Abstract: This invention allows to form a nitrided hard layer on the surface of an austenitic stainless steel screw by forming a nitrided layer thereon and to prevent causing rust on some parts such as a screw head portion which is in contact with the outside air by removing the nitrided hard layer to expose austenitic stainless steel base which has sufficient corrosion resistance. On the contrary, in a thread part and the like of the screw, the nitrided hard layer is left and to thereby improves hardness and the like to strengthen tapping functions and the like of the screw. In the method for manufacturing the austenitic stainless steel screw according to the invention, the austenitic stainless steel screw is held in a fluorine- or fluoride-containing gas atmosphere prior to nitriding to form a fluorided film on its surface and then is nitrided in that state. Accordingly, so formed nitrided hard layer becomes uniform and deep to obtain an austenitic stainless steel screw having excellent surface properties.

Abstract: A screw-threaded connection incorporates dual synchronized threads, that is, one connection element has a set of external male threads that mates with a corresponding set of internal female threads on the mating connection element, in customary fashion. The first connection element additionally includes a second set of internal female threads synchronized with the first set such that the leads of both sets of threads are the same. This second set of internal female threads mates with a corresponding set of external male threads on the mating connection element. Of course, the two sets of threads on the mating connection element are synchronized such that their leads are the same, and, of course, the same as first sets of mating dual synchronized threads. This dual synchronized thread connection has application to any fluid connector and particularly to fluid connectors in wide-variant temperature deviation, high-pressure, and/or mechanical vibration environments.

Abstract: A fastener is formed with an elongated threaded portion defined by a central shank and a thread formed on the shank, a neck collinear with the shank, and a head provided with a recess adapted to receive a tool for rotating the fastener. The shank of the threaded portion includes a cylindrical body and a tapered penetrating point extending longitudinally from the body. The thread is provided with a constant diameter section along the cylindrical body and a tapered section along the tapered penetrating point. The constant diameter section defines a major diameter that is more than about double the minor diameter defined by the body of the shank. The thread defines a pitch greater than the cross-sectional thickness of the thread along the shank so that the cylindrical shank is exposed within each pitch of the thread.

Abstract: This invention allows the surface of an austenitic stainless steel screw surface to be formed into a hard nitrided layer so as to harden and a part such as a screw head which is in contact with outside air is removed its own ultra hard surface layer in the hard nitrided layer by scouring or the like to be rust preventive. Even if the ultra hard surface layer is thus removed, an inner hard layer in the hard nitrided layer is present beneath the surface layer to be able to maintain a hard state of the screw surface. In the method for manufacturing the austenitic stainless steel screw according to the invention, upon forming said hard nitrided layer on the screw surface by nitriding, the austenitic stainless steel screw surface is cleaned with a fluorine- or fluoride-containing gas prior to nitriding.

Abstract: A bone screw having a helical thread that gradually increases in thickness from the tip to the head of the screw. The thin thread at the tip of the screw can be inserted into a bone with minimal tearing or cracking of the bone. The thicker treads ascending from the tip to the head of the screw displaces bone against the superior (top) thread surfaces. This displacement of bone increases the screw's resistance to being pulled-out of the bone. The thicker core just below the screw head increases the screw's ability to withstand compressive and distractive loads. The core is thickest just below the head because it is at that point on the screw that the fulcrum loads are greatest.

Abstract: An end link and swivel assembly for chaincables, wherein the end link comprises a drilled head followed by a threaded pin which is rotatingly mounted on a passage formed at the link and secured by an adjusting nut. The pin and nut threads are of the rounded corner type, wherein between the pitches and roots thereof essentially planar flank regions as contact surfaces are defined. Therefore, the pin and nut may be manufactured by casting.

Abstract: A bin aeration device includes a skirt mounted to a bin wall by a stem including an exterior surface with a first portion having straight American National Standard pipe threads. A second portion on the exterior surface includes American National Standard Taper Pipe Threads. The American taper pipe threads permit attachment of either an internally American taper threaded fitting or an internally British taper threaded fitting if provided with 1/2 inch or 3/4 inch--14 threads per inch threads. An interior surface through the stem defines a passageway for pressurized gas to exit through an air port adjacent the skirt. A portion of the interior surface of the stem includes British Standard Taper Pipe threads. The British taper pipe threads permit attachment of either an externally American taper threaded fitting or an externally British taper threaded fitting if provided with 1/2 inch or 3/4 inch--14 threads per inch threads.

