ET22 (also manufactured as Pafawag 201E) is a Polish six-axle electric freight locomotive built by Pafawag from 1969 to 1989. Factory designation is 201E. With 1183 units, it is one of the most numerous standard gauge electric locomotive built in Europe. Further 23 units were built for Morocco as E-1000 class. History Soon after Pafawag started the production of a universal EU07 locomotive, The Rolling-stock Industry Central Bureau of Construction (Pl.: Centralne Biuro Konstrukcyjne Przemysłu Taboru Kolejowego) began to develop a new heavy Co-Co freight locomotive. The electrical part of the locomotive including the traction motors was based on the equipment used in EU07 locomotive. The new locomotive had some modern features, including its body. The first two prototypes of the class 201E were ready by the end of 1969 (ET22-001 and 002). A short series of ten was made in 1971, and large scale production started next year. PKP bought 1183 locomotives until the production was ceased in 1989 (numbered ET22-001 to ET22-1183, including two 201Ec type). Last were delivered in 1990. This made the ET22 class the most numerous standard gauge electric locomotive built in Europe. During the production the design of the ET22 locomotive was slightly altered. Some changes were also made during repair and maintenance. The body of the locomotives in use is different from the prototypes in details. There are three basic types of locomotive bodies where the main differences are the size and placement of the side windows, air intakes and ventilation grids. From ET22-013 big grids on the left side for resistors' cooling were moved from upper part to lower part of the body. From ET22-242 air intakes for engines' cooling were moved from a roof edge to side walls, on both sides, which is most popular configuration. ET22-001 - left side: four big ventilation grids in an upper part of the body, six air intakes and seven air outlets on a roof edge; right side: six air intakes in two groups on the roof edge. ET22-013 - left side: five ventilation grids in a lower part of the body, six air intakes and seven air outlets on a roof edge; right side as above. ET22-242 - left side: seven ventilation grids in a lower part and two in an upper part of the body, seven air outlets on a roof edge; right side: two ventilation grids in a lower part and two