The method for installing carbon-based contact strips on pantograph heads is very important from the operational point of view. Carbon contact strips are generally manufactured with a dovetail base that can be clad with a close-fitting steel sheath, or a fabricated metal holder that grips a full-length carbon strip and has installation bolts for mounting on a pantograph head. The authors have developed three other installation methods. This paper describes the development of carbon-based contact strip materials over the past two decades in Japan, and the results of laboratory or field tests on the installation methods that have been developed.

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In order to ascertain a suitable oil-change interval for the higher grade diesel engine oils introduced on diesel railcars, we investigated their durability through field test and then examined the condition of the engines. Based on the test results, we verified that their introduction has enabled oil-change intervals to be extended from the current 20-35, 000 km to 45, 000 km, while keeping good conditions inside the engine.

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This paper investigates possible electric railway applications for superconducting technology, assuming that rapid advances are made in superconducting materials and the relevant R&D is carried out. First, it reviews the high-Tc superconducting materials that have been discovered since 1986. The remarkable development of silver sheathed, BiSrCaCuO-based superconducting wires and melt-processed REBaCuO (RE standing for rare earth) bulks with a high critical current density (Jc) at 77 K in magnetic fields will benefit their applications. Secondly, power transformers for rolling stock, superconducting magnetic energy storage (SMES) systems, flywheels, and cables are introduced as examples of possible candidate applications on conventional railways. Superconducting technology will contribute to solving global environmental problems and energy issues in the 21st century.

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After a few decades of studies to establish a theoretical basis, the continuum damage mechanics is now finding engineering applications as an effective modeling method to evaluate the damage, fatigue and life of materials. Before applying the method, it is necessary to determine some material parameters to characterize the damage and fatigue behaviors of the material in question. In this study, the material parameters of the rail steel used for the JIS 50kg N rail were determined based on its stress-strain curve and S-N curve. By using these parameters it was demonstrated that numerical analyses could successfully reproduce these curves. As a simple application of the method, the fatigue life of a bar made of rail steel subjected to repeated three-point bending was predicted and compared with the fatigue life obtained experimentally. That the life span values obtained through analysis agreed well with those from experiments shows that the analysis based on damage mechanics is a useful method to predict rail fatigue life.

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The magnetic rubber damper with a constraining layer (MRDC), which we developed, is easy to install on steel vibrating objects and has proven to be an excellent vibration damper. The damping property of an MRDC is substantially attributable to the frictional loss between its magnetic rubber layer and a steel object. The authors devised a theory to predict its damping properties by taking friction into consideration, the theory itself being based on an analysis of the flexural vibration of a beam with MRDC. The accuracy of the proposed theory has been verified by comparing analytical and experimental results, and a design to optimize MRDCs has been determined from those obtained from calculation and measurement.

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As chloride ions that have been introduced into the concrete from outside by diffusion cause deterioration due to reinforcing bar corrosion, experimental studies were conducted into the critical chloride ion concentration and corrosion weight loss of reinforcing bars. As a result, within the limits of these experiments, it was verified that the critical chloride ion concentration was 1.5 kg/m³ at the depth of the reinforcing bar and that concrete started to crack at a corrosion weight loss of 170 mg/cm² per unit corrosion area of the reinforcing bar surface.

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It is difficult to completely prevent water from leaking into underground concrete structures when using normal waterproof sheeting. As the sheeting is not chemically bonded to the structures, underground water penetrates cracks through in the sheeting. We have developed a type of waterproof sheeting that chemically adheres to structural concrete after it is cast, and confirmed its performance through laboratory tests. This paper introduces the newly developed waterproof sheeting and test results.

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