5. Development of iron-based sintered metal contact strip with extended service life, for use on Shinkansen trains

The main properties required for contact strips used on a high speed train pantographs are lubricity and wear resistance. One of the contact strip materials developed in recent years employs sulfidizing to improve lubricity, however sulfidized strips rust easily when exposed to air. To solve this problem and to improve the wear performance of the existing material, it was proposed to apply free-cutting manganese sulphide iron powder which possesses self-lubricating properties. A prototype material was made by sintering the manganese sulphide iron powder together with the iron powder currently used. Comparing the results of wear tests, it was confirmed that the newly developed material caused 40% less wear on the trolley wire and had better lubricating properties than the specimen made with existing iron powder (Fig.1).

Increasing lubricating properties led to a concern about higher contact strip wear in the newly developed material. Therefore, the amount of hard alloy in the new material was increased to maintain wear resistance

Results of comparative wear tests, confirmed that the wear rate on the trolley wire was approximately the same for both strips, and the specific wear rate of the developed contact strip itself was lower by approximately 30-40% compared to the existing contact strip (Fig.2). Field tests were performed on both the newly developed contact strip and existing contact strips to compare their influence on a trolley wire and wear resistance. Results showed that the wear rate on the trolley wire for both contact strips was approximately the same, whereas the wear rate of the contact strip was lower on the developed strip by approximately 5-7% (Fig.3).