| 摘要 |
PURPOSE:To contrive an improvement in durability by so constituting that the effect of concentration of stress becomes minimum, by a method wherein a fitting part provided within a specific angle range centering around a line connecting the center of rotation of a movable component with an impressing point of stress and a fitting part on a rotary shaft are connected by a stationary component with each other. CONSTITUTION:A pin hole is provided on a movable arm 4 so that the center of the pin hole 14 is positioned within an angle range of 1/+ or -sin(1/alpha) to a neutral shaft in case a coefficient of concentration of stress in the pin hole 14' is given as alpha and the movable arm 4 and its rotary shaft 4' are secured by driving a pin into the pin hole 14'. When the above-mentioned device is compared with a conventional case wherein the movable arm 4 and its rotary shaft 4' are secured so that the pin hole 14' meets at right angles with the neutral shaft, distribution of impact bending stress to be generated at the time of interrupting action is different from that of the foregoing device, through which influence of concentration f stress due to the pin hole 14' is small. Even the maximum stress due to the concentration of the stress at a part of the pin hole 14' does not exceed the maximum bending stress of the external circumferential part of the shaft. Then it does not happen that the pin hole 14' becomes a generating point of fatigue crack of the rotary shaft 4'. |
