US2920305A

US2920305A - Set-screw type terminal connector lug

Info

Publication number: US2920305A
Application number: US650595A
Authority: US
Inventors: Howard B Gibson; Howard G Tomer
Original assignee: Thomas and Betts Corp
Current assignee: ABB Installation Products Inc
Priority date: 1957-04-04
Filing date: 1957-04-04
Publication date: 1960-01-05
Anticipated expiration: 1977-01-05

Description

Jan. 5, 1960 H. B. GIBSON ET AL 2,920,305

SET-SCREW TYPE TERMINAL CONNECTOR we Filed April 4, 1957 AZ INVENTORS flan A20 5. 6/550 flag Aka 6. 7oq=k ATTORNEY United States Patent SET-SCREW TYPE TERMINAL CONNECTOR LUG Howard B. Gibson, Glen Ridge, and Howard G. Tomer, North Arlington, N.J., assignors to The Thomas & Betts Co., Elizabeth, NJ., a corporation of New Jersey Application April 4, 1957, Serial No. 650,595

9 Claims. (Cl. 339-272) The invention relates to electric terminal connectors of the heavy duty, set-screw type, adapted for detachably connecting thereto any one of a plurality of multistrand cable conductors having different circular mil areas, and more particularly to a terminal connector of the character wherein the set-screw coacts, in diiferent positions of adjustment, with the body of the terminal connector to provide a gage whereby a predetermined compressive binding force may be applied on a cable able tool connecting or receiving means surrounded by a plurality of stepped plane segmental surfaces adapted to be selectively aligned flush'with said barrel portion, in accordance with the circular mil area of the cable conductor end portion to be secured therein by said set-screw.

Electric terminal connectors of the set-screw type, as known heretofore, were subject to certain disadvantages in that a cable conductor was intruded into a circular bore, and the set-screw secured thereon with random compressive force, whereby the intruded portion of the conductor was subjected to an indefinite amount of deformation and often with severance of at least some of the conductor strands. Thus, a good mechanical connection was not practical, relative movement therebetween unavoidable, and maximum current-carrying capacity of the cable conductor more or less impaired.

Accordingly, it is an object of the invention to provide an improved terminal lug connector of the setscrew type which is not subject to the above-noted disadvantages. 1

A further object of the invention is to provide a terminal lug connector as specified, wherein the set-screw for securing a multi-strand cable conductor therein, is adapted for obviating transverse resistance between the inner and outer strands thereof at its secured end portion.

Another object of the invention is to provide a terminal lug connector as specified, wherein the set-screw includes gage means coactable with the body of the connector, whereby predetermined amounts of compression may be selectively applied on cable conductors of different circular mil area. 7

A further object of the invention is to provide a terminal lug connector as specified, whereby the set-screw is secured upon the intruded portion of a cable conductor in accordance with a predetermined amount of compressive force for a cable conductor having a given circular mil area.

Another object of the invention is to provide a terminal lug connector as specified, wherein the conductorreceiving bore in the barrel portion of the lug is adapted to align cable conductors of varying circular mil area with the axial center of the set-screw 24, whereby the entire bearing end face of the set-screw is brought into intimate engagement square therewith in response to a predetermined amount of compression applied thereon by said set-screw.

'A further object of the invention is to provide a terminal lug connector as specified which is particularly adapted for eifecting good internal and external mechanical and electrical contact with cable conductors having a relatively small circular mil area, as well as cable conductors having a larger circular mil area.

With the above and other objects in view, the inven; tion resides inthe novel construction, combination, and arrangement of parts, the novel features of which are set forth with particularity in the appended claims. The invention, both as to its organization and method of construction, together with additional objects and advantages thereof, will be understood from the following description of a specific embodiment, when taken in connection with the accompanying drawing, in which:

Fig. 1 is a view in perspective showing the improved terminal lug connector;

Fig. 2 is a top plan view of the improved terminal lug connector;

Fig. 3 is an end elevation of the terminal lug connector showing the non-circular bore in the conductorreceiving end thereof;

Fig. 4 is a longitudinal sectional view taken on the line 44 of Fig. 2; and

Fig. 5 is a transverse sectional view of the conductorreceiving end portion of the terminal connector and showing the set-screw more or less in an initial position on the intruded portion of a cable conductor.

