US3596971A

US3596971A - Anchor insert and pickup unit assembly for a concrete slab

Info

Publication number: US3596971A
Application number: US792115*A
Authority: US
Inventors: Peter D Courtois; George J Eriksson
Original assignee: Superior Concrete Accessories Inc
Current assignee: Superior Concrete Accessories Inc
Priority date: 1969-01-17
Filing date: 1969-01-17
Publication date: 1971-08-03
Anticipated expiration: 1988-08-03

Abstract

An anchor insert adapted to be positioned on the foundation surface of a concrete slab form so that when concrete is poured into the form the insert becomes embedded therein, and a separate pickup unit including a torque stem which, when introduced through a hole in the concrete leading to the embedded insert and then twisted through an angle of 60*, becomes interlocked with the insert. A bail on the pickup unit enables the latter to be connected to an overhead hoisting mechanism.

Description

United States Patent 2] lnventors Peterll).Courtois Des Plnines; George J. Eriltsson, Morton Grove, both of, ill.

I 2 l 1 Appl. No. 792,115

[22] Filed ,lnlm. 17, 1969 {45] Patented Aug. 3. 1971 (73] Assignee Superior Concrete Accessories, Inc.

Franklin Park, ill].

[54] ANCHOR lNSERT AND lPllCKlUP UNIT ASSEMBLY FOR A CONCRETE SLAB 5 Claims, 9 Drawing Figs.

[52] US. Cl 294/89 [51] lnt.Cl..., B661: 1/00 [50] Field of Search 294/89, 67,

[56] References Cited UNITED STATES PATENTS 3,154,338 l0/1964 Leach 294/81 X 3,404,503 10/1968 Courtois et al. 294/89 X 3,431,012 3/1969 Courtois et al. l. 294/86 Primary Examiner-Evon Cl Blunk Assistant Examiner-Douglas D, Watts A!I0mey-Norman H, Gerlach ABSTRACT: An anchor insert adapted to be positioned on the foundation surface of a concrete slab form so that when concrete is poured into the form the insert becomes embedded therein, and a separate pickup unit including a torque stem which, when introduced through a hole in the concrete leading to the embedded insert and then twisted through an angle of 60, becomes interlocked with the insert. A bail on the pickup unit enables the latter to be connected to an overhead hoisting mechanism.

PATENTEUAUB alsm 3.598971 SHEET 1 UF 3 FIG. 3

||I 74 94 74 INVENTORS:

T6 76 PETER D.COURTOIS GEORGE J. ERIKSSON PATENTEBAUB 3&9?! 3,696,971

sum 2 OF 3 PETER D. COURTOIS GEORGE ERlKSSON Altomev PATENIEMus 3:971 3,596,971

sum 3 [1F 3 III II.

INVENTORS PETER D. COURTOlS GEORG J. ERIKSSON ANCHOR INSERT AND PICKUP UNIT ASSEMBLY son A concurs SLAB The present invention relates to a novel anchor insert and pickup unit assembly which is designed primarily for use in connection with the relocation of a preformed concrete wall slab by hoisting and tilting the slab from the original horizontal position in which it was formed to a final vertical position which it assumes when it constitutes one wall or a portion of a wall of a concrete building or other structure. Specifically, the invention is concerned with an anchor insert and pickup unit assembly of the general type which is shown an described in our copending U.S. Pat. No. 3,431,012, granted on Mar. 4, 1969 and entitled ANCHOR INSERT AND PICKUP UNIT FOR A CONCRETE SLAB." The present anchor insert and pickup unit assembly is an improvement on that of said application and has certain advantages thereon.

