CA1111118A - Strain relief - Google Patents
Strain reliefInfo
- Publication number
- CA1111118A CA1111118A CA366,181A CA366181A CA1111118A CA 1111118 A CA1111118 A CA 1111118A CA 366181 A CA366181 A CA 366181A CA 1111118 A CA1111118 A CA 1111118A
- Authority
- CA
- Canada
- Prior art keywords
- screw
- head
- passage
- conductor
- cable
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Details Of Connecting Devices For Male And Female Coupling (AREA)
Abstract
ELECTRICAL CONNECTOR ATTACHABLE
TO AN END PORTION OF A POWER CABLE
ABSTRACT OF THE DISCLOSURE
An electrical connector having a tubular support through which a power cable extends, and a contact housing within which the cable is connected to male or female contacts.
The support and housing have mating quick threads facilitating their assembly after connection of the cable to the contacts.
A lock means on the support automatically responds to connection of the support and housing to each other, to prevent their accidental separation. Normal operation of a cable clamping device on the support clamps and strain-relieves the cable within the support. Deformation of the cable to offer strain relief acts upon the lock means to prevent its movement from the position in which it locks the housing and support against accidental separation. A cable-clamping and strain-relieving device is disclosed, including a screw threadable laterally through an opening of a wiring device body into a power cable-receiving passage formed in the body.
A swiveled head on the screw bears against the insulation of the conductor. Through the provision of guide slots in the body in which the screw is mounted, the head is maintained against rotation during advancement of the screw and removal of the screw from the body is prevented.
TO AN END PORTION OF A POWER CABLE
ABSTRACT OF THE DISCLOSURE
An electrical connector having a tubular support through which a power cable extends, and a contact housing within which the cable is connected to male or female contacts.
The support and housing have mating quick threads facilitating their assembly after connection of the cable to the contacts.
A lock means on the support automatically responds to connection of the support and housing to each other, to prevent their accidental separation. Normal operation of a cable clamping device on the support clamps and strain-relieves the cable within the support. Deformation of the cable to offer strain relief acts upon the lock means to prevent its movement from the position in which it locks the housing and support against accidental separation. A cable-clamping and strain-relieving device is disclosed, including a screw threadable laterally through an opening of a wiring device body into a power cable-receiving passage formed in the body.
A swiveled head on the screw bears against the insulation of the conductor. Through the provision of guide slots in the body in which the screw is mounted, the head is maintained against rotation during advancement of the screw and removal of the screw from the body is prevented.
Description
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B7~CK~ROUND OF THE INVENTION
1. Field of the Invention The dead front electrical connector comprising the present invention falls into that category of electrical wiring devices known generally to the trade as cord connectors. Con-nectors of this type may be male or female, and are generally attached to the ends of insulated conductors or cables for use in supplying power to portable machinery, motors, or other electrical equipment or applicances, at locations which may be remote from a permanent electrical outlet.
Connectors of this type are often attached to the associated conductors ln situ, and in the circumstances it is `~
important that the connector be adapted for quick and sure attachment to its associated conductor, and in a manner to assure to the maximum extent against loosening of the desired electrical connection of the conductor to the connector during regular use of the device. This is of particular importance considering the fact that the device may be subjected to hard and frequent use in shops, factories, and other commercial establishments, as well as in residential environments.
The connector may be generally classified as being of the type in which the conductor is inserted in one end of a body portion, which thereafter is coupled to a forward portion having male or female contacts, and provided, in the present / ; instance, with a "dead front" for safety purposes.
,~ The strain-relief means of the present invention may have general application to any type of electrical connector in which a conductor is to be engaged within and strain-relieved in the body of a wiring device, whether it be a male or a female -cord connectorj a cube tap, a cord-mounted switch, or an electrical plug or cap, to state some examples adapted for . ,, ~ : :
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incorporation of the strain-relief therein. Other examples are electrical connections in a panel or wiring box or appliance housing.
B7~CK~ROUND OF THE INVENTION
1. Field of the Invention The dead front electrical connector comprising the present invention falls into that category of electrical wiring devices known generally to the trade as cord connectors. Con-nectors of this type may be male or female, and are generally attached to the ends of insulated conductors or cables for use in supplying power to portable machinery, motors, or other electrical equipment or applicances, at locations which may be remote from a permanent electrical outlet.
Connectors of this type are often attached to the associated conductors ln situ, and in the circumstances it is `~
important that the connector be adapted for quick and sure attachment to its associated conductor, and in a manner to assure to the maximum extent against loosening of the desired electrical connection of the conductor to the connector during regular use of the device. This is of particular importance considering the fact that the device may be subjected to hard and frequent use in shops, factories, and other commercial establishments, as well as in residential environments.
The connector may be generally classified as being of the type in which the conductor is inserted in one end of a body portion, which thereafter is coupled to a forward portion having male or female contacts, and provided, in the present / ; instance, with a "dead front" for safety purposes.
,~ The strain-relief means of the present invention may have general application to any type of electrical connector in which a conductor is to be engaged within and strain-relieved in the body of a wiring device, whether it be a male or a female -cord connectorj a cube tap, a cord-mounted switch, or an electrical plug or cap, to state some examples adapted for . ,, ~ : :
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incorporation of the strain-relief therein. Other examples are electrical connections in a panel or wiring box or appliance housing.
