The

Pennsylvania Railroad The Pennsylvania Railroad (reporting mark PRR), legal name The Pennsylvania Railroad Company also known as the "Pennsy", was an American Class I railroad that was established in 1846 and headquartered in Philadelphia, Pennsylvania. It was named ...

's class FF1 was an American

electric locomotive An electric locomotive is a locomotive powered by electricity from overhead lines, a third rail or on-board energy storage such as a battery or a supercapacitor. Locomotives with on-board fuelled prime movers, such as diesel engines or g ...

, a prototype numbered #3931 and nicknamed "Big Liz". It was built in 1917 to haul freight trains across the

Allegheny Mountains The Allegheny Mountain Range (; also spelled Alleghany or Allegany), informally the Alleghenies, is part of the vast Appalachian Mountain Range of the Eastern United States and Canada and posed a significant barrier to land travel in less devel ...

where the PRR planned to electrify. "Big Liz" proved workable but too powerful for the freight cars of the time with its 4600 available horsepower and astonishing of tractive effort. Pulling the train it regularly snapped

couplers Coupler may refer to: Engineering Mechanical * Railway coupler, a mechanism for connecting rolling stock in a train device ** Janney coupler ** SA3 coupler ** Scharfenberg coupler for multiple unit passenger cars * Quick coupler, used in construc ...

and when moved to the rear as a pusher its force was sufficient to

pop Pop or POP may refer to: Arts, entertainment, and media Music * Pop music, a musical genre Artists * POP, a Japanese idol group now known as Gang Parade * Pop!, a UK pop group * Pop! featuring Angie Hart, an Australian band Albums * ''Pop'' ( ...

cars in the middle of the train off the tracks. It had a

2-6-6-2 Under the Whyte notation for the classification of steam locomotives by wheel arrangement, a is a locomotive with one pair of unpowered leading wheels, followed by two sets of three pairs of powered driving wheels and one pair of trailing wheel ...

wheel arrangement in two half- frames, connected in the center. Each frame had a pair of three-phase AC induction motors driving a

jackshaft A jackshaft, also called a ''countershaft'', is a common mechanical design component used to transfer or synchronize rotational force in a machine. A jackshaft is often just a short stub with supporting bearings on the ends and two pulleys, gear ...

through gearing and a spring drive;

side rod A coupling rod or side rod connects the driving wheels of a locomotive. Steam locomotives in particular usually have them, but some diesel and electric locomotives, especially older ones and shunters, also have them. The coupling rods transfer t ...

s then drove the wheels. The jackshafts can be mistaken for an additional fourth axle but the "wheels" are cogwheels to transfer power from the motors to the jackshaft.

Three-phase Three-phase electric power (abbreviated 3φ) is a common type of alternating current used in electricity generation, transmission, and distribution. It is a type of polyphase system employing three wires (or four including an optional neutral ...

power for the 4 massive motors was supplied from the single phase overhead supply via a large

rotary converter A rotary converter is a type of electrical machine which acts as a mechanical rectifier, inverter or frequency converter. Rotary converters were used to convert alternating current (AC) to direct current (DC), or DC to AC power, before the adv ...

housed in the body of the locomotive. Combined rated output of the motors was , but the converter could only supply a short term or a continuous . With three-phase induction motors there was no way to control the speed of the motors; changing the wiring of the motor poles allowed for two speed settings, , which were considered enough to drag heavy freight trains up and down steep grades. Its intended use as an Allegheny climber never realized and its power too much for the

rolling stock The term rolling stock in the rail transport industry refers to railway vehicles, including both powered and unpowered vehicles: for example, locomotives, freight and passenger cars (or coaches), and non-revenue cars. Passenger vehicles ca ...

in service at the time, Big Liz was sidelined until being cut up for

scrap Scrap consists of recyclable materials, usually metals, left over from product manufacturing and consumption, such as parts of vehicles, building supplies, and surplus materials. Unlike waste, scrap has monetary value, especially recovered m ...

in 1940.

References

* * * 11 kV AC locomotives FF1 1′C+C1′ locomotives Experimental locomotives Individual locomotives of the United States Electric locomotives of the United States Unique locomotives Scrapped locomotives Standard gauge locomotives of the United States Railway locomotives introduced in 1917 {{US-train-stub