The EMD F40PH is a four-axle 3,000–3,200 hp (2.2–2.4 MW) B-B diesel-electric locomotive built by General Motors Electro-Motive Division in several variants from 1975 to 1992. Intended for use on Amtrak's short-haul passenger routes, it became the backbone of Amtrak's diesel fleet after the failure of the EMD SDP40F. The F40PH also found widespread use on commuter railroads in the United States and with VIA Rail in Canada. Additional F40PH variants were manufactured by Morrison-Knudsen and MotivePower between 1988 and 1998, mostly rebuilt from older locomotives.
The National Railroad Passenger Corporation, doing business as Amtrak, is the national passenger railroad company of the United States. It operates intercity rail service in every contiguous U.S. state except for Wyoming and South Dakota as well as three Canadian provinces. Amtrak is a portmanteau of the words America and track.
A locomotive is a rail vehicle that provides the motive power for a train. Traditionally, locomotives pulled trains from the front. However, push–pull operation has become common, and in the pursuit for longer and heavier freight trains, companies are increasingly using distributed power: single or multiple locomotives placed at the front and rear and at intermediate points throughout the train under the control of the leading locomotive.