Come funziona una LOCOMOTIVA a VAPORE? Tutti i SEGRETI della 740, la più famosa d'ITALIA

The 740 steam locomotive, 470 of which were built starting in 1911, primarily by Breda, is known as the "Locomotive of Italy." Designed for freight transport, it entered service in 1920, remaining operational, incredibly, until 1977—a period not so distant from our own. Model 740.244, the focus of our "Mezzi Speciali" episode, develops approximately 980 hp and reaches a top speed of 65 km/h: numbers that today seem modest, but which, at one time, radically revolutionized transport, which until then had been almost exclusively relied on animal-drawn trains. Alongside the locomotive always travels a tender, an auxiliary wagon carrying 22 tons of water and 6 tons of coal, in addition to another 8 tons of water contained within the steam engine itself. Consumption is significant: to cover the 144 km of our journey through the Sienese countryside, approximately 3 tons of coal and 40 tons of water are needed. The locomotive is composed of two main parts: the carriage and the boiler. The latter includes the furnace and its casing, in which the coal burns; the cylindrical body, traversed by 135 small and 21 large tubes, which transfer the heat of the fumes and preheat the water; and finally the smokebox. Here, the Venturi effect, generated by the escaping steam, creates a vacuum and draws the fumes toward the smokestack, simultaneously feeding the furnace with fresh air to intensify combustion. The steam collects in the dome and is regulated by the engineer using the Zara valve. After being heated to 350°C, it reaches the cylinders through the distributor, which manages the intake, allows for reversing, and regulates power. The pistons convert the reciprocating motion into rotation thanks to the connecting rod and crank system, transmitting energy to the wheels. The cycle is open: once used, the steam is expelled. The water must then be replenished with injectors, which use the steam itself to push it from the tender to the boiler. Other systems are crucial: the Westinghouse brake compressor, powered by steam, and automatic lubrication, with pumps that send thick oil to the cylinders, atomized by the heat. Safety is ensured by three relief valves, two Coali valves set at 12 bar and one rocker valve, as well as double manual controls to check the water level: a vital parameter, as a lack of water would risk melting the boiler walls. Driving the 740 requires two figures: the engineer, who regulates pressure and speed, and the stoker, who stokes the furnace and maintains a stable temperature. The working environment is extreme, filled with heat, soot, and a lot of noise, with instruments that must be constantly monitored. Ignition is not immediate: it takes at least 12 hours to bring the boiler up to pressure, starting with wood and small spark plugs, and gradually adding coal, often with the help of a dedicated worker, the "caretaker." When running, the locomotive exhibits typical phenomena such as snaking, due to the reciprocating motion of the external pistons, or galloping in versions with internal motors. To facilitate curves, the first axle of the 740 is radial and moves about 5 cm. This locomotive is not just a transport machine, but a complex engineering system, requiring technical knowledge, coordination, and great physical effort. Its robustness and versatility have allowed it to operate for decades in difficult conditions and, today, allow it to continue to function perfectly. Filming and editing: Luca Catasta Filming and drone: Niccolò Franzosi, Leonardo Mannoli Author: Matteo Valenti Thanks for the images: Lorenzo Banfi, Davide Galli, Ambrogio Mortarino, Mattia Sacchiero, Arnold Siegrist, and Giuliano Sodi Thanks to Fondazione FS Italiane for their valuable collaboration. For historic train travel information: https://www.fondazionefs.it/ Visit our website: www.automoto.it Subscribe to our channel:    / redazioneautomoto   Facebook:   / automoto.it   Instagram: https://www.instagram.com/automoto_it... Twitter:   / automoto_it   TikTok:   / automotoit   Whatsapp: https://bit.ly/47CNr3k