US3492630A - Electrical connector - Google Patents

Description

ELECTRICAL CONNECTOR Filed Jan. 25, 1968 3 Sheets-Sheet l FIG.

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BY SIDNEY GERHARD ymfi ffizh dill S. GERHARD ELECTRICAL CONNECTOR Jan. 27, 1970 3 Sheets-Sheet 2 Filed Jan. 25, 1968 S] DNEY GERHARD 5 h THE. E by E A 0 m: MQ NE m8 0& m3 N9 QE 0: 08 mm WWW www ,W/ w .H www v v S. GERHARD Jan. 27, I970 ELECTRICAL commcwon 3 Sheets-Sheet 5 Filed Jan. 25, 1968 m3 mom IUWMHHWWHWWMN.

Nmm 3mm QM Sm m \wm INVENTOR. SIDNEY GERHARD QR MMQ ATTORNEY United States Patent 3,492,630 ELECTRICAL CONNECTOR Sidney Gerhard, Norwalk, Conn., assignor to Burndy Corporation, a corporation of New York Filed Jan. 25, 1968, Ser. No. 700,449 Int. Cl. H01r 11/20 U.S.- Cl. 339-100 12 Claims ABSTRACT OF THE DISCLOSURE For establishing electrical connections with electrical cables which are formed of an outer insulating jacket surrounding a central conductive core of highly ductile metal, the electrical connectors of this invention are provided with threaded means for engaging the insulating jacket and cooperating threaded contact means which axially advance a contact member into the central conductive core of ductile metal. O-rings and washers are used for sealing purposes between cooperating members and for retaining contact members in their assembled positions. Interference-fit between cooperating parts is also used for sealing purposes to prevent escape of the ductile core material which is displaced on penetration by the axially advanced contact members.

This invention relates generally to electrical connections and connectors, and specifically to electrical connectors which are adapted for use with electrical cable of the type which comprises a core of highly ductile conductive material such as sodium, encased within a tubular insulating jacket of strong flexible material such as commercially available polyethylene.

Sodium conductor cables are of significant interest to the electrical power industry because the metal offers electrical characteristics comparable to the more commonly used copper and aluminum conductors, at substantially lower cost. It is known, however, that certain other physical characteristics of sodium and similar conductive metals differ substantially from those of the standard cable conductors.

Sodium, for example, is characterized by a high degree of chemical reactivity with air and water. The high ductility of the metal causes it to behave in a pseudofluid manner in response to unbalanced forces. And, the relatively low tensile strength of the material makes it a generally poor structural element.

As used herein the term sodium conductor refers to an electrical conductor of the type more fully described in US. Patents 3,333,049 and 3,333,050. The term sodium is illustrative of other alkali metals as explained in the aforementioned references. The term ductile as used herein is meant to characterize the physical characteristics of these pseudo-fluid metals to distinguish them from the permanently deformable electrically conductive metals such as copper or aluminum.

It has been found that many of the previously used connection and connector techniques for standard electrical conductors are not readily adaptable to conductor materials which cannot be welded, soldered, crimped or physically clamped in any manner. The establishment of electrical connections to cables of the sodium conductor type is further complicated by the necessity for protecting the conductor from exposure to air, water, and other reactive elements.

Accordingly, it is an object of this invention to provide an electrical connector which can establish a firm, positive electrical connection with the ductile metal conductor of an electrical cable.

A further object of this invention is to provide an elec- "ice trical connector which effectively seals the exposed end of a cable, to which it is applied, against exposure to reactive elements.

Further objects of this invention are directed generally toward providing reliable, inexpensive, and easily applied connectors and connection techniques for establishing secure electrical and mechanical contacts with an electrical cable having a conductor formed of relatively ductile material.

Features of this invention include the use, in an electrical connector, of a ferrule member, a collet member, and an electrical contact member adapted to axially penetrate the ductile metal core of an electrical cable. The contact member is mounted within a central bore in the collet member; the collet member is provided with a threaded portion which mates with a cooperating threaded portion on the ferrule member so that the collet may be axially advanced relative to the ferrule by rotation of one relative to the other; and the ferrule is provided with a second threaded portion which is adapted to axially engage the inner or outer surface of the insulating jacket of an electrical cable to secure the ferrule thereto.

