Abstract: The invention relates to a fixing device, such as a screw (1) a plain washer, a nut or a rivet, with an information memory that can be read from the exterior. The information memory (4) is machine readable. According to the invention, the information memory contains optically readable information.

Abstract: The invention proposes a connecting element (5) with an elongated shaft (19), in particular a screw or bolt, for connecting two bodies, wherein at least part of the shaft (19) has a slot (14) and a recess (13). The invention also proposes that a component (10) that generates a magnetic field, and spaced apart from it, a magnetically sensitive element (11) be disposed in the vicinity of the recess (13). The proposed connecting element is particularly suitable for detecting a force or mechanical strain acting on the seat of a motor vehicle.

Abstract: A screw-and-nut assembly comprising a support secured to the nut, which support is provided with a surface in contact with the thread of the screw, and an electrical sensing member responsive to mechanical interaction with the thread of the screw, the sensing member being placed in the support close to said surface to come into interaction with the thread of the screw in the event of said surface wearing, wherein the support and the nut are constituted by the same block of material, the sensing member thus being placed inside the nut.

Abstract: A tamper-indicating fastener has a cylindrical body with threads extending from one end along a portion of the body, and a tamper indicating having a transducer for converting physical properties of the body into electronic data; electronics for recording the electronic data; and means for communicating the recorded information to a remote location from said fastener. The electronics includes a capacitor that varies as a function of force applied by the fastener, and non-volatile memory for recording instances when the capacitance varies, providing an indication of unauthorized access.

Abstract: A fastener device comprising a nut, a threaded member for receiving the nut, and visual indicator means for visually indicating if the nut has become loose on the threaded member during use of the fastener device. The visual indicator means may comprise an indicator member which is mounted on the nut, biasing means which biases the indicator member to an indicating position in which the indicator member gives a visual indication that the nut has become loose, and at least one recess into which the indicator member is moved by the biasing means consequent upon the nut becoming loose, the indicator member then being in the indicating position.

Abstract: An intrinsic gauging device for a ferrule type tube fitting of the type having a coupling nut, a coupling body and at least one ferrule, includes a precisely formed marking on the coupling body that is visually perceptible when the coupling is in a finger tight position, and that is covered or visually imperceptible or otherwise has a predetermined relationship with the coupling nut when the fitting has been initially pulled-up. In a preferred form, the marking is realized as a precision groove or recess machined into a surface of the coupling body. The groove can be made more easily visually perceptible such as by roughening or knurling the surface, or coloring the surface, for example. The groove defines an edge at a precise position that corresponds to a predetermined axial displacement of the nut relative to the body for initial pull-up.

Abstract: A mechanical fastener such as a bolt or a nut for a bolt bears on its surface at least one indicium of at least one characteristic of the mechanical fastener, preferably including at least the thread diameter. As a result, such fasteners are more readily separated from similar appearing fasteners with which they may become mingled, and mistakes arising from inadvertent mismatching of two parts of a threaded fastener are minimized.

Abstract: A threaded bolt having a proximal head end and a distal insertion end, the proximal head end and the distal insertion end are each provided with a single, exposed radial measurement plane, the radial measurement plane at the distal insertion end is formed by a flat bottom of a recess at the distal insertion end, the recess is bounded by a circumferential wall which at a point of change transitions into the flank of the distal end via a buckle, and wherein the radial measurement planes are for use in ultrasonic length measurement for determining the tension in the threaded bolt after it has been used in a connection.

Abstract: An intrinsic gauging device for a ferrule type tube fitting of the type having a coupling nut, a coupling body and at least one ferrule, includes a precisely formed marking on the coupling body that is visually perceptible when the coupling is in a finger tight position, and that is covered or visually imperceptible or otherwise has a predetermined relationship with the coupling nut when the fitting has been initially pulled-up. In a preferred form, the marking is realized as a precision groove or recess machined into a surface of the coupling body. The groove can be made more easily visually perceptible such as by roughening or knurling the surface, or coloring the surface, for example. The groove defines an edge at a precise position that corresponds to a predetermined axial displacement of the nut relative to the body for initial pull-up.