2. Description of the Prior Art Heretofore, cord connectors of the type referred to have generally possessed one or more of a number of undesirable characteristics.
In some instances, the cord connectors of the prior ~art have been exceedingly expensive, having a large number of ;10 parts which not only are high in cost, considering the cost of the parts themselves, but also, involve excessive expenditure as regards assembly labor.
In other instances, the cord connectors of the present ;invention have had the undesirable characteristic wherein they can be assembled on the job, or by the ultimate purchaser, only at the cost of an excessive amount of time. In such instances, it has been common to provide a plurality of elongated screws, which must be individually threaded into cooperating openings on one of the connector parts, for the purpose of assembling the cooperating connector part or parts therewith.
In still other instances, the device, when assembled with a conductor, has failed to provide sufficient guarantee that the conductor will be securely locked in place. In some instances, the conductor or power cable has no capability of holding the parts of the connector against accidental disengage- -ment. Rather, the conductor is engaged in one of the connector parts by a means individual to that part. The connection of ;the connector parts, in the prior art, has then been achieved by means completely separate and distinct from the means employed -~
to engage the cable or conductor, In still other devices, after : .
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connection of the connector parts to each other, there isnothing that responds to the act of connecting the parts and the clamping of the cable to automatically lock them together against accidental separation. Locks against accidental separa-tion, if they do exist, in such instances must be a means separate and distinct from, and having no direct cooperation with, the means for coupling the connector body components and the clamping of the cable.
In the prior art, strain relief means has been pro-vided, usable in cord connectors of the type previously des-cribed herein as well as in other wiring devices, that have not`
been possessed of the desired high efficiency as regards gripping of the conductor or cable tightly within the wiring device body. In some instances, a strain relief means is built directly into cooperating, facing portions of the body, and a means of this type is obviously highly efficient, so long as the conductor is of a prescribed exterior diameter and has insulation of a predetermined deformability. In such instances, further, strain-relief is achieved only when the body is con-nected, and it is necessary to completely disconnect the sec-tions of the body, one from the other, in order to free the conductor. Such prior art devices, though efficient under the predetermined, controlled conditions described, do not allow ` effective discharge of the strain-relief function if the con-ductor size is not accurately maintained. Nor do the prior art devices allow adjustment of the strain relief according to the relative deformability of the insulation, that is, the strain l .
relief force exerted against the conductor cannot be increased or reduced, according to the needs of the particular situation ~1 30 as determined by the cable size and the type and relative ;'` resistance of the insulation to deformation.
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~ ~ _5_ , . _ l~lil~8 SUMMARY OF THE INVENTION
In accordance with the invention of the present divisional there is provided in one aspect in a wiring device of the type that includes a body of electrically insulative material having an axial passage for an electrical conductor, the improve- -ment comprising: 1) a screw threadedly engaged in the body for . .
advancement transversely of and into the passage, the body having a laterally inwardly extending opening entering upon the passage and formed with threads engaging the threads of the screw; and 2) : 10 a clamping head swivelled on the screw for advancement therewith into and transversely of the passage and having a clamping surface facing away from the screw adapted for exerting pressure on the - ~ -conductor effective to clampingly engage it against the wall of the passage at a location diametrically opposite that at which said opening enters upon the passage, when the screw is advanced.
According to a further aspect of the invention there is provided in a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement : comprising: 1) a screw threadedly engaged in the body for advance-ment into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, the body having guide slots paralleling the screw axis and slidably engaging portions of the head to prevent the head from rotating with the screw, the head and screw having complementary means producing interference between the screw and head at predetermined ;~ intervals during rotation of the screw relative to the head to ::
: provide at least a tactile reference to a user in the form of step-by-step indexing of the advancing screw.
According to a still further aspect of the invention there is provided in a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising: 1) a screw threadedly engaged in the body for advance-- 6 - -:
ment into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passages when the screw is advanced, the screw including a projection extending through the clamping head, the clamping head being rotatable upon said projection, said projection extending forwardly through the clamp-ing head for frictional, binding engagement against the conductor whereby to assist in clamping the conductor within said passage, while being retained frictionally by the conductor against rotation of the screw from selected positions to which it is advanced.
Accordingly, a still further aspect of the invention provides in a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising: 1) a screw threadedly engaged in the body for advance-ment into the passage; and 2) a clamping head swivelled on the ~
screw and adapted for exerting pressure on the conductor effective ::
: to clampingly engage it in the passage when the screw is advanced, said clamping head being formed with a plurality o~ parallel, forwardly projecting strain relief ribs adapted to bear againstthe conductor at selected locations longitudinally spaced along the conductor, for strain relief of the conductor responsive to threaded advancement of the screw.
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BRIEF DESCRIPTION OF THE DRAWINGS
While the invention is particularly pointed out and dis-tinctly claimed in the concluding portions herein, a preferred embodiment is set forth in the following detailed description which may be best understood when read in connection with the accompanying drawings, in which:
Figure 1 is a view showing male and female cord con-nectors constructed according to the present invention, said connectors being illustrated in side elevation and being shown approaching a connected relationship;
Figure 2 is a greatly enlarged, longitudinal sectional view through the male connector, taken on line 2-2 of Figure l;
Figure 3 is a transverse sPctional view, the scale being greater than that of Figure 1 but substantially reduced in respect to Figure 2, taken on line 3-3 of Figure 2 and illustra-ting in section the strain-relief means, the conductor being ~ :
shown in chain-dotted outline;
Figure 4 is a transverse sectional view on the same scale as Figure 3, on line 4-4 of Figure 2, in which the contact housing is shown in top plan;
Figure 5 is an enlarged, exploded perspective view of the strain-relief means;
Figure 6 is an exploded view illustrating the components of the male cord connector in side elevation, portions being :~
broken away; :.