Briefly, an anchor insert and pickup unit assembly of the general type with which the present invention is concerned consists of two parts, namely, an anchor insert and a cooperating releasable pickup unit. The anchor insert is adapted to be embedded in one corner portion of a horizontally disposed wall slab during formation of the latter and serves, in combination with similar anchor inserts in the other corner portions of the slab and after hardening of the poured concrete, as a medium whereby the slab may be detachably connected to a crane orsimilar overhead hoisting mechanism to the end that the slab may be first raised while in its horizontal position and then tilted into a vertical position adjacent to a concrete floor slab in order to form a principal component of a concrete building or other structure. The cooperating pickup unit consists of a tubular, vertically elongated member within which there is slidably disposed a locking stem having a pair of hook portions at its lower end. These hook portions are receivable in parts of the associated anchor insert and, by imparting a twisting or turning movement to the stem, the hook portions are caused to move into releasable interlocking relationship with respect to a pair of downwardly facing lift shoulders on the anchor insert. After such interlocking of the hook portions with the shoulders of the anchor insert, a nut which is threadedly received on the upper end of the stem may be tightened against the upper end of the member in order to prevent release of the interlocked parts until such time as the nut is subsequently loosened. Means are provided on the member whereby the pickup unit may be attached to the associated overhead crane or other hoisting mechanism in order to raise the interlocked parts of the assembly, and consequently, the slab, during actual slab-hoisiting and tiltup operations.

The novelty of the present invention resides in the improvements which have been effected both in the anchor insert and in the cooperating releasable pickup unit as related to the anchor insert and pickup unit assembly of our aforementioned U.S. Pat. No. 3,431,012. Insofar as the present anchor insert is concerned, a very material redesigning of the reaction rod structure which holds the insert in the hardened concrete has been effected, this redesigning resulting in the provision of a single lift shoulder on a single reaction rod in place of the two lift shoulders that were formerly provided by way of two reaction rods. Insofar as the present pickup unit is concerned, the redesigning thereof has resulted in the provision of two hook portions which have oppositely facing spaced apart hooks proper which may be caused to straddle the central portion of the single reaction rod and its associated lift shoulder when the locking stem of the unit is initially lowered into the confines of the anchor insert. After such insertion of the locking stem into the anchor insert, turning or rotation of the locking stem through an angle of 60 will serve to bring both hooks into underlying register with the single lift shoulder of the anchor insert whereupon, when lifting force is applied to the stem, the anchor insert, together with the corner of the concrete slab within which it is embedded, will be raised.

The advantages of the improved anchor insert and pickup unit assembly are manifold, one advantage being that over turning of the locking stem is positively prevented, either when locking the stem to the anchor insert or when releasing the same from the insert. Another advantage resides in the shortened twist movement that is necessary to lock or unlock the parts. An additional advantage resides in the use of less reaction rod stock with a consequent lightening of the anchor insert for any given rated lift capacity. Certain self-aligning and other advantageous features of our former design of anchor insert and pickup unit assembly have been carried forward into the present invention and these will be pointed out in detail presently.

The provision of an anchor insert and pickup unit assembly such as has been briefly outlined above and possessing the stated advantages, constitutes the principal object of the present invention. Numerous other objects and advantages of the invention, not at this time enumerated, will become readily apparent as the nature of the invention is better understood from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly pointed out by way of the claims at the conclusion hereof.

In the accompanying three sheets of drawings forming a part of this specification, one illustrative embodiment of the invention is shown.

In these drawings:

FIG. l is a top perspective view of the anchor insert component or part of the improved anchor insert and pickup unit assembly constituting the present invention;

FIG. 2 is a bottom perspective view of the counterpart pickup unit which is designed for cooperation with the anchor insert of FIG. 11;

FIG. 3 is a side elevational view on an enlarged scale and partly in section showing specifically and in detail the torque stem and hook assembly which forms a constituent part of the pickup unit of FIG. 2;

FIG. 4 is a side elevational view of the assembled anchor insert and pickup unit, showing the anchor insert embedded in a concrete slab and the pickup unit operatively applied thereto preparatory to a slab-hoisting operation;

FIG. 5 is a side elevational view, similar to FIG. 4 and partly in section, but with the tongue stem and hook assembly of the pickup unit being angularly displaced approximately 60 from the position in which it is shown in FIG. 4;

FIG. 5a is a vertical section taken on the line 5a-5a of FIG.

