I don't think this is the first time someone has questioned one of your responses to a question. Just get over the fact that you're not the ultimate source on everything railroad.

For two days the guy was waiting for answer, I tried to answer thats more than can be said for you big mouths !!

O.k., I've found a reference book: "How Diesel-Electric Locomotives Operate: the last 25 years including ACs," by Dr.W.J. White, D.B.A.(*)

According to it(**), all 40 series (both plain and Dash-2) FOUR-AXLE locomotives were set up for permanent parallel operation: no transition. Six-axle 40 series units DO make transition, at the motor level: SD-40 and SD-45 at low speeds have their motors wired into three parallel groups of two motors each, and at higher speeds make transition so that all motors are in parallel. SD-39 and SD-38-2 (the book makes no mention of plain SD-38, and seems to apply only to SD-39 with AC/DC transmission), units intended for low-speed lugging, start out with motors wired into two parallel groups of three motors each, and when they speed up to not-quite-so-slow make transition to the configuration SD-40 and SD-45 use at low speeds.

(Dutch, this is why, I assume, the others asked about your qualifications: in passenger work, and maybe also in your earlier work in a dieselshop if it was in ex-NYC territory, you would have had experience primarily with four-axle units. As long-time readers of Railroad-net forums know, you are generally knowledgeable, but you seemed to be denying their experience of transition on SD40-2, so....)

Apparently the change with Dash-2 was that plain 40 series, before making transition, went through several stages of "shunting" (field weakening), and this was eliminated (except on the SD38-2) in the Dash-2 models. (Hazen comment: even if this is true in general, I suppose there might be exceptions: units built for customers who thought they had special needs.) And apparently transition "at the alternator level" came in with the 50-series. (40-series-- both plain and Dash-2-- used the AR-10 alternator. 50-series and later (and also the small number of SD40-2SS built for BN and UP) used newer alterrnator models-- my guess is that alternator-level transition was only possible with the newer stuff.)

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(*) Copyright 1996,1997. Publisher identified only as "Peat". No ISBN that I can find. Address for enquiries: PEAT, Attn J.D., 1001 Pearce Dr., Mansfield, Ohio 44906.
(**) pages numbered separately in each chapter: the information cited is from pp. 2-6 to 2-11.

Thanks Allan for clarifying the 6 axle deal any of these guys couldf have provided the info you just did but they chose not to.
yes my experience is mainly with 4 axle power and a lot of it first and second generation.

Allen, you mention that the book referenced omitted the SD-38 and for what it's worth I recall that all of those that still used the D32 generator both employed transition and multiple steps of field shunt, like you'd find on a GP-30, GP-35, SD-35.

-Will Davis