The Pennsylvania Railroad

Pennsylvania Railroad

The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....

's class FF1 was an American electric locomotive

Electric locomotive

An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or an on-board energy storage device...

, a single prototype numbered #3931 and nicknamed "Big Liz" by its crews. It was built in 1917 for the task of hauling freight train

Freight train

A freight train or goods train is a group of freight cars or goods wagons hauled by one or more locomotives on a railway, ultimately transporting cargo between two points as part of the logistics chain...

s across the Allegheny Mountains

Allegheny Mountains

The Allegheny Mountain Range , also spelled Alleghany, Allegany and, informally, the Alleghenies, is part of the vast Appalachian Mountain Range of the eastern United States and Canada...

, which the PRR planned to electrify; this was never accomplished. In testing, "Big Liz" proved workable but simply too powerful for the freight cars of the time. On the front of the train, it regularly snapped couplers

Coupling (railway)

A coupling is a mechanism for connecting rolling stock in a train. The design of the coupler is standard, and is almost as important as the railway gauge, since flexibility and convenience are maximised if all rolling stock can be coupled together.The equipment that connects the couplings to the...

, while when used as a pusher on the rear its force was sufficient to destroy the cars it pushed.

It had a 1-C+C-1 wheel arrangement and consisted of two half-frames

Locomotive frame

A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure of some kind...

, articulated together in the center. Each frame mounted a pair of AC induction motors driving a jackshaft

Jackshaft

A jackshaft is a device for turning the wheels of a locomotive. It is essentially an axle with no wheels. Each end of the jackshaft has a crank pin and a counterweight. The driving wheels are then connected by side rods. The name may come from a combination of "jack," a slang term for a locomotive,...

 through gearing and a spring drive; side rods then drove the wheels.

Specifications

Builder	Pennsylvania Railroad Pennsylvania Railroad The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
Electrical equipment	Westinghouse
Built	1917
Withdrawn	1940
Quantity	1
Road #s	#3931
Driving wheels	72 in (1.82 m)
Total weight	516,000 lb (234,000 kg)
Adhesive weight	439,600 lb (199,000 kg)
Overall length	76 ft 6¼ in (23.32 m)
Tractive effort	One-hour: 88,000 lbf (390 kN) Continuous: 73,000 lbf (320 kN)