To avoid the use of helper locomotives or double heading altogether on the Gotthard, the SBB ordered two prototypes of heavy electric locomotives from the SLM. In order to use them on the whole route without changing the locomotives, they had to have a top speed that was fast enough for passenger trains on the flat sections. Each half of the double locomotives was built with four driving and three carrying axles. They had a device that could increase the adhesive weight by removing weight from the carrying axles.
The first prototype delivered in 1931 was No. 11801. It had Buchli drive units on one side and technically resembled a double Ae 4/7. 11851 delivered in 1932 had SLM universal drives and somewhat more power. In 1938, a third streamlined locomotive with a powertrain similar to 11851 was built. It got the number 11852 and was called “Landi-Lok” since it had been built to be exhibited at the Swiss National Exhibition. With an hourly output of 5,514, 6,470 and 8,162 kW (7,500, 8,800 and 11,100 hp) they were the most powerful locomotives in the world at this time.
After these three locomotives, no more Ae 8/14 have been built. With the advancements in multiple controls, it was more feasible to use a smaller locomotive on the flat sections and add another one at the beginning of the ramp. After only the first two had been built for the SBB, also the third was bought up by them since there was demand for heavy freight locomotives at that time. After the third was retired due to a fire in 1971, the others remained in service until 1975 and 1976. Today the first one is operational and the third one came to the SBB Historic team at Erstfeld in June 2024 after being on static display in Lucerne.
