US 3627929 A
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United States Patent inventors Appl. No.
Filed Patented Assignee Priority Hermanus Petrus Johannes Gllissen Vlijmen;
Lucas Gerardus Christianus Teurllngs, S- Hertogenbosch, both of Netherlands 878,468
Nov. 20, 1969 Dec. 14, 197 1 AMP Incorporated Harrisburg, Pa.
Nov. 22, 1968 Netherlands ELECTRICAL CONNECTOR HAVING NORMALLY ENGAGED CAMMABLY OPERATED CONTACTS 7 Claims, 9 Drawing Figs.
ILLS. Cl 179/96, 200/5 1.]
lint. Cll non- 17/00  Field of Search l79/96; ZOO/51.1, 51.09; 339/183  References Cited UNITED STATES PATENTS 1,780,413 I H1930 Williams ZOO/51.1
Primary Examiner-Kathleen H. Clalffy Assistant Examiner-Jan S. Black Attorneys-Curtis, Morris and Safiord, William J. Keating,
William Hintze, Frederick W. Rating, John R. Hopkins, Adrian J. La Rue and Jay L. Seitchik ABSTRACT: An electrical connector comprises an insulating housing containing pairs of contact springs. the springs of each pair normally engaging one another. The springs of the pairs can be cummed apart by insulating plugs inserted through holes in the housing to isolate subscribers and to allow line testing by test tabs inserted through liurther holes in the housing to engage the contact springs.
ELECTRICAL CONNECTOR HAVING NORMALLY ENGAGED CAMMABLY OPERATED CONTACTS This invention relates to electrical connectors and more particularly to electrical connectors having normally engaged contacts disposed in a housing which are capable of being cammed apart.
Main distribution frames in automatic telephone exchanges are used for the cross-connection of incoming (topographic side) wire pairs with the central office (numerical side) terminals of the exchange, breaking the cross-connections for the purpose of testing for network faults, isolation of individual subscribers from the exchange, tapping lines for purposes of listening in and the connection of spare incoming wire pairs.
A conventional main distribution frame consists of two distributing frames known asthe horizontal side" frame and the vertical side frame. n the horizontal side frame, test and break jacks are mounted in horizontal rows, the terminals of one side of each break jack being connected in numerical sequence to line finders of the exchange. On the vertical side frame, terminal blocks are mounted in vertical rows, the terminals of one side of each of these blocks being connected to incoming wire pairs.
The two frames are disposed in back-to-back relationship, the space (known as the cross-connection field") between the frames being used to accommodate jumper wires which connect the terminals of the other sides of the terminal blocks to the terminals of the other sides of break jacks. The jumper wires serve for the cross-connection of the incoming wire pairs to the line finders, the break jacks serving for the disconnection of the crossconnections for test purposes, the isolation of individual subscribers, and for the line tapping, the terminal blocks serving for the connection of the incoming spare wire pairs.
Each break jack has four contact springs mounted in an insulating housing to provide two normally closed contacts, twenty or more such break jacks being assembled in a block. The distance between the rows must be such as to permit maintenance staff to manually connect and disconnect the jumper wires.
According to an object of the invention, a break jack assembly for an automatic telephone exchange distribution frame comprises an insulating housing in which are arranged pairs of contact springs, each contact spring having a terminal for connection to an external electrical lead, contact surfaces of the contact springs of each pair normally engaging one another electrically to connect the terminals of the pair of contact springs, and is characterized in that the contact springs of the pair are separable from one another electrically to disconnect these terminals by inserting an insulating plug through a first hole in the housing to engage between the contact springs so as to move the contact surfaces of the contact springs apart from one another, each contact spring having a contact portion for engagement by an electrically conductive tab inserted through a second hole in the housing to be resiliently engaged by the contact portion of the contact spring.
Another object is that the tab may conveniently be engaged between the contact portion of the contact spring and a wall of the housing.
A further object is that the contact springs of each pair conveniently cooperate to define a recess for receiving the insulating plug so that the insulating plug does not engage the contact surfaces of the contact springs.
An additional object is that the contact springs of each pair may be guided by ribs on the internal wall of the housing.
A still further object is that the insulating plug and the tabs may be carried by a common plug unit so that the contact springs are simultaneously disconnected from one another and each contact spring of the pair is connected to one of the tabs for line-testing purposes.
