Class 150 Electric Locomotive In the DB type program of 1954, the six-axle E 50 was the largest, heaviest, and most powerful electric locomotive. Its task was to haul heavy freight trains and its maximum speed of 100 km/h / 63 mph was also supposed to make it usable in heavy express train service. Road numbers E 50 001 and 002 were the first units to be delivered in January of 1957. The first 25 units were still equipped with axle-suspended drive, but starting with road number E 50 026 rubber ring spring drive prevailed. By 1973, 194 units had been built, starting with sequence number 140 with the computer-generated class designation 150. These units turned in excellent results in heavy freight service, especially in hilly terrain. Starting in 1998, the class 150 units were largely replaced by delivery of the regular production new class 152. At the end of 2003, the last units were taken out of service and the first of the four standard design electric locomotive classes were completely gone from the DB roster.