US2044444A - Bushings for connecters - Google Patents

Description

June 16, 1936. D w. POND 2,044,444

BUSHINGS FOR CONNECTERS Filed Jan. 22, 1951 Fig.1.-

N V EN TOR. 1

TORNEY Patented June 16, 1936 UNITED STATES BUsnrNGs ron oonunc'mns Dwight W. Pond, Terryville, Conn assignor to National Engineering Corporation, Terryville, Conn., a corporation of Connecticut Application January 22, 1931, Serial No. 510,374

4Claims.

This invention relates to bushings, and more particularly to bushings for connecters which are used to couple conduit, loom, flexible armored cable, and the like, to outlet boxes and similar electrical fittings.

Such cable connecters have been used for along time and their design is more or less standardized. They usually comprise a tubular body with a reduced neck portion attachable to an outlet box or the like and at its other end have a squeeze jaw or any other suitable clamping means which is normally used to hold the cable in the cable connecter and hence in the outlet box or the like. Some of these connecters have been provided with an inwardly projecting flange or stop shoulder which extends part way into the bore, in order to limit the movement of the armored shell of the cable into the connecter body and into the outlet box or similar fitting, and it has been proposed to use an insulating sleeve which is slidable within the armored shell and provided with a flange to engage the burred and sharp ends of the cable arm in order to protect the conductors against short circuiting and other damage. In such cases, the stop flange on the connecter body also serves to keep the insulator sleeve within the armored shell once the cable clamp was tightened.

When the connecter body was provided with this inwardly projecting stop flange, the end of the armored cable, or the insulating sleeve when the latter was used, were substantially enclosed so that it was impossible for a person to inspect the same to determine whether or not it had chafed the insulation on the conductors, or to be sure that the insulating sleeve was used.

In order to accommodate such examination, it has heretofore been proposed to provide radial slots across the connecter body stop flange. But, with this provision, only a very superficial examination was possible for the construction was such that it was impossible to determine if a sleeve had been properly assembled to the cable armor because only the end of the cable insulating sleeve could be viewed. with the provision of these so-called peep slots it was possible for unscrupulous workmen with fraudulent intent to use a cheap plain washer instead of the insulating sleeve with a flange which is costlier and much slower to assemble. Such a washer would have all the appearances of the much more desirable, and in some places required sleeve, once it was assembled to the connecter and outlet box.

This deception was possible in spite of a close examination by the electrical inspector or by the owner for whom the work was being done, because once the connection was completed by the electrician, and especially after the wall was lathed and plastered, the end of the cable armor or anything carried thereby was permanently enclosed 5 by the inwardly projecting flange on the connecter, and to actually detect it, it was necessary toentirely disassemble the coupling and in cases remove the outlet box or similar fitting from the plaster wall, with the obvious inconvenience and cost.

Even if no deception was intended, the electrician would have to take the same steps and have the same inconvenience if he should find upon examination that he had inadvertently l5 omitted an insulator sleeve.

All of these difliculties are obviated by the present invention and besides other advantages are obtained by providing a stop for the end of the armor of the cable, not onthe neck of the connecter body as heretofore, but on a cap which is threaded over the end of the connecter and which, in one embodiment of the invention herein illustrated, also constitutes the lock nut for securing the connecter to a wall of the outletv box, for with this arrangement, the mere removal or unscrewing of the cap from the connecter body will completely uncover and disclose the end of the cable armor, and adjacent parts of the cable and any thing carried thereby without necessi- 80 tating or requiring the removal of the connecter body from the outlet box or the removal of the cable from the connecter.

Further, this cap, since it is so easily removable, may be provided with a continuous annular stop flange if desired, but preferably has for the same purpose a plurality of arms so spaced that the end of the cable armor or whatever may be carried thereby may be superficially examined without removing the cap.

Other features and advantages will hereinafter appear.

In the drawing:

Figure 1 shows part of an outlet box with a cable connecter attached thereto by the combined cap and lock nut of this invention, the latter being shown in section and the connecter body being broken away at one end to more clearly show the cable and insulating sleeve.

Fig. 2 is an end view of a connecter assembly with the cap of the present invention applied thereto.

Fig. 3 is a sectional view of a castingfrom which, according to the present invention, the

combined cap and lock nut may be made. 56

Fig. 4 is an end view of the casting shown in Fig. 3.