Figure 7 is a perspective view, on an enlarged scale, of the plunger element or lock pin, per se;
Figure 8 is a perspective view of the cover member of . the contact housing;
Figure 9 is an exploded perspective view of one of the contact assemblies of the male cord connector;
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Figure 10 is a transverse sectional view on the same scale as Figure 3, taken on line 10-10 of Figure 2;
Figure 11 is an exploded view of the contact housing and its associated support, said housing and support being shown in side elevation with portions being broken away as they appear prior to connection of the cable to the housing and assembly of the housing with its associated support;
Figure 12 is a fragmentary, detail sectional view on the same scale as Figure 2, showing the lock pin in a retracted position to permit disassembly of the contact housing from its support;
Figure 13 is a fragmentary view, partly in side eleva-tion and partly in longitudinal section, showing the lock pin as it appears while being shifted to its retracted, unlocking position;
Figure 14 is a view like Figure 5 showing a modified strain-relief means; and Figure 15 is a fragmentary transverse sectional view similar to Figure 3, illustrating the strain-relief means of Figure 14 mounted in the cord connector.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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Referring to Figure 1, there are here illustrated a male cord connector 10 and a female connector 11 as they appear immediately prior to assembly. Hereinafter, the description of the preferred embodiment will proceed with reference to the male connector only. The female connector differs from the male con-i nector only with respect to the type of contacts employed, and ., modification of the components of the contact housing and support to accommodate the female contacts. Modification of a contact ~ 30 carrier to receive a particular type of contact, whether it be a ;I male or a female contact, is well known in the art, and accord-:
-ingly special illustration of the female connector details isnot believed necessary herein. The invention, it is important to note, will, however, be understood as being applicable both to connectors of the male type as well as those of the fema e variety.
The connector 10 may be considered as basically com-prising (see Figures 2 and 6) a contact housing generally desig-nated 12; a support for the contact housing generally designated 13; a lock means generally designated 14 mounted in the support and adapted for holding the support 13 and housing 12 against I relative separation; and a strain-relief generally designated 30 -~
which for purposes of the present disclosure is incorporated in the support 13 but which is believed to have general utility as ; a strain-relief for wiring devices of varioùs types.
Each of these main assemblies or components will be , separately described herein.
Con*act Housing Support The support 13 for the contact housing comprises an elongated, cylindrical, hollow, two-piece body 16, that includes an elongated, sleeve-like front body portion or skirt 18, the rear end of which abuts against and is ultrasonically welded or otherwise permanently, fixedly secured to a relatively short rear end portion 20. The permanent connection of the skirt 18 ~ and the rear end portion 20, at the interface 22 thereof, is ¦ ~ effected after assembly of the lock means 14 therewith (see Figure 6). Since the strain-relief means is, like the lock means, interposed between the skirt and the rear end portion, it also, if deslred, may be dropped into place before the skirt and rear end portion are assembled. The skirt and the rear end portion may in this event be formed with cooperating means in the form of a shoulder or shoulders, not shown, to hold the strain-relief permanently captive within the body 16.
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In some instances, the cord connectors of the prior ~art have been exceedingly expensive, having a large number of ;10 parts which not only are high in cost, considering the cost of the parts themselves, but also, involve excessive expenditure as regards assembly labor.
In other instances, the cord connectors of the present ;invention have had the undesirable characteristic wherein they can be assembled on the job, or by the ultimate purchaser, only at the cost of an excessive amount of time. In such instances, it has been common to provide a plurality of elongated screws, which must be individually threaded into cooperating openings on one of the connector parts, for the purpose of assembling the cooperating connector part or parts therewith.
In still other instances, the device, when assembled with a conductor, has failed to provide sufficient guarantee that the conductor will be securely locked in place. In some instances, the conductor or power cable has no capability of holding the parts of the connector against accidental disengage- -ment. Rather, the conductor is engaged in one of the connector parts by a means individual to that part. The connection of ;the connector parts, in the prior art, has then been achieved by means completely separate and distinct from the means employed -~
to engage the cable or conductor, In still other devices, after : .
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connection of the connector parts to each other, there isnothing that responds to the act of connecting the parts and the clamping of the cable to automatically lock them together against accidental separation. Locks against accidental separa-tion, if they do exist, in such instances must be a means separate and distinct from, and having no direct cooperation with, the means for coupling the connector body components and the clamping of the cable.
In the prior art, strain relief means has been pro-vided, usable in cord connectors of the type previously des-cribed herein as well as in other wiring devices, that have not`
been possessed of the desired high efficiency as regards gripping of the conductor or cable tightly within the wiring device body. In some instances, a strain relief means is built directly into cooperating, facing portions of the body, and a means of this type is obviously highly efficient, so long as the conductor is of a prescribed exterior diameter and has insulation of a predetermined deformability. In such instances, further, strain-relief is achieved only when the body is con-nected, and it is necessary to completely disconnect the sec-tions of the body, one from the other, in order to free the conductor. Such prior art devices, though efficient under the predetermined, controlled conditions described, do not allow ` effective discharge of the strain-relief function if the con-ductor size is not accurately maintained. Nor do the prior art devices allow adjustment of the strain relief according to the relative deformability of the insulation, that is, the strain l .
relief force exerted against the conductor cannot be increased or reduced, according to the needs of the particular situation ~1 30 as determined by the cable size and the type and relative ;'` resistance of the insulation to deformation.
