US3910546A

US3910546A - She-bolt type gripper device for a concrete wall form tie rod

Info

Publication number: US3910546A
Application number: US526076A
Authority: US
Inventors: Frank T Connors
Original assignee: Symons Corp
Current assignee: General Electric Co
Priority date: 1974-11-22
Filing date: 1974-11-22
Publication date: 1975-10-07
Anticipated expiration: 1992-10-07
Also published as: CA1024724A

Abstract

A releasable, reusable, slip-on, she-bolt type gripper device designed for telescopic reception therein of one end of a cylindrical horizontally extending tie rod for use in connection with a concrete wall form in the form of a pair of spaced apart, upstanding sides and adapted to receive the reaction pull of the tie rod when the latter is under tension as the result of pouring of wet concrete between the sides of the form. Longitudinally shiftable, chuck-forming jaw segments within a tapered casing or shell are spring-biased so that they frictionally engage the adjacent end of the associated tie rod and are self-energized by the longitudinal pull of the latter. A spring-biased pull rod is connected in common to all of the jaw segments, projects rearwardly through the outer end of the shell and, when pulled rearwardly, releases the jaw segments from the tie rod. When the gripper device projects through the adjacent side of the associated form and into the poured concrete, an elastomeric sealing ring at the forward end of the shell prevents seepage of concrete thereinto. When the gripper device is used with concrete wall forms of the ''''Steel-Ply'''' type, it remains exteriorly of the adjacent form side and does not project into the concrete with the result that the sealing ring may be omitted.

Description

United States Patent [191 Connors Oct. 7, 1975 SHE-BOLT TYPE GRIIPER DEVICE FOR A CONCRETE WALL FORM TIE ROD [75] Inventor: Frank T. Connors, Deerfield, Ill.

[73] Assignee: Symons Corporation, Des Plaines,

Ill.

[22] Filed: Nov. 22, 1974 [21] Appl. No.: 526,076

[52] US. Cl. 249/40; 24/136 R; 52/223 L;

249/216; 254/29 A; 425/111 [51] Int. Cl. E04G 11/06; E04G 17/06 [58] Field of Search 249/40, 213, 215, 216,

249/217, 219 R, 219 W, 190, 43, 91, 97; 264/228, 229; 24/136 R; 52/223 L; 425/111 Primary Examiner-Francis S. Husar Assistant Examiner-John S. Brown Attorney, Agent, or FirmNorman H. Gerlach [57] ABSTRACT A releasable, reusable, slip-on, she-bolt type gripper device designed for telescopic reception therein of one end of a cylindrical horizontally extending tie rod for use in connection with a concrete wall form in the form of a pair of spaced apart, upstanding sides and adapted to receive the reaction pull of the tie rod when the latter is under tension as the result of pouring of wet concrete between the sides of the form. Longitudinally shiftable, chuck-forming jaw segments within a tapered casing or shell are spring-biased so that they frictionally engage the adjacent end of the associated tie rod and are self-energized by the longitudinal pull of the latter. A spring-biased pull rod is connected in common to all of the jaw segments, projects rearwardly through the outer end of the shell and, when pulled rearwardly, releases the jaw segments from the tie rod. When the gripper device projects through the adjacent side of the associated form and into the poured concrete, an elastomeric sealing ring at the forward end of the shell prevents seepage of concrete thereinto. When the gripper device is used with concrete wall forms of the Steel- Ply type, it remains exteriorly of the adjacent form side and does not project into the concrete with the result that the sealing ring may be omitted.

16 Claims, 7 Drawing Figures US. Patent Oct. 7,1975 Sheet 10f3 3,910,546

I m F FIG. 2

76 m mm U.S. Patent Oct. 7,1975 Sheet 2 of3 3,910,546

The improved, releasable, reusable gripper device comprising the present invention is designed primarily for use as a slip-on she-bolt for use in connection with a concrete wall or other form where it is telescopically received over one end of a horizontally extending tie rod during concrete-pouring operations. The invention is, however, capable of other uses and a gripper device embodying the principles thereof may if desired be employed either with or without modification as desired for other uses, as, for example, a dead-end anchor device for a tensioned rod-like member, wire, or the like, or as a pulling device by means of which tension may be applied to a rod or wire. Irrespective, however, of the particular use to which the invention may be put, the essential features thereof remain substantially the same.

