Socket wrenches
United States Patent [1 1 Erin [451 Apr. 15, 1975 1 SOCKET WRENCHES [76] Inventor: Harold Gustave Erm, 128 Westover Ave., West Caldwell, NJ. 07006 [22] Filed: Jan. 2, 1973 [21] Appl. No.2 320,658  
 [52] U.S. Cl 81/121 R [51] Int. Cl B25b 13/06 [58] Field of Search 81/121 R, 121 B, 177 B, 81/177 G, 185, 177 R [56] References Cited UNITED STATES PATENTS 838,109 12/1906 Hanes et a1. 81/121 RX 1,584,208 5/1926 Bellows 81/121 R 2,054,978 9/1936 Hoelscher.. 81/121 R X 2,502,587 4/1950 Phipps 81/185 2,878,701 3/1959 Weersma 81/121 R X FOREIGN PATENTS OR APPLICATIONS 1,240,971 8/1960 France 81/177 B Primary Examiner-A1 Lawrence Smith Assistant ExaminerJames G. Smith [57] ABSTRACT A wrench tool, such as a T wrench, including at least one wrench socket which can receive insertion into its recessed interior of a fastener-head of either of two types which differ from each other in shape and/or size and to engage the inserted head with an appropriate amount of torque-imparting contact between portions of the sockets interior surfaces and corresponding portions of outside surfaces of the head for it to be able to impart substantially as much torque thereto as it would be able to impart to a fastener head of the other type should that head, instead, be inserted into the socket. The recessed interior of the socket comprises: (1) an entrance-portion which extends into the socket for a distance d from its plane of entrance; and (2) a deeper-lying-portion which extends for a dis tance d from the bottom of the entrance portion to the bottom of the recessed interior of the socket. The entrance-portion can receive insertion of a fastenerhead of either of said two types and thereupon contact portions of exterior torque-receiving surfaces thereof with portions of its interior torque-imparting surfaces comprised in a respective one of two different groups thereof, but, depending upon the extent to which said heads differ from each other in shape and/or size, the sums of the areas of the head-contacting and torqueimparting surfaces comprised in the subdivisions included respectively in said two different groups thereof may be substantially unequal. To compensate for this the socket is so formed that any inserted fastener-head of the type which the entrance-portion is able to engage with substantially more of its torqueimparting interior-surface areas than it can a head of the other type is prevented from being inserted into the socket beyond the bottom of the entrance-portion whereas a fastener-head of the other type, after it has been fully inserted into the entrance portion, will be free to move more deeply into the socket and, if this fastener-head is long enough, to be fully inserted into the more-deeply-lying portion for its full depth d whereupon it will be engaged by additional torqueimparting interior surfaces of that portion. The ratio of (d plus d) to d is such that, due to the additional torque which can be imparted in this manner to a fastener-head of said other type by interior surfaces of the deeper-lying-portion, the socket is able to apply substantially equal amounts of torque to fastenerheads of the two types.  
 2 Claims, 11 Drawing Figures PATENTEDAPR 1 51975 3,877,  
 snmeq g 6Q SOCKET WRENCHES BACKGROUND OF THE INVENTION This invention relates generally to socket wrenches. More particularly it relates to a wrench of improved effeciency comprising at least one socket which is adapted to securely grip, for imparting rotational torque threto, fastenerheads of more than a single size and/or shape, e.g., for securely gripping different nuts (or stud-heads) which may be (I) of a single size but different shapes such as square or hexagonal; or (2) of different sizes and a same shape; or (3) of different sizes and different shapes.  