FIG. 6 is a fragmentary vertical sectional view similar to FIG. 5 but showing the anchor insert embedded within the associated concrete slab and prior to application thereto of the pickup unit;

FIG. 7 is a fragmentary exploded side elevational view similar to FIG. 6 but illustrating the embedded anchor insert and pickup unit in the positions which they assume immediately prior to effecting the interlock between such assembly parts; and

FIG. 8 is a perspective view of the pickup unit, illustrating the manner in which it is manipulated when operatively applied to its concrete-embedded counterpart anchor insert.

Referring now to the drawings in detail, the assembly constituting the invention consists of an anchor insert 10 and a cooperating pickup unit 12, the former being shown in detail in FIG. l and the latter being shown in detail in FIG. 2. The anchor insert 10 of the principal assembly comprises a reaction rod assembly 141 and a protective cup-shaped shield 16. The purpose of the rod assembly 14 is to provide a firm reaction or anchor support for the insert :in a mass of concrete, while the purpose of the cup-shaped shield 16 is to exclude concrete from the medial region of the rod assembly 14 during conrete-pouring operations by leaving in the concrete after the latter has become set a cylindrical access opening or void through which the pickup unit 112 may be introduced for cooperation with an exposed portion of the rod assembly for lifting purposes, all in a manner that will be described in detail presently. The anchor insert in its entirety is disposable, which is to say, it remains embedded in concrete, while the pickup unit 12 is reusable with other anchor inserts in other concrete slabs.

The reaction rod assembly 14 of the principal assembly is comprised of two identical, spaced apart, parallel foot sections and a single central lift rod 22, the latter being at right angles to the foot sections and so termed because it presents a lift shoulder beneath which a pair of hook members is associated relation with the pickup unit 12 extend during actual slabhoisting operations to the end that the rod 22 assimilates the entire weight of the concrete mass which the pickup unit 12 is designed to hoist. Each foot section 20 is in the form of an arched embedment rod having a straight horizontal medial part 23 and downtumed end parts 24 which constitute or form feet proper. Elastomeric sleeves 26 are telescopically received over the end parts 24 of the foot sections 20 in order to minimize surface defects in the bottom surface of the finished wall slab resulting from pouring of the concrete onto the form foundation surface on which the feet proper are supported. The extreme end portions 28 of the lift rod 22 cross the horizontal medial parts 23 of the 2 foot sections 20 and are welded thereto so that the entire reaction rod assembly 14, when viewed in plan from above, presents a generally l-I- shaped structure. The end portions 28 of the lift rod 22 are straight, while the medial region 30 is arched upwardly on a curved bias of long radius, the contour of the rod 22 being best ascertained from an inspection of FIGS. 1, 4 and 6 of the drawings.

The aforementioned upwardly arched medial region 30 of the lift rod 22 of the reaction rod assembly 14 serves to support thereon the aforementioned cup-shaped shield 16, this shield being formed of a suitable thermoplastic moldable plastic material which is, at least in part, molded in situ directly on the lift rod 22. The purpose of this shield is to create a void in the poured concrete in which the anchor insert 10 is embedded, the void leading from the upper surface of the slab downwardly into the central regions of the anchor insert so as to provide a path for entry of the aforementioned hook portions of the pickup unit 12 when the latter is applied to the embedded anchor insert 10. The shield 16 is provided with a dished bottom wall 32 and a cylindrical sidewall 34 through which the end regions of the arched medial region 30 of the lift rod 22 project outwardly as best illustrated in FIG. 6. Various ways of applying the cup-shaped shield 16 to the lift rod 22 may be employed and one convenient way is initially to fonn the bottom wall 32 as a separate unit at the factory and then position the same within a suitable injection mold in the approximate position which it will assume in the completed anchor insert 12, after which the molding operation may be effected so that the cylindrical sidewall 34 is formed about the lift rod 22. In this manner, the cup-shaped shield 16 emerges from the mold as a one-piece member and no voids are left in the vicinity of the points of entry of the rod 22 into the shield so that when concrete-pouring operations are resorted to, the wet concrete is excluded from entering the cup-shaped shield. It is to be noted at this point that when the four sleeve-encased end parts 24 of the foot sections 20 rest upon the aforementioned foundation surface, the bottom wall 32 of the shield 16 is disposed a slight distance above such foundation surface.

