| 摘要 |
PURPOSE:To improve measurement accuracy by supporting a center test-piece above or below a reference line which connects the axial centers of two driving disks and arranging the axial center of the center test-piece at the vertex of an isosceles triangle having the base on the reference line. CONSTITUTION:Nuts 27a and 27b engaged threadably with both upper and lower screw parts 26a and 26b of a support member 26 for the test-piece 30 are turned to move the axial center O3 of the test-piece 30 to above and below the reference line U1-U2. Then, the nuts 27a and 27b are stopped when the difference between detected values of load cells 28 and 29 becomes zero, namely, pushing-up force and pushing-down force which operate on the test-piece 30 become equal to each other to enter a balanced state. In this state, the angle thetabetween the oblique sides O3U1 and O3U2 and base U1U2 of the isosceles triangle O3U1U2 formed of the axial center O3 of the test-piece 30 and axial centers U1 and U2 of the driving disks 10 and 12 is found to obtain a traction coefficient. Thus, the traction coefficient is found with high accuracy.
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