Abstract: Squeaks in a floor or stair are eliminated by driving screws in the area. At least one scored screw to be driven into the squeak area combines with a specialized driving bit and a alignment and depth control fixture to eliminate the squeak. The alignment and depth control fixture can be used to direct the scored screw to the proper point while the driving bit can stop driving the screw at the desired position. After the alignment and depth control fixture is removed, the screw is broken at the prescored position. To minimize damage to an in place carpet, a tape is wrapped around the threads of the screw.

Abstract: At least one scored screw is driven into the squeak area with a specialized driving bit and an alignment and depth control fixture. The alignment and depth control fixture is used to direct the scored screw to the proper point into the floor so that the scored area is at or beneath the surface of the floor. The driving bit can stop driving the screw at the desired position. After the alignment and depth control fixture is removed, a gripping tool is used to apply force to the screw and break the screw at the prescored position. The barrel of the screw being left in the floor locks the floor or the step to the desired support. One screw or series of these screws in usually an arcuate or a radial fashion around the squeak area, can eliminate the squeak.

Abstract: A thread forming screw for cold forming, using primarily compressive forces, internal threads in a workpiece comprised of a low ductility material, such as magnesium and the like, comprises a shank having an entering end and a head end. External threads are disposed on the shank between the entering end and the head end. The external threads define an angular configuration with the angular configuration defining an angle measuring substantially within the range of ninety degrees to one hundred and twenty degrees.

Abstract: The puncturing stimulation needle has an insertion part (2) and a holder part (3). The insertion part (2) is structured as a screw with one or more threads, the thread height (6) of which is greater than twice the diameter (7) of the insertion part (2) at its thickest point. Preferably, the holder part (3) is structured in the form of a ring or small disk, with its side facing the insertion part (2) lying in a plane approximately perpendicular to the geometric axis of the insertion part. The puncturing stimulation therapy apparatus has a portable, battery-powered treatment current generator (17), with at least one electrode (23, 24) in the form of a puncturing stimulation needle being connected with the generator via a flexible line (21, 22), with this needle having an insertion part (2) which is shorter than 4 mm, and a holder part (3) in the form of a ring or small disk. A surface electrode (29) can also be provided at the housing of the treatment current generator (17).

Abstract: A fastener includes an annular body having a screw thread spiraling therearound. The thread has a crest and a pair of front and back flanks extending laterally therefrom, with a start end disposed adjacent to a front end of the body. The start end is flat from the back flank to the front flank and is inclined at an acute back angle relative to a helical axis of the crest for facing the start end toward a back end of the body.

Abstract: A screw has a thread (3), whose front and rear flanks have a different angle with respect to the screw longitudinal axis. The screw tip (2) can contain a scraping groove (6), which extends as a notch in the screw longitudinal direction. In the front, conically tapering area of the screw the thread course is constructed symmetrically and extends up to the tip.

Abstract: A screw of the self-drilling and self-tapping kind intended to be used in fastening corrugated or similar cladding to a support structure is disclosed. The screw shank is provided with a feature, such as, for example, a circumferential series of axially extending ribs, which is operable to enlarge (such as, for example, by means of a reaming process) a hole formed through the cladding by means of the drilling tip of the screw. The hole enlarging feature is positioned at or adjacent to the junction defined between a threaded section of the shank and a non-threaded section which extends from the screw head. The hole enlarging feature is arranged so as to ensure that the aforementioned hole, as enlarged, has a diameter which is not less than that of the non-threaded section of the shank.

Abstract: A fastener is provided which is adapted to be at least partially embedded within a molded workpiece. The fastener comprises a first threaded section and a second section. The second section has a first end part defining a shoulder for making contact with a first portion of a mold during formation of the workpiece and a second end part having an outer end face for making contact with a second portion of the mold during formation of the workpiece. The second section further includes a crush-boss extending outwardly from the outer end face for contacting the second portion of the mold and thereby ensuring that the second section of the fastener is compressively engaged by the first and second portions of the mold during formation of the workpiece.

Abstract: A fixing element for connecting materials of relatively low strength includes a unitary, one-piece plastic body. An external thread is formed on the plastic body for compressing and compacting the low strength material in the thread turns of the external thread. A first external thread portion has a taper at one end of the plastic body. A second portion has a taper at another end of the plastic body, while a third portion has no taper and extends between the first and second external portions. A penetration tip is connected to the smaller diameter end of the first external thread portion. Further, a stop collar is provided at the large diameter end of the second external thread portion. The penetration tip preferably is a self tapping screw made of a harder material than the plastic body. Further, the thread depth of the second external thread portion decreases along the second external portion as the second external portion approaches the larger diameter of the screw.