In FIG. 2, the pickup unit 12 of the principal assembly is shown in its free state, but in FIGS. 4 and 5 it is shown in cooperation with its counterpart anchor insert 10. This pickup unit 12 involves in its general organization a normally vertical, tubular member which is in the form of a machined forging or casting 40 and comprises a tubular body portion 42 from the lower rim of which there extends outwards a flat rectangular seating flange 44. Two diametrically disposed aligned trunnions 46 overhang opposed side edge portions of the seating flange 44, are formed integrally with and project outwards in opposite directions from the body portion 42, and serve pivotally to support an inverted U-shaped lifting bail 48 having parallel arms 50 which are connected together by a semicircular bight portion 52. The distal or free ends of the arms 50 of the bail 48 are provided with eyelets 54 which encompass the trunnions 46 and serve pivotally to connect the bail 48 to the body portion 42 of the member 40. The bight portion 52 of the bail is designed for cooperation with a suitable lifting hook, a

fragment of which is shown at 56 in FIGS. 4 and 5, such hook being associated with an overhead crane or other hoisting mechanism (not shown) by means of which the pickup unit may be raised after it has been operatively applied to an interlocked with the associated anchor unit 10 in the hardened concrete slab for slab-hoisting purposes in a manner that will be set forth in greater detail presently.

The member 40 of the pickup unit 12 is provided with a central vertical bore 60 and an enlarged shallow counterbore 62 at the lower end of the bore 60. In addition to the member 40, the pickup unit includes a normally vertical torque stem 64 which projects loosely through the aforementioned bore and counterbore and the lower end of which is formed with an enlarged cylindrical head 66. The latter is bifurcated in order to provide two parallel depending

hook portions

70 and 72 of identical configuration but which face in opposite directions. These hook portions are each provided with reentrant hooks proper 74 which present a pair of hook troughs 76, the axes of which are in alignment and extend at an angle of approximately 60 to the general planes of the hooks proper. The troughs 76 have curved bottoms 78 (see FIGS. 5a) in order to accommodate the curvature of the underneath side of the medial region 30 of the lift rod 22 which they underlie when the pickup unit 12 and the anchor insert 10 are operatively coupled together for slab-hoisting purposes.

In the interests of avoidance of confusion during further reference to the two

hook portions

70 and 72 as illustrated in FIGS. 4 and 5, it should be borne in mind that these two views are taken from directions which are angularly displaced 60 so that FIG. 5 is not a side elevational view of the structure that is shown in FIG. 4. FIG. 5a, however, represents a sectional view which is taken at an angle of 90 with respect to the structure of FIG. 5.

The upper and major portion of the torque stem 64 (see FIGS. 2, 3, 4 and 7) is externally threaded as at 80 for reception of a locking nut 82 of the ball nut variety. A horizontally extending torque-applying handle 84 projects through a transverse bore 86 in the extreme upper end region of the stem 64, this handle serving to capture the locking nut 82 so that it may not be removed from the stem 64. The nut 82 has a frustospherical bottom surface 88 and cooperates with a frustospherical seat 90 at the upper rim or end of the bore 60 (see FIG. 5) in the member 40.

The lower portion of the torque stem 64 is hollow, which is to say, that it is formed with a relatively deep, axially disposed socket 92 (see FIG. 3) within which there is slidably disposer; a generally cylindrical, vertically extending plunger 94. The latter is provided near its lower end with a vertical slot 96, and a drive pin 98 projects radially through the enlarged head 66 of the torque stem 64 and extends into the slot 96 so that the plunger 94 is captured in its socket 92 against removal. A vertically extending helical compression spring 100 is disposed within the upper portion of the socket 92 and yieldingly urges the plunger downwardly to the projected position in which it is shown in FIG. 3 of the drawings. The lower projecting end of the plunger 94 is designed for seating engagement on the crest portion of the medial region 30 of the lift rod 22 in order to maintain the two

hook portions

70 and 72 in latched relation with the lift rod when the pickup unit 12 and the anchor insert 10 are coupled together.