These and other objects, features, and advantages of this invention will be distinctly and specifically pointed out in the attached claims, and will be more fully disclosed and explained in the following specification, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a partial, exploded, longitudinal section view of an electrical connector formed in accordance with this invention;

FIG. 2 is a complete longitudinal section view, showing the connector of FIG. 1 assembled, and coupled to an electrical conductor;

FIG. 3 is a longitudinal section view of an electrical splice connector formed in accordance with this invention;

FIG. 4 is a partial, longitudinal section view of another form of electrical connector constructed in accordance with this invention;

FIG. 5 is a partially sectioned longitudinal plan view of two elements of another form of electrical connector constructed in accordance with this invention; and

FIG. 6' is a longitudinal section view showing an electrical connector incorporating the elements of FIG. 5, and coupled to an electrical cable.

Referring now more particularly to the drawings, it may be seen that the electrical connector of FIGURES 1 and 2 comprises a ferrule body member 10, a collet member 12, and an electrical contact member 14. An electrical cable 16 having an outer insulating jacket 18 and a central core 20, is shown in FIG. 1 to illustrate the relative positions occupied by the cable and the elements of the connector. The collet 12 is provided with a central contact-receiving bore 22 which is adapted to receive tubular portion 24 of contact 14. The contact element 14 is further provided with an annular groove 26 which is adapted to receive a retaining ring 28 after tubular portion 24 has been inserted through bore 22. The retaining ring 28 is provided with an outer diameter greater than the inner diameter of bore 22 so as to prevent axial withdrawal of the contact 14 from the bore 22.

Ferr-ule body member 10 includes a central opening 30 which is provided with an internal threaded portion 32. Collet member 12 is provided with an externally threaded portion 34 adapted to mate with internal threads 32 in the ferrule. As shown, the threads on these two elements may be tapered relative to one another in the manner of pipe threads or similar threaded parts, to produce a wedging action as the two parts are threaded together. To assure firm, peripheral engagement between collet 12 and ferrule 10 when the two parts are threaded together, the central opening in ferrule may be pro vided with a reduced diameter portion 36 which forms a rearward facing shoulder 38 within the opening. Shoulder 38 is provided to firmly engage forward surface 40 of collet 12 when the collet and the ferrule have been fully engaged. Forward surface portion 40 may be provided with a recess 42, as shown, for receiving ring 28, to facilitate engagement between surface 40 and shoulder 38, free of interference.

Ferrule 10 is further provided with an external threaded portion 44 at the forward end thereof. The helical threads of portion 44 may be of sharp or edged configuration so that they may engage the inner surface of cable insulating jacket 18 in substantially self-tapping relationship. While helical threads are shown for illustrative purposes obviously other shapes may be utilized to engage ferrule 10 and the jacket 18. In addition annular ridges may be provided between the end of thread 44 and shoulder 60. Advancing threads 44 into the end of the cable pulls the annular ridges into the cable and the cable insulation may be deformed around the ridges, griping them tightly and additionally sealing the helical path for-med by the threads to direct access from outside the body. The outermost diameter 46 of ferrule 10 may be made substantially equal to the outer diameter of insulating jacket 18 so that the cable and ferrule will form a smooth joint of substantially uniform diameter when assembled together. Accordingly, threaded portion 44 may, in a preferable form be of lesser diameter than outer diameter 46 of ferrule 10.

FIGURE 2 illustrates how the elements shown in FIG. 1 appear when assembled together in operative relationship. In FIG. 2, contact element 14 may be seen to include a substantially flattened tail portion 48 which is provided with an aperture 50 for securing to a bolt or similar external electrical terminal. It may be seen from the drawings that contact element 14 is rotatable within contact receiving bore 22 in collet 12. As a result of this construction, the angular orientation of flat surface 48 may be changed conveniently, relative to a longitudinal axis through the cable 16; this feature is particularly advantageous when used in combination with relatively tough, stiff cable which cannot be bent or twisted easily into proper positions for coupling to fixed terminal connectors.

The tapering of threads 32 on ferrule 10 relative to threads 34 on collet 12, previously mentioned, serves a twofold purpose: It provides first for retention and sealing between the collet 12 and ferrule 10, and second, the wedging action which the taper produces, applies radial forces to collet 12 tending to constrict the diameter of contact receiving bore 22 into engagement with body portion 24 of contact 14. Constriction in this manner offers improved sealing engagement between the collet and the contact. Still further sealing between collet 12 and ferrule 10 is accomplished by the abutting relationship of collet surface 40 and ferrule shoulder 38, as previously described.

