Wrenching tool

Abstract: A rotary wrenching tool having an opening for receiving a polygonal head of a threaded member is sized to receive the heads of threaded members that are themselves sized in at least two different nominal sizes such that the ratio of the maximum and minimum of those nominal sizes lies in the range from 1.0053 to 1.1430 for square heads and from 1.0053 to 1.0600 for hexagonal heads, the tool bearing visible markings, preferably adjacent the opening of the tool, identifying said at least two nominal sizes. In a preferred form the visible markings identifying the at least two nominal sizes relate to nominal sizes in at least two different sizing systems, for example in metric, United States Standards or British Standard.

Description: This invention relates to rotary tools of the type used in rotating or "wrenching" fasteners such as bolts and screws having polygonal (e.g., square or hexagonal) heads. The invention particularly relates to tools capable of wrenching fastener heads designed, sized or marked in various measuring systems such as the metric system, the English or inch system such as the American fractional system (AF and SAE), and the British systems such as BA, BS and Whitworth (W). The tools have a uniquely configured opening for receiving a polygonal head of a threaded member. Many countries have adopted the metric measuring system for the manufacture of bolts, screws, nuts and wrenches. Such countries as France, Germany, Italy, Japan, Czechoslovakia and Russia today almost exclusively utilize the metric system for such manufactures. The United States, Canada, England, Australia, New Zealand and the like, use measuring systems based upon both the English (inch) and metric measuring systems. National standards or specifications have been adopted by many technically developed countries for sockets and other wrenches. These standards, which differ at least in part from one another, include SAE, ASTM, MIL, GGG-W, BS, FS, DIN, JS, CSN, JUS, and GOST. No uniform international standard has yet been accepted, although more than fifteen years have been devoted to the effort to reach a standard acceptable to all technically developed countries. Great Britain, for example, presently uses up to six different systems for marking spanners, sockets and other wrenches. The United States predominantly uses the English (inch) system (AF, ANSI, MIL and SAE) and, to some extent, the metric system (millimeters). The diversity in such standards has limited the development of new types of bolts, nuts and wrenching tools. Periodic reviews and revisions of such standards have not produced the necessary changes to cover rapid development of a new type of wrenches, and the issuance of new, updated standards often takes over fifteen years. Consequently, a vast number of different wrenching tools of various designs, openings and tolerances are manufactured throughout the world. A user is subjected to a never-ending inventory of wrenching tools to accommodate all of the sizes and measuring systems in existence today. This is costly and inconvenient for individuals and for industry in general. One attempt to simplify this situation is found in U.S. Patent 4,100,824 which desribes a wrench with a non-uniform interior configuration having one set of grooves sized in the English system and another set of grooves sized in the metric system. This patent does not address the problems created through the use of various additional measuring systems. Care needs to be taken with this system to insert the bolt or nut head in the correct set of grooves, and this wrenching system, moreover, generally is not suitable for use in impact or power sockets or in open end wrenches and British sized spanners and sockets. U.S.Patent 3 027 790 discloses a wrench having several moving parts as adaptors and does not appear to represent a practical solution to the problem, since professionals and serious amateurs appear to prefer solid one-piece wrenching tools with no extraneous parts. US-A-3 125 910 (Kavalar) discloses a wrench corresponding to the preamble of the appended Claim 1, and having an opening to receive a nut or other polygonal head, the opening consisting of inwardly and outwardly projecting lobes. The wrench, in use, applies pressure against flat faces of the nut by means of the inwardly extending lobes contacting the nut faces at specific locations. Moreover, a variance of more than 5° from that specific contact location has deleterious consequences. Kavalar makes no reference or suggestion that the tool disclosed is of any value in meeting the requirement for a wrench for use with polygonal heads sized according to two or more measuring systems. The present invention now provides a means of satisfying that requirement. Accordingly, the present invention provides a rotary wrenching tool having an opening for receiving a polygonal head of a threaded member, wherein: the opening has an axis of rotation and has an inner surface comprising a series of first surfaces concave to said axis of rotation and spaced about the circumference of the opening, and a series of second surfaces