Abstract: High tensile and torque strength threads are provided on a thermoplastic composite rod by first cutting a thread at a relatively short pitch into an end of the rod. Thermoplastic composite tape is then wound in tight conformance to the cut thread so that the fibers of the tape align with the desired helix angle of the thread to be created. The rod and the tape are heated at their junction to above melt temperatures during the winding process to increase adhesion between the rod and the tape. While the end of the rod and the wound tape are at above melt temperatures, the end of the rod and the tape are compressed in a die conforming to the desired ultimate configuration of the thread. The tape and rod are then permitted to cool until sufficiently hardened to permit release of the compressing die without deformation of the threaded end of the tape. The result is a thermoplastic composite rod having high tensile and torque strength at its threaded end.

Abstract: A connecting device connects a tailpipe to an exhaust pipe of an internal combustion engine for a vehicle. The tailpipe includes a smaller diameter section and a larger diameter section, and the free end of the exhaust pipe is received by the larger diameter section of the tailpipe. An annular space separates the larger diameter section of the tailpipe and the free end of the exhaust pipe. Screw threads are formed on the free end of the exhaust pipe. A connecting spring is configured as a conical helical spring, the larger diameter end of which is fixed to the tailpipe. The other end of the spring has coils configured as screw threads which screwed onto the screw threads which are formed on the free end of the exhaust pipe. The spring is relatively soft in a direction parallel to an axis of the tailpipe, and is relatively stiff in a direction transverse to an axis of the tailpipe. The spring absorbs vibrations of the engine and centers the pipes with respect to each other.

Abstract: A preheat device for preheating an internal combustion aircraft engine having an air intake pipe connected to a cylinder head by threaded mounting bolts is configured as a replacement bolt with a zinc - plated body having a bolt head and threaded shank. The body is made of steel heat treated to grade 8 hardness and tempered at apprximately 1,050 degrees F. and had an axial bore open at the head and extending toward and into the shank. An electric heating element surrounded by a stainless steel sheath is positioned in the bore. The shank has a thread with a flat root to provide a wall thickness approximately 0.060 inch. Each cylinder of the engine is provided with a preheat device in place of a mounting bolt and the preheat devices are connected to each other by a wiring harness connectable to an external power source. When energized the heating element of each preheat device generates heat that in transferred through the screw threads to the cylinder head of the engine cylinder.

Abstract: A self-tapping screw-type masonry anchor which when turned into a hole drilled in a masonry structure to secure an object thereto is then highly resistant to pull-out forces. The anchor is fabricated of a metal whose hardness is such that when it rubs against a masonry surface it is abraded and worn thereby. The anchor includes a head engageable by a torque-producing tool to rotate the anchor, and a shank extending therefrom provided with a root section surrounded by a helical male cutting thread whose series of convolutions have sharp crests and extend from the leading to the trailing end of the root section. The crests have diameters greater than that of the hole which decrease progressively from the leading to the trailing end to create a reverse taper.

Abstract: Trocar needle for laparoscopy with a truncated cone bit (1) having at its truncated cone end a cutting blade (2) with a rounded edge arranged obliquely to the axis of the needle and to the plane perpendicular to the axis of the needle which continues with a cutting thread (3) developing in a single turn around the truncated cone tip.

Abstract: A self drilling screw for thin metal applications. The screw has a small point for drilling a hole in the thin metal and a substantially larger diameter non-tapered threaded section. Between these portions is an extended length taper having a plurality of thread pitches each including swaging lobes.

Abstract: A fluid cooled thermal skin is bolted to a sufficient back structure. In-line coolant flow paths are arranged to pass the cooling fluid through the bolt head. The in-line paths are recessed adjacent the bolt head to mate with flow openings in the head. In one embodiment the paths through the bolt head are parallel paths, requiring alignment of the bolt head. In another embodiment alignment of the bolt head is not required.

Abstract: A fatigue resistant buttress thread. The thread has a load flank angle of approximately 30.degree. plus or minus approximately 5.degree. and a relief flank angle of approximately 46.degree. plus or minus approximately 5.degree.. The thread engaged depth is approximately 0.232 times the pitch of the thread, and the thread has a root radius approximately 0.175 times the pitch. The thread is particularly well adapted for use in cover retainers for holding valves and rupture discs in plunger pumps. Finite element analysis and actual tests indicate a greatly improved fatigue resistance compared to previously known buttress threads and other thread forms.