In the operation of the herein described anchor insert and pickup unit assembly, in order to form a concrete slab such as the wall slab S of FIGS. 4, 5, 6 and 7, the slab form is erected in the usual manner and, at each location within the form where an anchor point is to be effected in the finished slab, an anchor insert 10 with its plastic shield 16 is positioned on the form foundation with the four elastomeric sleeves 26 resting upon the upper surface of such foundation. An inverted, cupshaped, concretenexcluding member 110 (see Fit]. 6) which is formed of a suitable resilient plastic material is positioned on the upper region of the shield 16 of each anchor insert 110 so that it projects upwards to the level of the upper surface of the slab to be formed and this member 1 l precludes the entrance of poured concrete into the interior of the associated shield 16. The member 110 is provided with an upstanding flexible locating prong or finger 1112 on the top wall thereof and this projects above the level of the upper surface of the slab to be formed. The concrete is then poured into the form to the desired height and then subjected to the usual screeding operation to level the upper surface of the slab. During the screeding operation, the flexible prong or finger ll 12 yields to passage of the screed board thereover as indicated in dotted lines in FIG. 6 and, after the prong is released, it returns to its erect position. The prong llll2 serves as a locating element which enables the member lit) to be readily located or de' tected as a preliminary to its removal from the hardened concrete for subsequent reuse in a succeeding slab-forming operation. Removal of the four members lllt] leaves cylindrical holes 114 in the corner portions of the concrete slab and in vertical register with the cup-shaped shields 16 of the four anchor inserts. The anchor inserts W are then ready for interlocking cooperation with the corresponding counterpart pickup unim 12 for hoisting purposes, such cooperation being effected by lowering the units endwise through the cylindrical holes 114 and manipulating the torque stems 64 in a manner that will be described in detail presently.

The lowering operation of each pickup unit 12 as described above is accomplished by the operator who utilizes the bail 48 as a handle to align the torque stem 64 with the selected hole 114 in the hardened concrete slab S, the torque stem being oriented angularly as shown in FIG. 7 and so that the enlarged bifurcated head 66 willpass freely over the medial region of the lift rod 22of the associated anchor insert 10 with the bifurcation in angular register with such rod. Thereafter, the operator will apply downward pressure to the torque stem 6% in order to force the same downwardly against the yielding action of the spring-biased plunger 94 the lower end of which will rest upon the upper surface of the lift rod 22 while at the same time the two

hook portions

70 and 72 will straddle said medial portion of the lift rod 22 as clearly shown in this view in dotted lines. At this time, the two hooks proper 74 will be lowered below the level of the arched medial portion 30 of the lift rod 22, thus compressing the spring 1M0 within the socket 92 and holding the plunger 94 firmly against the upper side of said rod. As soon as the two hooks proper 74 have cleared the medial region 30 of the rod 22, the operator will turn or twist the stem 64 in a clockwise direction so as to swing the two hooks proper 74 beneath the rod 22 and align the curved bottoms 78 of the troughs 76 with the rod so that, upon release of the stem 64, the spring-biased plunger 9% will raise the torque stem to the position wherein it is shown in FIGS. 5, 5a and b and also shown in full lines in FIG. 7. In this raised position of the stem 64, the two hooks proper 74 of the

hook portions

70 and 72 will be in firm interlocking engagement with the arched medial portion 30 of the rod 22 with the curved bottoms 78 of the hooks bearing upwardly against said medial region 30 of the lift rod 22. The curved bottoms '78 of the hooks proper 74 thus establish upwardly facing lift shoulders while the underneath side of the arched medial region 30 of said lift rod establishes a downwardly facing single elongated thrust shoulder against which the upwardly facing lift shoulders bear upwardly with lifting force when the pickup unit 12 is hoisted vertically by the overhead hoist mechanism.

