a design for a small multi-service bo-bo locomotive, with speed up to , had been devised by giuseppe bianchi as early as in the 1930s, but the project had been halted by the introduction of the e.326 and e.428. after the realization of the 6-axle e.636, it was however decided to revamp the project by adapting to it some solutions already in use on the e.636 (engines, bogies, suspension etc.).