convex to said axis of rotation and spaced about the circumference of the opening, successive ones of said first surfaces being disposed between successive ones of said second surfaces around the circumference; each of the first surfaces is arcuate and is defined as the locus of points falling a given radial distance "r" from a first axis "a" itself spaced a distance "r 1 " from, but parallel to, said axis of rotation; each of the second surfaces is arcuate and is defined as the locus of points falling a radial distance R from a second axis spaced itself a distance R1 from, but parallel to, said axis of rotation; the dimensions and dispositions of the second surfaces are such that, in use, the contact made by the wrenching tool with the polygonal head is a contact between the arcuate second surfaces and the sides of the polygonal head of the threaded member; radial distance r equals radial distance R; and the tool does not include flat surfaces between and tangentially merging with the first and second surfaces; characterised in that: (a) each surface that forms part of the inner surface of the opening and is contiguous to an arcuate surface merges tangentially into that arcuate surface; (b) the tool is sized to engage the heads of threaded members that are sized in at least two different nominal sizes in at least two different sizing systems such that the ratio of the maximum and minimum of said nominal sizes ranges from 1.0053 to 1.1430 for square heads, and from 1.0053 to 1.0600 for hexagonal heads; and (c) the tool carries visible markings identifying said at least two different nominal sizes. With regard to the dimensions of the wrenching tool, R 1 desirably is larger than r 1 , and in the case where each second axis is angularly spaced from at least one next adjacent second axis by 60°, the ratio R 1 /r 1 desirably exceeds 1.5 and preferably exceeds 2.0. In this case also, R is equal to r. Also in this embodiment in which each second axis is angularly spaced by 60° from at least one next adjacent second axis, the adjacent arcuate surfaces preferably merge tangentially into one another. The terms "arc" and "arcuate" used herein refer to circles. The second axes of the embodiments described above may, if desired, be spaced from one another by 45° or by 90° to thereby provide an opening accommodating square heads of threaded members. Inwardly convex arcuate surfaces of different sizes may be interspersed with one another. The rotary wrenching tools of the invention preferably have head-contacting interiors sized to strongly and adequately grip polygonal fastener heads sized in two, preferably three, and up to six different nominal sizes. The ratio (determined as described above) for tools accepting square heads ranges from 1.0001 to about 1.1430 and for tools accepting hexagonal heads ranges from 1.0001 to about 1.0600. Also as the wrench opening sizes are varied (for example Figure 16) the included angle between any adjacent flats preferably is also varied to better accommodate fastener heads sized in different sizing systems. In a preferred form the wrenching tools of the invention are simple, single piece rotary wrenching tools having uniform interior configurations and no moving parts and which are specifically sized for turning fasteners (nuts, screws, bolts, etc.) having square, hexagonal or other polygonal heads such that one tool size is capable of strongly and adequately fitting polygonal heads nominally sized in at least two and up to six different nominal sizes and up to seven different system markings. By "rotary tool", "spanner" or "wrench", as used herein, reference is made to tools having openings which completely or partially encircle or encompass the polygonal beads of threaded fasteners such as bolts and screws to rotate the fasteners. Thus, such tools may be of the socket variety in which the rotary tool opening completely encircles the head of the threaded member and is moved into such position axially of the threaded member, or may be of the spanner or open-end wrench variety in which the rotary tool opening only partially encircles the head of the threaded member and may be moved into its wrenching position in a direction generally normal to the axis of the threaded member. Rotary tools include such tools as may commonly be referred to as socket wrenches, box-end spanners, ratcheting box-end, open end, nut drivers, flare-nut, lug-nut, crowfoot and combination wrenches, impact and power socket wrenches, flex-head wrenches, etc. In a preferred form of the invention wrenching tools are adapted for use with threaded members having square heads and are so sized as to accommodate maximum and minimum sized square-headed members such that the maximum ratio of the nominal distance across opposing flats of such maximum and minimum square-headed members ranges from about 1.0053 to about 1.1430. Similarly, wrenching tools adapted for use with threaded members having hexagonal heads are so sized as to accommodate maximum and minimum sized hexagonal headed members such that the maximum ratio of the nominal distance across opposing flats of such maximum and minimum sized