The Red Flag 6-class (Korean: 붉은기6 Pulg'ŭn'gi-6) is a 4,240 kW (5,690 hp)[2] two-section, permanently coupled electric locomotive built by the Kim Chong-t'ae Electric Locomotive Works and used by the Korean State Railway for heavy freight trains on mountainous lines.

However, with the electrification of steep mountain lines, it was realised that a more powerful locomotive was needed.

[5] Numbered in the 6000 series, production of the new design began in 1986, and was put into service in 1987 to haul freight trains on the P'yŏngra Line.

[6] These four-bogie, eight-axle articulated units are 33 metres (108 ft 3 in) long, weigh 176 tonnes (388,000 lb) and produce 4,240 kilowatts (5,690 hp).

They have a maximum speed of 100 kilometres per hour (62 mph) and can pull 3,200 tonnes (7,100,000 lb).