(Barcelona), Ateinsa (Madrid) and Babcock & Wilcox (Bilbao); the project was led by the Instituto Nacional de Industria.

[note 1] The prototype locomotive led to an order of 60 units, which were assigned to the subclass 311.1, and numbered 311.101 to 311.160.

The transmission system uses 4 axle hung pinion drive three-phase asynchronous motors powered by a three phase alternator driven by a MTU engine partly license built by Bazán.

As of 2010 most of the units are operated by Renfe Mercancías, about one third have been assigned to the infrastructure company Adif.

[4] The locomotives were a success for the Spanish engineering industry, and the design formed the basis of a number of locomotive types exported from the Meinfesa factory: the SBB Am 841 (40 units 1994), the GA DE900 locomotives for Mexico, Israel and Egypt (35 units, 1997-2000) and the SNCF Class BB 60000 (175 units, 2004-8).