The SS1 was the first mainline electric locomotive to be manufactured in China. The “SS” stood for “Shaoshan”, Mao’s birthplace. The first seven prototypes with the designation 6Y1 were built between 1958 and 1966 with Soviet help and were based on the ВЛ60. In the area of electronics, experience from the 6Y2 supplied by Alsthom was also incorporated.
In the years that followed, the prototypes were continuously improved. The actual production locomotives were ultimately only built between 1980 and 1988. Including all prototypes, 826 SS1s were built, which were used for various types of trains and the first of which had reached the end of their service life after almost 30 years. The last one ran for the last time on September 19, 2014.