  While it has not been an uncommon practice to attempt to use a socket wrench which was intended for gripping one particular type and/or size of fastenerhead for gripping one or more others, for example, to use a socket having a twelve-notched interior opening and intended specifically for gripping hexagonal fastener-heads of a particular size, for tightening or loosening a squareheaded nut or stud of some hopefully suitablyrelated size, this frequently incurs serious misuse of one or both of the wrench and the fastenerhead. Unfortunately, for one who attempts to do this. the respective dimensions measured across opposite corners of hexagonal and square fastener-heads of a same (or, for that matter, of nearly a same) size&#34; are quite different, e.g., that of an one-half-inch hexagonal fastener-head is: l very much smaller than; (2) substantially smaller than; and (3) substantially larger than those of square fastener-heads of one-half-inch; seven-sixteenths-inch; and three-eights-inch sizes respectively. Because of the existance of differences like these the usual practice among mechanics who seek to use .(or misuse) sockets in this way is for them to rely on trial and error in order to find a twelve-notched, or..for that matter., a sixnotched, socket, which will happen to afford an approximate fit for the four corners of a square-headed fastener and then to trust to luck that neither the fastener nor the tool will be damaged by using it in this unintended way. In any event this practice is always unsatisfactory to the extent that it occasions wastage of time due to the use of trial and error. Moreover the liklihood of damage is really considerable for an additional reason besides that of a probable poor size fit. This is that the gripping corners of either a twelve-notched or a sixnotched socket for hexagonal fastener-heads include a much wider angle (120 degrees) than that of a 90 degree corner which is most suitable for gripping a square-headed fastener. As a consequence and particularly if the fit is at all loose it is not at all uncommon to crack open an hexagonal socket when it is used for applying high torque substantial rotational forces to a squareheaded fastener, and/or to blunt or shearoff the corners of the fastener.  
  Accordingly it is an object of this invention to provide a wrench socket of improved suitability for quickly, safely, and effectively applying substantial amounts of torque to fastener-heads of more than a single shape and/or size.  
  It is a further object to provide a unitary tool which includes at least one of the novel sockets disclosed herein attached to a free end of one of at least two cross-connected arms, e.g., cross-connected like a T or L wrench handle, whereby it can handle a substantially larger number of fastener-heads than the number of its said sockets, and affords means for reaching into wells and/or recesses within which fasteners may be located, such as oil-drainage plugs in the bottoms of the crankcases of rotary lawn mowers, and for applying substantial torque to any of its sockets without any need of attaching a separate handle or handle-extension to it.  
  In general these and other objects may be attained in accordance with the present invention by departing from the prior and current practice of configuring and sizing a socket so that as many portions as possible, i.e., as large a percentage as possible, of the total area of its recessed interior will be usefully involved in, and therefore will contribute to, the functions of holding-captive and constraining-rotationally a fastener-head of a single particular predetermined type, i.e., a fastener-head of one particular shape and size, whenever the socket is used in its intended and normal manner to engage a fastener-head. Instead, according to the present invention a socket is so formed: (1) that respective groups of subdivisions the total interior torque-imparting surfaces of an entrance-portion of the recessed interior of the socket are shaped and sized for imparting torque to different ones of a plurality of fastener-heads of different types, i.e., of fastener-heads of different shapes and/or sizes; and (2) that to this end the torqueimparting surfaces comprised in each of said groups of subdivisions, are so configured and sized that they will very precisely conform to corresponding portions of outside surfaces of a predetermined different one of said plurality of fastener-heads of different types.  
  As will be seen, the sums of the torque-imparting areas of the subdivisions comprised in the abovementioned respective groups thereof may be substantially unequal whereby the entrance-portion may not be capable of imparting as much torque to heads ofone type as to others. To compensate for this the socket may be so formed: (1) that its recessed interior also comprises a deeper-lying-portion into which only a head of said one type can be inserted in torquereceiving relationship, and, more particularly, that it can do so because when such a head is inserted into the entrance-portion it will be guided by and thereupon pass thru it into the deeper-lying portion; and (2) that the deeper-lying-portion is provided with headcontacting, torque-imparting interior surfaces all of which are shaped and sized to contact exterior torquereceiving surfaces of only heads of said one type. Because of this the relative depths of the entrance-and deeper-lying-portions of the socket may be proportioned so that the socket can impart substantially equal amounts of torque to heads of said different types.  
