Soviet Steam Locomotive Em-735-28 (1934)

This is a mainline freight steam locomotive—a powerful steam-powered engine designed to haul heavy trains on broad-gauge railways. Its structure is based on a riveted steel frame supporting the boiler, cylinders, valve gear, and an extensive system of coupled driving wheels that transmit tractive effort directly to the rails. A cylindrical boiler—comprising the firebox and smokebox—occupies the forward section; sandboxes, the regulator, and safety fittings are mounted above it, while a distinctive smoke deflector and the chimney are positioned on the smokebox. Steam generated by fuel combustion in the firebox and heat transfer across the boiler's heating surfaces flows into the steam engine; as it expands within the cylinders, it drives the pistons, which are connected to the driving wheelsets via piston rods and a crank-and-connecting-rod mechanism. The reciprocating motion of the pistons is converted into wheel rotation while simultaneously actuating the valve gear. The engineer controls steam flow via the regulator, while the reversing mechanism adjusts the direction of travel and the degree of cylinder filling. To enhance traction when starting or hauling a heavy load, sand pipes located ahead of the driving wheels deposit sand onto the rails. The train is braked using a pneumatic system, supplemented by a manual brake on the locomotive itself. The engineer's cab is situated behind the boiler and houses the regulator, reversing gear, pressure gauges, brake control valves, water level indicators, and other monitoring instruments. At the rear, the locomotive connects to a tender that carries the water and fuel supply. The locomotive's visual profile is defined by its massive boiler, large coupled driving wheels, steam cylinders, exposed mechanical components, and a tall cab featuring windows for a clear view of the track. The design of a steam locomotive integrates a boiler, a steam engine, running gear, a tender, and braking equipment into a single locomotive that converts the energy of fuel combustion into mechanical work, driving the rotation of the driving wheels.