members ranges from about 1.0053 to about 1.0600. Visible indicia are preferably carried adjacent each wrench opening, such indicia comprising at least two and preferably three or more specific but different nominal sizes in at least two different sizing systems. There are now described, by way of example and with reference to the accompanying drawings, a wrenching tool (also referred to as "wrenching system" or "wrench") according to preferred embodiments (Figures 15, 16, 17 and 18) of the present invention, some of those embodiments being described, for the sake of comparison, with reference to wrenching tools (Figures 1 - 14) of the prior art. In the drawings: Figure 1 is a broken-away plan view of a conventional two-contact point drive wrench, the wrench flats making contact with corners of a square or hexagonal bolt head as shown in phantom lines; Figure 2 is a broken-away plan view of a conventional three-contact point drive wrench similar to that of Figure 1; Figure 3 is a broken-away plan view of a conventional four-contact point drive wrench similar to that of Figures 1 and 2; Figure 4 is a broken-away plan view of a conventional wrench similar to that of Figure 1 but having internal wrench flats designed for turning square bolt heads; Figure 5 is a broken-away plan view of a conventional six-driving point wrench described in British Patent 508,761 for use with hexagonal bolt heads and which avoids contact with corners of a bolt head; Figure 6 is a broken-away plan view of a conventional twelve-contact point drive wrench for turning hexagonal headed bolts; Figure 7 is a broken-away plan view of a twelve-contact point wrench designed to contact hexagonal bolt heads without corner contact, of the type described in U.S. Patent 3,125,910 (Kavalar); Figure 8 is a broken-away plan view of a twelve-point drive wrench which does not contact corners of a hexagonal bolt, one type of which is shown in U.S. Patents 3,272,430 and 3,495,485; Figure 9 is a broken-away plan view of a twelve-contact point wrenching system of the type shown in U.S. Patent 3,079,819; Figure 10 is a broken-away plan view of a two-contact point wrench driving square and hexagonal nuts; Figure 11 is a broken-away plan view of a four-contact point wrench similar to that of Figure 10; Figure 12 is a broken-away plan view of a three-contact point wrench of the type described in U.S. Patent 3,695,124, used for hexagonal bolt heads and, which does not contact the corners of the heads, in a manner similar to that shown in Figures 10 and 11; Figure 13 is a broken-away plan view of a six-contact point drive wrench used for hexagonal bolt heads and which does not contact the corners of the heads; Figure 14 is a broken-away plan view of a twelve-point "spline" drive wrench of the type shown in U.S. Patent 3,675,516, used for turning splined members and also hexagonal bolt heads; Figure 15 is a broken-away plan view of a novel six-contact point wrenching tool; Figure 16 is a broken-away plan view of a novel eight-contact point drive wrench for use with square bolt heads; Figure 17 is a broken-away plan view of a novel eighteen-contact point drive wrenching system for turning hexagonal bolt heads; and Figure 18 is a broken-away plan view of a novel twenty-four-contact point drive wrench. To aid in understanding the concept of rotary wrenching tools in general, a brief explanation is given below of the contact that occurs between the working surfaces of a rotary wrenching tool and a nut or bolt head. With reference to the conventional wrench of Figure 1, for example, the wrench (10) has wrench flats (11), (12) which are spaced apart a sufficient distance to loosely accommodate the confronting flat surfaces (13), (14) of a hexagonal bolt, shown in phantom lines. If the wrench is turned in the direction of arrow A, it will be understood that the wrench flats bear against the corners of the bolt head, rather than upon the flat surfaces of the bolt head; this is referred to as "corner contact", and use of wrenches of this type can readily score and round the corners of bolt heads, particularly hexagonal bolt heads. With wrenches of the type shown in Figure 7 on the other hand, the interior surface of the wrench opening makes contact not with the corners of the bolt head but rather at points (actually, lines) along the length of the flat bolt head edges. The rounded lobes (15) of the wrench (16) initially make line contact with the bolt head, but as pressure is applied, the bolt head edges are deformed slightly so that contact between the lobes and the bolt head occurs over a broader surface. Although certain wrench configurations, such as that depicted in Figure 8, have been advertised as providing "flat-to-flat" surface contact with hexagonal bolt heads, it will be understood that tolerances in the manufacture of both the wrench and the bolt heads prevent such contact from in fact being along the full surface of the wrench flats, such contact being in fact a line contact until the bolt head is suitably deformed by sharp edges of the wrench. Note that the wrench of Figure 8, in a manner similar to that shown in Figure 