Still another object is that a main distribution frame for an automatic telephone exchange may be formed by mounting a row of break jack assemblies according to the invention upon a supporting panel or frame with the housings of the assembly on one side of the panel or frame and the terminals of the contact springs, which are insulated from the panel or frame where the panel or frame is of metal, projecting from the other side of the panel or frame, a jumper wire being connected to one terminal of each contact spring pair, for example, by wrapping the bared end of the jumper wire about the terminal which is conveniently formed by an electrical post, or by connecting the jumper wires to the terminal by an electrical clip, by means for example, of a hand tool or an automatic magnetic tape controlled coordinate-connecting machine. Each jumper wire conveniently connects one of the terminals to one end of a further post, which extends through an insulating member, the other end of the further post being connected to an incoming wire. The other terminal of each pair of contact springs is connected to a numerical cable of the exchange.
A still additional object is that the break jack assemblies are readily accessible for isolation and test purposes from above the panel.
A still further object is that with a main distribution frame as just described, at least four times more subscribers per unit length can be accommodated than with the conventional main distribution frame described above.
Other objects and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings in which there is shown and described an illustrative embodiment of the invention; it is to be understood, however, that this embodiment is not intended to be exhaustive nor limiting of the invention but is given for purposes of illustration in order that others skilled in the art may fully understand the invention and the principles thereof and the manner of applying it in practical use so that they may modify it in various forms, each as may be best suited to the conditions of a particular use.
For a better understanding of the invention, reference will now be made by way of example to the accompanying drawings, in which:
FIG. I is a front plan view of a break jack assembly according to the invention;
FIG. 2 is a top plan view of the assembly;
FIG. 3 is an enlarged cross-sectional view of the assembly showing a test plug unit in the course of being mated with the break jack assembly, the test plug unit being shown only schematically;
FIG. 4 is a similar view to that of FIG. 3 but showing the test plug unit fully mated with the break jack assembly;
FIG. 5 is an enlarged rear elevational view of a contact spring of the break jack assembly, prior to being mounted in the assembly;
FIG. 6 is a side elevational view of the contact spring of FIG.
FIG. 7 is a front elevational view of the test plug unit;
FIG. 8 is a side elevational view of the test plug unit; and
FIG. 9 is a front plan view of the test plug unit.
Reference will now be made to FIGS. l to 6. The break jack assembly comprises an insulating housing I having lugs 2 with holes 3 for connecting the housing I to a panel or frame (not shown). The housing I has a removable cover plate 4 with rows of through holes 6, 8 and 10, the holes 8 being arranged in pairs of holes connected by blind slots I2 in the cover plate 4. The interior of the housingl, which is defined by the cover plate 4, a base wall I6 and sidewalls I7, is divided transversely of the length of the housing Iby partitions 14 to provide a series of compartments in the housing l with each of which one of the holes 6, one of the holes 8 and one of the holes 10 communicates.
Pairs of apertures 18 extend through the base wall 16, each pair of apertures I8 communicating with one of the compartments of the housing 1. Each aperture 18 has a portion 20 of increased cross-sectional area providing a shoulder 22. The base wall 116 has a central frustoconical section portion 24 projecting into each of the compartments and from which extend ribs 26, spaced from oneanother longitudinally of the housing 1 and terminating closely adjacent the cover plate 4. There are two ribs 26 in each compartment, only one of these ribs being shown (FIGS. 3 and 4).
In'each compartment, a pair of oppositely oriented contact elements 27 is disposed and each of which comprises a terminal post 28 (only six of these posts are shown in FIG. 2), an intermediate portion 30 from which has been stamped an obliquely extending locking tongue 32 engaging one of the shoulders 22, and a contact spring 34 extending from the opposite end of the post 28 to the intermediate portion 30. The contact spring 34 is divided longitudinally into two portions by a central through slot 36 which extends between points a and b on the contact spring, as indicated in FIGS. and 6.
Each contact spring 34 has a portion 38 converging upwardly (as seen in FIG. 3) towards the portion 38 of the other contact spring of the pair. Immediately above (as seen in FIGS. 4 to 6), the portion 38 is a rectilinearportion of the contact spring providing a flat contact surface 40 substantially parallel to the post 28. Immediately above (as seen in FIGS. 5 and 6) the portion 40, the contact spring has a portion 42 for cooperation with the portion 42 of the other contact spring of the pair to provide a recess 44 (FIG. 3), the portion 42 having a pair of laterally extending opposed ears 43. At its upper (as seen in FIGS. 4 to 6) end, each contact spring 38 has a bight 46 from which extends a contact arm 48 having a bowed contact portion 50.
