Patent ID: 7260997

Claim:
A device for adjusting and testing the axial force in screw joints, comprising: a first force applying element in the form of a bolt, a nut, or the like, and further comprising a thread; a second force applying element complementary to the thread; a measuring element in the form of a washer contacting the first force applying element or the second force applying element, wherein the measuring element comprises a piezoresistive coating of an amorphous, diamond-like, carbon compound, said peiezoresistive layer or coating comprising graphitic structures with sp 2 hybridization in combination with diamond-like structures with sp 3 hybridization, such that the electrical resistance of the measuring element is continuously variable as a function of the axial force applied by the first force applying element or the second force applying element to the washer; and a component for fixing the first force applying element or the second force applying element and preventing rotation thereof comprising means for contacting the measuring element and for signal pick-up.