Referring to the drawing, the improved terminal lug connector, of aluminum, bronze, or copper, for example, indicated generally at 10, comprises a flat tongue portion 12, provided with the usual aperture '14 for receiving a terminal stud or the like therethrough, a substantially rectangular barrel portion 16 provided with a circular or non-circular bore 18 adapted for the intrusion therein of an end portion of a multi-strand cable conductor 20, and a screw-threaded bore 22 normal thereto, for the reception of a set-screw 24 of compatible metal or equivalent, adapted for securing the cable conductor 20 to the terminal connector lug 10.

In accordance with the invention, the set-screw 24 of the headless type having either a V screw thread or a buttress screw thread 25, formed thereon, is provided with a bearing end face in the form of a flat, annular bearing face 26, square therewith, and a conical tip 28, having a blunt or rounded apex portion 30, depending therefrom in concentric relation and defining a continuation of the surface of the fiat annular face 26, whereby the set-screw is adapted for limited penetration of the intruded end portion of the multi-strand cable 20, to establish good mechanical and electrical contact with its inner strands, to obviate transverse resistance therebetween, and to clamp down on the outer strands engaged by its fiat bearing face 26, to lock the set screw in predetermined positions of adjustment.

The opposite or outer end face of the set-screw 24 is provided with a central, hexagonal recess 32, for example, for the insertion therein of an Allen wrench for manipulating the setscrew relative to the connector lug 10, in known manner.

Further in accordance with the invention, the recessed opposite end face of the set-screw 24 is formed to present a plurality of stepped surfaces 34 arranged in angular relation about the hexagonal recess 32 and offset from each other in the direction of the axis of the set-screw 24, each in a plane perpendicular thereto, whereby, when the set-screw 24 is rotated clockwise onto a selected cable conductor having a predetermined circular mil area, one of the stepped gaging surfaces 34, corresponding thereto, will register flush with the top side of the barrel portion 16, of the terminal connector lug 1i and thus indi cate that the appropriate compressive binding force for securing the selected size of cable conductor has been applied thereon, each of the stepped gage surfaces 34 being provided with suitable indicia, as at 36, for example, to identify the particular gage surface 34 for the corresponding size of cable conductor secured in the terminal connector. An example of such indicia 36 comprises American wire gage numbers designating 2/0, 3/0, 4/0 and 250 thousand circular mil cable conductor sizes for use with the terminal connector illustrated.

Further in accordance with the invention, the bore 18 in the terminal lug 18 is of substantially egg-shaped or inverted tear-drop configuration in outline by reason of its lower or bottom half having a relatively smaller radius than that of its upper half, whereby to assure maximum contact with small as well as larger size multi-strand conductors, and also for more effectively compacting the intruded end portion thereof in substantially wedge-like fashion, in response to the entire bearing end face of the set-screw 24, when turned down thereon.

Referring to Figs. 3 and 4, the screw-threaded bore 22 intersects the relatively smaller conductor-receiving bore 18 at right angles thereto, whereby the incursion there of into the side Walls of the bore 18 forms oppositely disposed arcuate steps or shoulders 33 therein with the defining surfaces thereof inclined downwardly toward the bottom or floor 49 thereof, to provide clearance for the lateral spread of a portion of the outer strands of the intruded conductor 20, into the path of the fiat, annular bearing face 26 of the set-screw 24, and for clamping the strands of the intruded conductor portion down on the steps or shoulders 38, and on the bottom or floor 49 of the bore 18, in response to the penetration of the conical tip portion 28 of the set-screw 24 into the intruded conductor portion 2%, whereby a greater area of contact between the entire bearing end of the set-screw 24 and the intruded conductor portion 29 is possible and the setscrew 24 caused to bottom thereon by the clamping action of its flat, annular bearing face 26, and thus secured against relative movement.