In the normal position (FIG. 3) of each contact element 27, the contact surface 40 of each element 27 engages the contact surface 40 of the other contact element of the pair. The crest of the bowed portion 50 of each contact element engages one of the sidewalls 17 of the housing 1 to maintain contact surfaces 40 in springable engagement with one another, and each lug 43 of the contact element is guided by one of the ribs 26 thus ensuring that the portion 43 cooperates with the portion 43 of the other contact element of the pair to define the recess 44. Each pair of elements 27 accordingly forms a normally closed switch.
As shown in detail in FIGS. 7 to 9, the test plug unit, which is generally referenced 52, comprises an insulating body 54 from which project four electrically conductive tabs 56, in quadrangular array each connected within the body 54 by means (not shown), for example by solder or crimping ferrules, to one wire of a four-wire multiple-conductor test cable 58. The body 54 has serrated finger grips 60 at its upper end. Formed integrally with the body 54 and projecting between the tabs 56 are two insulating plug members 62 spanned by and formed integrally with a rib 64 for engagement in one of the slots 12 of the cover plate 4 and being disposed unsymmetrically with respect to the longitudinal axes of the members 62. The plug members 62 have chamfered free ends 65.
To provide a main distribution frame for an automatic telephone exchange, a series of the break jack assemblies described above are secured to an insulating panel or frame (not shown) by screws or bolts passed through the holes 3 of the lugs 2 so that the housing 1 extends from one side of the panel, the posts 28 of the contact elements 27 extending from the opposite side of the panel or frame where the panel or frame is of metal, the posts 28 are insulated from the panel or frame. One post 28 of each pair of contact elements 27 is connected to ajumper wire (not shown) for example by wrapping the bared electrically conductive core of the jumper wire about the post 28 or by the use of an electrical clip (not shown) to connect the jumper Wire to the post. The other end of the jumper wire is connected to a terminal of a feed through block (not shown), this terminal also being connected to an incoming wire. The feedthrough block may comprise an insulating panel having electrical posts, each extending through the panel and projecting from either side thereof, one end of each post being connected to the jumper wire and the other to the incoming wire. The other post 28 of each pair of contact elements 27 is connected to a numerical wire which in turn is connected to a line finder of the telephone exchange. Each two adjacent pairs of contact elements 27 may thus be employed to connect an incoming and an outgoing pair of wires.
For testing a given line, the test plug unit 52, the cable 58 of which has been connected to suitable test equipment, is mated with the break jack assembly. To this end, as shown in FIG. 3, the tabs 56 of the unit 52 are inserted through two selected adjacent pairs of the holes 6 and 10 in accordance with the line to be tested, so that the plug members 62 of the unit 52 enter the corresponding pair of holes 8. Initially as the tabs 56 enter the two adjacent compartments with which these holes 6 and 10 communicate, the tabs 56 slide along the sidewalls 17 of the compartments and engage the contact arms 48 of the contact elements 27 therein, urging the arms 48 of each pair of the contact elements 27 towards one another until the insulating body 54 of the unit 52 engagesthe cover plate 4, as shown in FIG. 4, the rib 64 of the unit 52 engaging in the slot 12 between the two holes 8. By virtue of the rib 64 and slot 12, the unit 52 cannot be fully mated with the break jack assembly unless it is correctly orientated respect to the break jack assembly.
As the unit 52 is further advanced towards the break jack assembly, the bowed portions 50 of the contact springs 34 of the contact elements 27 resiliently engage the tabs 56 between the crests of the portion 50 and the sidewalls I7 to make secure electrical contact between the tabs 56 and the contact elements 27. v
During this mating operation, the chamfered ends 65 of the plug members 62 enter the recesses 44 defined by the portions 42 of the two pairs of contact elements 27 in each compartment, and via assistance of bights 46, the faces of the ends 65 engaging the portions 42 to cam the contact springs apart so that the contact surfaces 40 of these springs are moved out of engagement with one another. Tabs 56 therefore mate with contact potions 50 before contact surfaces 40 are disengaged from each other thereby providing a make-before-break switch arrangement. The wires connected to the posts 28 of the elements 27 of each of the two pairs of such elements are accordingly electrically disconnected from one another to enable testing of the lines by a test equipment connected to the wires of the cable 58 of the unit 52. The contact surfaces 40, which provide normally closed contacts, are so positioned that the plug members 62 cannot engage the contact surfaces 40 which are accordingly protected from wear by the members 62.
