Aug. 1, 1961 G. F. BowDl-:N
CONCRETE WALL FORM EXTENSION BRACKET 4 Sheets-Sheet 1 Filed Aug. 9, 1960 INVENTOR. Gemeaz F. Bawpeu Aug. 1, 1961 G. F. BowDEN CONCRETE WALL FORM EXTENSION BRACKET 4 Sheets Sheet 2 Filed Aug. 9] 1960 ww f a INVENTOR- GEoRGE F. BawoEN Aug. 1, 1961 G. F. BowDEN 2,994,120
CNCRETE WALL FORM EXTENSION BRACKET Filed Aug. 9, 1960 4 Sheets-Shee'l'l 3 Eig:
32 INVENTOR. 31 Geo RGE F. Bowoc-:N
35 WMM ATTY.
Augl, 1951 G. F. BowDEN CONCRETE WALL FORM EXTENSION BRACKET 4 Sheets-Shea?I 4 Filed Aug. 9, 1960 Z Z l INVENTOR. GEORGE F. BowosN United States Patent 2 994,120 CONCRETE WALL FRM 'EXTENSIN BRACKET George F. Bowden, Des Plaines, lll., assigner to Symons Clamp & Mfg. Co., Chicago, Ill., a corporation of Delaware Filed Aug. 9, 1960, Ser. No. 48,468 6 Claims. (Cl. 2'5-131) The present invention Irelates to concrete wall forms of the panel type wherein the opposed wall forms are each constructed of a group of rectangular panels assembled in edge-to-edge relationship, with the wet concrete being poured into the space existing between the walls, and with the two walls being connected by combinedtie and spreader devices to prevent the walls from bulging under the thrust of the wet concrete. The panels commonly employed in type of concrete wall form consist of facings of plywood against which the wet concrete lies, and stiening and strengthening frames which are applied to the outer sides of the facings. Such strengthening frames include marginal horizontal and vertical members and intermediate crossbars -which may extend either vertically or horizontally and which are connected at their ends to either the horizontal or the vertical marginal frame members. The present invention has particular reference to concrete wall forms of this sort but which are known as prcfabricated wall forms in that the individual panels are assembled at the factory rather than in the field, and in that the plywood .panel-reinforcing members, including the vertical and horizontal marginal Qmembers and any intermediate cross members which may be employed, are in the 'form of lengths of steel channel or angle stock which may 'be rolled to special shape and perforated, notched, grooved or otherwise fashioned to properly receive therein the plywood panel edges, as well as to facilitate the use of suitable fastening devices or other concrete form hardware whereby the adjacent panel units may be fastened together.
Specifically, 'the present invention is concerned with a novel form of extension which is capable of use in numerous ways to effect extension of a wall form which is made up of prefabricated panel units of the character briey outlined above.
I-n the erection of certain concrete structures, situations frequently arise wherein accommodations must be made for a projecting object which extends outwardly from the surface of the concrete structure. For example, a water pipe or other conduit'may extend laterally from the surface of va concrete wall undergoing formation, thus interfering with the normal installation of one or more of the regular prefabricated panels employed for the installation. Such panels are manufactured in standard sizes and they are designed with a view toward repeated use thereof. Thus, to modify a standard panel unit, for example by cutting a hole in the plywood facing thereof to accommodate the pipe or other projection would be to render the unit unit for subsequent use.
Other situations may arise wherein, in order to accommodate a specific dimension, an undersize panel is required with a facing which may either be imperforate or which may be cut away to accommodate a projection. The cost of producing a modiiied panel unit for such a purpose is relatively high in that it involves the use of skilled labor in cutting and tting one or more plywood facings associated with the unit or units. -ln such instances it is unlikely that such modified undersine panel units will find `further use beyond that for which they are designed.
Still further, in the erection of certain concrete structures, situations frequently arise where the height of a given installation is not an exact multiple in units of length, of the available prefabricated `form panels at the scene of installation. In other Words, no combination of available panels (which invariably are manufactured in standard sizes) can lbe selected to build up a wall form structure exactly equal to the desired concrete wall height. Occasions also arises in the ield where it is necessary to provide upward extensions of agiven-wall installation, either at the time the concrete is initially poured, or after the poured concrete has hardened so that a second ibring the level of the concrete above the top level of the first concrete pouring. In instances where Prefabricated wall panels are employed, it lis inconvenient to add to the wall form by the -use of additional full Iheight panels to accommodate afew inches increase in the form height.
