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Sept. 20, 1938. A. E. GRANT 2,130,424 ' ATTACHMENT PLUG I Filed June 29, 1936 2 Sheéts-Sheet 1 /. ATTORNEY Sept. 20, 1938. ‘ A, 5, GRANT 2,130,424 ATTACHMENT PLUG Filed June 29, 19,36 . ‘l’. ‘ 11 10 £0 20 53 40’ 2 Sheets-Sheet 2 I?’ f’)l 15 * 55 4/15], ' 30 ' (5'6" Q INVENTOR lb‘erf .?ranf ATTORNEY 2,130,424 Patented Sept. 20, 1938 UNITED ‘STATES PATENT OFFICE 2,130,424 ATTACHMENT PLUG Albert E. Grant, New York; N. Y., assignor to Albert T. Otto & Sons, 1110., New York, N. Y. Application June 29.1936. Serial No. 87.879 6 Claims. (01. 173-461) ' My invention relates to the male elements of to provide in an end plug a contact blade or electrical coupling devices of the type .commonly prong member having an integral ?anged foot known as attachment plugs, end plugs, or con portion in which the bend de?ning the foot por nector caps. Such devices are commonly carried tion is sturdily reinforced to stiffen and strength 5 on the ends of extension cords and comprise an en the construction and to insure that the prong a insulating cap or body and a pair of spaced metal will remain inalignment in use and will not be contact blades or prongs to which the extension subject to bending and breaking. Other and ' cord wires are connected. More particularly my further objects will appear from the following invention relates to the metal conducting parts an of such devices. - Male plugs of the character here dealt with are sold in large quantities at low prices and, commercial competition being keen, inferior de vices have become common in which the insulat 15 ing material is of comparatively lowvdielectric strength and the metal parts are formed of steel or other fast rusting metal of comparatively low conductivity rather than the. more expensive and highly desirable brass. The speci?cations which 20 the manufacturer is ordinarily required to meet speci?cation. 7 Referring to the drawings which form a part 10 of this speci?cation: -0 Figure 1 is an elevational view, partly in sec tion, showing an end plug embodying the features of my invention in coupled relation with a stand ard receptacle plug member. _ 15 Figure 2 is an inverted plan view of the male member embodying my invention. Figure 3 is a perspective view ofmy improved blade or prong. ' . demand that the blades or prongs comprise con Figure 4 is an elevational view, partly in sec- 20 tion, showing a modi?ed embodiment of my in ducting metal of approximately one-sixteenth inch thickness in order that they will have the vention. Figure 5 is a perspective view of the prong - necessary strength and stiffness to maintain their member shown in Figure 4. s. - 25 position and alignment, such requirements being directed to the mechanical efficiency of the device. Figure 6 is aview similar to Figure 1 showing 25 my improved end plug in coupled relation with Such weight of .blade material is not necessary Y a standard receptacle having contacts located for electrical e?iciency because, as will be readily adjacent to the inner walls of the sockets. The device comprises an insulating body or understood, the current load carried by the con to tact blades can be no greater than the capacity cap l0 having a central wire passage therethru 80 of the comparatively light wires of the extension at H, the face of the cap being recessed inter cord. ' mediate its margins at l2. A pair of plug-in It is a principal object of my invention there contact members "-44 are secured to the re fore to provide an end plug having improved cessed portion of the cap on opposite sides of the as blades or prongs so formed as to obtain greatly central wire passage Ii by means of studs or ‘ increased strength and sti?ness, thereby permit- _ ’ staples 20-20 which extend through the ?anged ting the use of blade metal of lighter gauge than foot portions l8 0! the members and into the has heretofore been practicable, and making it walls of the cap. A binding terminal 2| is possible to produce a device oi the highest quality - threaded through each of the foot portions and 40 at reduced cost. ‘ The blade or prong members of end plugs are usually formed with foot portions whereby they extends into a recess- in the cap formed to ‘3 receive it. ' The contact members are formed from iiat are attached to the insulating housing or cap, the metal by means of progressive dies adapted to [foot portions comprising i?anges integral with form a deep reinforcing channel I‘! in the prong 45 the projecting portions of the blades and pro- ‘ or blade portions I5 over the greater part of 45 their area intermediate their edge margins and . vided with means whereby the ends of the ex tension cord wires may be connected. These foot the bends at It, the opposite face of each blade portions are ordinarily de?ried by a bend in _.the - having a corresponding rib embossed thereon at i ?at metal from which the conducting parts of ll The reinforcement of the blades thus provided 50 50,the plug are formed. I have found that the weakening e?ect of such bends often results in imparts to them great sti?ness and the overall the projecting prong portions becoming disaligned blade thickness from the outer surface of the rib in use and, in some cases,‘ the blades actually to the inner face of the-blade is at least double break at or closely adjacent to the bends. the thicknessof the metal from which the con- . .55 ‘ It'is another object of my invention therefore tact member is formed. The entering ends of the 5‘ 2., _ 2,180,424 2. A plug-in contact member for'an attach ment plug comprising ?at conducting metal blades being unchanneled, however, have only the thickness of the metal stock and are readily in serted in the socket apertures 36 of a standard convenience outlet or a receptacle plug member such as 35. transversely bent to de?ne a foot portion'and a prong portion perpendicular to said foot portion, said member having an angular ?ange integral ' with a side edge thereof in the corner de?ned be tween said foot and prong portions whereby the member is braced at and adjacent the bend, said This construction permits the use of very light gauged conducting metal having thickness'only one-half or even one-third that ordinarily re prong portion having a stiffening rib embossed thereon extending over the greater portion of its‘ 10 quired in devices of this type, the saving in the material employed permitting the use of the high est grade of brass without increasing the cost contacting area, and means carried by the foot I portion for connecting a wire thereto. above that of the cheapest steel prongs. 