Expansion bolt and pivot and swivel mechanism therefor

Abstract

An expansion bolt and pivot and swivel mechanism therefor. The expansion bolt may have a base and a plurality of radially spreadable elongate elastic members cantileveredly projecting from the base at respective points of joinder to the base and terminating in respective spoons at respective points of joinder of the spoons, wherein the elongate elastic members have respective radially defined thicknesses at the points of joinder to the base that are substantially less than the corresponding thicknesses of the base, and respective radially defined thicknesses at the points of joinder of the spoons that are substantially less than the corresponding thicknesses of the spoons. The pivot and swivel mechanism may have a ring element that includes two spaced apart leg members having foot portions that turn to extend toward each other, the foot portions having respective, spaced-apart relatively enlarged ends; a swivel housing element having an open end for receiving and at least partially containing the ends of the foot portions so that the ring element can be substantially freely rotated about a pivot axis; and a capping element adapted for interlocking with the open end of the swivel housing element, the capping element having a bottom surface portion of radial symmetry about a swivel axis that is distinct from the pivot axis.

Claims

1. A pivot and swiveling mechanism, comprising: a ring element defining a closed or closeable attachment aperture, the ring element including two spaced apart leg members, the leg members including foot portions that turn to extend toward each other, the foot portions having respective, spaced-apart relatively enlarged ends; a swivel housing element having a first open end for receiving and at least partially containing the ends of the foot portions within the swivel housing element so that the ring element can be substantially freely rotated about a pivot axis; and a capping element adapted for interlocking with the first open end of the swivel housing element, the capping element having a bottom surface portion of radial symmetry about a swivel axis that is distinct from the pivot axis, wherein the swivel housing element including a first mating structure and the capping element includes a second mating structure complementary to the first mating structure, wherein the first mating structure and the second mating structure are structured to interlock the capping element with the first open end of the swivel housing element to resist pulling the capping element apart from the swivel housing along a longitudinal axis of the swivel housing element, wherein the swivel housing element has a second open end opposite the first open end, wherein the capping element has a hole therethrough, and further comprising a shaft extending through the hole in the capping element and the first and second open ends of the swivel housing element.

2. The pivot and swivel mechanism of claim 1, wherein the shaft is threaded proximate the second open end of the swivel housing element, the mechanism further comprising a nut threaded onto the threads of the shaft.

3. The pivot and swivel mechanism of claim 1, wherein the shaft has a ledge for receiving the capping element over the bottom surface portion thereof.

4. The pivot and swivel mechanism of claim 3, further comprising an annular element concentrically disposed around the shaft and supporting the capping element.

5. The pivot and swivel mechanism of claim 4, wherein the annular element is a flat washer.

6. The pivot and swivel mechanism of claim 5, wherein the flat washer comprises Teflon.

7. A pivot and swiveling mechanism, comprising: a ring element defining a closed or closeable attachment aperture, the ring element including two spaced apart leg members, the leg members including foot portions that turn to extend toward each other, the foot portions having respective, spaced-apart relatively enlarged ends; a swivel housing element having a first open end for receiving and at least partially containing the ends of the foot portions within the swivel housing element so that the ring element can be substantially freely rotated about a pivot axis; and a capping element adapted for interlocking with the first open end of the swivel housing element, the capping element having a bottom surface portion of radial symmetry about a swivel axis that is distinct from the pivot axis, wherein the swivel housing element including a first mating structure and the capping element includes a second mating structure complementary to the first mating structure, wherein the first mating structure and the second mating structure are structured to interlock the capping element with the first open end of the swivel housing element to resist pulling the capping element apart from the swivel housing along a longitudinal axis of the swivel housing element, wherein the first mating structure and the second mating structure form an interface that becomes progressively narrower in a radial dimension of the swivel housing element with increasing elevation in a direction in which the swivel housing element would be extracted from the capping element.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a pictorial elevation view of an exemplary prior art expansion bolt.