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~ ~ _5_ , . _ l~lil~8 SUMMARY OF THE INVENTION
In accordance with the invention of the present divisional there is provided in one aspect in a wiring device of the type that includes a body of electrically insulative material having an axial passage for an electrical conductor, the improve- -ment comprising: 1) a screw threadedly engaged in the body for . .
advancement transversely of and into the passage, the body having a laterally inwardly extending opening entering upon the passage and formed with threads engaging the threads of the screw; and 2) : 10 a clamping head swivelled on the screw for advancement therewith into and transversely of the passage and having a clamping surface facing away from the screw adapted for exerting pressure on the - ~ -conductor effective to clampingly engage it against the wall of the passage at a location diametrically opposite that at which said opening enters upon the passage, when the screw is advanced.
According to a further aspect of the invention there is provided in a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement : comprising: 1) a screw threadedly engaged in the body for advance-ment into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, the body having guide slots paralleling the screw axis and slidably engaging portions of the head to prevent the head from rotating with the screw, the head and screw having complementary means producing interference between the screw and head at predetermined ;~ intervals during rotation of the screw relative to the head to ::
: provide at least a tactile reference to a user in the form of step-by-step indexing of the advancing screw.
According to a still further aspect of the invention there is provided in a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising: 1) a screw threadedly engaged in the body for advance-- 6 - -:
ment into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passages when the screw is advanced, the screw including a projection extending through the clamping head, the clamping head being rotatable upon said projection, said projection extending forwardly through the clamp-ing head for frictional, binding engagement against the conductor whereby to assist in clamping the conductor within said passage, while being retained frictionally by the conductor against rotation of the screw from selected positions to which it is advanced.
Accordingly, a still further aspect of the invention provides in a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising: 1) a screw threadedly engaged in the body for advance-ment into the passage; and 2) a clamping head swivelled on the ~
screw and adapted for exerting pressure on the conductor effective ::
: to clampingly engage it in the passage when the screw is advanced, said clamping head being formed with a plurality o~ parallel, forwardly projecting strain relief ribs adapted to bear againstthe conductor at selected locations longitudinally spaced along the conductor, for strain relief of the conductor responsive to threaded advancement of the screw.
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BRIEF DESCRIPTION OF THE DRAWINGS
While the invention is particularly pointed out and dis-tinctly claimed in the concluding portions herein, a preferred embodiment is set forth in the following detailed description which may be best understood when read in connection with the accompanying drawings, in which:
Figure 1 is a view showing male and female cord con-nectors constructed according to the present invention, said connectors being illustrated in side elevation and being shown approaching a connected relationship;
Figure 2 is a greatly enlarged, longitudinal sectional view through the male connector, taken on line 2-2 of Figure l;
Figure 3 is a transverse sPctional view, the scale being greater than that of Figure 1 but substantially reduced in respect to Figure 2, taken on line 3-3 of Figure 2 and illustra-ting in section the strain-relief means, the conductor being ~ :
shown in chain-dotted outline;
Figure 4 is a transverse sectional view on the same scale as Figure 3, on line 4-4 of Figure 2, in which the contact housing is shown in top plan;
Figure 5 is an enlarged, exploded perspective view of the strain-relief means;
Figure 6 is an exploded view illustrating the components of the male cord connector in side elevation, portions being :~
broken away; :.
Figure 7 is a perspective view, on an enlarged scale, of the plunger element or lock pin, per se;
Figure 8 is a perspective view of the cover member of . the contact housing;
Figure 9 is an exploded perspective view of one of the contact assemblies of the male cord connector;
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Figure 10 is a transverse sectional view on the same scale as Figure 3, taken on line 10-10 of Figure 2;
Figure 11 is an exploded view of the contact housing and its associated support, said housing and support being shown in side elevation with portions being broken away as they appear prior to connection of the cable to the housing and assembly of the housing with its associated support;
Figure 12 is a fragmentary, detail sectional view on the same scale as Figure 2, showing the lock pin in a retracted position to permit disassembly of the contact housing from its support;
Figure 13 is a fragmentary view, partly in side eleva-tion and partly in longitudinal section, showing the lock pin as it appears while being shifted to its retracted, unlocking position;
Figure 14 is a view like Figure 5 showing a modified strain-relief means; and Figure 15 is a fragmentary transverse sectional view similar to Figure 3, illustrating the strain-relief means of Figure 14 mounted in the cord connector.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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Referring to Figure 1, there are here illustrated a male cord connector 10 and a female connector 11 as they appear immediately prior to assembly. Hereinafter, the description of the preferred embodiment will proceed with reference to the male connector only. The female connector differs from the male con-i nector only with respect to the type of contacts employed, and ., modification of the components of the contact housing and support to accommodate the female contacts. Modification of a contact ~ 30 carrier to receive a particular type of contact, whether it be a ;I male or a female contact, is well known in the art, and accord-:
-ingly special illustration of the female connector details isnot believed necessary herein. The invention, it is important to note, will, however, be understood as being applicable both to connectors of the male type as well as those of the fema e variety.