As soon as the previously described interlocking relationship between the pickup unit 12 and the anchor unit M) has been established, the operator will then screw the frustospherical nut 82 downwardly on the stem 64 in order to draw the latter upwardly under tension and positively lock the hooks proper 74 to the lift rod 22 of the anchor insert llll against dislodgernent. The nut, in addition to serving as a locking element, further serves as a reaction member to assimilate the upward thrust of the member all when the latter is lifted upwardly by the bail 4% under the influence of the aforementioned overhead hoisting mechanism. At such time as the hook 56 of the hoisting mechanism has been attached to the bail db and hoisting operations have commenced, the stem 64 and the locking nut @2 will assimilate the entire downward pulling force of the anchor insert lltl and the mass of hardened concrete wall slab S which is served by the particular involved anchor insert.

As soon as the slab S has been raised and tilted to the vertical position which it assumes for wall-forming purposes, release of the interlocking connection between the pickup unit 12 and the anchor insert 10 may be effected by backing off the nut 82 to such an extent that axial forward pressure upon the torque stem will permit shifting of the same against the yielding action of the plunger EM so as to force the two hook portions and 72 out of engagement with the medial region 30 of the lift rod 22. The torque stem M may then be rotated throughout an angle of 60 :in a counterclockwise direction so as to cause the two hooks proper 74 to swing back beneath the arched medial region 30 of the lift rod 22 to their initial positions, whereupon vertical clearance is afforded for axial withdrawal of the torque stem 64 from the cylindrical hole 11114 in the concrete slab S.

Removal of the pickup unit 12 from the anchor insert Ml exposes the hole llllt which may then be filled with a suitable patching cement or otherwise plugged. The withdrawn pickup unit is thus available for reuse in a subsequent slab pickup operation in connection with a different concrete installation.

it is to be noted at this point that the torque stem 64, and specifically its lower enlarged bifurcated head 66 is so designed that after interlocking register between the anchor insert and the pickup unit has been effected to the extent shown in FIG. 7, turning of the torque stern be in a clockwise direction is limited to an angle of 60 only because at the end of a 60 rotation the leading vertical edges of the

hook portions

70 and 72 will strike the opposite sides of the arched medial region 30 of the lift rod 22 and limit such rotation. By the same token, initial turning of the torque stem 64 in a counterclockwise direction is precluded altogether because the trailing vertical edges of the hook portions '70 and 72 will bear against the opposite sides of said medial region of the lift rod 22 and hold the stern against such counterclockwise movement.

The advantage of employing the frustospherical ball-type, locking nut 82 and its cooperating frustospherical seat (see FIG. 5) has been carried over from our aforementioned U.S. Pat. No. 3,431,012 where a similar ball nut and seat, designed for the same purpose, have been shown and described. it is deemed sufficient to state herein that by utilizing such a nut and seat, limited misalignment of the torque stem 64 and the surrounding bore fill in the member 40 may be accommodated and equal pressure of the seating flange M on the upper surface of the concrete wall slab S will be attained.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit or scope of the invention.

Having thus described the invention what we claim as new and desired to secure by letters patent is:

