What is the structure of diesel locomotive?

Diesel locomotive is a locomotive powered by internal combustion engine and driven by transmission device. According to the types of internal combustion engines on locomotives, they can be divided into diesel locomotives and gas turbine locomotive. The development of gas turbine locomotives lags behind that of diesel locomotives because of low efficiency, high cost of high temperature resistant materials and high noise. In China, the concept of diesel locomotive customarily refers to diesel engine.

The power plant of diesel locomotive is also called compression ignition internal combustion engine. The main structural features include cylinder number, cylinder arrangement, cylinder diameter, piston stroke, pressurization or not, etc. Diesel engines used in modern locomotives are all equipped with exhaust gas turbochargers, so that the exhaust gas of diesel engines can be used to drive turbocompressors, and the pressurized air is cooled by intercoolers and sent to the intake pipe of diesel engines, thus greatly improving the power and thermal efficiency of diesel engines. Diesel engine has two working modes: four-stroke and two-stroke. The thermal efficiency of a four-stroke engine with the same speed is generally higher than that of a two-stroke engine, so four-stroke engine is often used. In terms of rotational speed, it can be divided into high-speed machines (1500r/min or so), medium-speed machines (1000r/min) and low-speed machines (below the rotational speed of medium-speed machines). In order to meet the needs of various powers, products with the same cylinder diameter and different piston cylinders are produced. 6-cylinder, 8-cylinder in-line or 8-cylinder V-type is used for low power, 12, 16, 18 and 20-cylinder V-type is used for high power, among which 12 and 16 cylinders are the most commonly used.

The fuel burns in the cylinder, and the generated high-temperature and high-pressure gas expands in the cylinder, pushing the piston to reciprocate, and the connecting rod drives the crankshaft to rotate to do external work, and the heat energy of the fuel is converted into mechanical work. The power generated by the diesel engine is transmitted to the transmission device. Through the control and adjustment of diesel engine and transmission device, the output speed and torque suitable for locomotive operation conditions are sent to each axle gearbox to drive the moving wheels, and the traction around the wheels generated by the moving wheels is transmitted to the frame, and the coupler at the end of the frame becomes the traction of the hook to tow or push the vehicle.