The connector 10 may be considered as basically com-prising (see Figures 2 and 6) a contact housing generally desig-nated 12; a support for the contact housing generally designated 13; a lock means generally designated 14 mounted in the support and adapted for holding the support 13 and housing 12 against I relative separation; and a strain-relief generally designated 30 -~
which for purposes of the present disclosure is incorporated in the support 13 but which is believed to have general utility as ; a strain-relief for wiring devices of varioùs types.
Each of these main assemblies or components will be , separately described herein.
Con*act Housing Support The support 13 for the contact housing comprises an elongated, cylindrical, hollow, two-piece body 16, that includes an elongated, sleeve-like front body portion or skirt 18, the rear end of which abuts against and is ultrasonically welded or otherwise permanently, fixedly secured to a relatively short rear end portion 20. The permanent connection of the skirt 18 ~ and the rear end portion 20, at the interface 22 thereof, is ¦ ~ effected after assembly of the lock means 14 therewith (see Figure 6). Since the strain-relief means is, like the lock means, interposed between the skirt and the rear end portion, it also, if deslred, may be dropped into place before the skirt and rear end portion are assembled. The skirt and the rear end portion may in this event be formed with cooperating means in the form of a shoulder or shoulders, not shown, to hold the strain-relief permanently captive within the body 16.
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3 8 In the ~emale connector 11, the rear end portion 20, strain-relief 30, skirt 18, and lock means 14 would be the same as in the male connector, the only difference being a contact housing 12a elongated to accommodate female contacts, not shown, which in this event would be recessed wholly within the contact housing.
An axial passage 24 (Figures 2, 3, and 6) is formed in end portion 20, receiving an insulated power cable or conductor C. Formed in the passage 24, inwardly from the end thereof, is a strain-relief rib 26, molded integrally in the wall of the passage, and extending, in a preferred embodiment, through approximately 180. At its ends, strain-relief rib 26 merges smoothly into the surface of the passage wall. A similar strain-relief rib 26a is formed in the inner wall of sleeve or skirt 18 (see Figures 2 and 6).
Diametrically opposite the strain-relif ribs 26, 26a, there is formed in the two piece body 16 a laterally inwardly extending, threaded opening 28 in which the strain-relief means ~'l 30 is mounted. Referring to Figùre 6, it may be noted that the opening 28 is defined by confrontingl semi-circular recesses 28a, 28b of rear end portion 20 and skirt 18 respectively. The confronting recesses are formed with mating threads, so that in the assembled relationship of the skirt 18 and the rear end portion 20,'said recesses cooperate to define the threaded opening 28 in which is engaged the strain-relief 30.
! ~ - Strain-relief 30 comprises a screw 32 which, as is true also of the skirt 18 and rear end portion 20, may be of molded plastic material. Screw 32 (see Figure 5) is assembled with a swiveled clamping head generally designated 34. Head 34 is swivelly mounted upon the leading or inner end of the screw, and~extends into the passage is confronting relation to the I permanently molded strain~relief ribs 26, 26a.
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Since both screw 32 and head 34 may be molded of plastic material, they may also be transparent. This transparency of the two elements in combination with their large diameters, facilitates inspection of the clamped portion of the cord after it has been installed in the device. Thus, initial misplacement of the cord or possible slippage of the cord when the device is in use can readily be detected.
Referring to Figure 5, it will be seen that the screw 32 is formed with a deep recess 36 extending inwardly from the inner end thereof. Centrally disposed in the recess 36 is a molded boss 38 (Figures 2 and 5), which projects toward the open inner end Gf recess 36, and which is molded with an elongated I axial p~ojection 39 having a tapered inner end portion 39a centered upon and molded integrally with the boss 38.
Head 34 is also of molded plastic, and is formed with a circular, flat, disc-like base 40 integral with a reduced, "
circular, rearwardly extending portion 42 rotatably, snugly engaged in the inner end of recess 37 of screw 32. A center opening 44 of head 34 receives the distal end of projection 39 which, after extension through the center opening, is staked or otherwise expanded as shown at 46 in Figure 2 to hold the head and screw assembled. This may be achieved by ultrasonic, mechanical, or~thermal staking, all of these methods being known i in the art. In staking the end of the projection, a knurled or ¦ roughened surface may be imparted to the staked-over portion, to ; increase the frictional binding of the projection against the I insulation of the conductor or cable C, when the conductor is ! .
clamped. This enhanced frictional engagement of the projection with the cable inhibits rotational movement of the screw in a reverse direction after it has been advanced to a position in which the swiveled clamping head is fully engaged against the .
; ' ' 8 ~-cable insulation in a strain-relieving relationship to the cable.
On the front surface of the head 34, there is integrally formed a center strain-relief rib 50 extending diametrically across and molded integrally with the base, midway between a pair of like, side strain-relief ribs 54 laterally spaced from and parallel with the rib 50. In the preferred embodiment, the rib 50 projects forwardly a greater distance than do the side ribs 54. Rib 50 has, at the center of the head, an open area 52 communicating with the projection-receiving opening 44, the projection extending through the opening and being staked over the portion of the head surrounding the projection-receiving opening.
The rlb 50 is formed in halves respectively disposed at opposite sides of projection 39 and extending forwardly beyond the staked end 46 thereof. Frictional engagement of the con-ductor insulation by end 46, is thus promoted while destructive penetration of the cable jacket by the end 46 is prevented by the adjacent rib halves.