Abstract: A method and apparatus for determining fastener axial loading includes a fastener insert having an arched bottom surface, which deflects correlative to the level of axial loading. A load indicating mechanism determines axial loading by measuring the amount of deflection experienced by the arched insert. In addition, the arched insert stores elastic energy which is added to the overall elastic energy of the fastener, thereby aiding the fastener integrity during use. The system comprises a zeroing mechanism and full-scale adjustment mechanism for calibration of the system, and an apparatus for measuring in-service load.

Abstract: A screw-and-nut assembly comprising a support secured to the nut, which support is provided with a surface in contact with the thread of the screw, and an electrical sensing member responsive to mechanical interaction with the thread of the screw, the sensing member being placed in the support close to said surface to come into interaction with the thread of the screw in the event of said surface wearing, wherein the support and the nut are constituted by the same block of material, the sensing member thus being placed inside the nut.

Abstract: An anti-loosening nut assembly is composed of an upper nut 3 and a lower nut 2 that engage with each other in an eccentric manner to afford the so-called ‘wedging’ effect of surely inhibiting them from loosening themselves. The upper nut 3 has one or more lateral lugs to be brought into contact with the lower end of a fastening tool such as a spanner. The lug or lugs 3b protrudes or protrude from the outer peripheral portion or portions of the upper nut 3 for the purpose of visual detection of rotation angle of this nut.

Abstract: A color pressure-sensitive fastener capable of providing a visual indication of a pressure threshold applied to the fastener is disclosed. The fastener includes a fastening portion which is actuated to fasten by way of application of a sufficient actuating pressure on an actuating surface of the fastening portion; and a pressure-sensitive substance associated with the actuating surface such that the actuating surface visibly changes color after the sufficient actuating pressure is applied to the actuating surface. This invention at least partially overcomes some of the disadvantages of typical fasteners, such as the lack of visual indication of proper installation of the fastener.

Abstract: A method and apparatus for determining fastener axial loading includes a fastener insert having an arched bottom surface, which deflects correlative to the level of axial loading. A load indicating apparatus determines axial loading by measuring the amount of deflection experienced by the arched bottom surface of the insert. In addition, the arched insert stores elastic energy which is added to the overall elastic energy of the fastener, thereby aiding the fastener integrity during use.

Abstract: In order to provide a visible indication of loosening of a nut or a bolt relative to another member to which it is threadably engaged, a rotation indicator assembly comprises a first element, which is permanently secured to the nut or bolt and a second element which is adapted to be releasably and non-rotatably mounted in or on the first element, e.g. by interengagement with teeth in any chosen rotational position, and incorporates means, such as pointer, for indicating its rotational position relative to a fixed reference. The first element may take the form of an insert, an integral formation, or an external fitment. The fixed reference may be provided by an independently mounted marker secured by the nut or bolt.

Abstract: A transducer mounting device comprised of a monolith of moldable material overlying and supporting a self-tapping screw at one end for coupling to a target such as a machine casing or bearing housing and a fabricated insert at an opposite end for mating with a monitoring transducer. In a further preferred form a transducer mounting device is comprised of a preform including an internal cavity overlying a magnetic component, an adhesive interposed between the magnetic component and a target such as a machine casing or bearing housing at one end for magnetically and adhesively bonding said preform to the target and a threaded member disposed at an opposite end of the preform for mating with a monitoring transducer.

Abstract: A tension indicator for use with a fastener that is formed from a stack of conical washers confined in the stack by a cage having a longitudinally extending slot formed therein provides readily discernible visual indication of tension or loss of tension in the fastener joint. The indicator includes a body configured for receipt over the stack of conical washers. The body can include at least one stanchion extending inwardly of the body from the interior surface to define a stanchion end longitudinally spaced from the body end. At least one detent extends inwardly of the body and is longitudinally spaced from the body end. When the stack of conical washers is placed under tension with the uppermost washer in a planar condition, the stanchion lies adjacent the uppermost washer at the interior region.