 BRIEF DESCRIPTION OF THE DRAWING FIG. 1 illustrates the undesireability of using an hexagonal socket for engaging a square-headed fastener;  
  FIG. 2 is a side, partially-sectioned view of a T wrench which includes two sockets of the kind disclosed herein;  
  FIGS. 2a, 2b, and 2c are end views of three sockets included in the T wrench of FIG. 2; and  
  FIGS. 3a, 3b, 3c, 3d, 3e, and 3f are end views of respective sockets embodying this invention, FIG. 32 being an enlargement of FIG. 2a and FIG. 312 being an enlargement of FIG. 2b.  
 DESCRIPTION OF EXEMPLARY PREFERRED EMBODIMENTS Referring now to FIG. 1, which illustrates a common prior and current practice, the recessed interior of a socket is formed with twelve notches 11 which are so formed that any set of six alternate ones thereof (a set comprising half of the notches) can fit snugly over and hold closely-captive by all of its six corners an hexagonal fastener-head of just one predetermined size, and, more particularly and to this end, the notches are formed so that each of them includes an angle of 120 degrees. A square fastener-head 12 of a size which, in the example shown, is 25% smaller than the hexagonal-head for which the socket 10 is intended, e.g., a six eighths inch square head assuming that the socket 10 of FIG. 1 is of one inch size is represented as contained within the socket. Partly because of the fact that the fit of the head 12 in the socket 10 will usually be a very loose one (as a consequence of its being randomly arrived at and therefore largely a matter of almost pure chance), but also and more so because of the fact that the square, ninety degree corners of the head 12 can not be gripped snugly in the 120 degree notches 11, when torque is applied, as shown as rotational force at 13, it will cause the corners of the head 12 to slide against the sloped sides 14 of the notches causing a large part of that force to be converted into components-which are directed outward radially and which in actual practice will often prove to be large enough to stretch the recessed interior of the socket along a diameter thereof and even to break it open. If the material of the head is softer than that of the socket its corners may become rounded and/or shorn-off, and, if the socket material be quite brittle, both undesireable types of damage may ensue.  
  Referring now to FIG. 2, there is shown a T wrench comprising a lever-arm 21 and a cross-arm 22 and three sockets 23, 24, and attached respectively to: the free end of the lever-arm; the left free end of the cross-arm; and the right free end of the cross-arm (as they appear in the drawing). In the socket 23 (see FIGS. 2a and 3e) and also in the somewhat similar socket 23 (see FIG. 3e), the periphery of the recessed interior of the socket, i.e., the distance around its recessed interior near to the entrance thereof, comprises two groups of subdivisions: a first group of subdivisions 31 which provide the socket with the capability of holding snugly captive within the socket a first particular type of fastener-head, namely a square head represented in dotted outline at 34, of a predetermined size; and, (b) a second group of subdivisions 32 which provide the socket with the same capability with respect to a second particular type, namely an hexagonal head represented in dotted outline at 35, of slightly larger size. It is to be understood that for the purposes of this specification the intended meaning of the word size is: (l as applied to a fastener head, the distance between pairs of opposite, parallel, and similiarly spaced external flat sides of the head, such as the distance between the sides 36 of head 34 or the distance between the sides 37 of the head 35; and (2) as applied to a socket, the distance between respestive pairs of internal flat surfaces thereof between which pairs ofthe above mentioned external flat sides will be held captve in the intended use of the socket.  
  The particular size relationship between the heads 34 and 35 which has been chosen as an illustrative example herein, i.e., solely by way of example, is that the size of the square one is 12 and /2 percent smaller than that of the hexagonal one, e.g., that the former may be 7/l6ths of an inch in an embodiment of this sort wherein the latter is one-half inch.  