Abstract: A carbon and/or ceramic fiber reinforced carbon and/or ceramic matrix composite threaded member including a core, a fiber containing thread-defining element bonded to the exterior of the core and a reinforcing fabric layer securing the thread-defining element to the core. The thread-defining element may be an integral part of a tubular braided reinforcing fabric or applied to the core prior to application of a reinforcing fabric layer. Externally and internally threaded members and methods for their manufacture are described.

Abstract: A mining bolt for holding rock comprised of an elongate shaft at least a portion of which has threads. The threads directly thread into the rock and are capable of supporting the bolt under tension in the rock. The mining bolt is also comprised of a flange system disposed about the shaft in proximity to one end thereof such that when the shaft is threaded into the rock, the flange system abuts under tension the rock's face. A method for holding rock in a mine comprising the steps of drilling a bore hole into the rock; and inserting the shaft of a mining bolt into the bore hole. The shaft has a flange system disposed about the shaft in proximity to the end thereof. The shaft has threads and is of a length longer than the length of the bore hole. There is also the step of screwing the shaft into the rock at the top of the bore hole such that the threads of the shaft penetrate into the rock and the flange abuts under tension the rock face.

Abstract: A threaded member including a core, a thread-defining element helically extending around and along the core and a reinforcing tubular fabric layer bonded to the exterior surface of the combined core and thread-defining element. The radial projection of the thread-defining element defines a helical thread whose contour is followed by the fabric layer and the exterior surface of the threaded member. The composite threaded member may be formed by forming a braided or knit fabric layer on an elongated spiral wrapped core. The spiral wrapped thread-defining element and the fabric reinforcing layer is bonded to the core. A polymer sheath protects the underlying structure.

Abstract: A screw type coupling device includidng a male screw element formed by installing a coil spring form helical component on the outer surface of a columnar element and a female screw element formed by installing a coil spring form helical component in a tubular element so that the two helical components are screw engaged with each other. With the application of such coupling device to an antenna for vehicles, the antenna having the male screw element at the base is removably attached to a vehicle body by screwing the male screw element of the antenna to the female screw element installed in the vehicle body.

Abstract: A threaded member including a core having an integral tubular braided layer bonded to the exterior surface of the core. The braided layer includes at least one element of greater radial projection which defines a helical thread on the exterior surface of the core. The composite threaded member may be formed by forming a braided layer on an elongated core. The braided layer includes at least one element of greater radial projection relative to the core than the remainder of the elements forming the braided layer. The element of greater radial projection defines a helical thread on the core. The braided layer is bonded to the core.

Abstract: A threaded coupling includes a male part and a female part, of which one is made of a hard material such as metal and another of soft material such as plastic. The part made of the soft material is formed with a groove at a first turn of the screw thread thereof, which receives a metallic resilient ring to define a guide portion for the part of the hard material as the latter is being threaded to another part having the ring in the groove thereof.

Abstract: A threaded fastener is presented of the thread-forming type, wherein there is defined, during driving thereof relative to a workpiece a combination of force couples and a resultant moment of force couples to develop material flow of the workpiece material about the threads to give face contact between the mating threads of the fastener and threads formed in the workpiece thereby for improved loading.

Abstract: A flooring system comprising a flooring panel having a panel body, and detachable support legs is disclosed. The panel body has a set of threaded holes having internal threads of a given pitch extending uniformly throughout the hole (the regular threads). One end of the detachable support legs is provided with a threaded section having two types of external threads of the identical pitch to the internal threads; one type is the regular threads and the other type has the crest of each thread wider than the crest of the regular threads, and the wider crest is formed with a slit extending continuously on the tip of each crest (the split threads). At least the leading end the threaded section of the leg is provided with the regular threads. The placement of the regular and split-threads can be reversed on the panel body and on the threaded section of the leg, to achieve the same purpose of providing firm and efficient locking system.

Abstract: Adjacent the free end of a flexible hose (22) an external thread (20) of elastomeric material is bonded or vulcanized to the external surface (21) of hose (22). A sleeve (1) is threaded onto and adhesively bonded to the external thread (20). The sleeve (1) consists of a sleeve body (2) of plastic or elastomeric material and a metallic ring (3) preferably of spring steel. The ring (3) is molded into the sleeve body (2). Part of its surface constitutes a shoulder for engagement by a cam of a coupling lock. The sleeve (1) is cheaper to manufacture and more durable than metallic sleeves.

