As all other types of the Einheitslokomotiven program the class E 40 had welded bogies with central pins.

Instead the formerly used axle hung motors it used a quill drive with a circular rubber spring as a connecting element ("Gummiringfeder" in German) reducing unsprung mass.

879 units were built, making it the Einheitslokomotive (standard locomotive) of its era.

The original speed was 100 km/h, this was enhanced to 110 km/h in 1969 in order to allow better usability also for commuter trains.

Starting in 1959, 31 locomotives were equipped with electrical brakes (as all class E 10 units were) for the ramp near Erkrath-Hochdahl between Düsseldorf and Wuppertal and the Höllentalbahn in southern Germany.