  It is noted that the sum of the lengths of the subdivisions 32 comprising one group thereof which are allotted to contacting external surfaces of the hexagonal head 35 for imparting torque thereto comprises about of the total peripheral distance as measured around the recessed interior of the socket 23 in a plane parallel to its plane of entrance and that the sum of the lengths of those 31, comprising a second group thereof which are allotted to so contacting exterior surfaces of the square head 34 comprises a substantially smaller percentage thereof, namely 40% thereof, which in this embodiment is the remainder of that total distance, inasmuch as in this embodiment the subdivisions are mutually exclusive. Tho in the case of the particular embodiment 23 the groups comprising the subdivisions 31 and 32 respectfully do happen to be mutuallyexclusive, as shown in FIG. 3d they do not necessarily have to be, and, in fact, whenever possible it will be advantageous if they are not, since this will usually increase the over-all torque-imparting capability of the socket.  
  As shown in various forms in each of FIGS. 2, 3a, 3b, 3c, 3d, 3e, and 3f, it is also possible to allott respective portions of the potentially usable areas of interior surfaces of sockets as measured in the depth direction (i.e., as measured inwards from the entrance planes of sockets toward their bottoms) to afford the respective portions with the capability, in the manner explained above, of imparting torque to different predetermined types of fastener-heads. For example in the case of the socket 23, two portions of its recessed interior, an entrance-portion a (of a depth d as measured into the socket towards its bottom from its plane of entrance) and a deeper-lying-portion d (of a depth d&#39; as measured from the bottom of the entrance-portion to the bottom of the socket), are respectively allotted as follows: l the portion d is allotted to holding captive for imparting torque thereto either an hexagonal head of a certain size or a square head of a 12.5% smaller size, this portion of the socket being capable of receiving only a portion of the end of such an hexagonal head which, as measured along its length-dimension (measured in the direction of its rotational axis for tightening or loosening), is no longer than the distance d (or of receiving all of such an hexagonal head if its length is no greater than (I); and (2) the deeper-lying-portion d is allotted to holding captive the end portion of a square fastener-head which is long enough to be insertable into the socket more deeply than the distance d. It will be apparent from the foregoing that by proper choice of the ratio between the dimensions d and d it will be possible to compensate for the difference (60% vs 40%) between the respective amounts of peripheral engagement between the entrance-portion of the recessed interior of the socket and the two different fastener-heads which that portion is adapted to grip whereby to provide the socket with substantially equal torque-imparting capability with respect to both.  
  Referring now to FIG. 3d, the socket 43 shown therein, like the socket 23 of FIG. 30, comprises two groups of subdivisions of the peripheral distance around its recessed interior (groups 41 and 42) which are allotted respectively to providing it with the capability of contacting to impart torque to two different types of fastener-heads, namely hexagonal and square heads of a same size. It is noted that in this case, as contrasted to that of the socket 23, not all of the peripheral subdivisions are mutually exclusive. Thus in this socket: (l) a central peripheral subdivision 42 of each of the two flat inside surfaces 45 of the recessed interior of the socket 43 is adapted to engage all of one of the six flat surfaces comprising the exterior of an hexagaonal head; and (2) all of each of these same surfaces 45 is adapted to engage all of one of the four flat exterior surfaces of a square head. The above referances to subdivisions of (or all of) an interior wall&#34; or of an external surface&#34; are intended to mean of the peripheral distance across said wall as measured in a direction parallel to the plane of entrance of the socket and of the corresponding peripheral distance across said exterior surface measured in a direction which is parallel to its intended plane of rotation. Insofar as the two fasteners which the socket 43 is intended to engage are hexagonal and square it resembles the socket 23. However it does not resemble it in that the present fasteners are of the same size. In the use of this socket (43) about 51% of the total peripheral distance around an hexagonal head can be contacted in torque-imparting relationship by a group of surfaces the sum of whose widths as measured in a plane of rotation of the socket comprises about 33% of the total peripheral distance measured around the recessed interior of the entrance-portion of the socket. While this is very good, e.g., it compares very favorably with what can be provided by the use of a conventional twelve-notched socket, this same socket (43) affords very much better gripping capability with respect to how much of the peripheral distance around a square head it can contact. namely, about 86%.  