While the contact element 14 should be manufactured of an electrically conductive metal such as copper, the ferrule 10 and collet 12 may be manufactured of any suitable material. It has been found desirable to utilize poly-sulfone plastics in making these elements although other plastic, insulating or metallic elements are suitable.

In use, the connector of FIGURES 1 and 2 would be assembled to cable 16 as follows:

The bevelled end 54 at the forward end of threaded portion 44 on ferrule 10 would be inserted into the cut end of cable 16 between outer insulating jacket 18 and central core 20. To facilitate this initial insertion the core material at the cut end of cable 16 may be preshaped as shown at 52 in FIGURE 1, by any suitable shaping means. A novel method of accomplishing this preshaping has been achieved. Compression forces are applied about the end of the conductor 16 compressing the flexible cable jacket 18 so as to extrude and shape the ductile metal 20 and releasing the compression force allowing the jacket to return to its initial shape providing a space between the core 20 and the inner diameter of jacket 18. Following the initial insertion, ferrule 10 may be ro tated relative to cable 16 so that self-tapping threads 44 engage the inner surface of jacket 18 and advance the ferrule relative to the cable until the cut end 56 of the cable abuts against shoulder 60 on the ferrule. Then, collet 12, with contact element 14 assembled thereto as previously described, may be engaged with threads 32 in ferrule 10 and advanced until the collet 12 is fully seated within the ferrule 10. At that point, forward contact portion 62 on contact element 14 will have been embedded into the ductile core material 20 of cable 16 as a result of the advance of collet 12 relative to ferrule 10 which is fixed in position relative to cable 16. In addition core material 20 may be extruded beyond end 56 of the conductor 16 ensuring better contact due to the greater surface area of core material 20 and contact portion 62 being in contact. A durable, convenient, sealed, and positive electrical connection between conductor material 20 and contact element 14 will thus have been established.

FIGURE 3 illustrates a splice connector for joining together the ends of two ductile-core conductor cables in accordance with this invention. In general conformity with the concepts described relative to FIGURES l and 2, this connector may be seen to comprise a pair of ferrule body members and 111, a contact collet member 112, and an elongate conductive contact member 114. The ferrule members 110 and 111 include forward threaded portions 144 and 144 adapted to engage the inner diameter of cables 116 and 116' and are provided with outer diameter portions 146 and 146" which are substantially equal to the outer diameter of cables 116 and 116. Collet member 112 includes a first threaded portion 134 adapted to engage the interior threaded portion 132 in first ferrule member 110, and also includes a second threaded portion adapted to engage the interior threaded portion 132' in the second ferrule member 111. So that the collet member 112 may be simultaneously engaged to both ferrules 110, 111, in the direction of the helical threads on threaded portions 134 and 135 may be reversed relative to one another, with the threaded portions 134 in each of ferrules 110, 111, differing correspondingly. Then, rotation of collet member 112 in only one direction rela. tive to ferrules 110 and 111 will cause the threaded portions in each to engage simultaneously. To further facilitate coupling of collet member 112 to ferrules 110 and 111, the collet may be provided with a plurality of peripheral wrench flats 166 which will allow the collet to be engaged conveniently by any standard wrench or similar tool. And, to preclude disengagement of the ferrules from the connected cable during rotation of the collet member into the ferrules, the cable-engaging threads 144 and 144 on ferrules 110, 111 may be reversed relative to each other as are interior threaded portions 132 and 132'. The rotational forces transmitted to the ferrules by engagement of collet 112 will then tend to rotate the ferrules in the direction of engagement, rather than disengagement, with cable 116 and 116'. Gripping of the cable jackets 118 and 118' by threaded portions 144 and 144 of ferrules 110, 111 may be improved by tapering the threads relative to the inner diameter of the cables shown.

In this embodiment, the collet 112 and ferrules 110, 111 are provided with cooperating, abutting, sealing shoulders 138, and 140', 138' respectively. Shoulders 138 and 138 may be seen to be rearwardly-facing, inwardly-tapered annular surfaces formed on ferrules 110, 111. Cooperating shoulders 1'40 and 140' on collet 112 are annular surfaces of curvilinear cross section which mate with tapered surfaces 138 to produce substantially linear, peripheral contact between the two parts. Additional sealing between the two parts may be provided,

as in the case of the embodiment illustrated in FIGURES 1 and 2, by providing for a tapered relationship between threads 134, 135 and inner threaded portions 132 and 132'.