Abstract: An intrinsic gauging device for a ferrule type tube fitting of the type having a coupling nut, a coupling body and at least one ferrule, includes a precisely formed marking on the coupling body that is visually perceptible when the coupling is in a finger tight position, and that is covered or visually imperceptible or otherwise has a predetermined relationship with the coupling nut when the fitting has been initially pulled-up. In a preferred form, the marking is realized as a precision groove or recess machined into a surface of the coupling body. The groove can be made more easily visually perceptible such as by roughening or knurling the surface, or coloring the surface, for example. The groove defines an edge at a precise position that corresponds to a predetermined axial displacement of the nut relative to the body for initial pull-up.

Abstract: A washer extrudes indicating material of varying colors depending on the compression force applied to it by providing a first and second surface having respective bumps and indentations. The compression force on the washer is equal to the tension of a bolt passing through the washer. The indentations in the second surface are filled with a solid extrudable colored material. By making at least a first bump taller than at least a second bump, the first bump will compress before the second bump, causing it to extrude the color material in its corresponding indentation before the second bump does the same as the tension in the bolt is increased. By making the material under the first bump a different color than the material under the second bump, an operator can determine which of two desired tensions the bolt has reached.

Abstract: The torque confirmation fitting is used for coupling one section of tubing to another and includes a fitting body, a fitting nut, and a torque confirmation portion. The fitting body has a nose section that supports an end of one of the sections of tubing. The torque confirmation portion has a collar portion and one or more prongs. The fitting nut is operably joinable to the fitting body and engageable with the torque confirmation portion. To operate, the non-supported end of the tubing is inserted through the torque confirmation portion and the fitting nut. The fitting nut is then joined to the fitting body and in doing so engages the torque confirmation portion. The continued joining of the fitting nut to the fitting body causes the prong of the torque confirmation portion to provide a visual indication that the fitting nut has been sufficiently, tightly joined to the fitting body.

Abstract: A connection bolt (1) for repeated tightening beyond yield point which bolt (1) comprises a head (2) and a shank which shank is provided with a thread, whereby said head (2) of said connection bolt (1) is provided with at least one indication mark (9) at a fixed defined mutual angle position to at least one indication sign (10), which sign (10) is provided on the free shank (5) end relative to the axis (q—q) of the bolt (1) rotation. This system of marking allows to determine the damage of said bolt (1) exactly and to decide about further ability of said bolt (1) to be used next time without any risk of destruction or decrease in quality of a joint.

Abstract: For indicating relative rotational displacement between a fixed first member, such as a stud (20) on a wheel hub, and a second member, such as a wheel nut (22), which is rotatably engaged with the first member, a safety device (24) comprises a body (26) having a bore formed with equispaced grooves enabling the device to be releasably secured to the second member (22) in one position of a plurality of positions and having indicating means, such as a pointer (28), to indicate the position of the device (24) relative to a reference, such as a mark (32) on the rim (16) covering the wheel hub (14). The bore within the body (26) is closed at one end, e.g. by bevelled top wall (36), so that the body additionally serves as a dust cap for the conjoined first and second members (20, 22).

Abstract: An intrinsic gauging device for a ferrule type tube fitting of the type having a coupling nut, a coupling body and at least one ferrule, includes a precisely formed marking on the coupling body that is visually perceptible when the coupling is in a finger tight position, and that is covered or visually imperceptible or otherwise has a predetermined relationship with the coupling nut when the fitting has been initially pulled-up. In a preferred form, the marking is realized as a precision groove or recess machined into a surface of the coupling body. The groove can be made more easily visually perceptible such as by roughening or knurling the surface, or coloring the surface, for example. The groove defines an edge at a precise position that corresponds to a predetermined axial displacement of the nut relative to the body for initial pull-up.

