OK, I nominate this post for amature question of the century, but what is a GP-15? Yes, I know it is a general purpose four-axle unit built by EMD.
However, I thought the number designations for GP and SD units worked kind of like military fighters–the F-4 came before the F-5, the F-5 came before the F-14, the F-15 came before the F-18, you get the point.
However, I seem to remember something from the last Trains Magazine mentioning GP-15s built in 1979, I think for Conrail–indicating their production lasted into the 80s. I believe the last 4 GP-40s were built for FEC in 1984. Thus, it seems like the production time for a GP-15 is a bit off. Didn’t the GP-30s cease production well before 1979? Surely the GP-18 ceased production before 1979.
I am getting well beyond my amaturish knowledge with this, but the GP-38s used a variant of the 645 right? Didn’t the GP-40 as well, just with a turbo charger or something like that?
What engine was in the GP-15.
Was the GP-15 built for a more specific purpose than a GP-38?
Gp-15 was a 1500 HP combination road engine and switcher hence the GP-15 designation. It was a stop gap engine in GMs catalogue for awhile until the MP-15AC and DC came along. Only ones I ever saw were Conrail engines but I believe Mopac and CNW had them also.
Think baby tunnelmotor with a normally aspirated 8 cylinder 645. They were to be the next generation GP-7/9’s used as branchline and switch engines w/o endcabs (some came with cramped potties)… (and the GP30 was a GP22 before the marketing people got a hold of it)
True, except. There were three versions of the GP15. There was the standard GP15-1 which used a 12 cylinder 645 engine to develop 1500 horsepower. Purchasers that I am aware of were Conrail, Frisco, CNW and, MOPAC (GP15-1 and GP15AC). There was also a GP15AC version which also had a 12 cylinder 645 engine, but used an AR10 alternator instead of a trade in D32 main generator. Only MOPAC bought this version. Lastly there was also a GP15-T variant which used a turbocharged 8 cylinder 645 engine. I believe CSX (25) and the Appalachicola Northern (AN) (3) in Florida bought these.
Also, the GP15 was an alternative to the MP15/MP15AC and was not truly replaced by it. GP15s began production in 1976 and GP15 production lasted until 1983. The first MP15DC was built in 1974 and MP15 production ended in 1987.
The GP15 was a response by EMD to all the railroad rebuilding programs for GP7/9/18s. EMD wanted to get more business by replacing the locomotives with new EMD products, using some rebuilt parts. Missouri Pacific and Conrail were the biggest buyers, with C&NW and Frisco each buying a small batch. Compared to the big rebuilding programs, EMD’s success was very limited. Later models GP15AC and GP15T could be considered differently as although there were trade-ins used on them, neither MP nor CSX had a competitive rebuild program. Both the GP15AC and GP15T used the AR8 Traction Alternator rather than the AR10 (MP15AC and MP15T did also). EMD made one more try at the rebuild market with the BL20-2 which tested on BN, this model used more parts from the original locomotive than the GP15, but it debuted too late as the 80’s recession started to bite, and only the three demos were ever rebuilt. Finally EMD decided if you can’t beat them join them and rebuilt some of BN’s (later BNSF’s) GP39E and GP40E locomotives.
Um, the GP15-1 came after the MP15 and MP15AC. The purpose of the GP15-1 was to combat the GP8 and GP10 market of rebuilds that were coming on line at the time. The idea was that components from traded in Fs or GPs would make for new locomotives. It had the -1 designation to show it was different from the rest of the line (which at that time was GP38-2, GP39-2, GP40-2, SD38-2, SD39-2, SD40-2, SD45-2).
The MP15 was built because railroads wanted to use their SW1500s on the road, but the road trucks wouldn’t fit. The MP15 could fit those trucks. The MP15AC was an AC version, with the tunnel motor. After it was introduced, people started calling the MP15 the MP15DC, but I’m not sure that was ever an official designation.
FWIW I always thought (when I was a kid) that the number after the EMD engine designator was related to horsepower. It would have made some kind of sense to me to have the #s follow an order like jets but I guess that’s what the -2 and -3 designators do.
The meanings behind the designations changed over time and often stopped meaning anything.
GP7 was General Purpose and was introduced at the time that the F7 and E7 were being made. Also true with the GP9. By GP18 and GP20 it was the horsepower (1800 and 2000). As noted above, the next engine would have been the GP22 but it had thirty improvements and became the GP30. After that they went back to the series idea, hence GP35 matched SD35.
In the meantime, SW was assumed to be Switcher, but it was originally Six Hundred Horsepower Welded frame.
F is lost to the ages, but it did not start out as Freight.
Interestingly, the main freight locomotive of today is SD, which stood for Special Duty. Today, I don’t believe it stands for anything.
The Rock Island SW1500s had Flexicoil trucks. While these were designed to go out on the road by allowing for higher speeds, they are not the heavy duty Blomberg trucks as found on GEEPs and the MP15.
Thus, the MP15 was created to fit the Blomberg truck, which didn’t fit on the SW1500.
There was an interim unit called the SW1504, which had a stretched frame to hold the Blomberg.