Railway accessories also include connecting parts, ballast, turnouts and other categories, which are briefly introduced respectively. Connecting parts Connecting parts are divided into two categories. The parts connecting the ends of two rails are called joint connecting parts; The parts connecting the rail and the sleeper are called intermediate connecting parts, that is, fasteners. The joint connecting parts enable the wheels to roll smoothly over the rail joints and keep the front and rear rails working coordinately. Fasteners integrate the rail and the sleeper into a track frame, keeping the two rails in the correct relative position; Fasteners provide enough pressure to prevent rail overturning and longitudinal movement of rail. Ballast The ballast usually refers to the gravel (ballast) cushion laid under the sleeper and on the subgrade. Its main function is to support the sleeper, distribute the huge load from the upper part of the sleeper evenly on the subgrade surface, and greatly reduce the deformation of the subgrade. The ballast is small granular granite with a diameter of 20~70mm. There are gaps and friction between the blocks, so that the track has a certain elasticity. This elasticity can not only absorb the impact and vibration of locomotives and vehicles and make the train run relatively smoothly, but also greatly improve the working conditions of locomotives and vehicles, rails, sleepers and other components and extend their service life. Once the elasticity of the ballast is lost, the load on the reinforced concrete sleeper will increase by 50~80% compared with the normal state. Turnout A turnout is a line connecting device that allows locomotives and vehicles to transfer from one track to another. It is usually laid in large quantities in stations and marshalling stations. With turnouts, the passing ability of the line can be brought into full play. Even if it is a single line railway, laying turnouts and constructing a fork line longer than the train length can open the train. Source of this article: Huafeng Railway Accessories (http://www.hftlpj.com/)