Czechoslovak State Railways classes E 669.0 to E 669.3

The E 669 is a series of six-axle freight locomotives designed by Škoda for operation under 3 kV DC. The first two prototypes were built in 1958 and 1959 as a development of the four-axle E 499.0. They had a top speed of 120 km/h, what turned out to be too high for heavy trains in the Slovak Tatra mountains. For this reason, the subsequent production models had a gear ratio for 90 km/h, what increased their starting tractive effort from 231 to 345 kN. The two prototypes were later also rebuilt to 90 km/h and used until 1996.

The first series was the E 669 .1 of which 150 were built in 1961 and 1962. The first 80 were additionally suited for 1.5 kV DC. The demand for more locomotives led to the E 669 .2, of which 168 were delivered between 1963 and 1965. Still more demand led to the E 669 .3 that was built 43 times in 1971. From the second batch of the E 669 .1 to the E 669 .3, all were nearly identical.

In 1988, the sub classes 0 to 3 became the new classes 180 to 183. After the breakup of Czechoslovakia, the sub classes were split among Czechia and Slovakia depending on their former area of operation. The 181 only came to the ČD, the 182 came to both the ČD and the ZSSK and the 183 only came to the ZSSK. Later they lost many services to four-axle locomotives like the class 163 which do less damage to the rails. From 2005, many came to private operators which will use them for some more years.