5, employs recessed portions to accommodate corners edges of fastener heads to thereby avoid corner contact with the heads. With reference to the tools exemplified in the drawings, such tools are characterized as having uniform interior configuration. That is, similarly configured interior surface elements (e.g., lobes) are radially spaced the same distance from the axis of the wrenching tool opening. For example, the lobes (15) depicted in Figure 7 are equally radially spaced from the axis X. The present invention provides rotary wrenching tools which have no moving parts and which are specifically sized for turning fasteners such as nuts, screws and bolts that have square, hexagonal or other polygonal heads. These wrenching tools are characterized by being capable of strongly and adequately fitting polygonal heads nominally sized in at least two different systems such as, for example, the American Fractional standard ("AF") and the British Standards ("BS", for example), and carrying at least two and preferably three or more suitable size markings in different size systems. That is, the rotary wrenching tools of the invention fit polygonal fastener heads such that scoring or rounding of the heads does not occur even when substantial wrenching torque is applied thereto. Such strong and adequate fitting of the tool to the head of the fastener is such that the application of excessive substantial wrenching torque is more apt to cause physical breakage of the fastener head from the threaded stem of the fastener, or simply cause the deformation ("stripping") of the stem threads. Of particular importance to this embodiment of the invention are those wrenches which have head-confronting surfaces that are contoured to provide recesses opposite corners of the heads to thereby avoid contact with the head corners. Most preferably, the head-confronting surfaces of the rotary tool are provided with inwardly protruding, rounded lobes positioned to encounter the head of a fastening member along flat surfaces of the head, rather than at its corners, the lobe, upon the application of substantial torque, tending to slightly deform the flat surfaces of the head to provide surface-to-surface contact between the wrench and head. The driving heads of bolts and similar fastening members can be sized in the metric system (e.g., mm) and also in inches using American Fractional ("AF") standards (SAE, MIL, etc.) and British standards such as "BS", "BA" and "W" (Whitworth) measurements. The wrenches are sized so as strongly and adequately accommodate fastener heads of at least two different nominal sizes such that the ratio of the nominal distances across opposing head surfaces falls, in the case of square heads, within the range of 1.0053 to 1.1430, and, in the case of hexagonal heads, with the range of 1.0053 to 1.0600. Table I set out below provides a non-inclusive, exemplary list of nominal head openings and size combinations for square and hexagonal head fasteners. Referring, for ease of explanation, to the first entry in the table, this entry describes a wrench which will fully and adequately engage the polygonal head of a threaded fastener that has the nominal dimensions of 1.5mm & 1/16 (AF, U.S. standard) & 16 BA (British standard). As shown in the table, 1/16 inches converts to 1.5875 millimeters. 16 BA, in the British standard, corresponds to 1.4224mm. 1.5mm, in the metric system, is, of course, 1.5mm. The maximum ratio of the maximum nominal distance across flats (1.5875) to the minimum nominal distance across flats (1.4224) is 1.1161, and this is recorded in the final column of the table. As further explanation, the last entry in the table refers to a fastener head having a nominal distance across opposing flats of 220mm. The wrench of the invention, suitably sized, also fully and adequately fits fastener heads sized in the U.S. American Fractional system as 8 5/8" & 8 3/4". The latter nominal values correspond to 219.0731mm and 222.2481mm, respectively. The maximum ratio of the maximum nominal size to the minimum nominal size hence is 222.2481/219.0731, or 1.0145. The ratios thus referred to are calculated according to the following formula: Ratio = maximum nominal head size in millimeters minimum nominal head size in millimeters The rotary wrenching tools of the invention carry visible markings identifying at least two different nominal sizes on at least two different sizing systems, for example visually readable markings indicating the at least two and preferably three different head sizes for which they were designed. For example, the first wrench appearing in Table I may be marked "1.5 mm & 1/16in. & 16 BA". The table has been computed using international (ISO) and many national standards and specifications from the United States (SAE, ANSI, MIL, ASTM), British (BS), German (DIN), France (FS), Yogoslavia (JUS), Japan (JS) and specifications from various manufacturers in the United States, England, France, Germany, Canada, Japan, Italy, Sweden, Spain, Czechoslavakia, Yugoslavia, Taiwan, China, Brazil, etc. With reference to the drawings, each figure shows positions of a bolt head within