 If desired it is possible to compensate for this disparity by allotting more of the depth of the socket 43 to holding an hexagonal than a square head. Thus the depth down to which a square head may go when it is inserted into this socket is limited by four shoulders (or ledges) 44 beyond which there is located a and deeperlying portion of the recessed interior of the socket 100% of the periphery of which is allotted to gripping the top portion of an hexagonal head which can reach into the socket deeply enough to pass the plane of the shoulders 44.  
  The socket 24 shown in FIG. 3b is adapted to grip either of two fastener-heads both of which are hexagonal but one of which is slightly, about 8%, smaller than the other, and also, optionally as explained below, one which is square. Examples of heads of such relative sizes are those of the 13/16 and three-fourths inch spark plugs employed in large numbers on small (yard power-tool) gasoline motors. In this embodiment the allottment of respective subdivisions of interior surfaces of the socket 24 to the function of engaging different types of fastener-heads is made only in the direction of its depth-dimension (d&#34; and d&#39; FIG. 2). If these subdivisions, i.e., entrance-portion d&#34; and deeper-lying-portion d, are made to be substantially equal to each other and if their sum be made equal to the average of the depth-dimensions of an adequate-numerical sampling of (N) heads of the two types, e.g., of thirteen-sixteenths and three-fourths inch hexagonal heads, which the socket is intended to engage, then in most cases it will be able to engage about 50% of the exterior torque-imparting surfaces of any particular one of these heads. In general this should be quite adequate, since, for example, it greatly exceeds the percentage of such surfaces of such hexagonal heads which can be gripped by either an open-end wrench (whether of fixed size or adjustible, i.e., or a monkey&#34; wrench) or a twelve-notched box wrench. Moreover in the particular case of spark plugs which do not require the use of extreme amounts of torque in either rotational direction, it should be even more adequate. Because of this it may be quite feasable, for such a specific embodiment, i.e., where the socket is intended for sparkplugs and therefore the torque-imparting requirements are moderate, to further reduce the respective percentages of the total area of interior surfaces of the socket 24 which are allotted to the gripping of the two types of heads mentioned above by suitably notching both the entranceand deeper-lying portions of the recessed interior of the socket to form additional peripheral subdivisions 46 whereby to enabling the socket to accept insertion of a third type of fastener-head, in the example suggested by the dotted lines 47 in FIG. 3a, a five-eighths inch square head and to engage that head in the subdivisions 46. Moreover, since a socket of this type is unusually deep because it is intended to accept insertion of the porcelain tips of spark plugs, the most-deeply-lying-portion of the recessed interior of the socket may be shaped and sized to engage top portions of exterior surfaces of a head 47 should it be long enough to extend into the socket beyond both the entrance-portion d and the deeper-lying-portion d&#34; of its recessed interior.  
  Tho the socket 50 of FIG. 3f embodies a different specific way of practicing the present invention than the socket 24 of FIG. 3b, they are both adapted to engage the same two different types of fastener-heads (both hexagonal but one 8% smaller than the other). In the socket 50 certain peripheral subdivisions 48 of its entrance-portion are allotted exclusively to the function of engaging corresponding portions of exterior surfaces of hexagonal heads of the smaller of the two sizes. i.e., they do not engage any portion of the periphery of exterior surfaces of heads of the larger of the two sizes. In this embodiment the shoulders (or ledges) 49 establish a stopping-plane or depth-limit beyond which a head of the&#39;larger of the two sizes will be unable to move more deeply into the socket whereas a head of the smaller size will be free to move into the socket for I all of its length dimension.  
