Research On Overhauling Method Of Main Valves For Type 120 Control Valves

The type 120 control valves are the major air brakes in current railway wagons. Their performance plays a critical role on the quality of operation. On the basis of brake valves’ overhauling in national railway wagons and refer to the research by predecessors, the thesis studies on a series of overhauling process of the type 120 main control valves. Including preliminary test, cleaning up, repairing, assembling and test method. This paper aims to make sure the best scheme of repairing and loading operation. The main work includes the following aspects:Firstly, the thesis studies on the preliminary test of repairing in the type 120 main control valves. Through summarizing on the failure experience of the fault rework valves to make sure the necessity of the preliminary test. Meanwhile, on the basis of summarizing, the paper analyzes project to further determine the preliminary test indicators. According to the indicators, the main valves are classified by rank to confirm the repairing scheme of different quality rank valves.Then, the thesis studies on the overhauling method of the type 120 main control valves. With researching the advantage and disadvantage on the exterior cleaning up method, the study aims to confirm the best method of different valve types. With analyzing the process and the difficulty of supersonic clearing and second clearing, the study aims to define the solution. With exploring two drying methods, the study aims to determine the best way of drying. And the study also defines the best cleanliness determination methods.In aspect of the main valve repairing, the study determines the distribution of the springs and rubber parts firstly, then classifies the testing standard of spare parts, focus on the exploring main valve grinding work, analysis the advantage and disadvantage of the machine grinding and manual grinding finally, to draw the optimal combination scheme of their applicable scope and the daily grinding.Again, in the type 120 main valve assembly, this paper introduces a concept of group assembly and large assembly, ensure the cleanliness controlling of the valve cavity parts, and quantify the lubrication working of the main pistons.Finally, in the type 120 main valve test, the thesis introduces concept of standard calibration and inverse ratio test on faulty valves, ensure the faulty judgment capacity. At the same time, in the routine test of main unqualified project is analyzed, the study find out the cause of the problem, guides the faulty valve repairing. On the results of qualified main valves, the paper introduces concept of quality grading, divides the main valves into "high quality, good, general" three levels. And according to the grade quality and the period of repair cycle, the thesis discusses the best loading matching scheme on different ranks of the type 120 main valves.