Análisis de las distancias y tiempos de frenado de los trenes formados por locomotora y vagones para velocidades estándar

Abstract

ABSTRACT. Rail transport has drastically evolved since its birth around the mining of the past to the present in which it is configured as a core element of the first order in all countries where it is implanted. However, by its nature, it involves a critical point: safety when braking railway vehicles. It can even be said that trains are designed (redundantly) to effectively secure their come to halt. Research work in this field cannot be considered closed. The result of decades of research have promoted improvements in braking systems, from primitive manual devices, to automatic braking systems, combined with other complementary type, such as eddy current brake, brake recovery or dynamic brake. These types of braking have proved highly effective, to the point of being able, under certain conditions, to stop the vehicle without having to resort to conventional automatic compressed air brake. The clearest evidence of the enormous power of a braking system is undoubtedly its ability to stop in a certain distance and time, based on a high speed: There's the case of the French TGV, which, in April 2007, the Paris - Strasbourg exceeded 570 km/h. Recently, a Japanese maglev exceeded 600 km/h. As is known, this type of transport has the driving elements on the road (shifting, not running) rather than on the vehicle (called magnetic levitation train), which moves about 10 mm above the plane sliding, developed by powerful magnetic fields that interact with the vehicle and the road, some to lift it from the ground and others to promote the lineal movement. However, this type of vehicle cannot be considered a conventional train, since it provides no rail wheels. The present work has been focused in the same research field, that in the past led to shorten the stopping distances, appreciating, in this case, the possibilities of reducing the transmission time of the order brake from the locomotive to towed vehicles. To do this, using the same engine brake fluid (compressed air) the behavior has been tested introducing changes in density (varying the temperature) and simulating a brake order by abrupt opening to the atmosphere of the pneumatic circuit, to study the times of arrival of the pressure wave generated at the end of the circuit. The temperature variations induced in the fluid used as transmitting brake control, modify, in turn, the density of pressurized air within a closed conduit. Thus the speed of the resulting pressure wave is varied, resulting in a shortening of transmission thereof. It is recalled that in a second to 72 km/h, the vehicle travels 20 meters. Any reduction in downtime between making the order brake and the start of implementation of it clearly affects the safety circulation rail vehicles and is a step in this direction. The author of this thesis is currently working in the company Renfe Metric Gauge, with an experience of over thirty years, the company initiated in FEVE. For more than two thirds of that career was devoted to teaching, within the company; the result of which was the development of more than a dozen technical manuals - training. Indeed, thanks to this teaching, can assess the potential contribution of this paper, pointing, as the most interesting, reducing transmission times orders brake modification of certain terms of the working fluid (density, temperature) without prejudice to others that remain, as no feedback loop, the explosion being, the economy of production and be storable. Keywords: Railways, train braking system, stopping distance, transmission time brake order, automatic brake, air density, air temperature, pressure wave speed, downtime.