STRUCTURE FOR PREVENTING LOOSENING OF THREADED FASTENERS

摘要

A first washer is disposed on an upper surface of a member to be tightened and its projecting portion is inserted into a clearance formed between a trunk of a bolt and a piercing hole of the member to be tightened. A second washer is disposed on an upper surface of the first washer and its claw portion is met with engaging teeth of the first washer. A head portion of the bolt is fitted into a fitting portion of the second washer. The first washer and the second washer are allowed to relatively rotate in a direction of tightening the bolt which is achieved by the claw portion sliding along sloped wall surfaces of the engaging teeth and are prevented from relative rotation in a direction of loosening the bolt which is achieved by the claw portion engaging with substantially vertical wall surfaces of the engaging teeth. The bolt may not be rotated though one should try to rotate the bolt in the loosening direction after tightening since the second washer is prevented from relatively rotating with respect to the first washer in this direction. <IMAGE>