The contact wire is one of the essential components of electric traction system. This paper shows an overview of the contact wire and its development history. This paper also mentions some new contact wires with enhanced performance such as improved maintainability, high reliability, or high-speed capability. Furthermore, this paper describes CPS contact wire, we have developed. This contact wire is lower in cost than PHC contact wire, which is one of the standard contact wires for high-speed operation, although both of them have almost same level of high-speed capability.

For pantograph sliding material (electricity collection material) various materials have been used. This paper describes the characteristics and transition of the materials; copper-based and iron-based sintered alloy sliding material manufactured by powder metallurgy and increasingly adopted carbon-based sliding material (carbon and copper or copper alloy composite). Recently, C / C (carbon fiber reinforced carbon) composite contact strips made of high-strength C / C composite have been developed. The wear characteristics of the C / C contact strips were confirmed by actual vehicle tests, and 35% improvement in the characteristics over the copper-based sintered alloy contact strips was confirmed.

The maximum speed of the Shinkansen vehicles has increased by more than 100 km / h since the service of the Shinkansen started,and now the speed reaches over 300 km / h. At the condition of increasing further speed, a friction material is required to handle the increased heat load associated with the improved braking force. A full-size bench test is essential for evaluating the performance of the mechanical brake conclusively, but it takes a lot of time and efforts to evaluate the friction coefficient of the brake friction materials at high temperature. Therefore, we research a method for evaluating the brake friction materials more easily than evaluating them using a full-size bench test. This paper as a new evaluation method for Shinkansen vehicle brake friction materials, introduces a method for experimentally investigating and analyzing the relationship between the heat resistance and the friction coefficient of the solid lubricant contained in the friction material.

For railway vehicles, several brake systems and the brake materials have been developed and turned in practical use. In the case of electrical cars, friction brake is regularly used conjunction with electrical brake. In recent years, the proportion of friction brake use has decreased, and the reason is recognized as the fact that the friction interface between the brake shoe and the wheels was unstable with respect to the environment. This paper describes the problems in railway brake systems from the standpoint of brake shoe. A new method in the configuration design of brace shoe is also introduced.

This paper describes recent topics on railway rail tribology. The tribology phenomena on rail are wear, slip, flaw, vibration and noise. These phenomena are caused by contact between rail crown and wheel tread. Moreover, various types of rail and wheel and various surroundings, for example, tangent tracks and curved tracks, outside and inside tunnels, are also causing the phenomena in rail tribology. This paper introduces four topics on rail caused by the tribology phenomena. The topics are squeak noise at low rail, rolling contact fatigue cracks on rail crown, the cracks and wear of common crossing which is a component of turnout, and wheel slip at steep slope sections in mountainous areas.

Contaminants at the wheel-rail interface, such as water, oil or fallen leaves, decrease the coefficient of friction and lead to wheel spin and braking lock-up sometimes. Such significant sliding can cause not only performance problems in terms of delays and safety issues from over-running, but also thermal damage and abnormal deformation of wheel and rail. Also, it is known that high friction coefficient and slip at curves could lead to severe wear and deformation of wheel and rail, high energy consumption and wheel-rail noise. Additionally, it increases the risk of a wheel climb derailment occurring. Therefore, the friction management between the wheel and rail is important for the rail operation. This paper provides the knowledge regarding the methods and materials to manage the friction condition appropriately.

Metal-to-metal seals in premium threaded joints (PJ) for Oil Country Tubular Goods need to have high-pressure gas tightness. The gas tightness of such seals is affected by sliding of contact surfaces during integration, the kind of applied greases, temperature and pressure. In this study, a new fundamental testing method is proposed that enables quantitative evaluation of the impact of these factors on the gas tightness. In the proposal method, specific greases as well as helical sliding are employed in order to simulate the sliding conditions in practical PJ. In addition, the seal portions are baked at 180°C to simulate the high temperature condition of oil or gas wells. The gas pressure was applied until leakage was occurred. The proposed method provides more realistic contact conditions of PJ than those of conventional method in which seal surfaces are subject to rotary sliding before gas tightness tests. It is found that the gas tightness of the grease specified by American Petroleum Institute standards is about 2.8 times higher than that of the environmentally friendly grease.