According to the presentinvention, when a situation such as those which- -have briey been outlined above arises, the use of a small temporary lform is contemplated, the [form useful in that area of the install-ation which, otherwise, would require the use of one or more regular but modified panel units. The invention thus provides a relatively simple and inexpensive wall form extension whereby the original wall form, consisting entirely of full width and height prefabricated panel units, may be extended either horizontally or-vertically to the desired degree without necessitating the use offu-ll sizev Prefabricated panel and utilizing' a minimum ofY horizontal marginal'frame members of a panel unit, or
of adjacent panel such. bracket having means associated therewith whereby a wooden plank or board, or
a specially constructed temporary panel facing. of the.
necessary length may be conveniently attached to the bracket in accurate edge-toedge relationship with the adjacent panel unit or units, either to extend the height of a given installation, to extend its width, or to lill in a vertical or horizontal distance between adjacent panel facings.
Another object of the invention is to provide an extension bracket of Ithis character which will enable the extension board or panel to lie with the inside face thereof `accurately aligned in the plane of the inside faces of the adjacent panel unit or units.
It is a. further object of the invention to provide such an extension bracket having means associated therewith whereby opposed `braclzets on opposite sides of the form structure may be tied together by conventional tie rod structures.
Another object of the invention is to provide an extension bracket which is so designed that it may be applied to the marginal frame members of the adjacent panelunit or uni-ts, utilizing only conventional concrete wall form hardware so that, lapart from the fabrication of the bracket itself, no special manufacturing operations are required.
Yet another object of the invention, in an extension bracket of this character, is to provide means for accommodating the attachment 'thereto of alignment walers, such means embodying only conventional waler-clamping hardware. 1
Finally, it is a further object of the invention -to provide an extension bracket which is capable of independent removal from any given installati-on, regardless of its manner of use, i.e. of whether it be employed as a terminal vertical or horizontal extension member or as a fill-in extension member.
The provision of an extension bracket which is of one piece construction and which may readily be manufactured as a metal stamping; one which is inherently reinforced against lateral and torsional stresses; one which is rugged and durable and which therefore will withstand rough usage; one which is capable of repeated use; and one which, otherwise, is well adapted to perform the services required of it, are further desiderata which have been borne in mind in the production and development of the present invention.
Other objects and advantages of the invention, not at this time enumerated, will become more readily apparent as the nature of vthe invention is better understood.
In the accompanying four sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown in several different environments.
In these drawings:
FIG. l is a fragmentary perspective view of one side of a concrete wall form, showing a plurality of extension brackets constructed in accordance with the principles of the present invention operatively applied to Ia horizontal ll-in form extension assembly;
FIG. 2 is a fragmentary perspective view similar to FIG. 1 showing a pair of the extension brackets operatively applied to the upper edge of one side of a concrete wall form for form extension purposes;
FIG. 3 is a fragmentary perspective view similar to FIG. 2 showing a pair of walers operatively applied to one of the extension brackets;
FIG. 4 Iis an enlarged perspective view of one of the improved extension brackets of the present invention;
FIG 4a lis a transverse section on the line 4a-4a of FIG. 4;
FIG. 5 is an enlarged sectional view taken substantially on the horizontal plane indicated by the line 5 5 of FIG. 1 in the direction indicated by the arrows;
FIG. 6 is an enlarged sectional view taken substantially on the horizontal plane indicated by the line 6--6 of FIG. 1 in the direction indicated by lthe arrows;
FIG. 7 is a fragmentary side elevational view of a portion of the structure shown in FIG. l;
FIG. 8 is an enlarged fragmentary perspective view, partly in section, of a portion of the installation shown in FIG. 2, the fragment being taken in the vicinity of the juncture -between an extension bracket and one of the wall form panels;
FIG. 9 is -a fragmentary side elevational view of a portion of the structure shown in FIG. 8;
FIG. 10 is a sectional view taken substantially along the line 10-10 of FIG. 2;
FIG. 11 is an enlarged perspective view of a portion of the structure shown in FIG. 2 and illustrating the manner in which a pair of oppositely disposed extension brackets may be connected together by a tie rod assembly;
FIG. 12 is an enlarged fragmentary perspective view, partly rin section, of a port-ion of the structure shown in FIG. 3; and
FIG. 13 is ra vertical sectional view of the structure shown in FIGS. 3 and 12.