-Rib 50 projects, at its ends, beyond the periphery of the base 40, and the projecting ends of the rib engage in dia-metrically opposed, elongated, parallel guide slots 56 formed in the wall of threaded opening 28. The rib ends are freely slidable within the guide slots, which engage the head against rotation, during advancement or retraction of the screw.
By reason of this arrangement, when the screw is threaded inwardly, ultimately the head will be forced against the insulation of cable C, and will be pressed into said insula-tion, effectively deforming or crimping the insulation about the ribs in the manner shown to particular advantage in Figure 2.
The cable is forced by the head against the opposite side of the cable passage 24, where it is further deformed and hence -~
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strain-relieved by the integral ribs 26, 26a. Ribs 26, 26a are offset longitudinally of the passage 24 from the center rib 50 and the ribs 54. The ribs 26, 26a occur between the center rib 50 and the respective ribs 54 as shown to best advantage in Figure 2.
Further strain-relieving of the connection of the cable to its associated terminals, and clamping of the cable, is -achieved by the lock means 14, in a manner to be discussed in further detail herein.
When the strain-relief screw 32 is advanced, as for example to the Figure 2 position, the head 34, as it is forced into the insulation of the cable, exerts a reverse or rearwardly directed pressure against the screw. This pressure is exerted by the periphery of the base 40, against the adjacent, open end of the screw. The thread, as a consequence, is caused to bind at the location of its threads, against the female threads of the opening 28. This locks the screw frictionally against reverse rotation from a full, cable-clamping position.
At the same time, the cable engages the roughened end 46 of the projection 39, and this engagement further serves to inhibit rotational movement of the screw from its advanced, opera-tive position. As previously noted herein, pressure of the end 46 of projection 39 against the cable jacket is limited by the rib 50 to inhibit rotation of the screw while avoiding penetra-tion of the jacket.
Referring to Figure 2, in the forward end of skirt 18, there is formed a bottom recess or counter bore 60, in communi-cation with the axial passage 24, and integrally molded in the wall of the recess 60 are female threads or slots 62. The par-ticular form of these slots is shown to best advantage in Figure- 6, from which it is seen that the slots are steeply pitched and .:
are widely spaced. In a preferred embodiment, three, uniformly angularaly spaced slots are utilized. As a result, when the contact housing 12 is to be assembled with the skirt 18, they are simply brought together without need for aligning the male and female threads. A pilot section of the contact housing less than or equal to the minor diameter of the male thread facili-tates axial alignment of the contact housing and skirt. A
simple, partial rotation of the skirt and contact housing rela-tive to one another is effective to register the male and female threads and thereafter quickly couple the contact housing and skirt in a position in which they are fully assembled as in Figure 2, the dead front of the contact housing having a knurled portion protruding from the leading or forward edge of the skirt 18 to facilitate grasping thereof during assembly or disassembly.
Also formed in the skirt 18 of the body 16 (see Figures 2 and 6), in parallel relation to the centrally disposed con-ductor passage or bore 24, is a plunger or lock pin bore 64, aligned axially with a recess 66 (Figure 2) formed in the inner face of the end portion 20. Communicating with the plunger bore 64, and opening through the side wall of the skirt 18, is a plunger handle guide slot 68.
Locking Assembly A locking assembly or lock means generally designated 14 includes (Figure 2) a molded, plastic, elongated locking plunger 70 formed to include a one-piece plunger element or lock pin 71 having flat sides so as to be non-rotatable in the com-plementarily shaped plunger bore 64 while being freely slidable in the bore in the direction of the plunger length. Projecting laterally outwardly from the lock pin 71, and molded integrally therewith, is an elongated handle 72 projecting laterally out-~ wardly through and shiftable longitudinally within the handle :
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guide slot 68. To save material and to shorten cure time in the mold, recesses or openings 73 are formed in the lock pin.
The lock pin is molded integrally with triangular clamping lugs 74 at opposite sides of a coil-spring-receiving, longitudinally extending recess 75 opening upon one end of the lock pin and adapted to receive a coil spring 76 held under com-pression (Figure 2) between the lock pin and a projection 76a extending from the end wall of recess 66. The clamping lugs extend laterally inwardly, adjacent the spring-receiving end of the lock pin, through orifice 77 communicating between the cable - or conductor passage 24, and the plunger bore 64.
Spring 76 normally biases the lock pin 71 in an axial direction, to the position shown in Figure 2, in which position it is adapted, as will be described in full detail hereinafter, to releasably interlock the contact housing 12 and the contact housing support 13 against relative separation from their assembled, Figure 2 position.
Contac* Hoùsing The contact housing 12 is illustrated to best advantage in Figures 2, 4, ~, and 11. In its fully assembled condition it appears as in Figure 11.
The contact housing in the male connector 10 includes male contacts that project forwardly in the manner shown in Figures 1, 2, and 11. If the contact housing is of the type that receives female contacts, it would be elongated downwardly in Figure 2, for recessing of the female contacts entirely within the body of the housing, as distinguished from the Figure 2 arrangement in which the male contacts project beyond the -insulative, plastic carrier provided therefor. ~ ~
In Figure 1, the contact housing has been generally -designated 12a and except for elongation thereof to receive .' .
