EMD rebuilds with "Dash-2" electrics

[Allen Hazen]

Typewriters---
Certainly I would assume that SD38 with DC/DC transmission would be electrically similar to SD35 (so with transition and field shunting), but once people start disagreeing I feel uneasy about ASSUMING anything about locomotive designs: too many surprises! ... I do recall seeing a list somewhere-- maybe in some incarnation of the old "Diesel Spotter's Guide"-- that more SD38 were built with DC than with AC/DC transmission but that almost all -- maybe only one exception -- SD39 had AC/DC. My impression is that it is now generally felt that AC/DC is hands down the better technology... was it an extra cost option on early 38 and 39, or were some customers just very cautious about anything new?
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As for my thought that the Santa Fe might have had SD45 set up for permanent parallel operation at a time when other customers got them with transition: I checked what I thought might have been my source and didn't find any mention of it. So maybe I imagined that one.

[BDA]

Hi all , I can pass on a bit more about what we have in Australia anyway .

I believe the first production locomotives (non Pilbra) to have EMD's Super Series were the 81 class JT26C-2 SS . They have a 16 645 E3 (B or C I can't remember) and the alternator is an AR16 . Later EMD based Clyde built locomotives use the AR11 alternator which I call the "power glide alt" because of the distinctive lurch when they do the up/down shift . The AR11 I'm told is smaller and lighter than AR16's but the change is anything but gentle at times . We also have a couple of loco classes that have an AR11 behind a 16 710 which is a bit weak because the AR11 can only use ~ 3840 Hp . As we know the 16 710 can easily put out 4000 + .
I am going a bit OT so will start a new thread asking about 40/50/60/70 series upgrades .

Cheers BDA .

[WVU]

The GP38-2, GP39-2 and the GP40-2 does not make transistion, but at 28 mph they make recalibration. What recalibration is, the WO module will change the allowable Field Amps that can be pumped into the AR10 form 144 down to 108 field amps. 144 X 43.5 = 6264 MGA output while 108 X 43.5 = 4698 MGA. When recalibration occurs, the WO changes the limits of GX, EL & WS. Once the unit goes below 28 mph the limits will return to normal. There is no contactors involved. It is all done thru the modules.