To ensure the safety of train operation, signalling equipment is installed along railway lines. For the maintenance of this equipment, a dedicated train called an "electric testing car" has been used. But this train is operated on the individual sections only twice a year and requires skill to analyze the collected data. Furthermore, the organizations of maintenance and surrounding environment are increasingly becoming difficult for railway companies in recent years. So we have developed a compact maintenance system that can be mounted on a commercial train and analyze data easily. In this paper, we explain the method of measuring signalling equipment, function of this system, and the results of field test.

View full abstract

We manufactured a prototype long-life PHC messenger wire with high-strength and high-conductivity Cr-Zr Precipitation-Hardened Copper alloys to reduce the maintenance costs of overhead catenary system. We are now testing it for corrosion-resistance and durability in a tunnel subjected to water leakage and a section suffering from salt damage between Tsukumi and Azamui on the Nippo line, JR Kyushu. In a spot observation after it was used for seven years, we found that it had no significant corrosion.

View full abstract

To complement the electric characteristics of contact wires, additional feeder cables are installed in railways in Japan. To save installation costs, lightweight and inexpensive stranded aluminum wires are used as additional feeder cables. They are bridged to contact wires every 250 meters and some strands break by the compression sleeve which connects the copper bridge wire and the aluminum wire, often resulting in disconnection accidents. We have obtained samples of broken strands which were 38 years old, and performed current loading experiments and material analysis. Through these experiments and analysis we found that the uneven contact resistance between aluminum sleeve and strand concentrates their current at only a few strands, which results in the strands being cut off by the Joule heat. On the other hand, There is concern about a disconnection accident occurring when the compression sleeve, which connects the aluminum wire and copper wire on the main circuits of power supply system, is superannuated. We have obtained superannuated samples which were 27 years old, and performed current loading experiments. Through these experiments we found that Joule heat is caused by the contact-resistance between the aluminum wire and aluminum sleeve, then the heat melts or deteriorates the alloy between the copper wire and aluminum sleeve to increase resistance value and Joule heat, and then the sleeve is overheated and at last melted down.

View full abstract

In order to inspect the inner failure of gear units without dismantling through analysis of wear particles in lubricant, the following two types of gear failures are intentionally caused and examined. One type is abnormal wear acceleration caused by contamination in lubricant. The other is seizure between pinion and gear. Gear oil is sampled periodically during the test. Analyzing the wear particles in the sampled oil by ferrography, relationship between typical failures in gear unit and features of wear particles generated in oil is revealed.

View full abstract

The purpose of this study is to establish an evaluation method for ballast grains shape, which effect the deformation property of ballast. In this study, the "normal argument function" and "radius functions" are calculated from the contour data of ballast grain read by a digital camera. According to the result of these analysis, it is assumed that the "flatness" or the "elongation" is decided by the value of the 2nd magnitude spectrum of "Radius function" wave of grain shape.

View full abstract

Thirty years have passed since the world's first use of slab tracks by the former Japanese National Railways. It is recognized that they have excellent performance for maintaining good track geometries and reduce track maintenance costs through this experience. However, there were still some points to be improved. This paper describes the present condition of slab tracks, development of a new structure on earthworks and reduction of construction costs for the Hokuriku Shinkansen line.

View full abstract

We performed fatigue tests by using full-scale axles on which numerous artificial flaws were incised at their wheelseats. The tests were performed in order to reconsider the inspection system for narrow-gauge line vehicle axles. The axles that were tested at a nominal stress of 80 MPa developed fractures at the wheelseat due to the propagation of fretting fatigue cracks. On the other hand, axles that were tested at the nominal stress of 60 MPa did not fracture, even at the maximum number of cycles of 5.4 × 10⁷. In the case where the maximum service stress does not exceed 60 MPa, it is possible to reduce the inspection work to only when wheels are renewed.

View full abstract

Reinforcing bar corrosion by salt injury (or salt damage) is a most serious problem that threatens the durability and strength of a concrete structure. It was clarified that the half-cell potential could be influenced by some properties of cover concrete, and a half-cell potential correction procedure taking the properties of cover concrete into account was proposed. Then, to suppress the reinforcing bar corrosion caused by salt injury, an anion adsorbent was chemically synthesized which could adsorb excess amounts of chlorine ions, releasing nitrous ions at the same time. Using materials containing this adsorbent, we propose a new repair method named Suppressing Salt Injury method (SSI method).

View full abstract

The Railway Technical Research Institute is promoting research and development for maintenance technologies by regarding the maintenance of facilities as one of the most important subjects for the railway industry. When it revised the medium- and long-term basic plan in 1995, it started a new maintenance project on the technological development for the maintenance of rolling stock, track and trolley wire system, and has promoted research and development for about five years while focusing on the development of element technologies, in order to save manpower and extend the life of facilities by using new materials and establish a new maintenance control system. This paper summarizes the research and development themes and results obtained by the project.

View full abstract