A dead-end type anchor or gripper device of the general character under consideration consists mainly of a tapered tubular casing or shell within which there are slidingly disposed a series of contiguous and circumferentially arranged tooth-equipped jaw segments which form a one-way clutch and grip the rod or wire which is to be held therebetween when tension is applied thereto in one direction. Such an anchor or gripper device is not well adaptable for use as a she-bolt in connection with concrete formwork unless it is regarded as being disposable inasmuch as to render it reusable it is necessary to provide a means for releasing the chuckforming jaw segments which are associated therewith. Furthermore, if such a device projects into the space between the sides of a concrete form where wet concrete is poured, the problem of preventing concrete form seeping into the shell which encloses the chuckforming jaw segments arises.

In the electrical industry, gripper devices of the aforementioned character are made in tandemarranged pairs and are used as permanent wire splices. They also are made as dead-end devices for stranded wire or cable. Certain of these gripper devices are of the type which is releasable in that when tension in the wire is released, the wire may be shoved rearwardly into the shell of the device in order to release the pressure of the jaw segments, after which a tool may be introduced through an opening in the side wall of the shell to hold the segments released until the wire is drawn from the shell. One particular gripper device which is currently on the market employs a slotted shell through which a radially extending segmentmanipulating finger extends so that it is possible collectively to release the jaw segments while the wire is still under tension. These various gripper devices are not well adapted for use as she-bolts in the concrete form industry inasmuch as with the slotted type of shell, it is impossible to release the tension in the tie rod after the concrete has become hardened. Where a radial finger is used for jaw segment release, such finger is not always disposed in a convenient place where it is readily accessible for manipulation due to the presence of adjacent obstructions such as waler boards, strongbacks, or nearby concrete form hardware.

The present invention is designed to overcome the above-noted limitations that are attendant upon the construction and use of conventional gripper devices of the character under consideration and, toward this end,

the invention contemplates the provision of a gripper device which is particularly well-adapted for use as a she-bolt in a concrete wall or other form, regardless of whether the latter be comprised of plywood panels wherein the device projects through the adjacent side of the concrete form and into the area where concrete is poured or whether the form be comprised of Steel- Ply form panels of the type which is manufactured and sold by Symons Corporation of Des Plaines, Ill. In the latter instance, the gripper device which is employed in connection with the form must necessarily remain on the outer side of the adjacent form side where it is not exposed to concrete-pouring operations. The provision of such a gripper device constitutes the principal object of the present invention.

Briefly, in carrying out this object the invention contemplates the provision of a gripper device which has the usual tapered shell with internal chuck-forming segments but instead of embodying a radial chuck release finger which projects laterally through and from the shell, employs a longitudinally extending pull rod which is coaxial with the shell, is connected in common to the rear ends of the chuck-forming segments and extends rearwardly of the shell and, therefore, is also coaxial with the tie rod which is gripped. The device is thus necessarily a dead-end gripper device and its use as a wire or rod splice is not intended. Additionally, in order further to adapt the gripper for use as a she-bolt, the pull rod extends only a slight distance rearwardly of the chuck-enclosing shell and it is provided on its extreme rear end with an enlarged pry head which may be engaged by a suitable tool such as a carpenters claw ham mer for chuck-release purposes. By such an arrangement, when it is desired to dismantle a concrete form, it is merely necessary to pry the pull rod rearwardly in order to release the chuck-forming jaw segments from the adjacent end of the tie rod, after which the device may be slid bodily as a unit from the tie rod and, consequently, from the form where it may be reused in connection with another concrete form.

A further object of the invention is to provide a shebolt type gripper device which is generally of new and improved construction and combines high efficiency with cheapness of construction.

Other objects of the invention and the advantages and characteristics of the present gripper device will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particu larly defined by the claims at the conclusion hereof.

