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  • GP15-1s & B40-8s

  • Discussion relating to the NS operations. Official web site can be found here: NSCORP.COM.
Discussion relating to the NS operations. Official web site can be found here: NSCORP.COM.

 #427089  by es80ac
 
Perhaps I could have been more specific about my question.

If you were serious about your answer, and I interprepted the wrong way, sorry about that.

 #427772  by SOU2645
 
The B32's are owned outright by NS and always have been. 12 cylinder GE's tend to have slightly longer lifespans for some reason. All are mostly in the pig fleet based out of Atlanta.
Larry

 #428039  by Tadman
 
Where I used to work the GP15 was used as a yard switcher or local power. They're good on highly industrial areas where the train doesn't do much other than shunting and transfers. This was on UP's chicago heights terminal trackage, and they seem to work quite well there. Other power is MP15's with blomberg road trucks. They are used interchangeably.

 #429028  by Luther Brefo
 
SOU2645 wrote:NS got rid of them due to lack of dynamic brakes, low horsepower and the fact they are DC locomotives with more expensive to maintain DC generators.
The first two points are potentially plausible, however, the third point about it being a DC locomotive is far from the truth. Almost all locomotives on the NS roster are DC locomotives. The only AC locomotives on the roster came from Conrail. Even the engines NS orders today (ES40DC and SD70M-2) are DC traction.

 #429064  by LCJ
 
Almost all locomotives on the NS roster are DC locomotives. The only AC locomotives on the roster came from Conrail. Even the engines NS orders today (ES40DC and SD70M-2) are DC traction.
The general category, "DC locomotives" is not specific enough here. Original nomenclature termed units as being "DC" because they had DC main generators, as opposed to the more modern alternator/rectifier units. In those days, all diesel-electric locomotive traction motors were DC.

EMD began using alternator/rectifier main generators on their 40 series units, in the mid-1960s, in order to overcome the problems associated with DC generators producing high amounts of current. GE began to use them on their higher horsepower units in the same timeframe. GE U23B/C units were among the last "DC" units, as termed in that time period. EMD GP/SD38s, ditto.

Indeed, the majority of today's NS fleet is equipped with DC traction motors. Their main generators, however, are predominently 3-phase AC, rectified to DC for traction.

I hope I've made that clear, anyway.

 #429168  by Luther Brefo
 
LCJ wrote:
Almost all locomotives on the NS roster are DC locomotives. The only AC locomotives on the roster came from Conrail. Even the engines NS orders today (ES40DC and SD70M-2) are DC traction.
The general category, "DC locomotives" is not specific enough here. Original nomenclature termed units as being "DC" because they had DC main generators, as opposed to the more modern alternator/rectifier units. In those days, all diesel-electric locomotive traction motors were DC.

EMD began using alternator/rectifier main generators on their 40 series units, in the mid-1960s, in order to overcome the problems associated with DC generators producing high amounts of current. GE began to use them on their higher horsepower units in the same timeframe. GE U23B/C units were among the last "DC" units, as termed in that time period. EMD GP/SD38s, ditto.

Indeed, the majority of today's NS fleet is equipped with DC traction motors. Their main generators, however, are predominently 3-phase AC, rectified to DC for traction.

I hope I've made that clear, anyway.
Crystal clear. Just after I posted that, I wondered to myself...could he mean what you just explained...

Now the question in my mind in this...The GP40 showed up in 1965 with AC/DC drive and the GP15-1 came a little over a decade after that in 1976, so why did EMD decide to stick with DC/DC drive? Was it a cost issue or was this at the option of the customers (in this case, Conrail?)

Alco started using AC/DC when the C430 (1966) and C630 (1965) came about because DC/DC would have required an oversized DC generator to handle the 3000 HP being output by the prime mover. The C628 was the last Alco locomotive to utilize pure DC/DC.

 #429176  by LCJ
 
The GP15-1s, I believe I've read somewhere, were built primarily from trade-in equipment (like GP9s and such) -- all of which would have been DC/DC units.

Anyway, DC main generators work just fine in lower hp set-ups. It when the hp gets above about 2500 that the design falters (with armature flashover, and stuff like that) since high levels of current flowing through contact brushes gets tricky.

 #429417  by Allen Hazen
 
I agree with LCJ. A few more details...

(1) AC generators were introduced (1966-1967) on 3000 hp units. Initially, lower horsepower units continued to be built with DC generators (initial 2000hp GP-38 from EMD, first 2250hp U23B/U23C from GE were all DC).

(2) Gradually the railroads seem to have found advantages in AC/DC power (i.e. locomotives with AC main generator, current rectified for use in DC traction motors) even at lower power. EMD introduced an AC/DC option on the GP38 ("GP38AC") in 1971, standardized on AC/DC for the GP38-2. GE continued to offer DC in the U23B, but later orders for this type tended to be AC/DC.

(3) GE seems to have been happier with its DC design than EMD: the U18B was never built with AC/DC transmission. Even GE, however, stopped making straight DC units at higher powers: the B23-7 successor to the U23B was built only with AC/DC transmission.

(4) EMD eventually introduced AC/DC even in switchers: the initial MP15 (successor to the SW-1500) was a traditional, straight DC, design, but was joined by an MP15AC with an alternator in the late 1970s.

(5) The GP15-1 (the dash-1 was part of the official model number: emphasizing that it was a cheap, low-tech, unit) was introduced to compete with rebuilds (e.g. the ICG's "Paducah rebuild" GP-8 and GP-10 program of modernizing GP-7 and GP-9). Initially it was announced that it would only be sold with an F-unit or GP trade-in, and they were built with generators from the older units.

(6) Even for a 1500hp unit for switching and local freight however, AC/DC seems to have been thought superior. The MP, after buying a lot of GP15-1, got a final order of the light roadswitchers built with new components: GP15AC, with the same alternator used in bigger EMD types!

 #429433  by LCJ
 
Now we know
the rest
of the story...

Thanks Allen.

 #431550  by scottychaos
 
NS might not want the GP15-1's, but they will probably have a continuing career on shortlines..
caught these two a few weeks ago, lettered for Larrys:

Image

Image


10-20 or so of them have gone to AMP (American Motive Power) in Dansville, NY for rebuilding.

Scot

 #432266  by washingtonsecondary
 
I've always wondered why the GP-15 has it's intakes laid out like a tunnel motor. Is it a space issue because of equipment in the long hood?