Fig. 5 is a sectional view of the modified form of the present invention, similar to Fig. 3, which may be threaded on an automatic or continuous threading machine.

Fig. 6 is a view similar to Fig. 4, showing the combined nut and bushing after it has been threaded.

Fig. 7 is similar to Figs. 5 and 6 but shows the previously ooaxially extending arms forced inwardly to provide a flange against which the cable armor is stopped.

Fig. 8 is a perspective of the combined nut and bushing shown in Figs. 3 and 4, after-the flange has been formed, looking at it from the top.

Fig. 9 is a perspective view of the bushing shown in Fig. 8, looking at it from the bottom.

Fig. 10 is a sectional view showing another embodiment of this invention wherein the cap and lock nut are made as separate pieces.

Fig. 11 is a perspective view of the cap shown in Fig. 10.

In the embodiment of the invention disclosed herein, there is applied to a cable, a connecter |2 of rather conventional design comprising a threaded neck l3 which extends through a knock-out hole I4 in the outlet box I 5 or any similar fitting until a shoulder l8 thereon engages the outer margin of the hole where it is usually held in place by a flat nut such as the nut 21 shown in Fig. 10. The other end of the connecter projects outwardly from the outlet box and forms a clamp II which in the present showing comprises a spring jaw which may be squeezed onto the conduit armored cable I8 or the like by tightening a screw l9. Any other suitable form of clamp. however, may be used.

Because connecters of this type and bushings of the present invention are used most often with flexible armored cable, this type of cable alone will be considered in the description which follows hereinafter, but it should be understood that the device of the invention may be used advantageously with loom, conduit and other cable protectors.

In preparing the flexible armored cable It for connection to the outlet box l5 and attachment to a switch or any similar receptacle usually placed in outlet boxes, it is customary for the electrician to saw across the helically wound metal strips 20 of the armor 2| as at 22 approximately two or three inches back from the end, after which this short section of armor is removed to expose the conductors 23, the ends of which are then stripped for connection to receptacle terminals.

Insawing across the cable at 22,. a sharp edge or burr often remains, which if left unprotected might chafe or cut into the insulation or the conductors 23 and in some cases short circuit the entire system. To guard against this, it has heretofore been proposed to provide an insulating sleeve 24 at the end of the armor, preferably one with a tubular b 25 fitting within the armor 2| and having an tegral flange 26 to engage over the end of the armor, as shown in Fig. 1. The insulation sleeve 24 when made continuous can be assembled by sliding the stripped ends of the conductors 23 through the hole therein, but usually it is split to be spread and fitted right over the side of the conductors.

After the cable is prepared in this manner, the conductors 23 are passed through a hole 28 in the connecter body until the cable armor 2| is properly positioned therein whereupon the clamp screw I! is tightened.

It has been usual to provide an inwardly projecting flange in the connecter body hole 28 which would pass the conductors 23 but engage and stop 5 the cable armor 2| and thereby limit its movement into the outlet box II; and, in those cases where an insulating sleeve 24 is used. the stop flange on the connecter body would locate the sleeve and prevent displacement of the latter 10 once the cable clamp is tightened. But, as heretofore stated, this construction makes a substan tially closed connecter end that necessitates digging the outlet box out of the plastered wall and removal of the cable from the connecter and outlet box if the electrical inspector or home owner wishes to be sure an insulating sleeve rather than a cheap and quickly assembled washer is used. Similar limitations prevail if a person tries to ascertain if the sleeve is still properly assembled 20 to the cable armor 2|, or if the electrician wishes to place or replace an insulator 24 after the connecter is assembled to the outlet box I3 and after the walls are plastered. This is equally true even when the stop flange on the connecter body is 25 notched or slotted, for the slots only permit a superficial examination, as above pointed out.

According to the present invention,- however, the connecter neck I! is not provided with a stop flange or, in fact, anything which would prevent 30 complete inspection of the cable end or anything carried thereby. Instead, the present invention provides a separate article which may or may not be removed for inspection of the underlying parts as desired, and which may be added to some old 86 forms of cable connecters long since installed, all without removing the outlet box or breaking the cable connection, as set forth more fully hereinafter.

In its preferred form, the present invention provides, for the threaded neck ll of the connecter body, a cap 29 which has one and partially closed so as to provide stop means for engaging the end of the cable armor or insulating bushing carried thereby if the latter is used. This cap is 45 provided with internal screw threads III fitting the external screw threads 3| on the neck of the connecter so that it may be applied to the connecter |2 after the latter has been inserted in the knock-out hole of the outlet box.