Two embodiments of the invention are disclosed in the accompanying three sheets of drawings in which:

FIG. 1 is a fragmentary perspective view, partly in section, of a concrete wall form showing one form of the improved gripper device in use as a slip-on she-bolt;

FIG. 2 is an enlarged longitudinal sectional view taken on the horizontal plane indicated by the line 22 of FIG. 1 and in the direction of the arrows;

F IG. 3 is a transverse sectional view taken on the line .33 of FIG. 2;

FIG. 4 is a fragmentary sectional view similar to FIG. 2 and somewhat schematic in it representation, illustrating the manner in which the gripper device is released from the associated tie rod;

FIG. 5 is an enlarged reentrant exploded perspective view of the gripper device of FIG. 2 showing all of the constituent parts thereof;

FIG. 6 is a fragmentary perspective view of a concrete wall form embodying wooden strongbacks and walers and showing a modified form of the gripper device employed as a she-bolt where it projects completely through the adjacent form side and into the poured concrete; and

FIG. 7 is an enlarged longitudinal sectional view taken on the horizontal plane indicated by the line 7-7 of FIG. 6 and in the direction of the arrows.

Referring now to the drawings in detail and in particular to FIGS. 1 and 2, a fragmentary portion of a concrete wall form of conventional construction is illustrated therein and designated in its entirety by the reference numeral 10. The wall form 10 is made up of two upstanding, spaced apart series 12 and 14 of rectangular panel units 16, the units of each series being arranged in edge-to-edgc relationship and forming one side of the wall form. The panel units 16 of the two series are maintained in spaced parallel relationship by means of combined spreader and tie rod assemblies 18, two such assembliesbeing illustrated in FIG. 1 as being associated with two adjacent panel units of each of the two series 12 and 14 in the production of a concrete wall 20 (see FIG. 2), such wall being omitted in FIG. 1 in the interest of clarity.

The individual panel units 16 which are illustrated in FIGS. 1 and 2 are in the form of conventional prefabricated Steel-Ply panels and no claim is made herein to any novelty associated with the same. The novelty of the present invention resides rather in the construction and design of the tie rod assemblies 18, and particularly in the construction of the specific gripper devices which form a part thereof. The nature and function of such gripper device will be described in detail presently, these gripper devices functioning in the manner of she-bolts for maintaining tension in the tie rods of the assemblies 18 when wet concrete is poured between the sides of the wall form 10, and being designated in their entirety by the reference numeral 22. The illustrated panel units 16 consist of rectangular plywood facings 24 and steel marginal rectangular reinforcing frames on the outer faces of the facings. As shown best in FIG. 1, the reinforcing frames of the panels l6 consist of vertical and horizontal frame mem bers, only the vertical frame members 26 being illustrated in the drawings. At appropriate levels in the form, suitable horizontal struts or crossbars 28 of angu lar construction extend across the panel units between the opposed vertical frame members 26. Specifically, the vertical frame members of the reinforcing frames are in the form of structural steel members which are generally of shallow U-shape cross section and comprise spaced marginal

parallel ribs

30 and 32 and a connecting base portion or web 34 between the ribs. On the sides of the web 34 which are opposite the

ribs

30 and 32 there are formed shallow longitudinally extending ribs'36 which define angular grooves or recesses 38 for reception therein of the extreme vertical edge regions of the plywood fac'ings 24. The horizontal crossbars 28 are welded to the inside faces of the vertical frame members 26. At vertically spaced regions along the vertical frame members 26, the ribs 30 and 32'are notched as at 40 .to accommodate the tie rod assemblies 18, while the web portions 34 of the bars 26 are formed with rectangular openings 42 in horizontal register with the notches 40 for reception therethrough of conventional connecting bolt and wedge assemblies 44 by means of which adjacent panel units are fastened together, all in a manner that will be made clear presently.

