US2114017A - Cable terminal - Google Patents

Description

April 12, 1938. A. w. DRING 2,114,017

CABLE TERMINAL Filed May 25, 1937 I 3 Sheets-Sheet 1 FIG? FIG! 1 a 0 I Q INVENTOR y A. W. DR/NG A T TORNEV April 12, 1938. A. w, DRING 2,114,017

CABLE TERMINAL Filed May 25, 1957 s Sheets-Sheet 2 FIG. 4 O

. mm k l 79 K I 25 57 67 FIGS 34 :IIIIEJDE 6 73 56 G 39 l 40 lNVEA/TOR ATTORNEY April 12, 1938. A. w. DRING 2,114,017

' CABLE TERMINAL Filed May 25, 1957 3 Sheets-Sheet 5 //v VEN TOR AWD/P/NG ATTORNEY Patented Apr. 12, 1938 UNITED STATES PATENT OFFICE CABLE TERMINAL Application May 25, 1937, Serial No. 144,633

Claims.

This invention relates to cable terminals and more particularly to terminals designed for use with repeater equipment on coaxial telephone and telegraph circuits.

The object of the present invention is to provide terminal facilities for the coaxial conductors and the two quads of ordinary conductors, that form a part of each coaxial cable.

Another object of the invention is the provision'o-f a terminal having means incorporated therein for making electrical tests on the coaxial cable conductors without exposing the person making such tests tothe hazard of electrical shock.

A still further object of the invention is the provision of means whereby the live conductors are short-circuited before access to them can be had.

In coaxial telephone and telegraph circuits, it is necessary to place repeater stations at certain intervals, for example, about every ten miles, along the transmission line and inasmuch as the wave bands carried by these cables are numerous and the frequency range is from 50 to 200,000 kilocycles, it is essential that'there be no leakage which would result in cross-talk and consequently impair the transmission. Furthermore, due to the large number of frequencies transmitted, the possibility of leakage and cross-talk is much greater than if only a small number of frequencies were used. It is, therefore, necessary that any apparatus designed for use in such systems incorporate in them structural means which will prevent such leakage and will provide, as near as possible, a structure equal, theoretically, of course, to an unbroken transmission line.

Applicant has provided a cable terminal for repeater stations which reduces to a minimum the possibility of cross-talk and has also provided means for gaining access to the coaxial conductors without impairing the shielding characteristics of the cable. I-le has also provided a cable terminal which embodies certain safety features which prevent a person from receiving an electrical shock when making tests on the cable, by making it necessary to perform certain acts, which in turn, short-circuit the transmission line and cut off thepower, before he can obtain access to the live portions of the cable.

Other novel features of the terminal will be readily apparent from the following detailed description taken in connection with the accompanying drawings in which Fig. l is a front view of applicants terminal with the cover portion broken away;

Fig. 2 is a vertical cross-sectional view taken on line 2--2 of Fig. 1 with a portion of the casing broken away;

Fig. 3 is a horizontal cross-sectional view taken on line 3-3 of Fig. 1;

Fig. 4 is a view similar to Fig. 1 except that the protecting or guard plate has been moved away to allow access to the test connections;

Fig. 5 is a horizontal cross-sectional view taken on line 55 of Fig. 4;

Fig. 6 is an enlarged fragmentary view of the locking mechanism;

Fig. 7 is a vertical cross-sectional view of the coupling device;

Fig. 8 is a top plan view of the coupling device with the center conductors joined to the conductors of the coaxial cable by means of sleeves;

and

Fig. 9 is a view partly in section of a testing plug suitable for use with the terminal of this invention.

