Fast 4-4-0 steamlocomotive Gr 552 # 036 of the Ferrovie dello Stato, built by Breda in 1900, exhibited in the Museo Nazionale Scienza e Tecnologia Leonardo da Vinci in Milan. 4-4-0 steam locomotive, consisting of two front load-bearing axles and two coupled driven axles. Above the boiler, which is equipped with a simple expansion saturated steam system, are the two distinct reliefs of the sandbox, with a rectangular plan, and the dome, with a circular plan, while at the front is a simple funnel, located at the smoke chamber. The locomotive has two external cylinders, fed by means of balanced box distributors according to the Stephenson distribution system. The braking system consists of an automatic air brake. The locomotive is complete with a three-axle tender for transporting water and coal supplies. The car is painted gloss black, except for the wheel spokes, buffer beam, chassis sides and connecting rod recess painted red and the wheel rims painted white.
Function: Gr 552s are fast train locomotives with 2 driving axles. The names of steam locomotives consist of the abbreviation Gr followed by a six-digit number with a definite meaning. The first number indicates the group, which identifies locomotives with similar technical specifications and uses. The second number indicates the model, which is a series of machines with the same chassis and equipment. The third number indicates a variation in some technical characteristics of the original model. The next set of three numbers indicates the machine sequence within the model. For example, 552 036 is the thirty-sixth type 52 machine in group 5. Main classification groups 4 Mountain line locomotives with 4 or 5 driving axles. 5 Locomotives for fast trains with 2 driving axles. 6 Locomotives for fast trains with 3 driving axles. 7 Locomotives for freight trains with 4 driving axles. 8 Shunting locomotives with 3 driving axles. 9 Line-haul locotenders.
From 1890 until 1914 Gr552s pulled the weekly London-Bombay mail convoy along the Italian Milan-Brindisi stretch. Ferried over the English Channel, the train crossed France and entered Italy through the Frejus tunnel. At Brindisi it boarded the British steamer, passed through the Suez Canal and continued to India, hence the nickname 'India Suitcase '. The train consisted of a mail baggage car, two sleping cars and a dining car. It reached a speed of 100 kilometers per hour, considerable for the time. The State Railways inherited Group 552 locomotives from the pre-existing Adriatic Network. These machines represented the maximum development of two-axle coupled locomotives, surpassed only by the introduction of three-axle coupled locomotives. During their peak period of use, Gr. 552 locomotives were considered highly valuable machines, intended to tow important trains on prestigious international lines. Once replaced by higher performance machines, Gr. 552 locomotives were destined for service on lowland lines, particularly in the Veneto region. Built in 36 examples, some of these locomotives remained in service until the early years after World War II.