Still referring to FIGS. 1 and 2 of the drawings, each combined spreader and tie rod assembly 18 is comprised of a horizontally extending tie rod and a pair of the aforementioned novel gripper device 22 which in the illustrated environment and as previously stated function in the manner of she-bolts for assimilating the tension in the tie rod 50 at such time as wet concrete is poured between the two sides of the form 10. At regions spaced inwardly from the ends of each tie rod 50 and slightly within the confines of the concrete form, the tie rod is provided with the usual weakened portions or breakbacks 51, thus dividing the tie rod into a medial portion 52 which remains embedded within the hardened concrete wall 20, and end portions 53 which normally project through the voids which are defined by the aforementioned registering notches 40 in the adjacent vertical frame members 26 and receive thereover the gripper devices 22.

Still referring to FIGS. 1 and 2, and additionally to FIGS. 3, 4 and 5, each gripper device 22 of each combined spreader and tie rod assembly 18 involves in its general organization an elongated tubular metal shell 54 having a rear cylindrical section 55 and a forward frusto-conical section 56, the shell being open-ended. Disposed within the forward frusto-conical section 56 is a chuck comprising a series of four jaw segments 58, each of which is of elongated tapered design as best shown in FIG. 5. Each jaw segment is provided with a curved outer surface 60 (see FIG. 3) which is adapted to slide longitudinally on the inner surface of the forward frusto-conical section 56 of the shell 54, and in addition a curved inner tie rod-gripping surface which is in the form of a longitudinal series of teeth 62, the latter extending along a major portion of the length of the segment. Except for the curvature of the aforementioned outer and inner surfaces, each jaw segment is generally trapezoidal in transverse cross section. The various jaw segments 58 are adapted to encompass the adjacent end of the tie rod 50 when the shell 54 is telescopically projected thereover as best illustrated in FIG. 2.

As clearly shown in FIG. 5 of the drawings, the rear end region of each jaw segment 58 is recessed as indicated at 64 so as to providea web 66 and a hook-like head portion 68 which, in effect, constitutes a longitudinally and rearwardly displaced extension of the main body portion of the segment. In the assembled position of the jaw segments about the adjacent projecting end of region 53 of the associated tie rod 50, the various re-. cesses 64 define a complementary sectional void for reception therein of a disk-like pull flange 70 which is in the form of a Maltese Cross and has extending therethrough a central opening 72. In the peripheral portion of the pull flange 70, there are formed four equidistantly spaced radially and inwardly extending notches 73 and these are adapted to receive and interlock with the webs 66 at the rear end regions of the jaw segments 58 to the end that the pull flange is in such fixed interconnected relation with the jaw segments as to cause axial displacement of the segments when the pull flange is pulled rearwards, while at the same time permitting the segments to move radially within the forward frusto-conical section 56 of the shell 54. The forward end region of a pull rod 74 extends through the opening 72. Said pull rod is disposed in coaxial relation with the shell 54 and embodies on its forward end a fixed enlargement 76 which, as shown in FIGS. 2 and 4 abuts against the front end face of the pull flange 70. The medial region of the pull rod 74 extends slidably through a circular opening or hole 78 in the central portion of a circular rear end wall 80 of the shell 54. The rear rim 82 of the rear cylindrical section 55 of the shell 54 is beaded over the periphery of the end wall 80 in order fixedly to hold the latter in place, while the rear end of the pull rod 74 is provided with a fixed cap 84 which may be threaded thereon or otherwise fixedly secured thereto. A helical compression spring 86 is disposed within the shell 54 and encompasses the medial region of the pull rod 74. The rear end of the spring 86 bears against the end wall 80 and the front end of the spring abuts against the rear end faces of the hook-like head portions 68 of the segments 58. When the jaw segments 58 are pulled rearwards by exerting a pulling force either manually or by way of a tool on the cap 84 at the rear end of the pull rod, they are permitted to move ra dially outwards into an expanded position wherein they are released from gripping relation with the adjacent end region of the tie rod 50. However, when no rearward force is exerted on the pull rod, the helical compression spring 68 serves to urge the jaw segments forwards to the end that they are contracted by the camming action of the forward frusto-conical section of the shell into firm gripping relation with the adjacent end region of the tie rod.

