Abstract: A load indicating fastener composed of a body (2) having an abutment (9) which is moved by the changing length of the body (2) under an applied load, and a load sensing member (10) composed of an element (11) disposed in the direction in which a load is applied to the body (2) when the fastener is in the user characterized in that the element (11) is of elongated U-shape, a first limb (13) of the U providing an anchorage part (14) which is rigidly anchored to the body (2), the closed end of the U providing a bearing part (15) which bears on the abutment (9) so as to move with the abutment relative to the anchorage part (14) in response to a load applied to the body, and a second limb (16) of the U having an indicator (17) at its outer end which responds movement of the bearing part (15) and registers the applied load related to that movement on a scale (19).

Abstract: Attainment of a predetermined stress in a bolt (10) which is being tightened is indicated by interference with the freedom of a pin (15) to rotate relative to the bolt. The pin extends along a bore (14) from an end of the bolt and the bore lies in that part of the bolt which presents the minimum diameter of the bolt. The invention is especially useful for detecting when the stress to which the bolt is subjected exceeds the elastic limit of the bolt, because the radial contraction of the bore which then occurs is large, relative to the contraction which occurs during elastic deformation of the bolt.

Abstract: An elongate pin extends in an axial bore in a threaded fastener, at least one end portion of the pin protruding from the bore. An abutment is provided on said one end portion, while when the fastener is in an unstressed condition may rotate about the longitudinal axis thereof. Conversely, when the fastener is subjected to a predetermined tension, rotation of the abutment is prevented by engagement with an end face of the fastener.