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Development of a Testing System for Springs Used in Brake Valves for Trains

Brake valve springs, such as 104 and F8 valve springs, are essential components in a braking system of a passenger train. Their maintenance quality has a direct impact on the vehicle operation security. In this paper, a new kind of testing system was developed for springs used in brake valves. This system overcame several shortcomings of existing ones and could meet the requirements of new standard. Firstly, technical specifications and overall design of this system were put forward on the basis of current passenger train maintenance standard. Secondly, its control system consisting of a microcontroller and a CPLD chip as the master controller, as well as its peripheral hardware circuit were designed. Then, a stepper motor is used to achieve accurate measurement of the spring parameters, including free height, assembly load and work load. After that, a computer software was coded by using VC++ platform. Finally, the relationship between the force loaded onto the weighting sensor and its corresponding deformation was obtained. Based on this relationship, the error caused by the deformation during the load measurement was compensated, and the performance specifications of the testing system were also verified.