In this report, the fatigue strength and drive elongation influenced by the various conditions of pre-tensile setting of roller chains are shown. The experimental results are as follows:
(1) The most favourable pre-tensile condition for their fatigue strength will be 1300 kg.
(2) From the view point of resistance to drive elongation, the most favourable condition will be from 1000 kg to 1150 kg.
(3) The most favourable conditions considering both fatigue strength and drive elongation, will be 1000 kg. The highest fatigue strength is obtained under the condition of 1300 kg pre-tensile setting, but the optimum condition for the lowest drive elongation is different.

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A form grinding machine of spur gears, equipped with the dressing attachment drived by means of NC controllers, which is described as "form dressing an involute profile based on a circular arc movement" in the 2nd report written by authors, is developed. Here, an economical D. D. A. type NC controller, depending on a method of automatic interconnection among operational elements, is used. It enables, what you call "the on-line form grinding machine of gears", correcting the part of a punched tape, which allows easy and rapid grinding gears in obedience to their data: module, tooth number and pressure angle, further tooth profile modification. For example, standard and modified profiles, of which data is module; 2, number of tooth; 48, and pressure angle; 20 degrees, are ground by this machine, and results of profile and tooth trace inspection show the deviation from the ideal and the experimental are separately within 2 μm. Further, an automatic indexing machine using a rotary magnetic scale, which set a position demand counter to the total number corresponding to the angle required, then the dividing angle is a multiple of 10 minutes, is designed. The indexing accuracy of 17 seconds of arc, is demonstrated and its repeatability is high. Using the grind wheel of a finer grain size, the accumulated pitch error due to the abrasive wear appears with distinct increase. Then, the wear quantity being detected by means of air micrometer, the result of compensating the pitch error shows that it decreases from 51 seconds to 24 seconds.

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It has been experimentally suggested that the plastic deformation beneath any indenter is similar in pattern to the stress distribution obtained by the theoretical elastic analysis. When it is attempted to theoretically analyze the stress distribution beneath the wedge and the circular cylinder indenters, it is seen that the discontinuity occurs in the process of analysis. But, the logical development is revived the validity by introducing the result of rectangular block into the analysis. This paper is to be said that such an approach is useful for the stress analysis of two dimensional indentation.

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It is well known that grooving wear which is formed on the end cutting edge is extremely harmful to surface finish in turning. Although much effort has been devoted hitherto to clarify the mechanism of grooving wear and to prevent it, no appreciable solution or remedy has been found. In this report, the influence of gaseous environment and the physico-chemical properties of tool and work materials on the grooving wear have been analyzed experimentally, and the findings are as follows:
(1) The gaseous media have a remarkable effect on the wear process.
(2) The groove formation is accelerated with an easily oxidiable tool material.
(3) The grooving wear is little formed with a tool material on which a stable oxide film is formed during cutting.
In other words, the major cause of grooving wear is the chemical reactions on the tool face, and from this a practically acceptable remedy against grooving wear has been deduced.

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