(2) FIG. 2 is a cross-section of a portion of the expansion bolt of FIG. 1, shown installed in a hole.

(3) FIG. 3 is a sectional elevation view of a typical prior art concrete sleeve anchor.

(4) FIG. 4 is an isometric view of a preferred expansion bolt according to the present invention.

(5) FIG. 5 is an exploded isometric view of the expansion bolt of FIG. 4.

(6) FIG. 6 is an exploded isometric view of a first alternative expansion bolt according to the invention.

(7) FIG. 7 is an isometric view of a worker connected to the expansion bolt of FIG. 4 and is thereby tethered to a structure according to the present invention.

(8) FIG. 8 is a side elevation of the expansion bolt of FIG. 4 in a state of manipulation by which the expansion bolt is configured for insertion into a hole.

(9) FIG. 9 is a cross-section of the expansion bolt of FIGS. 4 and 8 being inserted into a hole.

(10) FIG. 10 is the same as FIG. 9 but with the expansion bolt in an anchoring configuration, seated in the hole.

(11) FIG. 10A is a detail view of a region of the expansion bolt of FIG. 10, showing bending of a leaf portion thereof.

(12) FIG. 11 is a broken side view of the expansion bolt as shown in FIG. 8 in the anchoring configuration shown in FIG. 10.

(13) FIG. 12 is a cross-section of the expansion bolt as shown in FIG. 11 taken a long a line 12-12 thereof.

(14) FIG. 13 is a cross-section of the expansion bolt as shown in FIG. 11 taken a long a line 13-13 thereof.

(15) FIG. 14 is an exploded isometric view of a second alternative expansion bolt according to the invention.

(16) FIG. 15 is an exploded isometric view of a portion of a pivot and swivel mechanism according to the present invention.

(17) FIG. 16 is a front broken cross-section of the pivot and swivel mechanism of FIG. 15 as provided in the expansion bolt of FIG. 5, taken along a line 16-16 thereof.

(18) FIG. 17 is a side broken cross-section of the pivot and swivel mechanism of FIG. 15 as provided in the expansion bolt of FIG. 5, taken along a line 17-17 thereof.

(19) FIG. 18 is an isometric cross-section of the expansion bolt of FIGS. 4 and 5.

(20) FIG. 19 is a broken isometric cross-section of the expansion bolt of FIG. 5, viewed from a different direction than that of FIG. 18.

(21) FIG. 20 is an isometric view of a third alternative expansion bolt according to the present invention.

(22) FIG. 21 is a cross-sectional side elevation of the expansion bolt of FIG. 20 installed in a hole.

DESCRIPTION OF PREFERRED EMBODIMENTS

(23) Embodiments of the present invention may be used to provide for the advantages of a prior art expansion bolt such as that disclosed in the '363 patent described above in a simplified and therefore cost-reduced configuration, and that does not require a tool for removal. In addition or in the alternative, embodiments of the present invention may be used to provide for the advantages of the more simply constructed prior art concrete anchor in a reusable configuration. Thus, embodiments of the present invention may be used either as expansion bolts or concrete anchors, and they may have other uses as well. Such uses may include, but are not limited to, supporting workers who are performing maintenance or construction work, and providing fall protection to such workers.

(24) FIGS. 4 and 5 show a preferred expansion bolt 100 according to the invention that provides for all the aforementioned advantages over the prior art.

(25) With particular reference to FIG. 5, the expansion bolt 100 includes a central shaft 112 terminating, at a proximal end “PE” of the central shaft, in a pivot and swivel mechanism 150, and at a distal end, a wedge element 126. The proximal end PE of the central shaft ultimately terminates in a capturing tip CT.sub.1 which is not shown in FIG. 5 but is discussed in connection with FIG. 17.

(26) The central shaft 112 is coaxially received through a central hole 114a in a cap 114, through a housing 116. The central hole 114a is large enough to loosely or slidable receive a shank 112b of the central shaft 112, but not so large as to allow passage of the wedge element 126.