In the installation of the herein described gripper device 22 over the adjacent outwardly projecting end portion 53 of the tie rod 50, a bottomless seating cup 90 is positioned against the outer side faces of the adjacent pair of adjacent vertical frame members 26. Such seat ing cup is provided therein with a frusto-conical seating socket 92 for the extreme forward end region of the forward frustoconical section of the gripper shell 54 as clearly shown in FIGS. 1 and 2. If desired, such seating cup may be permanently connected to the forward end of the shell.

It will be observed that in its normal state, the spring 86 within the shell 54 yielding urges the four chuck segments 58 forwardly so that thejaw teeth 62 of such segments tend to close upon one another. However, at such time as the shell 54 is inserted into the seating cup 90 as previously described, the extremity of the adjacent end portion 53 of the tie rod 50 forces the jaw segments rearwardly against the action of the spring 86, thus spreading the segments apart so that such end portion 53 may enter between the segments and become gripped thereby at such time as forward pressure on the device 22 is terminated. With the tie rod 50 thus gripped, the gripper device 22 functions as a she-bolt for the assembly 18 of which it forms a part.

When concrete form dismantling operations are resorted to, each ofthe various gripper devices 22 may be withdrawn from its associated tie rod end region 53 by the simple expedient of utilizing a suitable tool such as a pry bar or a claw hammer such as is illustrated in dotted lines in FIG. 4 against the cap 84 which, in effect, constitutes a pry head, thus drawing the pull rod 74 rearwardly and, as a consequence, pulling the four check segments 58 rearwardly so as to release their jaw pressure on the adjacent tie rod end region 53. The gripper device 22 may then be removed from the tie rod and reserved for reuse in a subsequent concrete form installation.

In FIGS. 6 and 7 of the drawings, a slightly modified form of gripper device 122 is disclosed, such device being suitable for use with an all wood concrete wall form such as is disclosed in these views. The illustrated form embodies plywood panels 124 which are backed by horizontal waler boards 123 and vertical strongbacks 125 conventionally arranged to produce the opposing form sides 112 and 114. Due to the similarity between the previously described gripper device 22 of FIGS. 1 to 5, inclusive, and the modified form of gripper device of FIGS. 6 and 7, and in order to avoid needless repetition of description, similar reference numerals but of a higher order have been applied to the cone sponding parts as between the disclosure of FIGS. 6 and 7 on the one hand and FIGS. 1 to 5 on the other.

The shell 154, chuck segments 158, pull rod 174 and spring 186 of the gripper device 122 remain substantially the same as the corresponding parts of the gripper device 22 with the sole exception that inasmuch as the forward end of the shell of the gripper device 154 projects through an opening 127 in the associated plywood panel 124, it is necessary to seal such forward end of the shell against the entrance of wet poured concrete. Accordingly, the forward frusto-conical section 156 of the shell 154 has its forward end cupped inwardly as indicated at 157 so as, in effect, to define an annular front wall for the shell. Seated within such cupped portion and forwardly of thefour chuck segments 158 there is disposed a doughnut-like sealing ring 159 of any suitable elastomeric material. Otherwise, the gripper device 122 remains substantially the same as the gripper device 22, both as regards its structure and its function.

In the installation of the gripper device 122 in a wall form such as the illustrated form 110, the device projects between the vertically disposed strongbacks 125 and beneath the waler 123 exteriorly of the plywood panel 124. In order to accommodate the gripper device 122, the hole 127 is formed in the plywood panel for projection therethrough of the forward tapered or frusto-conical section 156 of the shell 154.

In this second or modified form of the invention, since the forward end of the shell 154 projects through the plywood facing 124 and into the concrete, the seating cup 90 which is associated with the previously described first form of the invention is omitted and, in its place, there is provided a seating plate of rectangular configuration, the plate being formed with a central circular opening 129 therein through which extends the rear end region of the rear cylindrical section of the gripper shell 154. The beaded rim 182 of the shell 154 bears against this seating plate 190 as clearly shown in FIG. 7 and thus assimilates the tension in the associated tie rod assembly 118.