vReferring now to the drawings in detail and in particular to FIG. 1, a fragmentary portion of one side of a composite wall form of the prefabricated metal-reinforced panel -type has been illustrated herein and designated in its entirety at 10. The wall form is made up of a series of rectangular panel assemblies, only three of which have been fragmentarily shown herein at 12, 14 and 16, with the panels 14 and 16 being arranged in edge-to-edge relationship and with the panels 12 and 14 being laterally spaced from each other, the space existing between these latter two panel units being filled in so to speak, or bridged by the form extension assembly of the present invention.
Each panel un-it is in the form of a generally rectangular plywood facing 18 having a marginal reinforcing frame'applied to the outer face of the panel unit and consisting of vertical and horizontal marginal frame bars 20 and 22, only the upper frame bar 22 of each panel unit being shown herein. The bars 20 extend in contiguity at Athe juncture between the panel units 14 and 16, while the adjacent or opposed bars 20 associated with the panel units 12 and 14 remain spaced from each other. It will be understood that the wall form side 10 is arranged in spaced opposition to a similar wall side and is maintained in spaced relationship from such wall side by means of conventional .tie rod and spreader devices, fragments of which have been illustrated herein land designated in their entirety at 24. Intermediate horizontal frame members 26 extend across each panel unit and such members have their ends secured by welding to the opposed faces of the two vertical marginal frame bars 20.
The vertical frame bars 20 are of shallow channel shape in cross section and each =bar includes inside Iand outside marginal ribs or tlanges 30 and 32 respectively (FIGS. 5 and 6), and a connecting web portion 34. A lateral flange 35 spaced inwardly a slight distance from the inside edge of each frame -bar affords a right angle recess 36 in which the adjacent vertical edge of the plywood facing 18 or panel proper seats with its inside face extending ush with the inside edge of the frame bars 2G and 22.
In erecting the concrete wall form 10, .the two panel units -14 and 16 are brought into contiguity with adjacent vertical frame bars 20 abutting each other so that the respective ribs 30 and 32 are in edge-to-edge abutting relationship while the web portions 34 remain slightly separated. At vertically spaced regions along the marginal ribs 30 and 32, pairs of transversely registering notches 42 are provided and these notches, when the frame bars are in contiguity, deline therebetween horizontal channel voids adapted to receive therethrough the tie rods proper of the tie rod and spreader assemblies 24. A rectangular slot 46 is formed in the web portion 34 at t-hc horizontal level of each pair of notches 42 and is adapted to receive therethrough the usual T-bolt and wedge assembly devices 48 whereby the frame bars 22 may be drawn tightly together.
The horizontal frame bars 22 are substantially identical in their construction to the vertical frame bars 20 and, to avoid needless repetition of description, similar reference characters have been applied to the corresponding parts of both frame bars.
The arrangement of parts thus far described is purely conventional in its design and construction and no claim is made herein to any novelty associated with the same. Concerte walls of this type may vary widely in their details ofconstruction and it will be understood that the wall form illustrated herein is purely exemplary of one embodiment of a concrete wall form to which the form,
extension of the present invention is applicable. Only such portions of the wall form 10 as are operatively associated with, or bear a relation to, the present wall form extension have been illustrated herein.
Panel uni-ts of the type set forth above are generally made in standard sizes and occasionally a situation will arise where a pipe or other type of projection must be accommodated by the wall form at the point where the object protrudes from the wall or other structure. To
cut through the plywood panel of a full size panel unit would entail both the cost of labor involved and the cost of the lumber which would thus be rendered unlit for subsequent reuse. The present invention, in the environment in which it is illustrated in FIGS. l, 5, 6 and 7, precludes the necessity of modifying and using standard panel units in this manner and, accordingly, it contemplates the provision of a plurality of form extension brackets which have been designated in their entirety at 50, three such brackets appearing in FIG. 1 and one of the brackets per se being shown in detail in FIGS. 4 and 4a.