(27) The housing 116 houses a spring 120 which biases the housing 116 relative to the central shaft 112 during use of the device as will be explained further below. The housing 116 is captured between the cap 114 and the wedge element 126. The housing 116 has a base portion 116a and, as referenced in FIG. 4, a plurality of leaves “LV” (LVa, LVb are shown) depending from the base portion. The leaves are separated by first slots “SL.sub.1,” (two of these first slots SL.sub.1a, SL.sub.1b are shown). The leaves project as cantilevers from the base portion at respective points of joinder “PJ.sub.LV-B” (also referenced in FIG. 9) of the leaves to the base portion, and the first slots are defined by and between the leaves. In the preferred embodiment there: are 3 leaves and 3 of the first slots SL.sub.1 symmetrically radially disposed about a longitudinal axis “L.sub.1” (referenced in FIG. 8) of the expansion bolt 100, i.e., a 3-fold symmetry in this particular embodiment. But the number and spacing of the leaves can be varied, and radial symmetry is not essential either.

(28) The leaves are also preferably perforated, such as with second slots “SL.sub.2” that, along with the first slots SL.sub.1, provide migration paths for dust particles when the expansion bolt is installed in a hole.

(29) The leaves LV distally terminate in respective “spoons” “SP,” which are connected to the leaves at respective points of joinder “PJ.sub.LV-SP” (also referenced in FIG. 9) of the spoons to the leaves. The aforementioned second slots SL.sub.2 may also be used to assist to provide bending flexibility to the leaves, which is also preferably otherwise provided by making them thinner than the spoons as discussed further below.

(30) FIG. 6 shows a first alternative expansion bolt 200, which is the same as the expansion bolt 100 except the housing 116 is replaced with a housing 216 that replaces the leaves LV of the embodiment 100 with an equivalent number of discrete elongate elastic members 225. The discrete elongate elastic members 225 may be, without implying any material or shape limitation, rods, wires, or cables, any of which may be woven or non-woven. As for the embodiment 100, in the preferred embodiment 200 there are three of the discrete members 225, one for each of the three spoons SP. The spoons SP may be the same in the embodiment 200 as in the embodiment 100 but are preferably modified at the points of joinder connections with the elongate members 225 as shown.

(31) For purposes herein, the term “elongate elastic member” is intended to be generic for both the leaves LV of the embodiment 100 and the members 225 of the embodiment 200. The term “elastic” is intended herein to have its ordinary engineering meaning.

(32) Returning to FIG. 5, expansion bolts according to the invention preferably include a tethering ring, here referenced as 140, for connecting, to the expansion bolt, an additional article of hardware such as a carabiner, through a retaining aperture “A” defined by the tethering ring, such as shown in FIG. 7. The tethering ring may be provided in a standard form known in the fall-protection art as a “D-ring” but this is not essential. As shown, the aperture A would be circular over 360 degrees of arc; whereas in a D-ring, the aperture A would be circular over more than 180 degrees of arc, but less than 270 degrees of arc. Preferably, the radius of the circle defined by the aperture A is between 1.5 and 3.0 inches, more preferably between 2.0 and 2.5 inches, more preferably still between 2.20-2.30 inches, and most preferably 2.25 inches.

(33) For connection security, the retaining aperture A should be “closed” or “closeable.” For purposes herein, an aperture is “closeable” when it can be placed in a closed configuration, and an aperture is in a closed configuration for purposes herein when it is contiguously surrounded (360 degrees) by structure, so that a ring (which by this same definition also has a closed aperture) encircling any portion of the structure and passing through the aperture could not be removed from the aperture without changing the configuration of the device. As shown in preferred embodiments, the retaining aperture A is permanently closed; whereas the corresponding apertures defined by the carabiners 42 and 46 shown in FIG. 7 are closeable, and are shown in closed configurations.