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female contacts that are fully recessed, is identical in con-struction and use to the housing 12. Accordingly, the housing 12 description will be regarded herein as applying to the housing 12a except, of course, for the difference in lengths and the recessing of the contact housing 12a to receive female contacts, rather than projecting male contacts.
Contact housing 12 includes (see Figure 8) a circular, flanged, preferably transparent contact carrier cover 78 of a plastic, electrically insulative material, formed as a flat, circular body 79 integral with a central, molded boss formed with side-by-side wireways 80. A three-wire connector is illus-trated purely by way of example. Obviously, the number of wire-ways would depend upon whether the device is being made as a two-wire, three-wire, four-wire! or five-wire device, all of which are variations of the inventive concept disclosed.
; Referring to Figure 8, uniformly, angularly spaced about the periphery of the contact carrier cover body 79 are outwardly opening, shallow locking recesses 84, corresponding in number to the threads and thread grooves provided upon the contact housing and the interior of the skirt 18, respectively. The locking recesses are so disposed angularly upon the circumference of the carrier cover body that upon turning of the contact housing into the skirt, one of the recesses will move into axial align-ment with the plunger element 71, when the contact housing reaches its innermost, final position in respect to the support body 16. This position is shown in Figure 2. As the contact carrier cover nears the inner end wall of bottom recess 60 of skirt 18, it will slidably engage the projecting end of the spring biased lock pin or plunger element 71. Further rotatable advancement of the contact housing into the recess 60 will initially force the lock pin 71 inwardly, as shown in Figure 12.
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When, however, a locking recess 84 moves into full alignment with the plunger element 71 (this will occur when the contact housing has been rotatably, inwardly advanced 'co its full extent), the spring 76 will now be free to expand, and will bias the plunger element into the recess 84 aligned therewith. This interlocks the contact housing 12 with the contact housing support 13, in their assembled relation shown in Figure 2. When so interlocked, they cannot be relatively rotated from their fully assembled relationship shown in Figure 2.
The flat top surface of the carrier cover body 79 has been designated at 82, and recesses 84 are formed in said top - ;
surface, the bottoms of the recesses terminating short of the underside of the carrier cover. Molded integrally with the under-side of the carrier cover, and extending downwardly therefrom in alignment with the respective recesses 84, are downwardly tapering projections 90. These extend into upwardly opening recesses 88 of a contact carrier 86 also of molded plastic material. Recesses 88 and projections 90 provide for accurate orientation of the contact carrier cover 79 in respect to its associated, underlying contact carrier 86, not only for the purpose of properly locating the stripped ends E of the con-ductor in respect to terminals carried by the carrier 86, but also, for the important purpose of properly orienting the locking recesses 84 in relation to male threads integrally molded upon the exterior of the carrier 86 for engagement in grooves 60 of skirt 18.
In a preferred embodiment (see Figure 10) contact car-rier 86, unlike the carrier cover 79, is not transparent, but is nevertheless formed of molded plastic, electrically insulative material. As shown in Figure 10, the carrier 86 is molded integrally with a series of radial partitions 92 integrally . ~.
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joined at the center of the carrier and extending outwardly to an integral connection to the side wall 93 of the contact carrier.
The partitions 92 are also integral with a front wall 94 of the contact carrier, which constitutes the "dead front" of the cord connector. The term "dead front" is understood as meaning a front end construction, in an electrical connector, wherein the molded housing material extends fully across the front, with all terminal connections disposed in back of it and without access to the interior. In a "dead front" device such as that illus-trated, the only electrically conductive elements accessible atthe front are the male or female contacts themselves.
The partitions 92, side wall 93, and the dead front 94 cooperate to define rearwardly opening contact cavities 96 which ~ -~in the present instance, the connectors being a three-wire device, are three in number as shown in Figure 10, each receiving a contact and its associated terminal, in a manner to completely insulate the same electrically from contacts and terminals adjacent thereto.
Communicating with each contact cavity, as shown in Figures 2 and 10, are laterally opening, generally semi-circular terminal-screw-receiving notches or side openings 98. ~lso communicating with each contact cavity through the dead front, are contact-receiving slots. In the present instance, in a three-wire device of the type illustrated, there are two line contact slots 100, and one grounding contact slot 102, which differs from the line contact slots by reason of having a special lateral extension or extensions at its ends, according I to contact configurations that are standard in the wiring device j industry.
At this point it may be noted that the particular cord connector illustrated is of the locking type in which the male .
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and female cord connectors are relatively rotated to join the same, and move into a relationship in which they are inter-locked against accidental separation. The invention could, of course, be applied equally well to connectors of the straight blade type.
In the illustrated example, each contact is engaged in the associated contact cavity, at the inner end of the contact, through the provision of a terminal collar 104, which may be as shown, a wholly conventional type capable of being purchased on the open market. As shown in Figure 9, terminal 104 includes, in the illustrated example, a rectangular yoke 106, seeding in the associated cavity, and having a threaded opening 118 in one end adapted to receive a machine screw 120 which, in the illus-trated example, is of the washer head type.
It will be understood that the cover body 79 is ultra-sonically welded or otherwise permanently secured, during manu-facture, to the contact carrier 86. By making the cover trans-parent, the user can observe whether the terminals are in clamped -or open position and whether the inserted wires are properly located and fully inserted in the terminals.
