The EMD F40PH is a four-axle 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. Amtrak retired its fleet of F40PHs in the early-2000s in favor of the GE Genesis, but the locomotive remains the mainstay of Via Rail's long-distance trains; a depiction of the locomotive hauling The Canadian is featured on the reverse of the Frontier series Canadian $10 bill. The F40PHs are still a common sight on many other commuter railroads throughout the United States. In addition, Amtrak has kept 22 of its F40PHs in use as non-powered control units. Background Amtrak inherited an aging and mechanically-incompatible fleet of diesel locomotives from various private railroads on its startup in 1971. The most modern locomotives remained in private hands for freight service, or to operate the various commuter services which, by law, did not pass to Amtrak. To replace these Amtrak ordered 150 EMD SDP40F locomotives, which began entering service in 1973. These were supplemented by 25 GE P30CHs which entered service in 1975. The SDP40F was a troubled design; problems with weight distribution led to a series of derailments in the mid-1970s. Meanwhile, the poor truck design of the P30CH (and the electric GE E60CP) curtailed further orders of that unit when Amtrak found itself needing more short- and medium-distance power in the spring of 1975. Design The design of the F40PH was based on the EMD GP40-2 freight road-switcher and shared that locomotive's turbocharged EMD 645E3 V16 cylinder, two-stroke, water-cooled diesel engine (prime mover). The prime mover developed at 893 RPM. The main (traction) generator converts mechanical energy from the prime mover into electricity distributed through a high voltage cabinet to the traction motors. Each of the four traction motors is geared to a pair of driving wheels; the gear ratio determines the maximum speed of the locomotive. A standard F40PH has a gear ratio of 57:20, permitting a maximum speed of . Some Amtrak F40PHs were delivered with a 56:21 gearing for . The first 30 locomotives were built