EMD rebuilds with "Dash-2" electrics

[CN_Hogger]

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.

[DutchRailnut]

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.

[GOLDEN-ARM]

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..........

[CN_Hogger]

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??

[DutchRailnut]

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

[dash7]

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

[Allen Hazen]

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.)

[CN_Hogger]

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?

[CSX-COAL HAULER]

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--

[DutchRailnut]

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

[CN_Hogger]

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.

[DutchRailnut]

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

[Allen Hazen]

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.)

----

(*) 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.

[DutchRailnut]

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.

[Typewriters]

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