| 摘要 |
PURPOSE:To enhance measuring accuracy by locating a measuring head at a correct position with respect to a measuring shaft, by fixing the measuring head to the measuring shaft through first and second overload preventing mechanisms revolving in planes different from each other to absorb shock. CONSTITUTION:First and second overload preventing mechanisms 5, 6 are constituted so that the cylindrical housings thereof and the cylindrical hubs corresponding thereto are revolvable relatively and usually held to a stop state by preventing the revolution thereof by the engaging relation between a roller 55 and a circular arc groove 54. At the time of a so called overload state such that external force equal to or more than a predetermined value is applied by collision, the roller 55 is detached from the circular arc groove 54 to permit the relative revolution of the cylindrical housings and the cylindrical hubs. When measuring head 1 is rotated in an up-and-down direction or a horizontal direction to be returned to the original state, the roller 55 is again engaged with the circular arc groove 54 to stop the rotation thereof and the measuring head 1 can be located at a correct position with respect to a measuring shaft 9.
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