3. A plug-in contact member for an attach As shown, an opening is formed through the ment plug comprising ?at conducting metal embossed portion of each blade at 30 for engage transversely bent to de?ne a foot portion and a 15 15 ment by the usual protuberances 4| formed on the contact members 40 of female receptacles, prong portion perpendicular to said foot portion, . generally, where such female contacts are posi tionedagainst the outer walls of the receptacle " said member having an angular ?ange integral with a side edge thereof in the corner de?ned sockets. Where the female contacts are located 20 adjacent the inner walls of the sockets, as at -.40’ in Figure 6, their protuberances will be faced outwardly and will be engaged by the shoulders 3| de?ned at the lower end of the channel adjacent 25 the opening 30. To further strengthen and stiffen the struc ture, particularly where the lighter metal is em ‘ployed, an angular ?ange 33 is formed in the angle de?ned by the bend. l9 dividing the prong and foot portions of the device. This bracket-like ?ange is readily formed by swaging the metal at the time the bend I9 is imparted to it and braces the blade most e?iciently, holding it at all times in accurate alignment perpendicular to the foot portions and overcoming any tendency for the 35 blade to bend or break at or adjacent the bend. The modi?cation shown in Figures 4 and 5 em between said foot and prong portions whereby the member is braced at and adjacent the bend 20 therein, and means carried by the foot portion for connecting a wire thereto. 4. An attachment plug comprising a housing of insulating material having a wire passage therethrough and a pair of contact blades pro jectlng therefrom, each of said blades compris ing a straight strip of ?at conducting metal less than one-sixteenth inch in thickness having a longitudinally extending reenforcing rib em bossed on one face and a corresponding channel in the opposite face thereof, said channel ex‘ tending over the greater portion of the project ing area of the blade and terminating adjacent the free end of the blade to form a shoulder po sitioned for engagement with the usual protuber ances carried by the contact elements of standard bodies blades having the same structural'char- . receptacles. ‘ 5. A plug-‘in contact member for.an attach acteristics as the blades described in Figures 1 ment plug comprising a thin strip of ?at, conduct to 3 and in addition illustrates the blade tips 5!] ing metal having a _ longitudinal stiffening rib reduced in width, extended in length, and bent 40 back upon themselves to reinforce the structure. embossed on one face and a corresponding chan at that point and to provide shoulders 5l-5l de?ned by the inwardly turned blade ends, such shoulders being adapted for engagement under nel in the opposite face thereof, the end portion of the strip being of less width than said rib and _ reversely bent into said channel, the end edge of the strip terminating to form a transverse shoul 45 the protuberances ll’ of receptacle contact mem 45 der positioned for engagement by the usual pro bers 40' (indicated in‘ broken’ line in Figure 4) where such members are located adjacent th ' tuberance carried by the contact element of a inner walls of the socket openings. ,~ standard receptacle. . ' Having thus described my invention, I claim: 50 1. An attachment plug comprising an insulat ing body having a central wire passage therethru, conducting members carried by the body on op posite sides of said passage, said members each. comprising a strip of ?at conducting metal trans versely ‘bent to de?ne a foot portion whereby the 55 member is attached to, the body and a prong i portion projecting perpendicularly from the foot portion, said members each having an angular ?ange integral with a side edge thereof in the 60 corner de?ned between said foot and prongvpor tions to brace the, members at and adjacent the bends therein, each of said prong portions being stamped intermediate its margins to provide a longitudinal reinforcing rib on one face and a 65 corresponding channel on the other face thereof, and wire binding terminals carried by. each of said members. " 6. vA plug-in contact member for an attach ment plug comprising a thin strip of ?at conduct ing metal transversely bent to de?ne a foot, and 2. prong perpendicular to said foot, said member having an angular ?ange integral with a side edge thereof in the corner de?ned between said foot and prong whereby the member is braced‘ adjacent the bend therein, said prong havinga longitudinal stiffening rib embossed on one face and a corresponding channel in the opposite face" thereof-‘,the end portion of said‘ prong being of less width than said rib and reversely bent into‘ said channel. the end edge of the prong termi nating to form a transverse shoulder positioned for engagement by the usual protuberance car ried by the contact element of a standard re ceptacle. ' ALBERT E. GRANT.