Abstract: A tension indicating and cone lock washer (10) for use in connection with a headed fastener (B) and a bearing surface (S) is provided. The washer has a generally annular body (12) with an aperture (14) therethrough. The body is of a generally frustoconical cross-section. A generally radially extending through slot (22) is provided and the remaining material aligned with the slots define at least one web (24 or 26). The washer is intended to crack along the webs at a first compression force and to act as a lock washer and not completely flatten until a second compression force, greater than the first compression force, is applied thereto.

Abstract: A one-piece mechanical device for visually indicating the tension in a monitored bolt, such as a mine bolt or the like, is provided. The device comprises a specially configured spring washer, preferably a helical washer, which is inserted in between the head of the monitored bolt and the surface or backing plate against which the head of the bolt will bear for substantially resilient compression therebetween. The washer is selected with a spring constant such that substantial axial compression of the washer will occur only upon the application of a compressive force in the range of tensile forces to monitored in the monitored bolt. Preferably, the washer will only completely flatten between the bolt head and the bearing plate when the compressive force applied thereto exceeds the predetermined maximum tensile force in the bolt.

Abstract: A mechanical device for visually indicating the tension in a monitored bolt or the like. The device will visually indicate if the monitored bolt is subject to greater than a predetermined maximum tension or is subject to less than a predetermined minimum acceptable tension. The device will also give visual indication, generally proportional to the tension in the monitored bolt, when the tension in the monitored bolt is at less than the predetermined maximum but more than the predetermined acceptable minimum. The device includes a spring washer, preferably a helical washer, which is inserted inbetween the head of the bolt and the surface or backing plate against which the head of the bolt will bear for substantially resilient compression therebetween. The washer is selected with a spring constant such that the washer will be substantially flattened between the bolt head and the plate only upon the application of a tension to the bolt exceeding the predetermined maximum.