Abstract: A washer having a plurality of strain gauges, at least one of which is positioned on a portion of the washer subjected to axial force and at least one of which is positioned on a portion of the washer not subjected to axial force. In a preferred embodiment, each such washer portion has two strain gauges and the total of four strain gauges are connected into a common bridge circuit. In the preferred embodiment the portion of the washer not subjected to axial force is a wedge partially cut into the washer structure and shortened axially to form a gap between the wedge and a surface abutting the washer. In this manner, axial force applied to the washer is not applied to the wedge. The resulting strain gauge configuration provides an electrical signal indication of axial stress that is high resolution and temperature insensitive.

Abstract: The present invention provides several embodiments of tension-indicating fasteners that include tension indicators having indicating arms equipped with a laterally-extending contact member or a foot portion. A contact member extends in a tangential direction from the fastener head. The indicating arm is secured to the fastener and, by having laterally-distant contact points, the deflection of a substrate caused by the fastener head causes a distal end of the indicating arm to move with amplified magnitude. In still other embodiments of the invention, a fastener includes tension indicia for indicating a target degree of substrate deflection. The tension indicator may be disposed within a recess in the fastener head to allow the use of conventional tightening tools.

Abstract: A fastener system employs a portable, sensing device, such as one or more reactance capacitors or an image processor such as a camera or a laser, which removably attaches adjacent to the fastener to detect and measure the change in a gap or specialized form of the bolt head or associated washer caused by the relative movement of portions of the fastener system when the fastener is under strain without contacting the sensed portions undergoing the significant relative movement. Associated electronic components process and indicate the clamp load of the fastener system.

Abstract: A diet cap device for visually indicating rotation of a fastener and for keeping the fastener clean. The device includes a base and a receptacle. The base has a central portion that is circular-shape and has a circumference and a extended diameter that extends past the circumference and an extended diameter that extends past the circumference thereof. The receptacle is disposed on the base and receives the fastener and includes a collar that is concentrically disposed on the central portion of the base and spaces the base away from direct contact with a wheel and a cap that is concentrically disposed on the central portion of the vase, opposes, and is coaxial with, the collar and cover and protects the fastener from dirt.

Abstract: A device used to indicate whether a predetermined compressive load has been applied to the device. The device is formed to receive an anchor member upon which a tensioning force is to be applied in conjunction with loading the device. The device itself has an upper press that has an aperture formed to receive the anchor member and also has means for manipulating a washer. The device also has a lower die with an aperture formed to receive the anchor member. The lower die is formed so as to be able to work in conjunction with the upper press when the upper press and lower die are aligned and moved towards each other. The lower die also has means for manipulating the washer. The means for manipulating the washer are also formed to cooperate with the means for manipulating the washer on the upper press. The device also has a washer that lies between the upper press and the lower die.

Abstract: A safety device used in preloading of bolts for providing the bolts with an internal stress in a mounted condition, wherein a first end of the bolt is secured to a first element and extends through a second element, which clamps to the first element, and where a hydraulic preloading device is temporarily applied to a second end of the bolt for axially stretching the bolt to create the external stress. The safety device incorporates a safety tensile bar detachably fitted to the first end of the bolt, and extending through a central bore in the bolt, and further through the hydraulic preloading device while being held adjacent its opposite end in an expanding plug. The expanding plug is provided in a frictional contact with a sleeve, which guides the plug to create a counter hold for absorbing relieved energy in case of the breaking of the bolt during the preloading operation.