(34) FIG. 8 shows an example of how the expansion bolt 100 may be manipulated to place it in a minimum diameter configuration, measured radially of the longitudinal axis L.sub.1, so that it can be inserted into a hole with the assistance of the cap 114.

(35) Such a hole 9a in a structure 9 is shown in FIGS. 9 and 10, in which the embodiment 100 is shown. For reference in both FIGS. 9 and 10, the longitudinal axis L.sub.1 of the expansion bolt 100 shown in FIG. 8 is coincident with a longitudinal axis “L.sub.2” of the hole 9a.

(36) The hole 9a may be adapted in advance for receiving the expansion bolt; or the expansion bolt nay be adapted in advance for use in an existing hole. Typically, the hole 9a is a drilled hole and is therefore substantially cylindrical. But the hole 9a could be a cast or existing hole, and the hole 9a need not be cylindrical; the expansion bolt could easily be adapted for use in a square (using four leaves) or triangular shaped hole, for example. In all cases, however, the hole will have a longitudinal axis L.sub.2 which, in the case of a cylindrical hole, is the cylindrical axis of the hole. The longitudinal axis L.sub.2 of the hole aligns substantially with the longitudinal axis L.sub.1 of the expansion bolt as the expansion bolt 10 is inserted into the hole.

(37) Returning to FIG. 8, the cap 114 has a flange portion 114b with an undersurface “US,” and a reduced diameter body portion 114c, which is reduced in diameter relative to the flange portion, the diameters measured radial to the longitudinal axis L.sub.1.

(38) In the example, a user's thumb may be positioned to press down on the top of the pivot and swivel mechanism 150, and the user's index and middle fingers placed on an under-surface “US” of the flange portion 114b for pulling on the flange portion, against a spring bias provided by the spring 120.

(39) FIG. 9 shows the expansion bolt 100 partially inserted into the hole 9a. The expansion bolt is held as shown in FIG. 8, and the spring 120 is compressed as a consequence of being captured between a ledge “LG.sub.116” of the housing 116 and a bottom or distal portion of the pivot and swivel mechanism 150. The expansion bolt is thus caused to adopt a contracted, minimal diameter configuration, measured radially from the longitudinal axis L.sub.1, so that the expansion bolt can be inserted into the hole 9a with the assistance of the cap 114.

(40) FIG. 10 shows the expansion bolt after it has been seated in the hole and the user has let go of it. The spring 120 is allowed to extend and thereby force the central shaft 112 upwardly relative to the housing 116, drawing the wedge member 126 into a cavity “CVT” defined interiorly between the spoons SP of the housing, thereby radially spreading the spoons so as to produce a larger diameter, expanded configuration of the expansion bolt, which by forcing the spoons against the interior surface of the hole to anchor the expansion bolt in the hole defines an “anchoring configuration” of the expansion bolt in which the expansion bolt is both seated in the hole and expanded.

(41) The spring 120 may be a coiled compression spring such as shown in, e.g., FIGS. 5 and 6, but other spring configurations could be used to achieve the same results.

(42) FIG. 10 also shows that in the anchoring configuration of the expansion bolt, the leaves LV are caused to bend into a slight “S” configuration by their reaction to the hole, in the region indicated at “S.sub.LV” (see FIG. 10A) as a consequence of the spoons SP moving radially outwardly in response to receiving the wedge member 126, closing the slight gap between the spoons and the surface of the hole 9a that can be seen in FIG. 9, and as a consequence of the fact that the outer surfaces of the spoons, “OS.sub.SP” as referenced in FIG. 9, are substantially parallel to the surface of the hole, before being expanded against the surface of the hole as shown in FIG. 10.