Referring to Fig. 5, it will be apparent that when a bare end portion of a multi-strand conductor of predetermined circular mil area is intruded into the bore 18 of the terminal lug 1i and the set-screw 24 initially turned down thereon, the conical tip portion 28 thereof penetrates and spreads the strands thereof more or less, de pending on its circular mil area, substantially laterally in opposite directions toward and over the respective steps or shoulders 38, where they are engaged by the flat, an nular bearing face 26 of the set-screw 24 as it is turned down further to exert a predetermined amount of compression thereon in accordance with its circular mil area, to secure the conductor 2b to the terminal lug it and at the same time lock the set-screw 24 against relative movement, as will be understood.

From the foregoing, it will be readily apparent that the present invention provides an improved mechanical and electrical connection between a terminal connector lug of the set-screw type and a multi-strand cable conductor by reason of a larger area of contact between the setscrew 24- and the cable conductor a connection in which the strands, at the intruded end portion of the conductor, are not damaged or impaired; a connection which obviates relative movement during the manipulation of the cable conductor and/ or terminal lug, as in the installation thereof or subsequent thereto, and a connection which obviates transverse resistance between the strands of the secured end portion of the conductor.

While the invention has been illustrated and described with respect to a preferred embodiment thereof, it is to be expressly understood that various changes, modifications and substitutions in the material and/or construction of the improved terminal lug connector may be made without departing from the inventive concept un derlying the same. Therefore, the invention is not to be limited except as is necessitated by the prior art and the scope of the appended claims.

We claim:

1. A terminal connector lug, for cable conductors of different circular mil area, including a substantially rectangular body portion having a cable conductor-receiving bore therein, adjustable means carried by said body portion in intersecting relation with said bore including bearing means adapted for respectively penetrating and clamping a conductor end portion in said bore, and stepped gaging means formed on said adjustable means adapted to be selectively brought into register with the adjacent surface of said body portion whereby to indicate a predetermined adjustment thereof in accordance with the circular mil area of a selected cable conductor.

2. A terminal connector lug, for multi-strand cable conductors, including a substantially rectangular body portion provided with an axial bore adapted for the reception of cable conductors having different circular mil areas, adjustable means carried by said body portion in intersecting relation with said bore including bearing means adapted for respectively penetrating and clamping a conductor end portion in said bore, a wrench receiving means integral with said adjustable means, and stepped gaging means formed on said adjustable means adapted to be selectively brought into registration with one face of said body portion for indicating a predetermined adjustment of said adjustable means in accordance with the circular mil area of a selected cable conductor.

3. A terminal connector lug, for cable conductors of different circular mil area, including a substantially rectangular body portion having a non-circular axial bore adapted for the intrusion therein of a selected cable conductor, adjustable means carried by said body portion in intersecting relation with said bore for securing a selected cable conductor therein, and stepped gaging means integral with said adjustable means adapted for selective registration with one face of said body portion for indicating a predetermined adjustment thereof on a cable conductor end portion in accordance with its circular mil area.

4. A terminal connector lug including a substantially rectangular body portion having a cable conductor-receiving bore therein, and a set-screw carried by said body portion in intersecting relation with said bore including stepped gaging surfaces adapted to be brought into registration with one face of said body portion for selectively indicating a predetermined adjustment thereof on an end portion of a circle conductor in accordance with its circular mil area.

5. A terminal connector lug including a substantially rectangular body portion having an axial bore therein for freely receiving an end portion of a multi-strand cable conductor, and a set-screw carried by said body portion in intersecting relation with said bore for securing said conductor end portion in said bore, said set-screw including plane bearing means normal thereto adapted for clamping down on the outer strands of said conductor end portion, conical bearing means concentric with and depending from said clamping means adapted for limited penetration of said conductor end portion for effecting direct contact with the inner strands thereof, and stepped gaging surfaces adapted to be selectively brought into registration with one face of said body portion for indieating a predetermined adjustment of said set-screw on a cable conductor end portion in accordance with its circular mil area.