Abstract: An arrangement for detecting a fatigue fracture caused by overstressing of a bolted connection including a bolt and an internal-thread-bearing hollow section which is alternately stressed by an axial flux of force between zero and different maximal values. A transverse crack forms at a predetermined breaking point of the bolted connection, at which the hollow section breaks due to fatigue. The spacing of the predetermined breaking point from the connection ends, and the interaction of the bolt and the hollow section, are designed such that, after the breakage, the bolt forms in the hollow section a residual joining connection which can be alternatingly stressed. In order to signal the occurrence of a crack on the hollow section of the bolted connection in the event of a fracture caused by fatigue in a simple and always noticeable manner, the arrangement has an additional signaling device.

Abstract: There is provided a new and improved wheel nut locking assembly for use on a wheel nut on a hub of a vehicle wheel, in which the wheel nut comprises a polygonal outer surface and a threaded inner surface which is constructed so as to engage a shaft. The shaft has a threaded portion and a non-threaded polygonal head extension with a threaded aperture therein. The assembly comprises a locking cap which has a recess adapted to receive the wheel nut in one of a plurality of orientations in a rotationally locked arrangement relative to the shaft. There is also provided an aperture which is adapted to receive and engage the polygonal head extension so as to prevent rotation of the locking cap and the wheel nut relative to the shaft.

Abstract: A loosening-resistant threaded fastener system and method of use includes a washer that is axially movable on a threaded stud, a threaded nut having threads which cooperate with the threaded stud, and a washer anti-rotation mechanism to prevent the washer from rotating on the stud about a fastening axis. One of the washer and the nut may include a plurality of protrusions while the other of the washer and the nut has a plurality of detents. The protrusions and the detents engage one another at a plurality of angular positions. Rotating the nut on the stud while in contact with the washer results in distinct, audible clicks which may be counted to obtain a pre-determined tightness.

Abstract: A direct tension indicating and maintaining washer has a first surface having at least one protuberance formed thereon and a second surface having at least one indentation formed therein opposite the protuberance. The inner diameter of the direct tension indicating and maintaining washer has an inner diameter wall meeting the second surface at an inner diameter edge. The outer diameter has an outer diameter wall meeting the second surface at an outer diameter edge. The inner diameter edge and the outer diameter edge lie in different planes. This causes the flattened direct tension indicating and maintaining washer to exert force against a bolt and maintain bolt tension. An alternative direct tension indicating and maintaining washer includes indicating material positioned in the indentation and a channel formed in the second surface leading from the indentation to the outside diameter of the direct tension indicating washer.

Abstract: A system for providing a visual body-length indicator for a group of mine roof stabilizers of various, unique lengths includes providing each stabilizer with a tubular body and a slot along the body. A bottom annular ring having a ring gap formed therein is attached to the body, with the ring gap and body slot being oriented in a unique relation for each unique body length, providing a visual indicator of body length that can be observed from a distance, even after the stabilizer is installed into a drill hole in a mine roof.

Abstract: A method and apparatus for mounting a trailer ball to a mounting platform. The apparatus includes a trailer ball having a threaded stem, a flat washer, and a nut having a plastic collar. The plastic collar includes a ring which is disposed between the nut and flat washer. The ring is formed of a plastic material which is extruded when the nut is tightened sufficiently to provide a positive indication that sufficient tension has been placed on the joint. The method also includes lubricating the stem before threading the nut onto the stem and removing the extruded ring after tightening.

Abstract: A mechanical sensor for use with bolts, nuts, eye bolts and other fasteners is provided to sense fastener tension and to mechanically indicate that tension and changes therein by mechanically measuring deformation of the substrate being clamped by the fastener relative to the distortion or lack thereof in the substrate immediately adjacent the deformed substrate. The differential substrate deformation produces measurable and often clearly visible movement of a portion of the sensor. Such movement may be interrogated through utilization of visual, optical, electro-optical means as desired.

Abstract: There is provided a fastening device which includes a nut having a body. The body has a top face and a bottom face. The body further has an orifice extending therethrough. The system also includes a clamp-force indicating insert for use with the nut. The insert includes a portion extrudable across the top face of the nut. The nut further includes at least one insert-engaging portion.

