SBB Am 4/4 1001–1002 - SBB Am 4/4 1001–1002

SBB Bm 4/4 II (bus 1963 Am 4/4)
Numbering: 18451–18452 (until 1959 1001–1002)
Number: 2 (1 historical)
Manufacturer: SLM, BBC, Sulzer
Year of construction (s): 1939
Axis formula : Bo'Bo '
Gauge : 1435 mm (Normalspur)
Length over buffers: 14900 mm
Trunnion Distance: 8300 mm
Bogie axle base: 2700 mm
Total wheelbase: 11000 mm
Service mass: 66 t
Friction mass: 66 t
Wheel set mass : 16,5 t
Top speed: 75 km / h (previously 110 km / h)
Traction power: 611 kW (830 PS)
Driving wheel diameter: 1040 mm
Motorentyp: Sulzer 8-cylinder
Power transmission: Diesel-electric
Number of traction motors: 4
Train heating: electrical 1000 V
Control: BBC resistance servo controller

The Am 4/4 is a mainline diesel locomotive of the Swiss Federal Railways ( SBB ). The two locomotives were delivered in 1939. Since the renovation in 1963/64, they have been referred to as Bm 4/4 II . One, the 18451, is preserved as a working historic locomotive.


Initially, the industry was supposed to build two diesel baggage cars, but due to the weight-performance problem, the order was changed to two main-line diesel locomotives. Together with the gas turbine locomotive SBB Am 4/6 , the SBB had three diesel locomotives that were designed for use in front of passenger trains. The Bm 4/4 II have an electrical heating cable with 1000 volts, which, however, has a variable frequency and can therefore only be used in vehicles with resistance heating without a static battery charger.

The vehicles were very innovative, even if they were never replicated. Swiss companies took over many of the achievements in later-built locomotives. For example, the concept of the locomotive body and bogies already meets the newer SBB RFe 4.4 and SBB Re 4/4 I .

The first locomotive, the Am 4/4 1001, was on display at the 1939 National Exhibition in Zurich.


Front view of the Bm 4/4 II

The mechanical part comes from the Swiss Locomotive and Machine Factory in Winterthur, where the locomotive was also assembled. Brown, Boveri & Cie supplied the electrical equipment and Sulzer AG supplied the diesel engine .

The locomotive body was self-supporting and supported on the two bogies. The locomotive had a driver's cab on both sides with a side door on the right in the direction of travel. The two driver's cabs are connected to one another by doors through the engine room in between and can thus be changed.

The construction and design of the locomotive body flowed into the test locomotive Am 4/6 and the light electric locomotive Re 4/4 I procured from 1946 to 1951 .


The two locomotives were rebuilt in the main workshop in Zurich. The gearbox was renewed and designed more for tractive power than speed. The top speed dropped from 110 km / h to 75 km / h. The workshop also installed an external ventilation system for the traction motors so that the locomotive couldn't get too hot at low speeds. Also nozzle fan grid were built into the side walls, as they have in the Re 4/4 I were used.

The 18451 was rebuilt between 1962 and 1963, the 18452 between 1963 and 1964.


The locomotives were temporarily shut down during World War II due to a lack of fuel. During the active period, one locomotive was normally assigned to the Winterthur depot, while the other locomotive was used in western Switzerland. Initially it drove in Lausanne for the Broye line, then in Geneva as a reserve vehicle for the Geneva-La Plaine route. In 1969, both locomotives were assigned to the Winterthur and Olten depot for covering the auxiliary car and as a thermal reserve.


The company HAG Modelleisenbahnen has a model of the locomotive no. Launched in 18451. In 2013 a new edition of the models of the locomotives No. 18451 and 18452 followed.


See also