The collet member 112 in this embodiment, as in the embodiment of FIGURES 1 and 2, may be seen to include a central contact receiving bore 122 in which the elongate contact element 114 is positioned. A reduced diameter portion 142 within the bore 122 engages a mating groove 126 in contact element 114 to retain the contact within the bore. In this respect, portion 142 corresponds in function to recess 42 in the embodiment of FIG. 1, in providing a peripheral shoulder which cooperates with the retaining means (groove 126) on contact element 114 to retain the contact within the contactreceiving bore 122. Obviously other means for retaining contact element 114 within bore 122 may be utilized.

FIGURE 3 further illustrates an additional sealing element in the form of tubular outer sleeve 168 which is telescopically disposed about the outermost surfaces of the completed splice connection. This sleeve may be in the form of the material commonly known as shrink-fit" tubing. The sleeve, having an original inner diameter somewhat larger than the outer diameters of the cables 116 and 116' and ferrule portions 146 and 146' may then be slipped over the end of one of the cables prior to establishment of the connection, and then slipped back over the ferrules and the ends of the cables after the connection has been completed. Heating of the tubing in the conventional manner, subsequent to its proper positioning over the completed connection, will then cause it to shrink into secure, sealing engagement with the outer surfaces of both cables and both ferrules.

In the embodiment of this invention illustrated in FIG. 4, the collet member 212 is provided with the internally threaded portion 234. Ferrule member 210 includes a first threaded portion 244 for engaging the inner diameter of cable insulating jacket 218, and a second externally threaded portion 232, for engaging the internally threaded portion 234 on collet member 212. The collet member is provided with a central contact receiving bore 222 in the rearward end, and the inner surface of the collet 212 circumjacent the bore forms a retaining shoulder which cooperates with ring 228 to provide means for retaining contact element 214- within the bore. In the manner similar to that illustrated in the embodiment of FIGURES 1 and 2, retaining ring 228 is removably engaged Within an annular groove 226 in the main body portion 224 of contact 214.

After attachment of ferrule 210 to the cable jacket, contact 214 is pushed through supporting and aligning bore 272 of ferrule 210 by advancing collet 212 on threads 234. Face 242 of collet 1 bears on the rear face of retaining ring 228 which in turn pushes against the front face of retaining ring groove 226, thereby advancing the contact 214 into the core material. As the contact 214 penetrates the core, core material is displaced along the contact and captured by inner surface 273 of ferrule 210. Air originally within volume 264 is vented between contact 214 and bore 272, and escapes from the assembly between threads 232 and 234. After sufiicient engagement between contact 224 and core material has been achieved, sealing grommet 239 is captured between face 238 of ferrule 210 and face 242 of collet 212. This deforms the grommet, forcing it into firm engagement with the two faces and with the body 224 of contact 214.

It is further noted that the exterior diameter 246 of ferrule 210, as shown in FIG. 4, is somewhat larger than the original outer diameter of cable 216, but it should be understood that this is by way of illustration only. The outer diameters of the ferrule, and the collet, and the cable jacket may be made equal to one another, in this embodiment as well as in those previously described, to attain the resultant advantages derivable from that structure.

FIGURES 5 and 6 illustrate still another embodiment of this invention in which the main body portion 324 of an elongate conductive contact element 314 is provided with a plurality of projecting annular ridges 329 and the collet member 312 is formed of a material sufficiently flexible to permit insertion of the contact element 314 together with projections 329 into contact receiving bore 322. The inner diameter of the contact receiving bore 322 is preferably smaller than the outermost diameter of projecting ridges 329 so that upon insertion of the contact into the bore a secure peripheral seal is achieved between the inner diameter of the bore and the contact element. The complete connector in this embodiment further includes a ferrule body member 310 which is provided with an internally threaded portion 332 for engaging the external threads 334 on collet member 312. The radially restrictive forces imposed on collet member 312 as it is threaded into ferrule 310 will tend to overcome any deformation of the collet member produced by insertion of ridges 329 on contact element 314, thereby further assuring firm peripheral engagement between the inner diameter of contact receiving bore 322 and contact element 314. Alternatively, one or a plurality of peripheral internal rotating shoulders 342 may be formed in the inner surface of contact receiving bore 322 prior to insertion of contact element 314. Such shoulders might permit easier insertion of contact element 314 and would facilitate preliminary positioning of the contact element relative to the collet. However, the functioning of the peripheral ridges 329 for sealing and retention purposes between the contact and the collet following assembly of the collet into the ferrule would not be substantially different.