Each extension bracket is in the form of an elongated sheet metal stamping of relatively heavy gauge, for example sheet metal approximately one-eighth inch in thickness, and which is generally U-shaped in transverse crosssection with lateral coplanar attachment anges at the free edges or extremities of the side legs. The sides 52 and 54 of the bracket 50 are substantially fiat and they are slightly divergent While the bight portion 56 which connects the sides is arcuate in cross section. Lateral flanges S8 and 60 are coplanar and each is provided with a series of nail-receiving holes 62 therethrough. In the bight portion 56 at the medial region thereof, there is formed an elongated slot 64, the axis of which extends longitudinally of the bracket as a whole. In transverse register with the slot 64, each side 52 and 54 is formed with a slot 66, the axis of which extends transversely of the side or, stated otherwise, at a right angle to the axis of the slot 64. A-t each end of the bight portion 56, the metal thereof is relieved to provide a shallow end notch 68. Near the ends of the bracket 50, the sides 52 and 54 are provided with transversely aligned slots 69, the axes of which extend longitudinally of the bracket. The purpose and function of the various slots 64, 66, 69, and of the notch 68, as well as of the holes 62 will become clear presently.
'Ihe nail holes 62 are provided for the purpose of facilitating nailing of the attachment brackets 50 to one orV more extension facing boards such as the board 70 shown in FIG. 1. The board 70 is shown herein as being ,formed with the necessary clearance region to accommodate any protruding object such as a pipe or the like which may project outwardly from the finished concrete jwall structure. I The extension brackets 50 are employed in the environment shown in FIG. 1 for the purpose of maintaining the board 70 in position between the adjacent panel units 12 "and 14 with the inside surface of the boards ush with the plywood panel facings 18 and, accordingly, the brackets are installed between -the opposed adjacent vertical frame bars 20. Installation of the brackets is made by aligning the ends of each bracket with the opposed slots v46 in adjacent vertical marginal members 20 with the Qcommon plane of the lateral anges 58 and 60 extending vertically and with the anges presented inwardly of the form. The shallow end notches 68 of the bracket 50 alord clearance regions so that the bight portion 56 may overlie the adjacent rib 32 (see FIGS. 5 and 6) and permit the end edges of the bracket to lie iush with the outer surface of the web portion 34 of the vertical member 20. With the bracket thus in position between the adjacent vertical members 20, conventional T-bolts 74 are installed in the aligned slits 46 by passing the shank portions 76 thereof through the slots so that the heads 78 of the bolts bear against the webs 34, after which wedges 80 are passed through the adjacent aligned slots 69 in the bracket sides 58 and 60 and through the slots 82 provided in the shank portions 76 to thus draw the ends of the brackets hard against the web portions 34 and securely maintain the brackets in position between the adjacent frame bars 20.
After the brackets 50 have been thus anchored between the opposed vertical frame bars 20, the extension board 70 is brought squarely against the inside faces of the lateral anges 58 and 60 of the various brackets 50 and the flanges are nailed to the board, utilizing dual head nails 83 which are passed through the nail holes 62 as best seen in FIGS. 5, 6 and 7. It is to be noted that the distance between the plane of the lateral flanges 58 and 60 of each bracket 50 and the inside edges of the adjacent frame bars 20 is precisely equal to the thickness of the extension board 70 so that the board will, when nailed in position against the anges, lie flush with the various panel facings 18 and present a uniform and unbroken extension of these facings.
In FIG. 2, a pair of the extension brackets 50 are shown as being operatively mounted on the upper horizontal marginal frame bars 22 of adjacent panel units 14 and 16 for the purpose of providing an upward extension of the wall form. Occasionally, in the field, a situation Will arise where the height of a particular concrete wall structure to be erected exceeds by a manner of inches, say from four to twelve inches, the height of a wall form which can be built up by the use of standard height panel units. While it would be possible to utilize an additional pair or pairs of panel units of minimum standard height in opposed relationship on opposite sides of the form, the use of such units would not only entail the cost of the units and their attendant concrete form hardware for fastening them in place and for spacing them across the form, but it would also preclude the use of screed devices at the top ofthe form. The present invention obviates the use of additional panel units in this manner, and, towardthis end, it contemplates the use of a plurality of the form extension brackets 50 in the environment in which they have been illustrated in FIGS. 2, 8, 9 and l0.
