Starting in 1959, the SBB motor coach of the type RBe 4/4 (designation at last RBe 540) was for a replacement of the old SBB electric locomotives Ae 3/6 I, Ae 3/6 II, Ae 3/6 III and SBB Ae 3/5 with three driving axles. As a consequence, they had much power at their disposal, even more than the Re 4/4 I locomotives, a regenerative brake, cabs on both ends with doors to passenger carriages as well as Multiple-unit train control SBB Vst IIId for multiple-unit or driving trailer. They originally motor coach had 64 seats, 32 smoking and 32 non-smoking, and were painted in ordinary SBB green. The first six prototypes, each costing one million swiss francs, were delivered 1959 and 1960, and first shown to the press at 24 May 1959. The prototypes had some issues which were fixed until the series production. The series units were four tonnes heavier, and 76 units were ordered, which were put into service between 1963 and 1966. Most of the technical equipment is installed below the passenger compartment, leading to a higher than usual floor level than ordinary carriages had. Some of the equipment and the toilet is installed in the middle of the multiple unit, instead of passenger compartments. The conventional transformer technology with its rough step controller (28 running notches) together with occasional heavy vibrations led to the nickname "Schüttelbecher" ("shaker"). Starting in 1992, all units (except for the prototypes) were modernized to fit the needs of S-Bahn operations. This included cloth seats instead of the plastic ones and some other interior modifications, NPZ livery, automatic doors for conductor-less operation as well as the installation of an additional thyristor controller, for which a passenger compartment had to be given up. The latter improved running smoothness considerably, especially when using the regenerative brake. At the same time, they were renumbered to the UIC scheme, which led to some inconsistencies due to vehicles already retired from service: RBe 540 006-4 to 540 017-1: Former units 1407 - 1418 RBe 540 018-9 to 540 051-0: Former units 1420 - 1453 RBe 540 052-8 to 540 079-1: Former units 1455 - 1482 The prototypes, which never got UIC numbers, got the nicknames "Seetal-RBe 4/4", due to their special warning livery for services on the dangerous Seetalbahn. So far, the prototypes 1401-1403 (due to old age), 1419 (accident in St.-Triphon), 1454 (fire between Uster and