It is generally known that the fatigue strength of the materials is increased by the workhardening of the materials before fatigue tests. Some reports, however, have recently published concerning a state that the stress of pre-loading given to mild steels which has been made just above the yield stress of the steels decreases the endurance limit of the materials.
Therefore, we made experiments to ascertain this result and further to obtain the endurance diagram of the work-hardened mild steel in the case of torsional fatigue.
The summary of the results is as follows. In case a comletely reversed alternating stress is given to the materials subjected to a pre-loading just above the yield stress, the endurance limit is reduced by about 10%. The pre-loading stress above this value hardly affects the endurance limit and it remains at nearly the some value with the non-preloaded specimens.
But in case fatigue tests where the mean stress is given to the materials subjected to a moderately high pre-loading tress, the endurance limit is increased by the pre-loading if the mean stress is applied in the same direction as the pre-loading stress, and it is almost equal to that of the non-preloaded specimens if this direction is reversed.

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We found that the best evaluation method of the adhesiveness of the shellac basing cements for electron tube is to keep the electron tube for 24 hours in a closed vessel, having a humidity of about 80%, and then conduct the 22kg-cm torque test.
The followings are our conclusions about the improvement of the adhesiveness of shellac basing cements:
(1) The base is assembled after the shellac resin solutions have been coated on the surface of glass bulb.
(2) The minimum temperature of 158°C is necessary for the baking of the shellac cements.
(3) Dow Corning DC-804 silicone resin equal to 6% of the shellac resin in the basing cements is useful as an additive of basing cements.

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Almost all of the troubles with transmission systems of railway vehicles are brought about by various phenomena occurred at the time of starting. The author probed into the cause of these troubles with the driving axle of diesel car of the KIHA type and measured strsses in parts of quill drive.
The results are arranged to clarify the cause and state of troubles. This will furnish some clues to locate the cause from the state of trouble and valuable data for future planning.

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This paper deals with no-load-fatigue test for belts conducted using several kinds of special V-belts for variable speed mechanisms. After the experiment, we decided what type of belt was the strongest, and improved the belt to make it stronger.
After having designed a new belt, we performed the fatigue test on it by changing the tension in it, and found the limit of safety tensions of the new belt. Fig. 1 and 2 show the testing apparatus employed.
In Fig. 1, (1) belt tested
(2) sheaves
(3) lock nuts
(4) plate on which sheaves are set, sliding through guides (5)
(5) guides of plate (4)
(6) pulleys for hanging the weight
(7) ropes
(8) rope fastening
(9) weight
(10) motor (7, 2000r.p.m.)
(11) transmission belts.
We used four kinds of belts for the fatigue test. Fig. 3 shows the dimension of the belt tested. Fig. 4-7 show the section of these belts. We indicate the endurance of belt by the number of bending.
If I put n, number of bending,
D, diameter of belt,
N, rpm,
L, belt length,
t, time of endurance,
then
Observing the fatigue test, we found that the initial crack took place in the core of V belt, and that, after a while, at both sides of V belt, it started to break. Gradually the cracks became larger, and at last, the side cracks and the core crack jointed together and then the belt broke.
While observing of the fatigue test, I designed new belts, which are shown in Fig. 9, 10. We call these belts device A, and device B. We made a running test, and measured the coefficient of friction and the amount of abrasion of belt, using these belts.

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