In the preferred form of this invention, the terminal comprises a casing having a rear wall or base I0, and end and side walls II, I2, 13 and I4 integral therewith which form the compartment or housing I5. Located in the side wall I3 and in the end walls II and I2 are suitable openings I6, I'l, I8 and I3 through which the ends of the coaxial cable are arranged to be inserted. The ends of the cable LI and L2 which comprise the line or main portion of the cable, terminate in a fixture which is known as a cable plug, 20 and 2| (not shown in detail) and which forms the subject-matter of a pending application in the name of J. J. Harley, Serial No. 113,133, filed November 28, 1936. These plugs 20 and 2| are secured in the openings I6 and IT on the top and bottom of the casing by means of the nuts 22 and permit the conductors of the cable to pass therethrough without the admit tance of air or moisture. The repeater cable stubs RI and R2 also terminate in the same type of plugs and are indicated at 23 and 24. The conductors are brought out in the same manner as described with reference to the main line cable LI and L2 and the plugs 23 and 24 are secured in the openings I8 and I9 in the side wall I3 of the casing III by means of the nuts 25.

Projecting from the ends of the plugs 20, 25, 23 and 24 and extending into the interior of the housing I5, are the shielded coaxial cable conductors 2G, 21, 28 and 29 and the quadded conductors 30, 3|, 32 and 33.

g The ends of the shielded conductors 26, 21, 28'and 29 are joined together by suitable means which provide easy access to the central conductor and at the same time prevent injury to the person testing the line by grounding or shortcircuiting the conductors, which in turn causes devices at the source of power supply (not shown) to cut off the power. The structure of the connections and protecting means will be described more fully further on in the description.

The quadded conductors 38, 3|, 32 and 33 are terminated on the binding posts 34 and 35 which are located on the insulated panels 36 and 31 and are used for talking and for pressure alarm circuits.

Located in the interior of the housing are the two couplers 38 and 39 which are shown in detail in Figs. '7 and 8. These couplers, as shown in Figs. 7 and 8, contain two insulated conductors 40 and 4| which correspond to the inner conductors of the coaxial cable and are joined thereto by means of the sleeves 42. The bodies of the couplers 38 and 39 are of metal and provide the circuit connections for the outer or shielded portions of the cable. The coupler is connected electrically to the outer shield of the individual coaxial conductors by means of the metallic sleeves 43 which fit snugly on the outer shield of the cable and the projecting portions 44 and 45 of the couplers 38 and 39. This provides a circuit from the main cable LI through the plug 20, over the individual conductors 28 through the outer sleeves 43, the projecting portions 44 on the coupler 88 through the sliding sleeve 46, over the conductor 23 into the plug 23 of the repeater cable stub RI. The circuit continues through the repeater equipment (not shown) and returns to the main cable L2 through the stub of the repeater cable R2, the plug 24, over the conductor 29, the sliding sleeve 41, through the projection 45 on the coupler 38, over'the sleeves 43, the conductors 21 in the plug of the cable L2, and back to the main line, thereby providing a loop circuit which includes the repeater equipment. The circuit just traced is for the outer portion or shield of the coaxial cable.

The circuit for the inner or central conductor of the coaxial cable may be similarly traced. Starting at the plug 20 of the L| main cable, the circuit is over the central conductors 40 and 4| of the coupler 38 to which they are joined by means of the sleeves 42, see Figs. 7 and 8; from the coupler 38 we pass to the center conductors of the RI cable stub ends 28 which are part of the plug 23, the circuit then may be traced through the repeater (not shown) back through the stub of the R2 cable, the center conductors of the cable ends 29, over the center conductors of the couplers 39 in a manner similar to that described with respect to the coupler 38, and back to the main cable L2 through the plug 2|, thereby completing the loop circuit for the inner conductor.

By referring to Figs. '7 and 8, it will be observed that the conductors 40 and 4| which are posi tioned in the coupler 38 by means of the insulating bushings 48, 49, 58 and are bent upwards at right angles to each other and extend some distance above the face of the coupler and in parallel relation to each other. The free or extending ends 52 and 53 are soldered together to form one continuous conductor and are confined in the metallic housings or caps 54 which are readily removable to permit access to these conductors for testing purposes.

The detail of the coupler 38, shown in Figs. 7 and 8, is substantially the same as the lower coupler 39, and the description with respect to coupler 38 applies with equal force to coupler 39.

