MICRO TRAINS NORTHERN PACIFIC LOCOMOTIVE Z SCALE These powered F7A and B unit locomotives are built by General Motors EMD and are painted in the well-known two-tone green scheme. NP assembled their F locos in three-unit sets for passenger service and four unit sets for freight service.
 
Prototype History:
The F7 was the fourth model in GM-EMD's successful line of F unit locomotives, and by far the best-selling cab unit of all time. In fact, more F7's were built than all other F units combined. It succeeded the F3 model in GM-EMD's F unit sequence, and was replaced in turn by the F9. Final assembly was at GM-EMD's La Grange, Illinois, plant or GMD's London, Ontario, facility.
The F7 differed from the F3 primarily in internal equipment (mostly electrical) and some external features. Its continuous tractive effort rating was 20% higher (e.g. 40,000 lb (18,000 kg) for an F7 with 65 mph (105 km/h) gearing, compared to 32,500 lb (14,700 kg) for an F3 with the same gearing.
A total of 2,366 cab-equipped lead A units and 1,483 cabless-booster or B units were built. (Note: the B unit is often referred to as an "F7B", whereas the A unit is simply an "F7".)
Many F7s remained in service for decades, as railroads found them economical to operate and maintain. However, the locomotive was not very popular with yard crews who operated them in switching service because they were difficult to mount and dismount, and it was also nearly impossible for the engineer to see hand signals from a ground crew without leaning way outside the window. As most of these engines were bought and operated before two-way radio became standard on most American railroads, this was a major point of contention. In later years, with the advent of the "road switchers" such as the EMD GP7, F units were primarily used in "through freight" and "unit train" service where there was very little or no switching to be done on line of road.