6. A terminal connector lug, for multi-strand cable conductors of different circular mil area, including a substantially rectangular body portion having an axial bore therein adapted for the reception of a selected cable conductor end portion, a set-screw carried by said body portion in intersecting relation with said bore for securing a conductor end portion therein, conical bearing means including a straight annular shoulder normal thereto integral with said set-screw adapted for respectively penetrating and clamping a conductor end portion in said bore whereby to obviate transverse resistance between the inner strands thereof and relative movement of said conductor end portion, and a plurality of stepped gaging surfaces formed on the opposite end portion of said set-screw adapted to be selectively brought into registration with the adjacent surface of said body portion for indicating a predetermined adjustment of said setscrew on a conductor end portion in accordance with its circular mil area.

7. A terminal connector lug for multi-strand cable conductors of different circular mil area, including a substantially rectangular body portion having a non-circular axial bore therein for the reception of an end portion of a selected cable conductor, a relatively large screwthreaded bore in said body portion opening into said noncircular bore providing oppositely disposed, inclined shoulders in the defining wall surface of the lower half of said non-circular bore, and a set screw in said threaded bore having a bearing end comprising a conical tip and a flat annular face about the base of said tip in concentric relation, said conical tip being adapted for penetrating a conductor end portion to directly contact its inner strands and for spreading its outer strands onto said shoulders, and said annular face adapted for compacting and clamping the intruded conductor end portion on the bottom of said non-circular bore while clamping the spread strands thereof on said shoulders to lock said set-screw and cable conductor against relative movement, the op posite end of said set-screw being provided with stepped gaging surfaces adapted for selective registration with the adjacent surface of said body portion to indicate predetermined adjustment thereof on a cable end portion in accordance with its circular mil area.

8. A terminal connector log, for multi-strand cable conductors of different circular mil area, including a substantially rectangular body portion having a non-circular axial bore therein for the reception of an end portion of a selected cable conductor, a relatively large screwthreaded bore in said body portion opening into said noncircular bore providing oppositely disposed, downwardly inclined shoulders in the defining wall surface of the lower half of said non-circular bore, and a set-screw in said threaded bore having a bearing end comprising a conical tip including a rounded apex portion, and a flat annular face about the base of said tip in concentric relation, said conical tip being adapted for penetrating a conductor end portion to directly contact its inner strands and for spreading its outer strands onto said shoulders, and said annular face adapted for compacting and clamp ing the intruded conductor end portion on the bottom of said non-circular bore while clamping the spread strands thereof on said shoulders to lock said set-screw and cable conductor against relative movement, the opposite end of said set-screw being provided with stepped gaging surfaces adapted for selective registration with the adjacent surface of said body portion to indicate predetermined adjustment thereof on a cable end portion in accordance with its circular mil area.

9. A terminal connector lug, for multi-strand cable conductors of different circular mil area, including a substantially rectangular body portion having a non-circular axial bore therein for the reception of an end portion of a selected cable conductor, a relatively large screwthreaded bore in said body portionopening into said non-circular bore providing oppositely disposed, downwardly inclined shoulders in the defining wall surface of the lower half of said non-circular bore of relatively smaller radius, and a set-screw in said threaded bore having a bearing end comprising a conical tip including a rounded apex portion, and a fiat annular face about the base of said tip in concentric relation, said conical tip being adapted for penetrating a conductor end portion to directly contact its inner strands and for spreading its outer strands onto said shoulders, and said annular face adapted for compacting and clamping the intruded conductor end portion on the bottom of said noncircular bore while clamping the spread strands thereof on said shoulders to lock said set-screw and cable conductor against relative movement, the opposite end of said set-screw being provided with stepped indicia bearing gaging surfaces adapted for selective registration with the adjacent surface of said body portion to indicate predetermined adjustment thereof on a cable end portion in accordance with its circular mil area.

References Cited in the file of this patent UNITED STATES PATENTS 411,444 Irmen Sept. 24, 1889 1,351,721 Eickhoff et a1 Aug. 31, 1920 2,083,923 Rowe June 15, 1934 2,232,857 Jackson Feb. 25, 1941 2,459,832 McKinley Jan. 25, 1949 2,514,794 Prince July 11, 1950 2,565,140 Leustig Aug. 21, 1951