Abstract: A gauge for measuring an internal thread formed within a passage in a nut or other member, and including two gauge elements having similar external threads adapted to project into the threaded passage along the axis of the internal thread and from opposite ends of the passage to engage opposite ends of the internal thread, and two indicators carried by the gauge elements at locations axially outwardly beyond the opposite ends of the passage and having portions extending externally of the passage to positions at which the rotary setting of one indicator can be read against the rotary setting of the other. At least one of the rotary elements (preferably both) is rotatably adjustable relative to the corresponding gauge element, and releasably lockable in any of different set positions relative thereto as an initial setting of the tool.

Abstract: A fatigue resistant threaded connection includes a nut having two threads which are aligned axially but turned relative to one another about their common axis through an angle great enough to cause development of large axial forces between the screw and nut threads when they are connected together, resulting in improved distribution of load forces between the two threads of the nut and improved resistance of the screw and nut to fatigue and tensile failures.

Abstract: A fatigue resistant threaded connection includes a nut having two threads which are aligned axially but turned relative to one another about their common axis through an angle great enough to cause development of large axial forces between the screw and nut threads when they are connected together, resulting in improved distribution of load forces between the two threads of the nut and improved resistance of the screw and nut to fatigue and tensile failures.

Abstract: A radiation collector having a flexible reflective wall which is deflected to a curved preferably paraboloidal configuration by application of differential pressures to opposites sides of the wall. In one form of the invention, the reflective wall forms the back wall of an inflatable bag having a forward flexible wall through which radiation from a source passes to the interior of the bag for reflection by the rear wall toward an axis of the device. In another form of the invention, the reflective flexible wall is the front wall of a vacuum chamber and is deflected rearwardly by the differential between a subatmospheric pressure in the chamber and atmospheric chamber at the front of the wall.

Abstract: A radiation collector includes a flexible inflatable unit having a portion constructed to concentrate radiation at generally a predetermined location when the unit is inflated, and including a structure positioned to absorb or receive the concentrated radiation. The inflatable unit is preferably a bag of circular cross-section having a front wall transparent to the radiation and a rear concave reflective wall acting to reflect the radiation to the absorbing or receiving structure at the center of the bag. The entire collector may be actuated to follow the sun for reception of solar energy therefrom, and may have photosensing means desirably mounted to the central light-collecting structure for responding to incoming radiation in a manner maintaining the overall assembly in alignment with the sun.

Abstract: The diameter of a thread is measured by screwing two gauge elements into simultaneous engagement with the thread to be measured, then turning the two gauge elements relative to one another to a setting in which their similar threads bear in opposite axial directions against the thread to be measured and confine that thread in a manner holding it against axial movement relative to the gauge elements, after which the diameter of the measured thread is determined by noting the relative rotary position of the two gauge elements, as indicated by relative positions of coacting markings on those parts.

Abstract: A fatigue resistant self-locking fastener is formed by screwing two threaded elements into engagement with a part having a thread which is slightly off-size with respect to the threads of those elements, locating the two elements just in contact with one another while in engagement with said part but without tightening them against one another sufficiently to develop any substantial stress in the threads, and then securing the elements together in that relative position, preferably by welding.

Abstract: A threaded nut having a case containing a separately formed essentially helical coil structure which forms an internal thread and is fusion bonded to the case, preferably by electron beam welding. The coil structure desirably has a locking portion which is substantially free of direct attachment to the adjacent portion of the case, with this locking portion and the surrounding portion of the case both being deformed to a condition requiring radially outward displacement thereof upon threaded engagement with a mating screw, to thereby attain a very effective self-locking action preventing unscrewing the nut.

Abstract: The method of manufacturing a threaded nut having a case containing a separately formed essentially helical coil structure which forms an internal thread and is fusion bonded to the case, preferably by electron beam welding. The coil structure desirably has a locking portion which is substantially free of direct attachment to the adjacent portion of the case, with this locking portion and the surrounding portion of the case both being deformed to a condition requiring radially outward displacement thereof upon threaded engagement with a mating screw, to thereby attain a very effective self-locking action preventing unscrewing of the nut.