Abstract: A tie-down comprising a flexible strap adapted to be wrapped around an object to be tied down, a first member at one end of the strap having a first hole formed therein and a second member to which the other end of the strap is attached having a second hole formed therein in alignment with the first hole. A fastener having a head and a threaded shank is arranged with the head engaging the first member and with the shank extending through the first and second holes and having a threaded end portion projecting out of the second hole. A nut is threaded on the projecting end portion of the shank and engaged against the second member for being turned to act through the fastener for drawing the first and second members together to tighten the strap around the object and place the fastener and the strap under a predetermined tension. The fastener has an indicator for indicating the tension in the fastener and thereby indicating the tension in the strap. The first member is formed for observation of the indicator.

Abstract: A screw and nut assembly comprises a screw having a hollow cavity extending longitudinally throughout, a nut configured to screw onto the screw, and an extension attached to the nut. The extension traverses the hollow cavity of the screw when the nut is placed on an end of the screw without being screwed on. The extension is displaced from the hollow cavity of the screw as the nut is screwed onto the screw. The status of the screw and nut connection may thus be determined from the screw side of the assembly, without observing the nut, by observing the extent to which the extension has emerged from the hollow cavity in the screw.

Abstract: A sealing fastener includes a unique identifier device for the individual fastener that enables ultrasonic identification of the device using an ultrasonic fault measuring system, and a frangible element within the fastener integrated with the identifier device that provides an ultrasonic signature indicating an attempt to loosen or remove the fastener when subjected to an ultrasonic signal generated by an ultrasonic fault measuring system. The unique identifier device includes a stack of individual metallic washer elements brazed together, with each washer element including discontinuities or cavities that are randomly arranged with respect to the cavities of the other washers in the stack. The fastener includes relatively movable portions that cause fracture of the frangible element upon any attempt to loosen or remove a fastener after it has been tightened or secured at its sealing location.

Abstract: A method and hydraulic nut for mounting a hollow article which has a conically shaped opening, such as a conical ring, on a conical shaft. The method comprises the following steps: a) installing the hollow article on the shaft, in order to fit the conically shaped surfaces of the article and the shaft against each other; b) moving the hollow article to a starting position (B), in order to provide an initial press fit; and c) moving the hollow article over a predetermined distance (S.sub.s) from the initial position to an end position (C), in order to provide a final press fit.

Abstract: A direct tension indicating and maintaining washer has a first surface having at least one protuberance formed thereon and a second surface having at least one indentation formed therein opposite the protuberance. The inner diameter of the direct tension indicating and maintaining washer has an inner diameter wall meeting the second surface at an inner diameter edge. The outer diameter has an outer diameter wall meeting the second surface at an outer diameter edge. The inner diameter edge and the outer diameter edge lie in different planes. This causes the flattened direct tension indicating and maintaining washer to exert force against a bolt and maintain bolt tension. An alternative direct tension indicating and maintaining washer includes indicating material positioned in the indentation and a channel formed in the second surface leading from the indentation to the outside diameter of the direct tension indicating washer.

Abstract: A coupler for connecting two axially aligned, rod-like reinforcing members or structural parts and which permits a visual confirmation that successful coupling of the two structural parts has been made. The coupler is fashioned as a sleeve with two opposed open ends, each open end for receivingly engaging a corresponding inserted end of one of the structural parts. The sleeve includes at least one inspection hole or through-hole disposed medial of the sleeve ends. The sleeve further includes a displaceable inspection element disposed inserted within the through-hole and a stop member for limiting the engagement depth of the structural parts within the respective open ends of the sleeve. The inserted structural parts engage the displaceble inspection element and forcibly cause it to displace outwardly of the through-hole and thereby provide a visual confirmation that the two structural parts have been successfully coupled with a desired engagement depth.

