This locomotive was one of the first with four axles in Spain, which gave it more power. It was also the first to use steam brakes.
As for its appearance, it is characterized by the short height of the steam boiler, which is due to the fact that all its mechanisms are external, and also, the large size of its dome.
The line where these locomotives were used more often, was from Madrid – Irun line.
This train engine and the 38 machines of its series, was very easy to operate and to maintain. Together with its power, became the main reason that it was still operational up to the year 1962.