(43) The wedge element 126 is typically frustoconical, as defined by its outer surface 126a. In that case, as suggested by comparison of FIGS. 12 and 13, the inside surfaces “IS.sub.SP” of the spoons SP are preferably cylindrical (not tapered), with radial curvature that matches that of the wedge element 126 where the wedge element is widest, nearest the distal end “DE” of the central shaft 112 (see FIG. 5), and which is therefore less than that of the wedge element where the wedge element is narrowest, farthest from the end DE. This provides for maximum surface contact between the spoons and the wedge element when the expansion bolt is anchored in the hole.

(44) As can be seen in FIGS. 9 and 10, the cylindrical inner surfaces IS.sub.SP identified in FIGS. 12 and 13 are angled a small amount from the longitudinal axis L.sub.1, such as by about 3-5 degrees.

(45) Staying with FIG. 5, the wedge element 126 need not be frustoconical. For example, it could be configured as a three-sided pyramid (or as another example, a two-sided wedge), for engaging three (or, in the case of a two-sided wedge, two) spoons having planar inner surfaces IS.sub.SP. The wedge element 126 may be integrally formed with the central shaft 112, although this is not essential.

(46) The tethering ring 140 is preferably connected to the central shaft 112 so as to allow the tethering ring to pivot about a pivot axis “PA” that is perpendicular to the longitudinal axis L.sub.1 of the expansion bolt. Preferably, the tethering ring is enabled to substantially freely pivot about the pivot axis PA through a pivot angle of at least 90 degrees, more preferably at least 170 degrees, and most preferably at least 180 degrees.

(47) It is also desirable to provide for swiveling the tethering ring 140 about the longitudinal axis L.sub.1. Providing for both pivoting and swivelling of the tethering ring is important for minimizing the effects of cross-loading conditions as noted previously.

(48) One way to provide a swivelling feature in expansion bolts according to the invention is to employ a frustoconically shaped wedge member 126 that is a separate part from the central shaft 112, such as in the embodiment 300 shown in FIG. 14. In the embodiment 300, the capability to pivot the ring 140 about the pivot axis PA is provided by a connecting ring 112a at the proximal end “PE” of the central shaft 112, and a pivot shaft 112d extending through the connecting ring and through corresponding holes at terminating ends 140a of the tethering ring 140. The ends of the pivot shaft may be swaged to capture the ends 140a of the tethering ring. Of course, there are many other ways to provide for pivotally connecting the tethering to the central shaft 112, as will be readily appreciated by persons of ordinary mechanical skill.

(49) To provide for swivelling the tethering ring in the embodiment 300, the wedge element 126 has a central hole 126b for loosely receiving the distal end DE of the central shaft 112 so that the wedge element can spin or swivel about the central shaft (axis L.sub.1). For this purpose, the distal end DE of the central shaft may have a reduced-diameter portion 112c, which is reduced in diameter relative to the diameter of the shank 112b, the diameters measured radially, perpendicular to the longitudinal axis L.sub.1.

(50) With the wedge element 126 in place, a capturing tip “CT.sub.2” may be provided or formed at the distal end DE of the central shaft 112, such as by swaging the end of the central shaft, in cases where the central shaft is formed of metal, or by an equivalent process in cases where the central shaft is formed of plastic, to produce in the capturing tip an outer diameter “D.sub.CT” that is larger than the diameter of the central shaft, for capturing and retaining the wedge element at the distal end of the central shaft. Of course, there are many other ways the wedge element 126 could be captured to the central shaft 112, as will be readily appreciated by persons of ordinary mechanical skill.

(51) Another way to provide for swiveling the tethering ring 140 about the longitudinal axis L.sub.1 is to incorporate a swivel mechanism on the central shaft 112. Any known swivel mechanism could be used, but a preferred and novel mechanism 150 is shown employed in the embodiment 100 of FIGS. 4 and 5 that provides for both pivoting and swivelling. Details of this pivot and swivel mechanism 150 are shown in FIGS. 15-19.

