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GE's 'Super 7' Series: "Super-7N" and "Super-7R"

Last revised: August 27, 2024

By: Adam Burns

The "Super 7 Series," a name coined by Monongahela Railway president Paul Reistrup, according to Brian Solomon's book "GE Locomotives," was a rebuild program implemented during the 1980s to breathe new life into older Universal and early "Dash 7" models.

With sales ramping up for its latest "Dash 8" line, and the expense of new locomotives climbing, GE believed a rebuild series would bring in new buyers while providing them a power plant that featured the latest in electronics and components.

Interestingly, this concept was relatively new at the time; while Electro-Motive had rebuilt some older Baldwins and Alcos with EMD prime mover, and upgraded a few of its own first-generation Geeps, the company had never offered a true rebuild program of like-new locomotives.

The closest in existence then included companies such as Morrison-Knudsen and Precision National, which rebuilt a variety of first, and early second, generation locomotives from Alco and EMD.

Unfortunately, the domestic market for the Super 7s never took off, thanks largely to a saturated market of older first generation EMDs that could be acquired for a fraction of the price.  

Interestingly, Super 7s did gain a large following in Mexico where Ferrocarriles Nacionales de México acquired a large fleet of six-axle variants, the C30-S7, during the early 1990s.

Photos

Monongahela "Super 7's" layover between assignments in Brownsville, Pennsylvania on October 5, 1990; #2302 began its career as Western Pacific U23B #2252 while #2300 as Western Pacific U23B #2254. Warren Calloway photo.

Background

The Monongahela Railway was the only American line to show interest in GE's Super 7 series.  The MGA, then-owned by CSX and Conrail, was a regional coal carrier situated in north-central West Virginia and southwestern Pennsylvania.

It ultimately picked up eleven examples, #2300-2310.  In addition, Roberval & Saguenay of Ontario acquired three units.  The MGA locomotives were all former Western Pacific U23Bs while Ferrocarriles Nacionales de México's were rebuilt from former U30Cs, U33Cs, U36Cs, U36CGs, C30-7s, and C36-7s.

As Greg McDonnell notes in his book, "U-boats," former Western Pacific U23B #2263 was the chassis selected to become the original "Super 7" variant.

To keep costs down, GE reused the prime mover, 752 traction motors, trucks, and frames.  The company, however, upgraded the locomotive with a new standard comfort cab, Dash 8 specifications, modern toilet, refrigerator, and GE's SENTRY wheel-slip control system.  The company detailed this system in the following:

"The SENTRY system used traction-motor shaft speed sensors in place of older axle-mounted systems.  The motor shaft sensors were as much as six times more sensitive to speed fluctuations, allowing for more detailed corrections to wheel slip and a better application of sand to the rail. 

Depending on the severity of wheel slip, the SENTRY system would automatically sand the rail and make small, calculated reductions to motor output."

With GE's Erie plant at record capacity outshopping new Dash 8 locomotives, the company acquired the old Montreal Locomotive Works facility in Montreal, Quebec to handle new "Super 7" builds.  

Interestingly, this facility had been American Locomotive's Canadian arm and completed many classic diesels, including some models never offered in the domestic United States.  At the time, Alco and GE worked closely manufacturing locomotives, a partnership which ended during the 1950s.

Data Sheets and Specifications

B23-S7 (Super7-23B)

C30-S7 (Super7-30C)

Production Roster

B23-S7 (Super7-23B)

All Monongahela "Super 7s" rode on Blomberg trucks.  These units were all ex-Western Pacific U23B's, which the railroad had equipped with Blombergs from trade-in EMD units.

C30-S7 (Super7-30C)

Sources

• Solomon, Brian. GE Locomotives: 110 Years Of General Electric Motive Power. St. Paul: MBI Publishing, 2003.

• McDonnell, Greg. U-boats.  Toronto: Stoddart Publishing, 1994.

In addition, GE subcontracted work out to Morrison-Knudsen's plant in Boise, Idaho.  In fact, MK completed two of the three demonstrators General Electric had built.

The Monongahela acquired one of these demos while the other two were never sold.  From an outward appearance, Super 7's appeared almost nothing like their U-boat predecessors while internally they carried many of the same components.

They became a popular subject on the late-era Monongahela and were the final locomotives to adorn the railroad's classic grey livery with the large stylized "M" adorning the nose and carbody.

The units spent a few years in their original livery before being repainted into Conrail blue.  They were subsequently split up between Norfolk Southern and CSX after the Conrail takeover.  Today, they are scattered around the country at various short lines and private industries.