ll. In combination, an anchor insert adapted for embedment in a concrete slab and a cooperating pickup unit therefor, said anchor insert comprising a tubular concrete-excluding shield across and through which there extends a single embedment rod defining an elongated downwardly facing thrust shoulder, said shield presenting an open upper rim, said pickup unit comprising a tubular member having a flat underneath surface adapted for positioning on the upper surface of the slab and also having formed therethrough a vertical bore designed for register with said upper rim of the shield when the member is in position on the slab, a torque stem projecting completely and loosely through said bore and having on its lower end a pair of laterally spaced apart, upwardly opening, oppositely facing hooks which face generally toward each other and are formed with bottom rod-engaging lift surfaces which are in diametric alignment with respect to the axis of the torque stem, said hooks being designed for interlocking engagement with said thrust shoulder when the stem is projected through said open rim to an extent sufficient to project said hooks below the level of said rod on opposite sides of the latter and then for turning movement through an angle in order to bring the hooks into simultaneous interlocking register with the rod, the lower end of the torque stem being bifurcated in order to provide two identical spaced apart depending hook portions including vertical hook shanks with reentrant bends terminating in upwardly projecting hook fingers, thus establishing said hooks, said reentrant bends establishing said lift surfaces, the distance between said hook portions and the curvature of said reentrant bends being such that when said hooks are below the level of said rod on opposite sides thereof, turning of the torque stern about its vertical axis is limited to approximately 60 whereby when the hooks are interlocked with the rod, the latter projects through the hook portions obliquely with respect to the general plane of the latter, the lower region of the torque stern immediately above the bifurcated end thereof being formed with a vertically disposed elongated axial socket which faces downwardly, and the pickup unit further comprising a biasing plunger which is slidable disposed in said socket and projects into the bifurcation of the stem for engagement with the upper portion of the exposed embedment rod section, spring means yieldingly biasing the plunger to its projected position, interengaging means on the plunger and torque stem for preventing withdrawal of the plunger from said socket, and a bail pivoted to said member and forming means whereby the pickup unit may be attached to an overhead hoisting mechanism for slab-lifting purposes.

2. The combination set forth in claim 1 and wherein the portion of said single embedment rod which projects through said tubular shield is upwardly bowed and in interlocking engagement between said lift surfaces and lift shoulder takes place on opposite sides of the apex region of said upwardly bowed portion of the rod.

3. The combination set forth in claim 2 and wherein the projecting lower end of said plunger is engageable with the crest region of the upwardly bowed portion of the rod.

4. The combination set forth in claim 1 and wherein the lower end of said torque stem is formed with an enlarged cylindrical head and in which the bifurcation of said torque stem is incident to the provision of a generally rectangular diametrically disposed downwardly facing slot which extends through said head and presents flat parallel opposed sides, said sides constituting the inside faces of said parallel hook portions.

5. A pickup unit adapted for engagement with an exposed embedment rod section which extends across a vertically disposed access opening in a concrete slab, said pickup unit comprising a tubular member having a flat underneath surface adapted for positioning on the upper surface of the slab and also having formed therethrough a vertical bore designed for register with the upper rim of the access opening when the member is in position on the slab, a torque stem projecting completely and loosely through said bore and having on its lower end a pair of laterally spaced apart, upwardly opening, oppositely facing hooks which face generally toward each other and are formed with bottom rod-engaging lift surfaces which are in diametric alignment with respect to the axis of the torque stem, said hooks being designed for interlocking engagement with said exposed embedment rod section when the stem is projected through said rim to an extent sufficient to project said hooks below the level of the embedment rod on opposite sides of the latter and then for turning movement through an angle in order to bring the hooks into simultaneous interlocking register with the rod, the lower end of the torque stem being bifurcatedin order to provide two identical s aeed apart depending hook portions including vertical hook s anks with reentrant bends terminating in upwardly projecting hook fingers, thus establishing said hooks, said reentrant bends establishing said lift surfaces, the distance between said hook portions and the curvature of said reentrant bends being such that when said hooks are below the level of said rod on opposite sides thereof, turning of the torque stem about its vertical axis is limited to approximately 60 whereby, when the hooks are interlocked with the rod, the latter projects through the hook portions obliquely with respect to the general plane of the latter, the lower region of the torque stem immediately above the bifurcated end thereof being formed with a vertically disposed elongated axial socket which faces downwardly, and the pickup unit further comprising a biasing plunger which is slidably disposed in said socket and projects into the bifurcation of the stem for engagement with the upper portion of the exposed embedment rod section, spring means yieldingly biasing the plunger to its projected position, interengaging means on the plunger and torque stem for preventing withdrawal of the plunger from said socket, and a bail pivoted to said member and forming means whereby the pickup unit may be attached to an overhead hoisting mechanism for slab-lifting purposes.