(52) With particular reference to FIG. 15, the pivot and swivel mechanism 150 includes the aforedescribed ring 140 (see, e.g., the discussion of FIGS. 4 and 5), a “swivel housing” 156, and a “cap” 158. The parts are shown exploded along a longitudinal axis “L.sub.3” of the pivot and swivel mechanism, which is congruent with the axis “L.sub.1” of the expansion bolt 100 when the pivot and swivel mechanism 150 is employed therein.

(53) The ring 140 has a closed retaining aperture “RA,” but it could be merely closeable. The ring 140 also has two leg portions “140L,” namely “140L.sub.1” and “140L.sub.2;” the leg portions 140L each have corresponding inwardly turned foot portions “140F,” namely “140F.sub.1” and “140F.sub.2;” and the foot portions each have enlarged, flanged ends “140FE,” namely, “140FE.sub.1” and “140FE.sub.2.” The foot portions and flanged ends are cylindrical to allow for pivoting the ring 140 about a pivot axis “PA,” and the leg portions define a clearance aperture “CA” therebetween in the ring 140 so that when the ring is pivoted about the pivot axis it can clear the swivel housing 156.

(54) The swivel housing 156 has two leg openings “LO” (only one is visible in FIG. 15) for receiving the leg portions 140L of the ring 140. The width “W” of each leg opening LO is sufficient for receiving the corresponding leg portion 140L, but smaller than the diameter of the flanged ends 140 FE to provide for partial capture of the flanged ends within the swivel housing 156. Capture of these ends inside the swivel housing is completed by fitting the cap 158 to a base “B.sub.156” of the swivel housing, to result in the configuration shown in FIG. 4.

(55) As best seen in FIG. 16, with the cap 158 fitted to the swivel housing 156, and with the flanged ends 140F of the ring 140 captured therebetween, there remains space for the central shaft 112 about which (axis L.sub.2) the ring 140 can swivel. The central shaft 112 may have a ledge “LG.sub.112” on which the cap 158 may be seated (see also FIG. 5).

(56) FIG. 18 shows the pivot and swivel mechanism 150 as employed in the expansion bolt 100, sectioned for clarity. This view shows the swivel housing 156 capped with the cap 158 as it appears in FIG. 15. With reference to the latter, the cap 158 has a proximally extending, annular cup portion “C.sub.158” for interfacing with the base B.sub.156 of the swivel housing.

(57) It is an outstanding feature of this interface that the swivel housing 156 “interlocks” into the cup portion of the cap 158, and consequently resists prying the swivel housing 156 apart from the cap 158, such as where the ring 140 is loaded downwardly, perpendicular to the axis L.sub.2.

(58) As best seen in FIG. 17, this interlocking feature may be provided by an interface between the base B.sub.156 of the swivel housing and the cup portion C.sub.158 of the cap that becomes progressively narrower in the radial dimension (see the angle θ) with increasing elevation in the direction in which the swivel housing would be extracted from the cap. This interlocking feature is generally defined for purposes herein as being complementary mating structures on the base and cap that provide resistance to pulling these two elements apart along the longitudinal axis L.sub.3 (FIG. 16). As will be readily appreciated by persons of ordinary mechanical skill, there are many other ways these two elements could be interlocked together, such as by providing complementary screw threads on the two elements, or by providing complementary “snap” fitting features on the two elements such as corresponding ribs and rib-receiving voids.

(59) Returning to FIG. 18, the swivel housing 156 may be enabled to resist being pulled out of the cap 158 in response to a force or component of force that is applied to the ring 140 axially, i.e., parallel to the axis L.sub.2, by a nut 160 that is threaded onto the distal end of the central shaft 112. With additional reference to FIG. 17, the nut 160 may be further captured by the capturing tip CT.sub.1 that was mentioned briefly above in connection with its omission from FIG. 5, that may be formed in the same manner as the capturing tip “CT.sub.2” described previously for capturing the wedge element 126 to the central shaft 112 in the embodiment 200 of the expansion bolt. Of course, there are many other ways the central shaft 112 could be adapted to resist thrust loads applied to the swivel housing, as will be readily appreciated by persons of ordinary mechanical skill.