Holes 55 are provided in the top of the couplers to permit the plungers 56 of the switching devices 61 and 68 to make contact with the inner conductors 48 and 4| for the purpose of shortcircuiting these conductors; this causes the current in the conductors to be cut oif by the operation of devices (not shown) which are located at the source of power. The operation of the short-circuiting mechanism will be explained in detail further on in the description. The couplers 38 and 39 heretofore referred to are secured in position in the compartment or housing l5 by means of suitable bolts 58 which pass through the holes 59 in the couplers and into the insulating plate 60 which, in turn, is bolted to the upstanding bosses 6| on the base ID of the housing l5 by means of the bolts 62.

As pointed out earlier in the specification, this terminal is equipped with safety means which must be operated before access to the live conductors can be made. This device removes the power from the conductors before they can be tested.

The points of access to the inner conductors 40 and 4|, for the purpose of making tests, are located under the sliding sleeves 46 and under the caps or housings 54 of the couplers 38 and 39. The sliding sleeves 46 may be moved only a very short distance when the screws 63 are loosened due to a portion of the guard assembly preventing any appreciable movement. However, with the locking device 51 in position as shown in Fig. 1, the sleeves 46 may be moved just enough to break the circuit of the outer conductor. This break in the outer conductor removes the ground from the outer circuit and allows for such tests as can be made without first removing the power from the inner circuit, but is not sufiicient to permit the accidental contacting with the inner conductor by the fingers of the man making the tests. The movement of the sleeves 46 also removes the ground from the coupler assemblies which are ordinarily grounded through the outer conductor of the coaxial cable and through the sleeves 46. When the locking device is operated and the current is cut oil? the guard plate moves out of the way and the sleeves 46 may be slid all the way back, as shown in Fig. 4.

As shown in Fig. 1, a guard plate 64 is positioned over the caps or housings 54 of the couplers 38 and 39, thereby preventing access thereto. It is, therefore, apparent from the foregoing that in order to get to the inner conductors 40 and 4|, the sleeves 46 must be slid all the way back and the caps or housings 54 must be removed, and as long as the guard is in the position as shown in Fig. 1, this cannot be accomplished. In order to gain access to the inner conductors, the guard plate 64 must assume the position as shown in Fig. 4.

In order to move the guard plate so that it assumes the position as shown in Fig. 4, the buttons 65 and 66 of the two switches 61 and 68 must be depressed simultaneously. The switch assemblies are secured to the insulating plate 60 by means of the bolts 69 and the guard plate 64 is secured to the two side plates and 1| of the locking device 51 by means of the screws 12. The bottom portion of the plates 10 and 1| are jointed together by means of the insulating plate 13 to which is secured the spring 14 for moving the guard plate 64 into the position as shown in Fig. 4 upon the depression of the buttons 65 and 66.

When t bns 65 and 66 of the switches 61 2. A cable terminal for coaxial cables comprisnd 68 are desed slmultaneously, the plungers ing a housing, openings in the side walls of said 55 ent t pertures 55 in the couplers and housing for the admittance of cable stubs which ake cont th the inner conductors 40 and 4|, comprise coaxial conductors and insulated con- 5 thereb circuiting these conductors and duo-tors, a cover on said housing, means on said cuttin off power. At the same time, it rehousing cooperating with said cover for securing leases th :h mechanism which holds the it in p binding p panels mounted on the plunger wn in Contact with the c du t interior of said housing, coupling devices mount- 0 and 4| ainst t tension of the springs 16 ed in said housing and having central conductors and 11, s also permits the guard plate asmounted therein, said conductors insulated from sembi ive out I the wa d t th spring the body of the couplers and having portions 14, as She in Fig 4 d 5, th b exposing thereof extending above the surface of said couthe ho e or caps 54 which may now be plers, removable caps positioned over the extendmoved, own in Fig. 8, and the sleeves 46 may ing portions of said central conductors, and a 15 be slid pe way back, as shown in Fig. 4. guard plate normally positioned over said caps. 15