Abstract: A method and device for monitoring fastener loads as well as clamp loads imposed on base metal with a special washer usable with bolt heads, nuts, and other fastener elements which washer has at least one integral arm whose position is indicative of fastener load as determined by the phenomenon of dishing of the base metal and washer.

Abstract: A fastener system includes an applicator for engagement by a tool, and a fastener such as a screw having a first surface with first screw threads in a one hand direction for engaging a workpiece. An attachment mechanism is provided to transfer rotational force from the applicator to the fastener and has second and third screw threads in an opposite hand direction to the first screw threads. The second and third screw threads are interfaced to establish a torque of the predefined magnitude prior to the fastener being attached to the workpiece. When the torque applied by the tool exceeds the predefined magnitude, the attachment mechanism begins to unthread and further application of torque from the tool to the fastener ceases, thereby controlling the applied torque to no greater than the predefined magnitude. The attachment mechanism can be used in a variety of applications including flush mounted heads, shallow aperture installations and multistage torque mountings.

Abstract: The present invention provides an innovative method and apparatus for determining continuous, visual clamp load status during tightening and throughout the life of a fastener. The present invention provides a nondeformable element (or in some cases elements) that is suitably configured and positioned within a fastener to amplify the deformation of the fastener as a load is applied to the fastener. In accordance with one aspect of the invention, a lever is connected at an internal pivot point of a cartridge. One end of the lever rests upon an abutment within the fastener, while the other end serves as an indicator. As the fastener is tightened, the fastener will elongate causing the abutment to move away form the lever end. As the abutment moves, the lever rotates causing the indicator end to move relative to the visual scale which is calibrated to indicate clamping force. If the fastener loses tension, the fastener will contract, thereby forcing the lever to rotate toward its original position.

Abstract: A pre-load indicating washer for properly tensioning a joint held together by an externally threaded member and an internally threaded member. The pre-load indicating washer has a plurality of protuberances, struck and partially sheared from the annular body of the washer, which are pushed under load back into a corresponding number of indentations in the annular body which are formed when the protuberances are formed. The protuberances of the pre-load indicating washer are curved in outline with no portion of the protuberances extending radially outward beyond the outer periphery of the bearing surface of an externally threaded member when the pre-load indicating washer is positioned adjacent the externally threaded member, or radially outward beyond the outer periphery of the bearing surface of an internally threaded member when the pre-load indicating washer is positioned adjacent the internally threaded member.

Abstract: A deformation indicator is disclosed for repeatably adjusting the fasteners on a flange assembly to maintain a leak-free joint. The indicator is mounted on one of the fasteners used for fastening together the flange members, and extends to a predetermined distance from the adjacent flange member. When the flange fasteners must be adjusted to account for creep in the packing material in the flange, they are adjusted to restore the distance between the indicator and the adjacent flange member to the predetermined value.

Abstract: A method to accurately determine and assure proper clamping force or bolt tension in fastening systems comprises statistically sampling washer or flanged bolt lots for clamping force versus deflection relationships, encoding the lots and subsequently installing the fasteners to the prescribed deflections of the lots. A validator and validation method is disclosed that provides the statistical sampling and a corresponding sensor device is disclosed for measuring the deflection as the fastener is installed. Thus, the deflection of the washer or bolt flange as the fastener is installed determines the clamping force applied by the fastener and assures that the proper clamping force has been obtained. The new method and sensor are applicable to special flanged bolt and standard bolt--Belleville washer combinations. No modification of the bolts or washers is required.

Abstract: A prestress-monitoring element for screw-type anchors is arranged to be inserted like a washer between a nut and an article to be fixed and includes a pressure ring and an expansion ring. If the nut provided for fixing is tightened, then the resultant axial prestress causes the pressure ring to expand the expansion ring until the nut lies against the expansion ring. In this end position, a prestress required by the construction of the prestress-monitoring element is achieved. The position of the nut on the pressure ring can be monitored visually, as a result of which the prestress can be indirectly monitored.