The collet member 312 of this embodiment is further shown to include a portion of increased diameter 323 at the rearward end of contact receiving bore 322. This increased diameter bore portion which surrounds body portion 324' of contact element 314 may be filled with any suitable sealing material such as moldable silicone rubber to provide improved sealing between collet member 312 and body 324 of contact member 314. A second increased diameter portion 321 of diameter greater than portion 323 may be provided in addition, to facilitate filling of portion 323 with a suitable sealing material.

In this embodiment as in the embodiment illustrated in FIG. 3 an outer sleeve 368 is shown encasing the completed connection extending from the end of cable insulating jacket 318, over the outer surface of ferrule body member 310, and covering the upper portion of collet member 312 and part of the extending terminal portion 348 of contact element 314. The sleeve is shown fitted to the various outer dimensions of the parts of the connector as could be accomplished by means of shrinkfit tubing as previously described. Although the cable jacket and various connector elements are shown as having differing external dimensions, it is understood that in this embodiment as in all other embodiments described and included within the scope of this specification, may be constructed, conveniently, so as to provide'a single, given external diameter in accordance with the features and the advantages to be derived from such structure.

In each of the embodiments which have been described in this specification, it may be seen that the ferrule body member 310 is arranged to provide a cavity portion, such as shown at 64 in FIGURE 1, which extends beyond the cut end of the cable when the ferrule has been assembled to the cable jacket. This feature is particularly advantageous in applications involving ductile metal core cables in which the ductile metal will necessarily be extruded beyond the normal end of the cable in response to insertion of elements such as the threaded portion of the ferrules and the projecting contact portions of the contact elements which have been described. By providing such a cavity for receiving the displaced core material this invention avoids the possibility of escape of the core material by avoiding the development of uncontrolled compressive forces upon the core during assembly of the connector to the cable end.

Generally, the proportions of contact and ferrule are so arranged that the entire volume within the ferrule is filled by the displaced core material. Air which is initially contained therein may be vented through clearances between the threads. This also insures good area contact between the contact element and conductor core. This extrusion of the core material provides an additional advantage because when the cable end contacts air the core material reacts with oxygen and water vapor, significantly increasing the electrical resistance of the surface relative to that resistance of the non-reacting material in the core. By extrusion of the core virgin metal is placed in area contact with the contact element improving the electrical characteristics of the connection.

This invention has thus been described but it is desired to be understood that it is not confined to the particular forms or usages shown and described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of the invention, therefore, the right is broadly claimed to employ all equivalent or the means by which objects of this invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to obtain these objects and accomplish these results.

What is claimed is:

1. An electrical connector adapted to be electrically coupled to the end of an electrical cable having a homogeneous central core of highly ductile conductive material enclosed within an insulating jacket, said connector comprising:

a ferrule body member having an opening therethrough, a threaded portion for securing a cable insulating jacket thereto, and a screw-threaded fastener means thereon for engaging a cooperating collet member;

a collet member having a cooperating screw-threaded fastener means engaging the said fastener means on said ferrule body member for advancing said collet member axially relative to said ferrule body member;

said collet member further including a contact-receiving bore therethrough having a shoulder associated therewith;

an elongate electrical contact member disposed within said contact-receiving bore and having an extending contact portion projecting from said contact-receiving bore;

and retention means on said electrical contact member cooperating with said shoulder on said collet member for limiting relative longitudinal motion between said contact member and said collet member as said collet member is advanced relative to said ferrule body member;

wherein the said screw-threaded fastener means on said ferrule member and on said collet member are tapered relative to one another to produce wedging action as the two are progressively engaged.

2. An electrical connector in accordance with claim 1, wherein said connector includes an interior bore portion adapted to form a receiving chamber extending from the end of an electrical cable coupled to said ferrule body member, for receiving central core material displaced from within the insulating jacket of said cable upon in sertion of said contact member into said core.

3. An electrical connector in accordance with claim 1, wherein said threaded portion on said ferrule member is tapered outwardly from one end thereof toward the other, producing wedging action as the insulating jacket of an electrical cable is threadedly engaged therewith.

4. An electrical connector in accordance with claim 1, wherein the said retention means on said contact member includes: an annular groove formed in said contact member; and, a flexible locking ring engaged in said groove forming an outwardly extending peripheral shoulder on said contact member.