In connection with either concrete form 10 or 1 10 as illustrated in the accompanying drawings, after the as sociated gripper device has been withdrawn from the adjacent projecting end region of the associated tie rod, it will be understood that said projecting end region will be wrested from the hardened concrete in a manner well-known in the art.

The invention is not to be limited to the exact ar rangement 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 in vention. Therefore, only insofar as the invention is particularly pointed out in the accompanying claims is the same to be limited.

I claim:

1. A gripper device adapted for application to one end of a cylindrical rod and comprising an open-ended, tapered, tubular shell having a small front end and a large rear end, a plurality of correspondingly tapered, tooth-equipped jaw segments slidably disposed within said shell in circumferentially arranged relationship and defining a chuck structure for reception ofsaid one end of the rod when it is projected into the front end of-the shell, a wall extending across the rear end of said shell, a compression spring disposed between said wall and jaw segments and effective to bias the latter forwardly in the shell, and a pull rod projecting centrally through said wall coaxially with the shell and having its forward end operatively connected in common to the rear ends of said jaw segments and effective when pulled rearwardly to release said segments from the rod.

2. A gripper device as set forth in claim 1 and wherein each of said jaw segments is formed with a hook-like head portion at its rear end, and the forward end of the pull rod carries a pull flange having interlocking engagement with said head portions.

3. A gripper device as set forth in claim 1 and wherein the rear end region of each jaw segment is recessed to provide a rearwardly displaced hooklike head portion which is connected to the main body of the segment by a web, and a pull flange is carried on the forward end of the pull rod and projects into the recessed portions of the chuck segments.

4. A gripper device as set forth in claim 3 and wherein said pull flange is in the form of a Maltese Cross which substantially fills the recessed portions of the jaw segments.

5. A gripper device as set forth in claim 4 and wherein said pull flange is slidable on the pull rod and the forward end of the latter is provided with an enlargement by means of which rearward pull of the pull rod is transmitted to the pull flange.

6. A gripper device as set forth in claim 5 and wherein said pull rod projects rearwardly of the wall a slight distance and is provided with an enlarged pry head which is designed for engagement by a pry tool for forcing the pull rod rearwardly.

7. A gripper device designed for use as a she-bolt in gripping the projecting end of a concrete-embedded tie rod in associated relation with a concrete wall form, said device comprising a tapered tubular shell of circular cross section and with a small front'end and a large rear end, a plurality of correspondingly tapered, toothed-equipped jaw segments slidably disposed within said shell in circumferentially arranged relationshipand defining a chuck structure for reception of said tie rod end, a rear circular wall extending across and fixedly connected to the rear end of said shell, a

compression spring interposed between said wall and said chuck segments and said front annular wall, and a pull rod projecting centrally through said rear annular wall coaxially with the shell, having its forward end operatively connected in common to the rear ends of said chuck segments, and effective when pulled rearwardly to release said segments from the tie rod.

8. A gripper device as set forth in claim 7 and wherein the forward end of said shell is cupped inwardly to provide said front annular wall.

9. A gripper device as set forth in claim 8 and wherein each of said jaw segments is formed with a hook-like head portion at its rear end, and the forward end of the pull rod carries a pull flange having interlocking engagement with said head portions.

10. A gripper device as set forth in claim 7 and wherein the rear end region of each jaw segment is recessed to provide a rearwardly displaced hook-like head portion which is connected to the main body of the segment by a web, and a pull flange is carried on the forward end of the pull rod and projects into the recessed portions of the chuck segments.

11. A gripper device as set forth in claim 10 and wherein said pull flange is in the form of a Maltese Cross which substantially fills the recessed portions of the jaw segments.

12. A gripper device as set forth in claim 11 and wherein said pull rod projects rearwardly of the rear circular wall a slight distance and is provided with an enlarged pry head designed for engagement by a pry tool for forcing the pull rod rearwardly.

