Proving ground tests of pin and link fi shplates

Introduction. Rail damages represented by railhead cracks in the area of joints and bolt holes prevail on railway sections with heavy traffic density and harsh climatic conditions. This is proved by the statistics of withdrawal of severely defective rails on the Trans-Baikal Railway. The analysis of scientific publications shows that in terms of increasing reliability the joint has an advantage with pin and link design of fishplates, which reduces stresses in the rail neck due to the modified support on the rail gorge. The aim of the study is to confirm the hypothesis about the possibility of reducing stresses in the rail neck by using a new fishplate design. In order to confirm the effectiveness of the construction the authors conducted com- parative operational tests with wedge-shaped fishplate construction.
Materials and methods. Strain gauge method was used to measure the stress-stain state of the rail neck at the joint. Fishplates were tested at various bolt tightening torques. During tests, the mounting stresses around the bolt hole were recorded first, and additional dynamic loads occurring during the passage of the train were measured after.
Results. The results show that the pin and link fishplates reduce the assembly tension stresses in the rail neck and increase the fatigue strength of the rails with an increase in the tightening torque of the butt bolts compared to the wedge-shaped design. Vertical loads have little effect on bolt tightening, and the stresses in the fishplates remain within safe limits. Joint monitoring also confirms the reliability of the pin and link design: bolt tightening torques decrease over time, but no defects or damage have been detected.
Discussion and conclusion. The advantages of the pin and link design of a fishplate are proposed and discussed. It is shown that it provides increased reliability of rail joints, reduces stresses in the rail neck and has an increased margin of fa- tigue strength. It was found that this construction retains a higher stability of bolt tightening during operation compared to wedge-shaped fishplates. This increases the durability of the butt joint, reduces the frequency of maintenance, and reduces operating costs. The solution is especially effective for areas with high traffi c density and severe climate.

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