Locat inder the screws 69, toward the hinged 3. A cable terminal fOl coaxial cables comside of t'terminal, are rotatable buttons 82 and prising a housing, p n s in e ide Wal s Of 83 whi may be moved to a position over t said housing for the admittance of cable stubs butt d 66 t i t i t in their 1 which comprise coaxial conductors and insu- 20 pr ;ositi Th is for t purpose of lated conductors, a cover on said housing, means 20 meihtamg ith one or t other of the on said housing cooperating with said cover for tons ihts depressed position when it is desired Securing it in P binding D P ne s mounted to h eh h t on th t or Side on the interior of said housing, coupling devices of the ne. mounted in said housing and having central 5 Theiurpese of t t plug 34 as Shown in conductors mounted therein, said conductors in- Fi 9 t provide means fo making eieetrieai sulated from the body of the couplers and having tests itheextending portions 52 and 53 of the Portions thereof te d ab ve the surface of coaxii conductors 4n and 4| without exposing Said Couplers, removable aps p sitwned over th km t t hazard of eieetrieai shock the extending portions of said central conductors, 30 The .esign of the plug is such that it can be a guard plate normally p s d Over sa d ps,

plated on th t t positions of t terminai, eniy and means comprising push buttons adjacent wh th terminal guard plate 54 is in the Open said caps and said guard plate for short-circuitpo i n as shown in Fjg 1 ing said inner conductors and moving the guard Tle test plug 84 consists of a shell of insulating plate out Of the y S0 hat the caps may be material in which is assembled a ball point 85 readily removedattached to a s rin as which in turn. is attached A cable terminal for coaxial cables pr sto the terminal 81 at the end of the plug 84. s a housing, Op gs in the Side Walls of said The spring 86 in addition to giving the required housing for the admittance of cable stubs which 4 re t t il point 5 t as eehdueter comprise coaxial conductors and insulated conthrough which the current passes to the terminal ductors, 11 cover on S u m ns on said 81 and thence to the flexible conductor 89. using coop With Bald COVeI for Securing In order to make a test the soldered joints at it in place, binding P p s moun ed on the th i t 52 d 53 are uhseidered and one of interior of said housing, coupling devices mountthe upstanding wires enters th t 33 in the ed in said housing and having central conductors in l t d portion of t plug 34 while the other mounted therein, said conductors insulated from wire makes electrical contact with the ball point the body of the Couplers and having port ons 85. Th arrangement makes t impgssible t thereof extending above the surface of said coumake contact with more than one wire at a time. P1613, remevable ps p n d ver the ex- After the tests have been made,the guard plate tending Portions of S d Central Conductors, a 50 64 is returned to its normal position, as shown in guard plate normally Positioned 0V8! Said PS. Fig. l, by moving it back against the tension of means Comprising P ns adjacent said the spring 14. caps and guard plate for short-circuiting said The ter ihai housing is provided with a deer inner conductors and moving the guard plate out 5 or cover 18 hingedly secured to the side wall 14 0f the Way so that the caps may be dily 55 in such a e th t it may b drawn down moved, and locking means associated with said tightly against the gasket 19 by means of wing push buttons for maintaining said buttons in a nuts 80 and the hinged bolts 81, in order to prodepressed Position vide a water-tight joint. 5. A cable terminal for coaxial cables compris- What is claimed is: ing a housing having openings therein for the 1. A cable terminal for coaxial cables comprisadmittance of cable Stubs, a cover 011 S d housing a housing, openings in the side walls of said for providing access to the interior thereof.

housing for the admittance of cable stubs which Said Cover Provided With a plurality of locking comprise coaxial conductors and insulated oondevices for maintaining Said usin in a Waterductors, a cover on said housing, means on said tight condition, binding p panels unted on housing, cooperating with said cover, for securing the interior Said housing, means o Connectit in place, binding post panels mounted on th ing together the ends of the cables terminated in interior of said housing, coupling devices mount- Said housing, locking means for P t g Sa d ed in said housing and having central conductors cable s positioned Over s connecting m ans,

mounted therein, said conductors insulated from and a p of p buttons f a in said the body of the couplers and having portions l ing means in order to provide access to the thereof extending above the surface of said coulive portions of the cable.

plers and removable caps positioned over the extending portions of said central conductors. ARTHU W. DRING.

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