In FIG. 2, the panel units 12, 14 and 16 remain the same as described in connection with the form installation of FIG. l, with the exception that the panel units 12 and 14 are not separated and are secured together in contiguity and edge-to-edge relationship by conventional bolt and wedge assemblies 48. The lbrackets 50 extend vertically and the lower end edges thereof seat squarely on the web portion 34 of the upper frame bars 22 as best seen -in FIG. 8 and in register with respective slots 46. The clearance notches 68 overlie the outer raised rib 32 of the frame bar 22. The lower ends of fthe brackets 50 are held in position on the frame -bars 22 by the use of T-bolts 74 which are passed upwardly Vthrough the adjacent slots slots 46 and which are anchored in position by wedges which are passed through the aligned slots 69 and 82 in the brackets and T-bolts respectively. The manner of securing the lower ends of the brackets 50 to the horizontal frame bars 22 is identical with the manner of securing the ends of the brackets to the vertical frame bars 2050 that further description is unnecessary.
With the brackets 50 in position on the upper frame bars 22, an extension board, or boards, such as the one shown at are brought squarely against the inside faces of the lateral flanges 58 and 60 and the anges are nailed to the boa-rd by dual head nails 83 as previously described in connection with the extension board 70 of FIG. 1. The distance between 'the planes of the flanges 58 and 60 and the inside edge of the adjacent frame bar 22 is precisely equal to the thickness of the extension board 90 so that the inside face of the board will lie ush with the inside faces of the various panel facings 18 and present a uniform unbroken extension-f the llatter, the intervening inside edges of the frame bars 22 serving to preserve the facing continuity.
The various medial slots 66 may be employed for tie rod attachment purposes or, alternatively, they may be employed in combination with the adjacent slots 64 for waler anchoring purposes, thislatter use being illustrated in FIGS. 3, 12 and 13 in a manner that win be described subsequently. Preferably, the upper free ends of the extension brackets 50 are employed for tie rod attachment purposes as shown in FIGS. 2 and l1. The connection at each end of the tie rod is made by passing the looped end 102 of the rod around the slotted shank portion 104 of a T-bolt 106 so that the head portion 108 of the bolt rests upon the loop. Thereafter a Wedge 110 is passed through the aligned slots 69 in the sides 58 and 60 of the U-shaped bracket and through the slot 112 -in the shank portion 104 of the bolt 106.
Where a waler or dual walers are to be applied to the outside portions of the brackets 50, the arrangement shown in FIGS. 12 and 13 may be employed although it is within the purview of the present invention to employ other conventional waler clamping means if desired.
7 The upper and lower walers 120 and 122 respectively are clamped hard against the crest of the bight portion 56 by means of a clamping plate 124 of shallow U-shape in ltransverse cross section. A short tie rod 126 passes through a hole 128 provided in the web portion of the plate 124, as well as through the slot 64 in the bight portion 56 of the bracket 56, and has its outer looped end 130 projecting outwardly beyond the outer face of the plate 124 for reception therethrough of a Wedge 132. The inner looped end 134 of the tie rod 126 passes around the shank portion 136 of a T-bolt 138 which extends through the aligned slo'ts 66, and which is secured by means of a wedge 140 which is driven through the wedge shank portion 136 and -bears against the bracket side 58.
There have been described above three contemplated environments for the improved extension bracket 50 of the present invention but it is to be distinctly understood that other environments are contemplated. The invention therefore is not to be limited to the exact arrangement of parts shown and described in connection with these environments, nor is it to be limited to the specific configuration of the bracket 50 illustrated herein. Various changes in the details of construction of the bracket 50 may be resorted to without departing from the spirit of the invention. Only insofar as the invention has particularly been pointed out in the accompanying claims is the same to be limited.
Having thus described the invention what I claim as new and desire to secure by Letters Patent is:
l. In a concrete wall form structure, in combination, a pair of aligned prefabricated panel units spaced laterally from each other and embodying opposed marginal vertical metal frame bars and plywood panel facings, there being an elongated slot in each of said opposed marginal frame bars at substantially the same height in the form wall, a horizontally disposed extension bracket extending between said opposed frame bars, said extension bracket comprising an elongated metal stamping of generally U-shape cross section and presenting spaced apart sides connected Itogether by a bight portion, Ithe free edge side marginal portions of said sides being turned laterally outwardly away from each other to provide a pair of coplanar attachment flanges, said sides being formed in the opposite end regions of the bracket with respective pairs of transversely aligned slots, a T-bolt projecting through each of said elongated slots in the frame bars and having a shank portion entering between the sides of the bracket, said shank portion being provided with a transverse slot therethrough, a wedge' member projecting through each pair of transversely aligned slots and through the slot in the adjacent T-bolt shank for clamping the adjacent end of the bracket against the adjacent frame bar, there being a series of nail holes in each of said attachment flanges, a form extension board bridging the distance between said opposed frame bars and having an inside face substantially ush with the inside faces of the panel unit facings, and a series of attachment nails extending through said nail holes and into said board.