(60) With reference to FIG. 16, the cap 158 can be made radially symmetric about the axis L.sub.3 where it contacts the ledge LG.sub.112 to provide the desired swiveling capability; no additional structure is necessary. However, with additional reference to FIG. 19, it may facilitate this swiveling capability to provide a “Teflon” washer 165, which may be but which need not necessarily be a flat washer, to provide a larger surface BS.sub.158 to ride on, which may be but need not necessarily be supported by the spring 120. This washer may also be used to keep the end of the spring 120 off the ledge LG.sub.112.

(61) As noted previously in connection with FIGS. 8-10, the expansion bolt 100 may be manipulated to place it in a minimum diameter configuration so that it can be inserted into a hole 9a in a structure 9 with the assistance of the cap 114. This will be explained further in the discussion to follow, with the understanding that this discussion applies equally as well to the embodiments 200 and 300.

(62) As indicated in FIG. 5, the cap 114 has a floor “FL;” and as indicated in FIG. 10, this floor has a top surface “TS.sub.114” and a bottom surface “BS.sub.114.” In the embodiment shown, both of these surfaces are annular, but that is not essential.

(63) Normally, the outer face 9b of the concrete structure in proximity to the hole is flat; so it is normally preferable to provide that the bottom surface BS.sub.114 of the cap 114 is flat, for seating on this typically flat outer surface of the structure. But in any case, at least some portions of the bottom surface of the cap should extend radially outwardly of the longitudinal axis L.sub.3 far enough, relative to the size of the hole 9a, to rest on the outer face 9b of the structure 9, as shown in FIG. 16.

(64) Also as best seen in FIG. 5, the base portion 116a of the housing 116 has a flange “FL.sub.116” at a proximal end thereof. With particular reference to FIG. 10, the flange. FL.sub.116 has a bottom surface “BS.sub.FL-116.sup.” that is adapted to rest on the top surface TS.sub.114 of the cap 114, as shown in both FIGS. 9 and 10. Contact between these surfaces is maintained by compression of the spring 120.

(65) In contrast to the prior art concrete anchor, the elongate elastic members of the housing 116 are adapted or configured to bend elastically in repeated normal use, so that the expansion bolt can be removed from the hole and reused if it has not been involved in arresting a fall; and the ends: of the leaves are adapted or configured to so that they will not crush if there is a fall.

(66) As best seen in FIG. 9, these features may be facilitated by use of a configuration of the leaves according to which the leaves LV have a radial thickness “t.sub.1” that is thinner than the minimum radial thickness “t.sub.2” of the spoons SP. A relatively small thickness t.sub.1 provides for greater bending elasticity, and a relatively large thickness t.sub.2 provides for greater crush resistance. Normally the t.sub.2 dimension is the same regardless of the t.sub.1 dimension. Providing for both the desired bending elasticity and crush resistance using leaves of constant thickness is possible, but there are undesirable consequences such as a need to substantially increase the overall length of the leaves LV (distance “OL” in FIG. 8).

(67) Preferably, where such differential in thickness is provided, t.sub.1 is no more than 90% of t.sub.2, and more preferably t.sub.1 is no more than 70% of t.sub.2. Generally, increasing the dimension t.sub.2 provides for greater crush resistance while decreasing the dimension t.sub.1 provides for greater bending elasticity. Both greater crush resistance and greater bending elasticity reduce the possibility of permanent deformation and thus increase the effectiveness of the expansion bolt for reuse.

(68) The same result could be provided in ways other than by use of different material thicknesses of the leg portions and the ends of the leaves. For example, the same or similar result could be provided by joining different materials; however, the use of leaves configured as shown with differential thicknesses allows for forming the leaves integrally or monolithically with the body, in a single piece of material, which provides manufacturing cost advantages over prior art expansion bolts.