the gripping opening of a rotary wrenching tool, the bolt head positions shown in phantom lines referring to the smallest bolt head that can be fully and adequately gripped by the tool. Certain of the Figures also show a wrenching tool in both a socket form (wherein a full circle in either solid or dotted lines appears about the bolt head) or in open-ended wrench form. In Figure 3, for example, a socket is shown in dotted lines as (17), the open-ended wrenching tool version being shown in solid lines as (18). In Figure 4, for example, similarly, the socket embodiment is shown in solid lines as (20) and the open-ended embodiment is shown in phantom lines as (22). Further, alternate positions for the ends of the open-ended embodiments may be varied, and several positions are shown, for example, in Figure 14. The following non-limiting examples will serve to more clearly illustrate various further embodiments of the invention. Example I With reference to the embodiment shown in Figure 15, socket and open-end rotary wrenching tools shown generally at (20) and (22) are sized so as to strongly and adequately grip the hexagonal heads of threaded fasteners sized 4 mm & 5/32" & 8 BA, giving a ratio of 1.0363. The wrench of Figure 15, as shown from the drawing, has an axis of rotation X that extends normal to the plane of the paper and has an opening for receiving the polygonal head of a threaded member, in this case, a hexagonal head shown as "H". The opening has an inner, head-confronting surface comprising a series of arcuate first surfaces (24) concave to the axis of the opening and spaced about the circumference of the opening. Each such first surface is defined generally as the locus of points falling a given radial distance r from a first axis "a" that is itself spaced a distance r 1 from, but parallel to, the axis X of the opening. Between the arcuate first surfaces (24) are positioned a series of arcuate second surfaces (26) which are convex to the axis of the opening and are spaced about its circumference, each such second arcuate surface being defined general as the locus of points falling a radial distance R from a second axis A which is itself spaced a distance R 1 from, but parallel to, the axis X of the opening. Each surface that forms the opening and that is contiguous to an arcuate surface tangentially merges into that arcuate surface. R 1 preferably is larger than r 1 , and the ratio R 1 /r 1 desirably exceeds 1.5 and preferably exceeds 2.0. The arcuate second surfaces (26), it will be noted, form "lobes" having rounded surfaces for making contact with the flats of a hexagonal head of a threaded member. One such member, designated "h," is shown in operative contact with the lobes. Each second axis A is angularly spaced from at least one next adjacent second axis A by 60°. With further reference to Figure 15, rotary wrenching tools of this general configuration may be manufactured as socket, box-end, open-end, flare nut, nut driver and crowfoot wrenches, sized for receiving hexagonal fastener heads nominally sized as follows: 10 mm & 3/8" (AF) (ratio of 1.0499); 11 mm & 7/16" (AF) & 3/16 W (Whitworth) & 1/4 BS (ratio of 1.0275); 19 mm & 3/4" (AF) & 3/8 W & 7/16 BS (ratio of 1.0563). Similarly, rotary wrenching tools configured as shown in Figure 15 may be designed as socket, box-end and crowfoot wrenches, sized to accommodate hexagonal fastener heads nominally sized as 28 mm & 27 mm & 1 1/16" (AF) & 1 1/8" (AF) & 5/8 W & 11/16 BS, the wrench having a ratio, as defined above, of 1.0588. Other wrenching tools configured as shown in Figure 15 may be provided as socket and box-end tools sized to receive hexagonal fastener heads nominally sized as 32 mm & 33 mm & 1 5/16" (AF) & 1 1/4" (AF) & 3/4 W & 7/8 BS, the wrench having a ratio of 1.0500. Yet another wrench configured as shown in Figure 15 may be provided as a socket wrench sized to receive hexagonal fastener heads nominally sized as 220 mm & 8 5/8" (AF) & 8 3/4" (AF), the ratio of which is 1.0145. Example II Socket and Box-End rotary wrenching tools of the invention can be sized to receive hexagonal heads of threaded members nominally sized 35 mm & 34 mm & 1 3/8" (AF) & 1 5/16" (AF) & 13/16W & 15/16 BS, the tool having a ratio, as defined above, of 1.0591. Similarly, socket wrenches nay be designed to receive hexagonal heads of threaded fasteners nominally sized as follows: a) 105 mm & 4 3/16" (AF) & 4 1/8" (AF) & 2 3/4 W & 3 BS, the ratio being 1.0152; b) 140 mm & 5 5/8" (AF) & 5 1/2" (AF) & 3 3/4 W & 4 BS, the ratio of which wrench is 1.0227. c) 200 mm & 7 7/8" (AF) & 8" (AF), with a ratio of 1.0160. If the wrenching tool shown in Figure 15 in which R is equal to r is modified so that R 1 is approximately equal to r 1 , then tools of the general type shown in Figures 16, 17 and 18 are obtained. Referring to Figure 16, eight contact points or lobes (26) are provided. This wrenching tool is particularly adapted for receiving square heads of threaded fasteners. The inner surface of the tool includes portions designated (30) which are generally flat surfaces and that extend between the arcuate first and second surfaces. Such