As the contact springs 34 of each of the two pairs of contact elements 27 are cammed apart from one another by the plug members 62, the bowed portions 50 of the contact arms 48 slide along the tabs 56 of the units 52 so that the contact forces between the portions 50 and the tabs 56 remain substantially constant during mating operation and plug members 62 place contact arms 48 under a bias so that bowed portions 50 remain in electrical engagement with tabs 56.
Where a subscriber is to be isolated from the exchange without a test operation being performed, the contact springs of the corresponding elements 27 may be cammed apart from one another by simple insulating plug members inserted through the appropriate holes 8. A cell may be listened in to by the use ofa unit similar to the unit 52 but in which the plug members 62 are not provided, or by inserting simple electrically conductive tabs through the holes 6 or 10.
It will, therefore, be appreciated that the aforementioned and other desirable objects have been achieved; however, it should be emphasized that the particular embodiment of the invention, which is shown and described herein, is intended as merely illustrative and not as restrictive of the invention.
The invention is claimed in accordance with the following:
1. An electrical connector comprising a dielectric housing having a compartment therein, a pair of electrical contact members having sections secured in said housing and spring contact sections disposed in said compartment, said spring contact sections having first, second, third and fourth sections, said first sections extending toward each other, said second sections in normal engagement with each other and defining contactsurfaces, said third sections spaced from each other and providing a recess therebetween, said fourth sections defining contact arms provided with bowed contact portions in engagement with walls of said compartment for slidable engagement therewith and thereby maintaining said contact surfaces in biased engagement with each other, said housing having a cover at an entrance to said compartment, said cover having openings in alignment with said bowed contact portions and another opening in alignment with said recess.
2. An electrical connector according to claim ll wherein said compartment includes ribs on opposing walls thereof in alignment with said recess, and third sections having lugs thereon for engagement with said ribs to assure that said recess is formed between said third sections.
3. A break jack assembly comprising, in combination, an electrical connector and a plug; said electrical connector having a dielectric housing and electrical contact members arranged in pairs in opening means of said housing, said contact members having conductor-engaging sections secured in said housing and spring contact sections, contact surfaces of said spring contact sections in normal engagement, camming portions of said spring contact sections adjacent said contact surfaces and spaced from each other defining recesses therebetween said recesses being directed toward entrances of said opening means, contact arms of said spring contact sections extending outwardly from said camming portions and extending in a rearward direction away from said entrance means and toward respective wall means of said opening means, ends of said contact arms in engagement with said wall means and adapted to be slidable therealong; plug means having a dielectric body and a dielectric plug member extending outwardly from a surface thereof for disposition into one of said recesses ofa selected pair of contact members, when said plug means is moved into an operating position with said electrical connector, to electrically separate said contact surfaces of said selected pair of contact members, and electrical terminals provided by said plug means which extend outwardly from said surface in the same direction as said plug member and said terminals electrically engaging said ends of said contact arms between said wall means and said contact arms when said plug means is moved into said operating position.
4. A break jack assembly according to claim 3 wherein said terminals are engageable with said ends of said selected pair of contact members before said plug member electrically separates said contact surfaces.
5. A break jack assembly according to claim 3 wherein said contact arms maintain said contact surfaces in normal biased engagement with each other.
6. A break jack assembly according to claim 3 wherein bight means connect said cam portions and said contact arms together and said bight means maintain said ends in biased engagement with said terminals when said plug member is in engagement therewith.
7. A break jack assembly for an automatic telephone exchange main distribution frame, the assembly comprising an insulating housing in which are arranged pairs of contact springs, each contact spring having a terminal for connection to an external electrical lead, contact surfaces of the contact springs of each pair normally engaging one another electrically to connect the terminals of each pair of contact springs, the contact springs of the pair being separable from one another electrically to disconnect the terminals, an insulating plug insertable through a hole in tlite housing to engage between the contact springs so as to move the contact surfaces of the contact springs apart from one another to thus effect the electrical disconnection, each contact spring also having a contact portion, the insulating plug having a pair of conductive tabs insertable through a pair of holes spaced from the first hole in the housing resiliently to engage the contact portion of the contact springs.