They were produced over a period of 21 years, from 1964 to 1985, and are currently used mainly for freight operations but still also for some push-pull passenger train services.

As of 2024[update], most standard gauge push-pull operations of passenger trains in Switzerland are run with Re 460 locomotives (respectively Re 450 on the Zurich S-Bahn network).

Between 22 May 1975 and 28 May 1982, Swiss Federal Railways ran trainsets composed of Re 4/4II engines and Einheitswagen III (lit.

They received an extended shock beam, new couplings and the appropriate paint in the Swiss Express colors orange-stone gray-orange.

With the adaptation of the Einheitswagen III for shuttle train operation, the ends of the compositions were given normal screw couplings, and subsequently the locomotives too.

After a general inspection in Bellinzona, the engine has been back in use since autumn 2009 in the red livery of the series, but keeping the SBB logo at the fronts.

As of 2025[update], locomotive 11109 (420 109-1) is the last one with the original Swiss Express scheme still in operation for passenger train services.

Each set is composed of six or ten DPZ double-deck cars plus one Re 420 LION locomotive at each end (head and tail configuration).

Six Re 4/4II (vehicle numbers 11196–11201; later 11195–11200) were equipped with a wider pantograph wiper in order to conform with Deutsche Bahn (DB) and Austrian Federal Railways (ÖBB) standards, which subsequently allowed these units to pull EuroCity (EC) trains over the borders to Bregenz (Austria) and Lindau (Germany).

These locomotives are classified Re 421 and are lettered for SBB Cargo but they also pulled passenger trains to Bregenz and Lindau (however, 11382 was never converted as it was already withdrawn with fire damage).

[18] With the December 2020 timetable change, in conjunction with the reopening of Lindau-Reutin station and electrification of the line to Munich, services between Zürich HB and Munich Central Station were no longer hauled by locomotives, but instead New Pendolino EMUs of SBB started operations on this line as EC/ECE.

When the former Südostbahn (SOB) had the opportunity to buy one of the first batch of 50 Re 4/4II locomotives before delivery, it had the gear modified for higher traction and lower speed for the steep routes on their network.

Locomotive Re 4/4II 11278 received the name and coat of arms of Cham from Re 6/6 11673, which was involved in an accident in May 2015 in Erstfeld and was subsequently used for spare parts.