Yasutomo Sone

Rail Corrugations Caused by Low Coefficient of Friction in a Submarine Railway Tunnel

One of some types of rail corrugations is caused on railway rail surface in a submarine tunnel. It poses a large problem from the aspects of railway vehicle and railway track deterioration. In this paper, the mechanism of the rail corrugations was studied with the focus placed on roll-slip of wheel and rail interface. Traction and vertical force interacting between wheel and rail were investigated by a vehicle/track interaction model, and the coefficient of friction (COF) on rail surface was measured. Also, the rail surface was analysed with infrared to understand the chemical composition of surface layer influenced by salty and very humid atmosphere in the submarine tunnel. β-FeOOH was found out as a cause of reducing COF on rail surface.Copyright

Effects on braking distance from the use of traction fluid as a wheel/rail lubricant

Mineral oil and other lubricants are commonly applied to the gauge corner of high rails to avoid wheel/rail interface wear on railways. Although not directly applied to the top of the rail, these lubricants sometimes end up on this surface, and the relatively low coefficient of friction they produce can cause slipping or sliding at the wheel/rail interface during vehicle acceleration or braking. It has been reported in the literature that the application of traction fluid (a modern technique involving the use of a synthetic lubricant) produced a higher coefficient of friction than that of a conventional wheel/rail interface lubricant. In this study, tests were performed using traction fluid to evaluate its influence on a vehicle’s braking distance and other important performance elements from a practical point of view. The results of the braking performance evaluation carried out on a braking test stand showed that the braking distance increase with synthetic traction fluids was roughly one-half of that observed with conventional wheel/rail lubrication oil. This suggests the potential of using traction fluid as a wheel/rail lubricant.

Determination of Shearing Stresses (τxz and τyz) Using X-Ray Diffraction Method with Two-Dimensional Detector

Measurement of shearing stresses, τxz and τyz, by X-ray diffraction technique with two-dimensional detector was studied. The principle which was developed for an area detector type X-ray triaxial stress analysis was adopted for this purpose. In the present method, Debye ring was measured first and its whole part was used for determining shearing stresses. One Debye ring is enough to determine shearing stresses without accurate diffraction data such as lattice spacing in stress free. The result of the simulation showed that the present method is useful for the evaluation of shearing stresses by X-ray diffraction technique.

Identification of Iron Rusts on Rail by X-Ray Diffraction and Vibrational Analysis

A periodical unevenness of the running surface of rails is formed on ascending slope of submarine railway tunnel. One of the causes has been concluded due to the combination of a low friction and wheel load variation induced by some kinds of iron oxides and oxyhydroxides with various coefficients of friction on the rail, though it has not been made clear yet. In this study, X-ray diffraction and Raman scattering spectroscopic analysis were attempted to identify iron rusts on the rail as a process to solve the periodic unevenness of the rail suffering many railway companies.

New Shape Grease Pocket for Traction Motors to Facilitate Base Oil Supply

The cycle of induction motor disassembly inspections depends on the durability of the grease, which is the least durable of all the bearing parts and materials used at present. It is therefore highly desirable to extend grease service life. To meet such requirements, a number of studies were made into grease pocket structures, which concluded that an improvement in structure was essential as grease pocket shapes have a direct relationship on grease lubrication effectiveness. A laboratory test under static conditions was performed with small grease pocket models of different shapes to formulate a grease pocket design guideline.