13. In a concrete wall form, in combination, a pair of upstanding wall form sides between which wet concrete is adapted to be poured in the formation of a concrete wall, each of said sides embodying edge-to-edge rectangular panels in the form of plywood facings and rectangular metallic reinforcing frames around the facings, a combined tie rod and spreader assembly for maintaining said form sides in their spaced apart relationship,

said tie rod and spreader assembly embodying a horizontal tie rod having a medial portion designed for embedment in the concrete which is poured between said form sides, and projecting end portions which extend between and beyond the abutting side members of the reinforcing frames of the panels, and a pair of gripper devices disposed in gripping relationship with respect to said projecting end portions of the tie rod, each gripper device comprising a tapered tubular shell embodying a small front end and a large rear end, a plurality of correspondingly tapered, toothed-equipped jaw segments slidably disposed within said shell in circumferentially-arranged relationship and defining a chuck structure which receives the adjacent projecting end portion of the tie rod, a compression spring disposed in the shell and effective to bias the jaw segments forwardly in the shell, and means for effecting release of said sections from the adjacent projecting end portion of the tie rod when it is desired to remove the gripper device from said projecting end portion of the tie rod, and a pair of bottomless seating cups positioned against the outer faces of the abutting side members of the re inforcing frames, surrounding said projecting end regions of the tie rod, and having the small ends of the shells of the gripper devices fitting snugly therein.

14. In a concrete wall form, the combination set forth in claim 13 and wherein said bottomless seating cups are permanently attached to the small ends of the shells of the gripper devices.

15. In a concrete wall form, in combination, a pair of upstanding wall form sides between which wet concrete is adapted to be poured incident to the creation of a concrete wall, each of said sides embodying an upstanding plywood panel together with outer wooden reinforcing members, and a combined tie rod and spreader assembly for maintaining said form sides in their spaced apart relationship, said tie rod and spreader assembly embodying a tie rod having a medial portion designed for embedment in the concrete which is poured between said form sides, and projecting end portions which extend through openings in the respective plywood panels, and a pair of gripper devices disposed in gripping relationship with respect to said projecting end portions of the tie rod, each gripper device comprising a tapered tubular shell embodying a small front end and a large rear end and having its front end projecting through the tie rod-receiving opening in the associated plywood panel in sealing relationship, a plurality of tapered, toothed-equipped, jaw segments slidably disposed within said shell in circumferentially ar ranged relationship and defining a chuck structure which receives the adjacent projecting end portion of the tie rod, a rear wall extending across the rear end of said shell, a compression spring disposed in the shell and interposed between said wall and jaw segments and effective to bias the latter forwardly in the shell, the forward end of said shell being cupped inwardly to provide a front wall for the shell and receiving said adjacent projecting end portion of the tie rod therethrough, an elastomeric sealing ring interposed between the forward ends of said jaw segments and said front wall of the shell, and a pull rod projecting centrally through said rear wall coaxially with the shell and having its forward end operatively connected in common to the rear ends of said jaw segmentsand effective when pulled rearwardly to release said segments from the adjacent projecting end portion of the tie rod.

16. In a concrete wall form, the combination set forth in claim 15 and wherein said pull rod projects rearwardly of the rear wall a slight distance, the rear rim of the shell is provided with an external bead, and a seating plate having a central opening therethrough is telescopically received over said shell, bears against wooden reinforcing members, and receives the inward thrust of said external bead incident to the tension in the tie rod and spreader assembly.

Claims

1. A gripper device adapted for application to one end of a cylindrical rod and comprising an open-ended, tapered, tubular shell having a small front end and a large rear end, a plurality of correspondingly tapered, tooth-equipped jaw segments slidably disposed within said shell in circumferentially arranged relationship and defining a chuck structure for reception of said one end of the rod when it is projected into the front end of the shell, a wall extending across the rear end of said shell, a compression spring disposed between said wall and jaw segments and effective to bias the latter forwardly in the shell, and a pull rod projecting centrally through said wall coaxially with the shell and having its forward end operatively connected in common to the rear ends of said jaw segments And effective when pulled rearwardly to release said segments from the rod.