flat surfaces (30) may be oriented so as to come into generally surface-to-surface contact with the flats of a threaded member head, as shown in Figure 16, the angular dimensions appearing in Figure 16 being adapted to promote such surface-to-surface contact. Figure 17 and 18 show tools somewhat similar to that shown in Figure 16, except that the tool of Figure 17 has its lobes angularly spaced 20° apart and the tool of Figure 18 has its lobes spaced angularly 15° apart. Note is made that the spacing between adjacent second axes A of the embodiments of Figures 16, 17 and 18 are generally less than 3R in which R is as described above in connection with Figure 15. Example III Socket and box-end rotary wrenching tools may be designed and manufactured in the configuration shown in Figure 16 and specifically sized in accordance with the invention to receive square heads of threaded fasteners nominally sized 13 mm & 1/2" (AF) & 1/4 W & 5/16 BS, and having a ratio of 1.0500. Similarly, socket, box-end and open-end wrenching tools may be designed and manufactured in accordance with the configuration of Figure 16 and sized for receiving square-headed fasteners nominally sized 16 mm & 5/8", and having a ratio of 1.0079. The same socket and box-end tools may be designed and manufactured in accordance with the configurations of Figures 17 and 18 and sized to receive hexagonal fastener heads nominally sized 16 mm & 5/8" (AF), the tools having a ratio of 1.0079. The visible markings carried by the tools of this invention are conveniently adjacent the tool opening, identifying at least two and preferably three or more different fastener head sizes. Exemplary markings are shown in Figure 15, the markings (4 mm & 5/32 AF & 8 BA) being stamped, in this example, onto or into the handle of the tool. Rotary wrenching tools in the form of sockets would normally have markings on the outer socket surfaces. While preferred embodiments of the present invention have been described, it should be understood that various changes, adaptations and modifications may be made therein without departing from the scope of the appended claims.

Claims: A rotary wrenching tool having an opening for receiving a polygonal head of a threaded member, wherein: the opening has an axis of rotation (X) and has an inner surface comprising a series of first surfaces (24) concave to said axis of rotation and spaced about the circumference of the opening, and a series of second surfaces (26) convex to said axis of rotation and spaced about the circumference of the opening, successive ones of said first surfaces (24) being disposed between successive ones of said second surfaces (26) around the circumference; each of the first surfaces (24) is arcuate and is defined as the locus of points falling a given radial distance "r" from a first axis "a" itself spaced a distance "r1" from, but parallel to, said axis of rotation (X); each of the second surfaces (26) is arcuate and is defined as the locus of points falling a radial distance R from a second axis (A) spaced itself a distance "R1" from, but parallel to, said axis of rotation (X); the dimensions and dispositions of the second surfaces (26) are such that, in use, the contact made by the wrenching tool with the polygonal head is a contact between the arcuate second surfaces and the sides of the polygonal head of the threaded member; radial distance r equals radial distance R; and the tool does not include flat surfaces between and tangentially merging with the first and second surfaces; characterised in that: (a) each surface that forms part of the inner surface of the opening and is contiguous to an arcuate surface merges tangentially into that arcuate surface; (b) the tool is sized to engage the heads of threaded members that are sized in at least two different nominal sizes in at least two different sizing systems such that the ratio of the maximum and minimum of said nominal sizes ranges from 1.0053 to 1.1430 for square heads, and from 1.0053 to 1.0600 for hexagonal heads; and (c) the tool carries visible markings identifying said at least two different nominal sizes. A tool according to Claim 1, which includes an inner surface contoured to provide, in use, recesses opposite corners of the heads of the threaded members so as to avoid contact with said corners. A tool according to Claim 1, which is specifically sized to receive heads of threaded members nominally sized in accordance with any one of the entries of the following table: A tool according to any of the preceding claims, which is a single piece tool. A tool according to any of the preceding claims, wherein said visible markings comprise at least two specific but different nominal sizes in at least two different sizing systems. A tool according to any of the preceding claims, wherein said visible markings are adjacent said opening.

Inventors: RUZICKA JOSEF, RUZICKA MILAN, RUZICKA PETR O, RUZICKA, JOSEF, RUZICKA, MILAN, RUZICKA, PETR O.
Applicants: RUZICKA JOSEF, RUZICKA MILAN, RUZICKA PETR O, RUZICKA, JOSEF, RUZICKA, MILAN, RUZICKA, PETR O.
Application year: 1986
Main classification: B25B13
IPC codes: B25B13