| 摘要 |
1535906 Tension indicating EATON CORP 6 July 1977 [23 July 1976] 28330/77 Heading G1W [Also in Division F2] A device for visually indicating if tension in a bolt 12 is within a predetermined range comprises a helical spring washer 17 with its axial length at its circumference constant and greater than the axial length of the remainder of the washer and indicea marks 19, 20 on the free ends of the outer surface. The tension of mine roof bolts is within the range if the alignment of the marks is within pre-set limits. Electrical switches may be connected to the devices.
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