In one embodiment of this invention, that shown in Figs. 10 and 11, the cap 29 is intended for use on the connecterbody neck IS without serving the function of holding the connecter in the outlet box and for use in conjunction with the usual check nut, while in the form of the invention shown in Figs. 1 to 9, that at present preferred, the cap is made long enough to constitute a combined cap and lock nut serving the additional function of securing the connecter body 60 in the outlet box.

Referring now to the embodiment of the invention shown in Figs. 10 and 11, where the cap is intended for use with the usual check nut 21, the cap is preferably provided on its surface with 65 notches 32 so that it may be driven on the neck l3 to the desired position by use of a spanner wrench or by inserting the bit of a screw driver and tapping the other end with a hammer.

The position to which the cap 29 shown in Figs. 70 10 and 11 may be driven depends upon the particular way in which it is to be employed. It may be made with very little length, so that it may be brought up firmly against the end of the armored cable, or an insulator carried thereby,

without first engaging the usual nut 21 on the neck, or it maybe made longer so as to engage the nut in which case it will serve to lock the nut against casual removal. with the former arrangement, the connecter body l2 may be clamped to the armored cable with the end of the armor protruding slightly beyond the neck I! of the connecter before the connecter is inserted in the outlet box since the cap can be tightened against the end of the armor or the insulator carried thereby whether the latter protrudes slightly more or less than is desired.

Where the cap za is intended to engage the lock nut to prevent its casual removal, it is the better practice to fasten the connecter body to the outlet box with the check nut 21, then apply the cap and drive it on until it firmly engages the check nut after which the cable end is pushed through the connecter body until the end of the armor 2| or the insulator 24 carried thereby is in firm engagement with the stopp means on the cap at which time the screw I! may be adjusted to clamp the cable in that position.

Although the invention may well be practiced as above outlined by having the cap and lock nut made in two separate parts, it is preferable for the sake of the economy effected thereby in the manufacture of the device, and because of its convenience in use, to make the lock nut and cap as an integral part, and in this way the double work of threading the two parts is obviated, and the electrician in making an installation need handle only one part or piece. I

This preferred form of the invention is illustrated in Figs. 1 to 9 in which the cap is made longer than in Figs. 10 and 11 so that its rear edge engages the margin of the hole l4 in the outlet box and the exterior of the cap is pro-.

vided with fiat surfaces 33 like those of anut for engagement by a wrench or the bit of a screw driver.

In either case, whether the cap is made to constitute a lock nut or to operate with a separate check nut, the stopping means for the end of the cable or an insulator carried thereby, may comprise a continuous annular flange 34 on one end of the cap, partially closing that end of the cap so that the conductors 23 will pass therethrough while the end of the armor II or the insulator 24 will be engaged by the same. flange may be slit so that the end of the cable or the insulator may be superficially examined without removing the cap from the connecter.

However, for reasons which will hereinafterappear, it is preferable that the stopping means be constituted by a plurality of arms 35 which project inwardly from the cap and which have between them spaces 36 through which the end of the cable armor or insulator may be superficially viewed.

In addition to permitting complete inspection of the end of the cable armor to see if an insulator bushing- 24, which is often required by the electrical code, has actually been used, the cap of the present invention, when removed, makes the armor 2i and the conductors 23 accessible so that an insulating sleeve, which was inadvertently omitted when making the installation, could be placed on the conductors and slid into position under the end of the armor, and this operation can be performed without removing the armor, the connecter or the outlet box, and without unsoldering the wires or disconnecting them from anything else because the cap after being unscrewed from the neck can be slid over the wires If desired, this outlet box.

.with the check nut 21 to secure the latter against 5 casual movement, and in the form of the invention shown in Figs. 1 to 9, the cap is made sufficiently long so that the stopping means, i. e. the arms 35 will not engage the end of the threaded neck. It! on the connecter when the cap is secured in position, and may therefore be brought into firm engagement with the end of the armor or the insulator protruding somewhat beyond the end of the neck. Preferably, the space 31 provided between the end of the neck and the 15 arms is such that these parts will not engage whether the connecter is used with an outlet box of light or heavy gauge metal.