Claims

1. In combination, an anchor insert adapted for embedment in a concrete slab and a cooperating pickup unit therefor, said anchor insert comprising a tubular concrete-excluding shield across and through which there extends a single embedment rod defining an elongated downwardly facing thrust shoulder, said shield presenting an open upper rim, said pickup unit comprising a tubular member having a flat underneath surface adapted for positioning on the upper surface of the slab and also having formed therethrough a vertical bore designed for register with said upper rim of the shield when the member is in position on the slab, a torque stem projecting completely and loosely through said bore and having on its lower end a pair of laterally spaced apart, upwardly opening, oppositely facing hooks which face generally toward each other and are formed with bottom rodengaging lift surfaces which are in diametric alignment with respect to the axis of the torque stem, said hooks being designed for interlocking engagement with said thrust shoulder when the stem is projected through said open rim to an extent sufficient to project said hooks below the level of said rod on opposite sides of the latter and then for turning movement through an angle in order to bring the hooks into simultaneous interlocking register with the rod, the lower end of the torque stem being bifurcated in order to provide two identical spaced apart depending hook portions including vertical hook shanks with reentrant bends terminating in upwardly projecting hook fingers, thus establishing said hooks, said reentrant bends establishing said lift surfaces, the distance between said hook portions and the curvature of said reentrant bends being such that when said hooks are below the level of said rod on opposite sides thereof, turning of the torque stem about its vertical axis is limited to approximately 60* whereby when the hooks are interlocked with the rod, the latter projects through the hook portions obliquely with respect to the general plane of the latter, the lower region of the torque stem immediately above the bifurcated end thereof being formed with a vertically disposed elongated axial socket which faces downwardly, and the pickup unit further comprising a biasing plunger which is slidable disposed in said socket and projects into the bifurcation of the stem for engagement with the upper portion of the exposed embedment rod section, spring means yieldingly biasing the plunger to its projected position, interengaging means on the plunger and torque stem for preventing withdrawal of the plunger from said socket, and a bail pivoted to said member and forming means whereby the pickup unit may be attached to an overhead hoisting mechanism for slab-lifting purposes.

5. A pickup unit adapted for engagement with an exposed embedment rod section which extends across a vertically disposed access opening in a concrete slab, said pickup unit comprising a tubular member having a flat underneath surface adapted for positioning on the upper surface of the slab and also having formed therethrough a vertical bore designed for register with the upper rim of the access opening when the member is in position on the slab, a torque stem projecting completely and loosely through said bore and having on its lower end a pair of laterally spaced apart, upwardly opening, oppositely facing hooks which face generally toward each other and are formed with bottom rod-engaging lift surfaces which are in diametric alignment with respect to the axis of the torque stem, said hooks being designed for interlocking engagement with said exposed embedment rod section when the stem is projected through said rim to an extent sufficient to project said hooks below the level of the embedment rod on opposite sides of the latter and then for turning movement through an angle in order to bring the hooks into simultaneous interlocking register with the rod, the lower end of the torque stem being bifurcated in order to provide two identical spaced apart depending hook portions including vertical hook shanks with reentrant bends terminating in upwardly projecting hook fingers, thus establishing said hooks, said reentrant bends establishing said lift surfaces, the distance between said hook portions and the curvature of said reentrant bends being such that when said hooks are below the level of said rod on opposite sides thereof, turning of the torque stem about its vertical axis is limited to approximately 60* whereby, when the hooks are interlocked with the rod, the latter projects through the hook portions obliquely with respect to the general plane of the latter, the lower region of the torque stem immediately above the bifurcated end thereof being formed with a vertically disposed elongated axial socket which faces downwardly, and the pickup unit further comprising a biasing plunger which is slidably disposed in said socket and projects into the bifurcaTion of the stem for engagement with the upper portion of the exposed embedment rod section, spring means yieldingly biasing the plunger to its projected position, interengaging means on the plunger and torque stem for preventing withdrawal of the plunger from said socket, and a bail pivoted to said member and forming means whereby the pickup unit may be attached to an overhead hoisting mechanism for slab-lifting purposes.