Load indicating fastener.

摘要

A fastener (20) indicates when a predetermined preload has been applied to the fastener. He includes a body section which is connected with a thread convolution (26). A load transmitting and indicating section (30) is connected with the body section and includes a bearing section (40) having a flat annular bottom surface (46) and an undulating annular spring section (42) which circumscribes the bearing section (40). The spring section (42) has a bottom surface (56) with crest (60) and trough portions (62). The crest portions (60) extend tangentially to the plane of the bottom surface (56) of the bearing section (40). The trough portions (62) are resiliently deflectable toward the body section to flatten the undulations in the spring section (42) upon application of the predetermined preload to the fastener (20). The spring section (42) is resiliently returnable toward an initial configuration to increase the amplitude of the undulations in the spring section (42) to provide a visual indication that the connection between the fastener (20) and a member (70) is loosening.