Abstract: A locking screw having a head at one end, a special entry portion at the other end, and a trilobular shank portion extending from the entry portion toward the head. The screw is further characterized in that the thread profile is of a double angle configuration symmetrical about an axis perpendicular to the longitudinal axis of the screw. The entry section is tapered and is formed with a series of truncations which serve to clear progressively a contaminating coating in an internally threaded workpiece, such as a nut, when the screw is threaded therein.

Abstract: A threaded fastener has a pin with a head, a cylindrical shank, a shoulder with reducing diameter, a radius at the least diameter of the shoulder whose region is work-hardened, and a threaded end, in that order. The thread extends into near-adjacency to the shoulder, and has no more than approximately one-half of a convolution of an incomplete thread at its end adjacent to the shoulder. A collar is threadable onto the thread. It has a counterbore no longer than the anticipated grip range plus approximately one-half of a thread pitch. The collar may be inherently torque-limited. The term "thread" also includes a peripheral groove.

Abstract: For the connection of two tubes (1, 2), one coupling piece (3, 4), consisting of an external thread (7) adhered, vulcanized or fused onto the end of the tube and a pipe coupling (8) screwed onto this by means of a slide adhesive is each connected with the tube ends. By means of the one coupling piece (4), a coupling lock (5) is slid from behind, which, by means of a flange (12), abuts on a shoulder unit (11). On the free end, the coupling lock (5) supports two swivelable levers (15) with eccentric cams (16), which abut on the shoulder unit (10) of the other coupling piece (3) and press this axially against the first coupling piece (4). By means of this construction, a non-tapered cross-sectional area is achieved in the tube coupling.

Abstract: The joining element comprising a fastener or screw shank having a head has adjacent to said head a portion with a plurality of parallel, concentric fit-stretch rings, whose external diameter is 0.1 to 0.5 mm larger than the external diameter of the fastening thread. A fit slot is formed between in each case two rings, with a notch groove radius which is two to three times the top radius of the fastening thread. In the transition region between the head and the aforementioned portion is provided a fillet with a rounded portion having a diameter corresponding roughly to the pitch diameter of the rings and with a radius of curvature amounting to approximately to 0.1 to 0.15 times the external diameter. The rings have a stressing cross-section in the notch groove corresponding to the stressing cross-section of the fastening thread. The top width of the rings approximately corresponds to the side width of the preliminary shape of the rings.

Abstract: A threaded fastener is made of a composite material made of layers extending parallel to the fastener axis and having elongated filament fibers. A portion of the fibers extend parallel to the axis of the fastener to provide tensile and shear strength to the fastener, and a portion of the fibers extend parallel to the load-bearing thread faces to enhance tensile strength to the threads.

Abstract: A sturdy threaded insert for screws having a trapezoidal thread. To keep the external diameter of this threaded insert small (due to the limited space often available), and to ensure that the female thread produces a perfect seal (if the threaded insert is closed in construction), the threaded insert is constructed as follows: The basic shape of the threaded insert represents a circumscribed quadrilateral, which is a rhombus if the trapezoidal thread is symmetrical and is a parallelogram if the trapezoidal thread is asymmetrical. The superimposed quadrilateral profiles are connected to one another by a web having a minimum wall thickness of about 30% of the useful profile depth of the screw thread, and in any case is at least 0.3 mm. In addition, the threaded flank projections of the annular surfaces are equal on the workpiece side and on the screw side.

Abstract: An anchor and stress plate assembly adapted to secure an insulation layer to the deck of a roof without penetrating the lower surface of the deck which is formed either of relatively soft or hard decking material. The anchor is provided with a flanged head and a shank whose leading section takes the form of an auger screw having a root which tapers toward the tip and a threading about the root whose crests are of approximately uniform diameter. When the anchor is turned into soft decking material, the tapered root of the auger screw then acts to pack this material into a dense mass in the region surrounding the screw to enhance the holding power of the anchor. In hard decking material, a hole must first be drilled therein to receive the auger screw whose root when the anchor is turned in fits within the hole and whose crests then cut a thread in the hole wall to securely retain the anchor.

Abstract: A fastening system including a two piece swage type fastener including a pin and a collar adapted to be swaged into lock grooves in the pin and in which the lock grooves are helical and with the collar having a limited female thread which is threadably engageable with the helical lock grooves for variably clamping work pieces to be secured prior to swage, with the collar thread being deformable in response to a relative axial load between the pin and collar at the initiation of the swage operation but prior to swaging and in which the lock grooves are shallow and have a ratio of (h/Du).times.10.sup.2 of four (4) or less and in which the lock grooves have a simulated streamlined root contour, with the collar having a wall thickness defining a volume of material sufficient to provide overpacking of the shallow grooves of around 16%, and with the pin and collar materials having ultimate shear strengths in a ratio of around 1.8:1 to 2.

