They commonly worked on Brussels - Luxembourg services, later sharing passenger duties with the CFL Class 3000s.

The four system requirement was later dropped and 15 of these locomotives, equipped to run only on 3000 volts DC, were ordered from BN in 1973.

There were no prototypes built and given that this locomotive was on the cutting edge of technology in its day, that turned out to be a mistake.

Oddly enough, the Type G transmission was the only part of the Class 20 that had been fully tested before entering service.

It was the first pure direct current locomotive in the world to make 7,000 hp (5,200 kW) or anything close.

Although it was not a technological first, the Class 20 was also the SNCB's first (and so far only) all service electric locomotive with a Co-Co wheel arrangement, a feature that helped it to pull heavy freight trains easily through the Ardennes in spite of its 160 km/h (99 mph) gearing.

Freight duties included heavy trains from the port of Antwerp to places like the yards at Stockkem, Montzen, Gent and Zeebrugge.

Until Class 13 arrived they were the only SNCB locos that could pull 1100 ton freight trains on the difficult line from Luxembourg to Brussels.

Multiple working with the class was tried with a driver in each locomotive (a system of light signals was used to inform the driver of the second locomotive of what was going on) soon after introduction but the practice was quickly banned because the current demand of the pair caused problems for the electrical substations which were then in use.

2005 in the original green color will be kept on the active list at least until the end of 2016 and 2021 was saved by the railway preservation group PFT-TSP.

Over the years the Austrian firm of Roco has made a series of models in HO scale of different Class 20's.