5. An electrical connector in accordance with claim 1, wherein:

said screw-threaded fastener means on said ferrule body member comprises an internal screw-thread formed within the said opening through said ferrule body member; the said cooperating screw-threaded fastener means on said collet member comprises an external screw-thread; said electrical contact member includes a projecting annular ridge thereon peripherally engaging said collet member;

and the screw-threaded fastener means on said collet member and the screw-threaded fastener means on said ferrule member are tapered relative to one another for producing wedging action tending to constrict the diameter of said contact-receiving bore into engagement with said contact member as said collet member is advanced relative to said ferrule member.

6. An electrical connector in accordance with claim 5, wherein said contact-receiving bore in said collet member includes a mating annular groove in the inner surface thereof interlocking with the said annular ridge on said contact member.

7. An electrical connector adapted to be electrically coupled to the end of an electrical cable having a homogeneous central core of highly ductile conductive material enclosed within an insulating jacket, said connector comprising:

a ferrule body member having an opening therethrough, a threaded portion for securing a cable insulating jacket thereto, and a fastener means thereon for engaging a cooperating collet member;

a collet member having a cooperating fastener means engaging the said fastener means on said ferrule body member for advancing said collet member axially relative to said ferrule body member;

said collet member further including a contact-receiving bore therethrough having a shoulder associated therewith;

an elongate electrical contact member disposed within said contact-receiving bore and having an extending contact portion projecting from said contact-receiving bore;

and retention means on said electrical contact member cooperating with said shoulder on said collet member for limiting relative longitudinal motion between said contact member and said collet member as said collet member is advanced relative to said ferrule body member;

wherein said ferrule body member and said collet member each includes cooperating annular sealing-shoulders positioned to meet in substantially abutting relationship when said ferrule and said collet member are engaged together.

8. An electrical connector in accordance with claim 7, wherein said cooperating sealing-shoulders comprise at least one annular surface of curvilinear cross-section and a mating annular surface which produces annular linecontact in engagement with said surface of curvilinear cross-section.

9. An electrical connector in accordance with claim 7, wherein said connector further includes a grommet of sealing material interposed between said cooperating annular sealing-shoulders, in circumferential engagement with said contact member, in position for compression between said sealing-shoulders when said ferrule member and said contact member are brought together.

10. An electrical connector in accordance with claim 7,

wherein said electrical contact member is rotatably mounted to said collet member within said contact-receiving bore.

11. An electrical connector in accordance with claim 10, wherein said contact-receiving bore in said collet member includes an enlarged diameter portion at one end thereof, forming a sealing chamber surrounding said contact element, and said sealing chamber contains a yieldable sealing material forming a peripheral seal between said contact member and said collet member.

12. An electrical splice-connector adapted to electrically couple the ends of a pair of electrical cables each having a central core of highly ductile conductive material enclosed within an outer insulating jacket, said spliceconnector comprising:

a first ferrule body member having an opening therethrough, a first screw-threaded portion thereon for securing the insulating jacket of a cable thereto, and a second screw-threaded portion, having a given directional configuration, for engaging a mating contact collet member;

a second ferrule body member having an opening therethrough, a first screw-threaded portion thereon for securing the insulating jacket of a cable thereto, and a second screw-threaded portion having a directional configuration opposite to that of the second screw-threaded portion on said first ferrule body member, for engaging a mating contact collet member;

a contact collet member having a first threaded portion of given directional configuration for threadedly engaging the said second threaded portion on said second ferrule body member;

said collet member further including a contact-receiving bore therethrough having a shoulder associated therewith;

an elongate electrical contact member disposed in said contact-receiving bore in said collet member and having a pair of oppositely disposed contact portions extending from opposite ends of said contact-receiving bore;

and retention means on said contact member cooperating with said shoulder in said collet member for limiting longitudinal relative motion between said electrical contact member and said collet member.

References Cited UNITED STATES PATENTS 982,563 1/1911 Baird 339- 3,090,937 5/1963 Keith ct al. 3392l7 3,345,453 10/ 1967 McNerney 17477 3,369,072 2/1968 Harris et al. 174-75 FOREIGN PATENTS 1,113,973 9/1961 Germany.

612,213 11/1948 Great Britain.

MARVIN A. CHAMPION, Primary Examiner JOSEPH H. MCGLYNN, Assistant Examiner US. Cl. X.R. 174-75

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