3. A gripper device as set forth in claim 1 and wherein the rear end region of each jaw segment is recessed to provide a rearwardly displaced hook-like head portion which is connected to the main body of the segment by a web, and a pull flange is carried on the forward end of the pull rod and projects into the recessed portions of the chuck segments.

7. A gripper device designed for use as a she-bolt in gripping the projecting end of a concrete-embedded tie rod in associated relation with a concrete wall form, said device comprising a tapered tubular shell of circular cross section and with a small front end and a large rear end, a plurality of correspondingly tapered, toothed-equipped jaw segments slidably disposed within said shell in circumferentially arranged relationship and defining a chuck structure for reception of said tie rod end, a rear circular wall extending across and fixedly connected to the rear end of said shell, a compression spring interposed between said wall and jaw segments and effective to bias the latter forwardly in the shell, a front annular wall extending across the front end of the shell and through which the projecting end of the tie rod is adapted to extend, an elastomeric sealing ring interposed between the forward ends of said chuck segments and said front annular wall, and a pull rod projecting centrally through said rear annular wall coaxially with the shell, having its forward end operatively connected in common to the rear ends of said chuck segments, and effective when pulled rearwardly to release said segments from the tie rod.

13. In a concrete wall form, in combination, a pair of upstanding wall form sides between which wet concrete is adapted to be poured in the formation of a concrete wall, each of said sides embodying edge-to-edge rectangular panels in the form of plywood facings and rectangular metallic reinforcing frames around the facings, a combined tie rod and spreader assembly for maintaining said form sides in their spaced apart relationship, said tie rod and spreader assembly embodying a horizontal tie rod having a medial portion designed for embedment in the concrete which is poured between said form sides, and projecting end portions which extend between and beyond the abutting side members of the reinforcing frames of the panels, and a pair of gripper devices disposed in gripping relationship with respect to said projecting end portions of the tie rod, each gripper device comprising a tapered tubular shell embodying a small front end and a large rear end, a plurality of correspondingly tapered, toothed-equipped jaw segments slidably disposed within said shell in circumferentially-arranged relationship and defining a chuck structure which receives the adjacent projecting end portion of the tie rod, a compression spring disposed in the shell and effective to bias the jaw segments forwardly in the shell, and means for effecting release of said sections from the adjacent projecting end portion of the tie rod when it is desired to remove the gripper device from said projecting end portion of the tie rod, and a pair of bottomless seating cups positioned against the outer faces of the abutting side members of the reinforcing frames, surrounding said projecting end regions of the tie rod, and having the small ends of the shells of the gripper devices fitting snugly therein.

15. In a concrete wall form, in combination, a pair of upstanding wall form sides between which wet concrete is adapted to be poured incident to the creation of a concrete wall, each of said sides embodying an upstanding plywood panel together with outer wooden reinforcing members, and a combined tie rod and spreader assembly for maintaining said form sides in their spaced apart relationship, said tie rod and spreader assembly embodying a tie rod having a medial portion designed for embedment in the concrete which is poured between said form sides, and projecting end portions which extend through openings in the respective plywood panels, and a pair of gripper devices disposed in gripping relationship with respect to said projecting end portions of the tie rod, each gripper device comprising a tapered tubular shell embodying a small front end and a large rear end and having its front end projecting through the tie rod-receiving opening in the associated plywood panel in sealing relationship, a plurality of tapered, toothed-equipped, jaw segments slidably disposed within said shell in circumferentially arranged relationship and defining a chuck structure which receives the adjacent projecting end portion of the tie rod, a rear wall extending across the rear end of said shell, a compression spring disposed in the shell and interposed between said wall and jaw segments and effective to bias the latter forwardly in the shell, the forward end of said shell being cupped inwardly to provide a front wall for the shell and receiving said adjacent projecting end portion of the tie rod therethrough, an elastomeric sealing ring interposed between the forward ends of said jaw segments and said front wall of the shell, and a pull rod projecting centrally through said rear wall coaxially with the shell and having its forward end operatively connected in common to the rear ends of said jaw segments and effective when pulled rearwardly to release said segments from the adjacent projecting end portion of the tie rod.