2. In a concrete wall form structure, the combination set forth in claim 1 and wherein the sides of said bracket are substantially flat and are slightly divergent and the bight portion of the bracket is arcuate in transverse cross section.
3. In a concrete wall form structure, in combination, a pair of aligned prefabricated panel units spaced laterally from each other and embodying opposed marginal vertical metal frame bars and plywood facings, each of said opposed marginal frame bars being generally channel-shape in cross section and embodying a pair of inner and outer marginal ribs respectively and a connecting at web, there being an elongated slot in said web intermediate said ribs with the two slots in the frame bars being disposed in substantially the same horizontal plane, a horizontally disposed extension bracket extending between the opposed marginal frame bars and having its ends anchored to the webs thereof respectively, said extension bracket comprising an elongated metal stamping of generally U-shape cross section and presenting spaced apart sides connected together by a bight portion, the free side marginal portions of said sides being turned laterally outwardly away from each other to provide a pair of coplanar attachment flanges, said sides being formed in the opposite end regions of the bracket with respective pairs of transversely aligned slots, a T-bolt projecting through each of said pairs of elongated slots in the frame bars and having a shank portion entering between the sides of the bracket, said shank portion being provided with a transverse slot therethrough, a Wedge member projecting through each pair of transversely aligned slots and through the slot in the adjacent T-bolt shank for clamping the adjacent end of the bracket against the adjacent frame bar with the bight portion of the bracket overlying the outer marginal rib of said frame bar, the end region or each bight portion at each end of the bracket being formed with a clearance notch therein to clear the outer marginal rib of the adjacent frame bar, there being a series of nail holes in each of said attachment tlanges, a form extension board bridging the distance between said opposed frame bars and having an inside face substantially liush with the inside faces of the panel unit facings, and a series of attachment nails extending through said nail holes and secured in said board.
4. In a concrete wall form structure, the combination set forth in claim 3 and wherein the sides of the bracket are substantially at and are slightly divergent and the bight portion of the bracket is arcuate in transverse cross section.
5. In a concrete wall form structure, in combination, an opstanding prefabrcated panel unit adapted with similar units in coplanar relation to form one side of the structure and embodying a rectangular facing and a rectangular reinforcing frame connected to and extending around the margin of the facing and embodying vertical and horizontal frame bars, there being an elongated slot in one of the bars of the reinforcing frame, an ertension bracket extending at right angles to and outwards from the one frame bar and having its inner end abutting against the slot-equipped portion of said one frame bar,- said extension bracket comprising an elongated metal stamping of generally U-shaped cross section consisting of spaced apart sides connected together by a bight portion, the free marginal portions of said sides being turned laterally outwardly -away from each other to provide a pair of coplanar attachment flanges, said sides being provided in the end portions thereof that are nearer said one frame bar with a pair of transversely aligned slots, a T-bolt projecting through the elongated slot in said one frame bar and having a shank portion entering between the adjacent end portions of the sides of the bracket, said shank portion being provided with a transverse slot therethrough, a wedge member projecting through the pair of transversely aligned slots in the sides of the bracket and through the slot in the shank of the T-bolt and serving to clamp the inner end of the bracket against said one frame bar, there being a series of nail holes in each of said attachment flanges, a form extension board disposed in coplanar relation with the facing of (References on following page) References Cited in the le of this patent UNITED STATES PATENTS Trester Nov. 3, 1925 Miller Sept. 10, 1929 Fischer July 14, 1931 Wales May 2, 1933 Roberg Feb. 27, 1934 Harrington Nov. 29, 1938 10 Symons June 2, 1953 Banneyer Nov. 9, 1954 Symons Dec. 17, 1957 Paxton Iuly 21, 1959 Imonetti Aug. 9, 1960 OTHER REFERENCES Symons Catalog M-7, pages 9 and 10, Symons Clamp & Mfg. Co., Chicago 39, Ill.