  It is noted that this socket may be misused in somewhat the same manner as was explained above with reference to FIG. 1 if one should be careless in attempting to employ it to engage a head of the smaller of the two sizes and if he should as a result insert it without the corners of the head being fitted into the subdivisions 48. As a result of doing this: (1) the fit will be loose; (2) the insertion of the head will be prematurely stopped at the shoulders 49; and (3) due to (1) and (2), it may be possible to impose undesirable stresses on the socket in directions which tend to spread or break it. However it should not be difficult to avoid such possible misuse by watching for loosness of fit and limited depth of insertion. Moreover, even if one should insert a small head incorrectly, the undesireable radial pressures which will be exerted when torque is applied will occur at six points which are symetrically distributed around the perimeter of the interior of the socket rather than just four points as shown in FIG. 1 and therefore the results may be less harmful. This will be especially true when the socket 50 is used for engaging spark plugs because of the relatively low torques required.  
  The socket 52 of FIG. 3c combines features of the socket 23 (of FIGS. 2, 2a, and 3e) and the socket 43 (of FIG. 3d) in such a way that this one socket is adapted to engage three different types of fastenerheads; (I) an hexagonal head of a predetermined size; (2) a square head of an approximately 12.5% smaller size; and a square head of the same size as the hexagonal head. As shown in FIG. 3d and explained above, an hexagonal head can be inserted more deeply into the socket 43 than an equally sized square head which is stopped by the shoulders 44 at the bottom of the entrance-portion of its recessed interior, and, as shown in FIG. 3e. a square head can be more deeply inserted into the socket 23 than a larger sized hexagonal head which is stopped by the shoulders 33 and 39 at the bottom of the entrance-portion of its recessed interior. Likewise, in the case of the socket 52 the larger of the two square heads which this socket is intended to engage and which is of the same size as an hexagonal head which it can also engage will be stopped by four shoulders 54 at the bottom of the entrance-portion of its recessed interior beyond which, however. such an hexagonal head will be able to move and to enter more deeply into the socket. It is noted that the shoulders 54 thus serve in the socket 52 a purpose which is similar to that served by the shoulders 44 of FIG. 3d. And, likewise, an hexagonal head which this socket is intended to engage will be stopped at the bottom of a more-deeply-lyingportion of its recessed interior by shoulders 55 and 56 (which correspond to the shoulders 33 and 39 of FIG. 3e). On the other hand, a square-headed fastener of the smaller of the two sizes will be free to move past the four shoulders 54 and all of the shoulders 55 and 56 and thus to enter an even-more-deeply-lying-portion of said recessed interior which is provided in this socket, i.e.. will be free to be inserted into the socket more deeply than either a square head of the larger size or an hexagonal head of the same size. This is desireable since the peripheral subdivisions 31 which are shaped and sized to contact the smaller square head can not engage it at all within said entrance-portion and, tho they do engage it within said deeper-lying-portion, the sum of their areas comprises only about 40% of the total area of all of the head-contacting surfaces therewithin. To compensate for this by an expediant already explained above the recessed interior of the socket 52 is formed so that the smaller square head is the most deeply insertable one of the three heads which this socket can engage.  
  The socket 60 shown in FIG. 3a is adapted to grip either of two square fastener heads one of which is about 12.5% smaller than the other, e.g., one of which is seven-sixteenths of an inch in size (a common size for square oil-drainage plugs of small gasoline motors used for yard power tools) whereas the larger of the two is of one-half inch size. In this socket mutually-exclusive peripheral subdivisions 61 and 62 are allotted to gripping respective heads of the smaller and larger sizes in the entrance-portion of the socket lying between its plane of entrance and a plane containing four shoulders 63 whereby about 43% of the torque-receiving exterior surfaces of a head of the smaller of the two sizes will be engaged by interior surfaces an entrance-portion of the socket (down to the shoulders 63) versus almost 70% of the torque-receiving exterior surfaces of a head of the larger size. To compensate for this, in a manner already explained above with reference to other embodiments, a deeper-lying-portion is provided for the socket 60 and four shoulders 63 are provided to limit the depth into the socket to which heads of the larger of the two sizes can enter. In this way: (1) less of the depthdimension of the socket 60 is allotted to gripping heads of the larger of the two sizes: and (2) of the peripheral distance around the inside of said deeperlying-portion, i.e., of the portion below the plane of the shoulders 63 is allotted to engaging heads of the smaller of the two sizes.  
