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Diesel Locomotive Clasifications

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  • Member since
    February 2017
  • 7 posts
Diesel Locomotive Clasifications
Posted by CP Modeller on Saturday, March 16, 2019 5:21 PM

Can someone help me with understanding how locos get moved from one company to another. The loco in question is a CPRail GP38-2 #4520, this loco was built for the Southern in the 1970s as a GP 50  which I believe was rated at 3500hp and ended up at CP in the late 1990s as a GP38 which is rated at 2000hp. Was the prime mover replaced or is it wrongly classed?


Also when locos move around, as this one has would the horn have been changed from whatever the Southern used to the CPs Nathan K3 variant, or would it have been left as original?

Any info would be most welcome

Kind regards Colin   U.K.

  • Member since
    October 2008
  • From: Canada
  • 1,269 posts
Posted by cv_acr on Monday, March 18, 2019 8:53 AM

I had to look this one up, it looks like this series is an interesting collection of GP50 and GP40X locos that have been rebuilt and downgraded to GP38-2s.

It was extensively rebuilt at some point to convert the unit to GP38-2 specs.

Note the GP50 style radiator side intakes, but the middle cooling fan has been removed, so it only has two radiator fans instead of three. The turbocharger has also been removed and replaced with a straight exhaust, and the signature paper filter box of the 38-series has been added.

It's probably the same prime mover, but the removal of the turbocharger and related reconfigurations drops the HP rating down by about 1000HP.

  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 11,644 posts
Posted by wjstix on Monday, March 18, 2019 11:30 AM

Turbocharging has caused troubles with engines over the years, it's not that unusual for a railroad to remove it and re-designate the now lower-horsepower engine. It could be something done by a company that deals in used engines - they buy an engine from CP, modify it, and sell it to BNSF.

I think the horns would be up to the new owner to decide. If they worked fine, I think they'd just leave them as is. (However at least at one time I believe diesels in Canada were required to have a particular kind of three-chime horn - the idea being people would recognize the sound better at grade crossings - so I suppose CP or CN buying a used engine from an American railroad might have to change the horns.)

  • Member since
    September 2003
  • From: Omaha, NE
  • 9,823 posts
Posted by dehusman on Monday, March 18, 2019 8:34 PM

Real railroads don't really care about the model as built, they care about the model as it currently is.  Often as engines get rebuilt, they are downgraded or changed to essentially have the same equipment as a another model, they are classified as that different model. The UP de-turbo'd SD40-2's and made SD38-2's.  It was quite common for 4 axle engines to be deturbo'd and made into the "GP38"s .

Dave H. Painted side goes up. My website :

  • Member since
    October 2007
  • From: Jersey Shore
  • 313 posts
Posted by wojosa31 on Sunday, March 24, 2019 11:11 AM

There is a large secondary market for rebuilt diesels. The most likely senario is that the NS elected to down rate it's fleet of GP 50s and put the unit throughtheir GP38-3 rebuilding program at Altoona, Backshop. Then later resold the unit, either to a broker or the CP directly. 

The major builders no longer manufacture 4 axle diesel units, so there is a demand for "new" 4 axle power that is met by rebuilding surplus locomotives into something else, more useful.

NS has the capability of building / re-building locomotives at the Juniata Locomotive Shops, which date back to the PRR / PC / Conrail.


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