As the Ae 3/5 designed for the newly electrified flat lines of the SBB had insufficient running characteristics in curves, a locomotive called Ae 3/6III was built in 1925 that was intended to solve this problem. By changing the Bissel axle on one end of the locomotive against a two-axle bogie, both the wheelbase and the guidance in curves were to be improved. Since the Ae 3/5 was called “small Sécheron”, the Ae 3/6III got the nickname “medium Sécheron”.
The electric part made by Sécheron was virtually identical to that of its predecessor. This means that they had the same 1,365 kW hourly output and the same Westinghouse quill drive. Apart from this, the changes in the chassis didn't bring the desired effect and the top speed was still limited to 90 km/h. Nevertheless, ten more have been built in 1925 and 1926. They were retired between 1968 and 1980 and today, 10264 is being preserved in an operational state by SBB historic. 