  Since all of the torque-imparting gripping surfaces of a wrench-socket are comprised in the side walls of its recessed interior, most of the improvements disclosed herein with respect to wrench-sockets per se can be embodied in box wrenches with substantially equal beneficial effects. Accordingly it is to be understood that the term wrench-socket as used herein and in the appended claims is intended to include sockets that are open at both ends and therefore have lever arms attached to their sides rather than to end closures, i.e., to include box wrenches.  
 It is also to be understood that any statements which may be made above to the effect that certain wrenchsockets and fastener-heads are of the same size are not intended to mean that they are exactly of the same size, since, of course, such a fastener-head must necessarily be slightly smaller than such a wrench-socket in order to enable it to be inserted thereinto without the use of undue force.  
 I claim:  
  1. A wrench-socket which is adapted to receive insertion into its recessed interior of a fastener-head of either of two different types, such as of different shapes and/or sizes, and to thereupon engage the inserted head with substantial torque-imparting contact between portions of interior surfaces of the socket and corresponding portions of outside surfaces of said head CHARAC- TERIZED IN:  
 that said recessed interior of the socket comprises (1) an entrance-portion which extends over a distance d between the plane of entrance of the socket and a bottom-plane which is parallel thereto and contains a plurality of shoulders for preventing fastenerheads of one of said two types from being more deeply inserted into the socket than said bottom-plane and (2) a deeper-lying-portion which extends over a distance a&#34; between said bottomplane and the bottom of the recessed interior of the socket; that said entrance-portion is adapted to receive insertion of a fastener-head of either of said two types as deeply as to said bottom-plane and to thereupon engage that head with a respective one of two different predetermined amounts of torqueimparting contact between portions of its interior surfaces and corresponding portions of outside surfaces of the inserted head and that, to that end, said entrance-portion comprises two different groups of peripheral subdivisions of its torque-imparting interior surfaces which are respectively adapted to closely-contact and thereby to engage in torque-imparting-relationship corresponding groups of torque-receiving peripheral subdivisions of exterior surfaces of fastener-heads of said two different types; that said deeper-lying-portion comprises interior surfaces which are adapted to closely-contact and thereby to engage in torque-imparting-relationship exterior surfaces of inserted heads of only the other of sad two types; that some of said Y group of subdivisions of interior surfaces of said entrance-portion which are adapted to contact exterior surfaces of fastener-heads of said other type are so alligned with predetermined portions of said interior surfaces of said deeper-lying-portion that a fastener-head of said other type upon being inserted into said entrance-portion is guided therethru past said shoulders and into the deeper-lyingportion whereby interior surfaces of both portions (1) and (2) of said recessed interior of the socket will engage that head in torque-impartingrelationship; that the sum of the areas of all torqueimparting surfaces comprised in the group of peripheral subdivisions of the entrance-portion which are adapted to engage a head of said other type comprises a substantially smaller percentage of the sum of all torque-imparting surfaces comprised in said entrance-portion than the percentage thereof comprised in the sum of the areas of all of said surfaces of said other group of peripheral subdivisions of the entrance-portion; and that the ratio of (d plus 1) to d is large enough, in proportion to the relative smallness of said substantially smaller percentage for said deeper-lying-portion to contribute enough additional torque-imparting contact to an inserted head of said other type to enable the socket to impart substantially equal amounts of torque to fastener-heads of said two types.  
  2. A wrench-tool according to claim 1 including a lever-arm and a cross-arm attached thereto, each of said arms having at least one free-end, wherein a wrench-socket is affixed to at least one free-end of one of said arms.