The usual method of manufacturing a part like the cap 29 would be to form it in a screw machine or cast it as shown in Figs. 10 and 11, leaving suflicient stock to cut the thread as shown in Fig. 10 with a back-out tapping operation. Because these parts are used in very large quantities by the electrical trade, even small savings are extremely important, and with this object in view, the present invention provides several methods of forming the cap so as to effect sub- 'stantial economies in time and labor.

This is accomplished, in one form, according 30 to the present invention, by casting the flange arms coaxial with the bore, as shown in Figs.

3 and 4 to permit casting a single thread 38 at the time the cap nut body is cast. By having the arms 35 extend coaxially in this manner 5 and providing a thread of less than one turn, it is possible to use a draw core in casting the cap. After the part is so cast the arms may be headed over to form the inwardly projecting flange 34 by peening, drop hammer or any other fast forming operation, and in this operation the apertures 36 close and form the narrow peep slots as shown in Figs. 8 and 9.

Another method of forming the cap 20, within the scope of this invention, is to cast the body as shown in Fig. 5 wherein flange arms 35 again extend coaxially, but in this case suflicient stock is left in the core at 39 to cut a female thread; and, because the arms 35 extend coaxially and are hence clear of the bore, it is possible to tap this cap in an automatic continuous tapping machine. After the tapping operation the arms may, as with the forms shown in Figs. 1 to 4, be bent or pressed together to provide the inwardly projecting flange 34 as shown in Fig. '1, and also, the apertures 36 if made sufilciently' wide form peep slots through which it is possible to view the end of the cable armor.

It should also be noted that the cap 29 is provided with a round head 40' which extends sub- 60 stantially to the wrench flats 33 to facilitate the operation of applying a wrench, by guiding the wrench to the flats, which is especially advantageous while working in the close confines of the 65 a cable connecter having a screw-threaded neck;

; of inwardly extending arms spaced from each other to afford peep slots for permitting superflcial inspection 'of the end of the cable armor and insulator bushing carried thereby.

2. In combination with a flexible armored cable, an insulator bushing on the end of the cable; a cable connecter having a screw-threaded neck; an apertured outlet box into which said neck extends; a cap including a tubular body having an internal thread for engagement with a thread on the neck 01' the connecter to anchor the connecter in the aperture of the outlet box; and means for securing the cable to the connecter with the end thereof adjacent the inner end of said neck; said cap having a plurality of annularly spaced arms having notches between them; said arms being headed over before the cap is assembled to the body to form an inward- 1y projecting flange serving as a stop for the inner end of the armored cable; said notches being of such width and depth as to constitute a series of peep slots through which the end 01 the cable and an insulator carried thereby may be observed and inspected.

3. In combination with a flexible armored cable, an insulator bushing on the end of the cable; a cable connecter having a screw-threaded neck; an apertured outlet box into which said neck extends; a cap including a tubular body having an internal thread for engagement with a thread on the neck of the connecter to anchor the connecter in the aperture of the outlet box; and means tor securing the cable to the connecter with the end thereof adjacent the inner end of said neck; said cap having a plurality of annularly spaced. arms having notches between them; said arms being headed over before the cap is assembled to the body to form an inwardly projecting flange serving as a stop for the inner end 01' the armored cable; said notches being of such width and depth as to constitute a series of peep slots through which the end of the cable and an insulator carried thereby may be observed and inspected, the length 01. the connecter being less than that of the cap so that when the cap is applied a space is left between the end of the connecter and the flange of the cap.

4. In combination, an armored cable; an outlet box; a cable connecter having a tubular neck adapted to flt through a hole in the outlet box, a clamp on said connecter adapted to engage and grip the armored cable passing through said tubular neck and into said outlet box; a flange on the connecter adapted to engage and stop against the margin of the hole in the outlet box; a screw thread on the tubular neck; a lock nut removably fitting on said screw thread and adapted to pull said connecter flange against the wall of the outlet box; an insulating bushing fitting within the end of the cable armor and curling over the edge of the latter; said nut having a plurality oi annularly spaced arms extending toward each other and toward the axis of the hole to partially close the hole at one end and limit the movement of the cable into. the box, the spaces between the annularly spaced arms pro-' viding peep slots permitting superficial inspection of the end of the cable after the connecter is completely assembled and fully exposing the end of the cable when the nut is disconnected.

DWIGHT W. POND.

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