Abstract: A plastic straddling or expansion plug having a closed plug neck and a closed plug foot both with a longitudinal aperture into which a screw can cut a thread. The plug includes a shank having a thin plug jacket on which a two-flight helix is integrally formed. In the region between the helices, the plug jacket is provided with longitudinal slits. On the outside of the helix, further ribs are provided which each extend over a 180.degree. arc and are integrally formed with the helix, alternating in orientation by a 90.degree. angle. The plug neck includes flange lugs oriented in the shape of a cross and adapted to be folded over.

Abstract: The present invention relates to an improved threaded element forming for example a screw, which comprises a thread (F) whose bottom (3) comprises two arcs of a circle (4) with equal radii (r.sub.1) which are connected tangentially with the sides (2) of thread (F) and one central arc of a circle (5) with a larger radius (r.sub.2), and which is connected tangentially with the two arcs of a circle (4).

Abstract: A threaded coupling for a high frequency percussion drill assembly comprises a rod and a sleeve having external and internal threads, respectively. The threads are of the asymmetrical type and make contact along opposing shoulder portions disposed on only one side of each crown portion. The threads have a maximum diameter from 30 to 40 mm, a pitch of 7 to 11 mm, and a height from 1.2 to 1.6 mm. The parts of the root and crown portions located immediate adjacent the contacting shoulder portions have radii from 3 to 5 mm.

Abstract: A fastening assembly for use in attaching articles to soft materials such as gypsum based and light weight concrete roofing. The assembly includes an anchoring element which has a high thread and an axial bore in one end. The thread has an included angle of less than 45.degree. and terminates in a sharp edge at the free end of the anchoring element. A headed screw is driven into the bore and becomes fixed to the anchoring element. A flange is integrally molded and frangibly connected to the bored end of the anchoring element, and becomes a washer upon breaking away therefrom.

Abstract: An artificial acetabulum is described comprising a metal cup having on its outer surface means for locking the cup in a pelvic cavity, a hollow locating peg projecting from the base of the cup and integral therewith, and a liner within the cup and having a projection which fits within the hollow peg.

Abstract: A screw-type fastening device including a male threaded element such as a bolt and a female threaded element such as a nut in which each element contains continuous helical root and crest disposed therein wherein the root and crest include cone-shaped crests and cone-shaped roots at an angle of about 45.degree. to 90.degree., respectively, external and internal chevron-shaped slots at angles of about 135.degree. to 225.degree., respectively, and three pairs of parallel load flanks, respectively, for easily releasing the threaded elements without abrasion and protecting them from self-loosening from each other.

Abstract: An aerospace fastener comprises a bolt with a roll formed thread, and a nut with a similar thread having a uniform pitch P. The bolt has a cylindrical shank, a threaded tip and a run-out zone between the shank and tip. In the run-out, which is no longer than 2P, and in preferred embodiments is in the range of from 1.6P to 1.9P, the root of the roll formed bolt thread increases diameter continuously from the minor diameter of the tip thread to the diameter of the shank. The nut has a conical run-in truncating the crest of the nut thread parallel to the run-out to clear the root of the bolt thread when the nut is assembled on the bolt in the minimum grip condition. This permits the nut to be assembled on the bolt further than in a conventional combination, and shortening of the nut and bolt to save weight. Preferably the crest of the bolt thread is at the major diameter of the tip thread at distances beyond 0.75P from the maximum grip plane of the bolt.

Abstract: The screw is provided with a three-lobed thread crest, followed by a threaded portion with a three-lobed thread geometry, which passes into a threaded portion with a circular thread geometry. In all three threaded portions the flank angle of the thread is 60.degree. and the flank angle of the thread crests extending beyond the nominal diameter of the screw is 30.degree..

Abstract: A screw-type fastening device including a male threaded element such as a bolt and a female threaded element such as a nut in which each element contains a continuous helical root and crest disposed therein wherein the root and crest include V-shaped crests and V-shaped roots at an angle of 45.degree., respectively, external and internal chevron-shaped slots at angles of 90.degree., respectively, and three pairs of parallel load flanks, respectively, for easily releasing the threaded elements without abrasion and protecting them from self-lossensing from each other.