(69) Preferably, the spoons SP have sufficient crush resistance to provide that the expansion bolt can support an axial load, i.e., a load directed along the longitudinal axis L.sub.1, of at least 450 pounds, with substantially no plastic deformation, i.e., no plastic deformation that would render, to a person of ordinary skill, reuse of the expansion bolt for supporting the same load, imprudent.

(70) It was noted previously that leaves LV with differential thicknesses can be formed integrally or monolithically with the body, in a single piece of material, which provides manufacturing cost advantages over prior art expansion bolts. The body can be formed of a metal, plastic, or composite material.

(71) Likewise, the central shaft 112 can be formed as an integral or monolithic single piece of material, such as metal, plastic, or composite material, which likewise provides manufacturing cost advantages over prior art expansion bolts, which typically employ braided cables.

(72) It is also advantageous to provide that the central shaft 112 is “rigid,” i.e., sufficient that a compression force applied to the central shaft, when it is otherwise unloaded, by pushing on the central shaft (such as by hammering on the capturing tip CT.sub.1 of the tethering ring 140) in the load-releasing direction “LRD” shown in FIG. 8, will force the wedging member 126 out of the aformentioned cavity CVT, to loosen the hold or grip the expansion bolt has on the interior of the hole into which it is installed. This provides the outstanding advantage of allowing a user to remove the expansion bolt without need for the prior art “cleaning bushing” 62 (FIG. 2) and punch, shown and described in the '363 patent.

(73) Achieving the desired rigidity in the central shaft 112 is facilitated by forming it as an integral, monolithic, or non-woven structure. Sufficient rigidity could be achieved with a central shaft 112 that is either partially or wholly in the form of a braided or woven cable, but cables by nature are less effective to resist compressive loads. So if the central shaft 112 were to be provided either partially or wholly in the form of a cable, that cable should be relatively thick, to compensate for its relative lack of resistance to buckling.

(74) FIG. 7 shows the expansion bolt 100 installed in the structure 9, and being used to tether a worker to the structure. A first carabiner 42 may be connected to the ring 140 of the cap 114 and one end of a lanyard 44. The other end of the lanyard 44 may be connected by a second carabiner 46 to a D-ring 48 which in turn connects to a harness 50 worn by the worker. Other equivalent structures as known in either the recreational climbing or the industrial fall protection arts could be used for connecting the worker to the expansion bolt 100.

(75) FIGS. 20 and 21 show another alternative expansion bolt 400 that replaces the spring 120 of the embodiment 100 with an alternative biasing member which is a cam 402. The cap 114 may be retained, or not, and the cam could be used in combination with the spring 120. The cam may be set by hand in the direction of the arrow in FIG. 21 to produce a bias equivalent to that of the spring 120, for drawing the central shaft 112 upwardly relative to the spoons SP and thereby radially spreading the spoons against the inner surface of the hole; and/or it may be set or urged to stay in place by gravity.

(76) It may be noted that the anchoring bolt in its unloaded anchoring configuration as shown in FIG. 10 is only subject to whatever anchoring force can be developed by the spring 120, but of course, the anchoring force will increase significantly if the worker falls. Although it may be possible to reuse the expansion bolt after such an event, this is not normally intended.

(77) While expansion bolts according to the invention are typically used for installation in holes in concrete structures for the purpose of tethering a worker engaged in construction work on the structure, they could be used for other attachment or connecting purposes, in holes in other types of structures or substrates, man-made or natural.

(78) It is to be understood that the pivot and swivel mechanism is not limited to use in expansion bolts generally or expansion bolts according to the present invention particularly. It may be used in any application in which a pivot and swivel mechanism or feature is desired.

(79) It is to be understood that, while a specific expansion bolt and pivot and swivel mechanism therefor has been shown and described as being preferred, variations may be made, in addition to those already mentioned, without departing from the principles of the invention.

(80) The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions to exclude equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.