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GE's 70-Tonner: Design For Light Branch Line Work

Last revised: August 27, 2024

By: Adam Burns

General Electric's 70-ton switcher is considered by many locomotive historians and enthusiasts as one of GE's masterpieces in terms of both engineering excellence and versatility.

Designed in the late 1940s, this compact locomotive swiftly became a valuable asset across a broad range of applications, its impact evident in the numerous industries it serviced over the subsequent four decades.

The model did not enjoy the 44-tonner's sales numbers but nevertheless sold more than 200 examples between 1946-1957. Today, several are preserved.

Photos

Belfast & Moosehead Lake 70-tonner #51 is seen here in Belfast, Maine on October 23, 1973. Photographer unknown. American-Rails.com collection.

Background

In terms of design, the 70-tonner was constructed with a solid steel frame, meticulously engineered to cope with the heavy loads and turns often required in switching operations.

Unlike the earlier 44-tonner - intended for common-carrier service and specifically aimed to avoid the "90,000 Pound Rule" - the 70-tonner was design for light branch lines with restricted axle loadings where 100-120 ton conventional yard switchers could not roam.

It boasted an overall length of 37 feet, a width of 10 feet, and a height of 13 feet and 5 ½ inches, allowing the switcher to be nimble on tighter networks. With a fuel capacity of approximately 500 gallons and sporting GE's rugged model 748 traction motors, the switcher was a robust and enduring presence on the tracks.

The 70-tonners were equipped with a six-cylinder Cooper-Bessemer model FWL-6T prime mover, originally capable of 550 horsepower (later upgraded to 600 horsepower). 

As Bob Hayden notes in his book, "Diesel Locomotives: Cyclopedia - Volume 2," this engine was the direct descendent of the sixteen-cylinder model 7FDL16 utilized in GE's first production road-switcher, the U25B.

For the time, the power plant showcased impressive torque and response, matched by its four-wheel, direct drive traction motors that ensured efficiency in power delivery.

From an operational perspective, the  switcher demonstrated outstanding tractive effort due to its low axle load and high adhesion design. With a starting tractive effort of 41,700 lbs, it successfully catered to steep gradients and heavy loads without compromising performance.

The true value of the locomotive lay in its versatility. It was used primarily as a yard switcher in railroads across the United States and Canada, and in a variety of industries ranging from timber to mining, cement plants to steel mills.

Its reliability and resilient nature made it an ideal locomotive for these challenging environments and their demanding work schedules.  However, as Jay Reed notes in his book, "Critters, Dinkys & Centercabs," in many ways the 70-tonner was GE's first locomotive designed for general road service as it was quite capable of short freight consists as well.

The switcher was produced mainly at the famous Erie, Pennsylvania manufacturing plant - over a period spanning 11 years a total of 239 units were built there for North American and Mexican customers.

For railfans and enthusiasts, the 70-tonner also offered a unique aesthetic presence. With its lean and compact body, front and back platforms, and distinctive livery options, it stood out from the often-crowded switchyards. It presented a simplified, purposeful design that was a departure from the larger and more complex locomotive designs of the era.

As the need for high-horsepower locomotives became increasingly prevalent in the 1970s, the prominence of the switcher slowly began to fade and production eventually ceased. Nonetheless, its lasting impact on the North American rail industry cannot be underestimated. This classic switcher has since found a new lease of life in museums and heritage railways across the continent.

Center Cabs

While the end cab 70-tonner is most widely known by enthusiasts, GE also produced a center-cab version, primarily between 1940-1942.  These units sported a rather boxy appearance and lacked the beveled and rounded aesthetic touches the company would later apply to its switchers.

Reed notes the first unit built was powered by a Cummins HBIS engine capable of producing 400 horsepower.  The next three examples utilized four Cummins HBI engines, paired side-by-side, and could produce 600 horsepower.  The final seven units were equipped with two supercharged HBIS power plants and - once more - offered 400 horsepower.

Production Roster

Center Cab

Canada

Export

Data Sheet and Specifications

Conclusion

In conclusion, the story of the 70-tonner is one of uncomplicated but highly effective engineering, meeting the specific demands of the rail industry during a pivotal time in its history. It is a testament to the prowess of General Electric's locomotive division, a machine that was not just a product of its era, but one that actually helped to define it.

Balancing power, versatility, and simplicity, the switcher might not have been the flashiest locomotive of its time, but it certainly was one of the most important. Its enduring respect amongst the industry and enthusiasts alike is a testament to its significant legacy within the annals of North American railroading.

Sources

• Hayden, Bob. Diesel Locomotives: Cyclopedia, Volume 2 (Model Railroader). Milwaukee: Kalmbach Publishing Company, 1980.

• General Electric, Apparatus Department. 380-HP, 44-Ton Diesel Electric Railroad Locomotive: For Yard Switching and Road Service. Schenectady: 1947.

• Marre, Louis A. Diesel Locomotives: The First 50 Years, A Guide To Diesels Built Before 1972. Milwaukee: Kalmbach Publishing Company, 1995.

• Rail Heritage Publications. Early Diesel-Electric and Electric Locomotives. Simmons-Boardman Publishing Corporation, 1983.

• Reed, Jay. Critters, Dinkys & Centercabs. Whittier: Rio Hondo, 2000.

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