In the illustrated example the line contacts have been designated 122, and as shown include laterally outwardly pro-jecting, curved lugs 124 which seat within the slots 100 to close the slots over the full length thereof in the assembled relation-ship of the contacts and carrier. Immediately adjacent the lugs 124 there are provided laterally outwardly extending stop shoulders 125, which are extended straight outwardly from the body of the contact, and as shown in Figure 2 are offset inwardly from the slots 100 so as to bear against the bottom surfaces of the contact cavities.
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At their inner ends, the contacts as noted above are slightly offset radially inwardly of the contact carrier (Figure 2), and extend into the terminal yokes 106, being formed at their inner ends with inwardly offset tabs 126 for this purpose.
Tabs 126 have partly-spherical projections 127 to improve the quality of the electrical connection between the terminals and the cable ends.
The stripped ends of the conductor, as shown in Figure 2, are extended into the yokes, and responsive to advancement of the screws, are effectively clamped between tabs 126 and the yoke walls remote from the screws.
The ground contact in the illustrated example has been designated 128 and of course has a standard configuration at its distal end, for ground contacts of the type and electrical rating illustrated by way of example. At its inner end, the ground contact is formed similarly to the line contacts. The contact carrier cover, as shown in Figure 8, may have a marking "G" adjacent one of the wireways to assure connection of the ground wire of conductor C to the ground contact 128.
Referring to Figure 1, in the female connector 11, terminals 104 are identical to those already described. In this form of the invention, however, the female contacts have been designated 122a, and at their distal ends are of well-known, -standard configuration adapted to receive the line contacts 122 or the grounding contact 128 as the case may be. At their inner ends, the contacts 122a would be formed similarly to the contacts 122, 128, that is, they would have the stop shoulders 125 and the tabs 126 extending into their associated yokes 104. In this -form of the invention, as previously noted, the contact slots lOOà are elongated in the axial direction, to accommodate the full length of the female contacts and assure their being wholly recessed within the material of the contact carrier 96a.
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Molded upon the exterior surface of the carrler side wall 93 (see Figures 6 and 11) is a series of uniformly, angu-larly spaced quick threads 130 corresponding in number to the thread grooves 60. In the form of the contact carrier used for the female connector 11, the quick threads would be identical to those shown in Figure 6 for the male connector, and it will be also understood that the female thread grooves 60 of skirt 18 would similarly be identical in length and location in both the -male and female connector structure.
Operation In use of the device, it will be understood that the contact housing 12 will be factory-assembled in the form shown in Figure 11. The same is true of the contact housing support 13 illustrated in its fully assembled form in Figure 11.
The user of the device first strips ends E of the conductor or power cable C, after e~tending the power cable through the conductor passage 24 to the position shown in Figure 11. The stripped ends E are then inserted through wire-ways 80, moving into the yokes 106 to the position shown in Figure 2. Screws 120 are then turned home, to tightly clamp the stripped ends in the yokes.
The contact housing is then assembled with the housing support 13 in the manner previously described herein, that is, the housing support 13 is merely moved downwardly along the cable after the cable ends have been secured within the yokes, until the pilot portion of the contact housing 12 ~or 12a in the case of the female connector) enters skirt 18. Then the skirt is rotated relative to the contact housing. This requires use - only of the tactile sense, rather than a conscious requirement of visual orientation of the skirt and housing relative to each other. Relative rotation through a few degrees will cause thread ; :
l8 grooves 62 to align with the inner ends of the male quick thréads 130 of the contact housing. It is immaterial which thread grooves align with which threads. Further relative rotation of the housing support 13 relative to the contact housing~ thrf~ugh per-haps 90, more or less, causes the housing and the housing sup-port to move into their fully assembled relationship shown in Figure 2. As previously noted herein, during this assembly the lock pin 71 is initially pressed back by the flat top surface of the carrier cover 78, but is biased forwardly into one of the locking recesses 84 in the fully assembled relationship of the contact housing and its associated support. The final position of the parts is shown in Figure 4, and also in Figure 2.
The strain-relief 30 is now operated, screw 32 being advanced until the cable is tightly engaged by and between strain-relief ribs 26, 26a and the ribs 50, 54 of the strain-relief head 34. In these circumstances the insulation of the cable is pressed inwardly and is deformed in the manner shown in Figure 2, at diametrically opposite locations on the cable, by the ribs 26, 26a, 50, 54.
When the cable is forced to its clamped, strain-relieved position shown in Figure 2, as previously noted the cable itself acts as a means (though not the only means) for locking the strain-relief screw against retrograd~ movement. Very important-ly, however, and as clearly shown in Figure 2, at a location ; ~ diametri~ally opposite the swiveled clamping head the cable insulation is forced into the clamping orifice 77, against the clamping lugs 74. The cable insulation bulges into the space between the angled surface of the lugs 74 and the wall of .
orifice 77 spaced from the lugs. ~ -The angled surface of lugs 74 serves a three-fold purpose. First, if plunger 70 does not seat fully in bore 64, ::
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the cable jacket when forced against the lugs will exert a cam action against the angled surface and will bias the plunger to a fully seated position. Second, on disassembly the cable insula-tion tends to remain deformed with its bulge remaining in the space above the lugs. The angled surface will cammingly bias the jacket material out of the path of the lugs as the plunger is ~' lifted, to free the contact housing for release. Third, because `
the angled surface is angled away from the cable and is recessed in respect to rib 26a (see Figure 2) any excessive, extremely heavy pull on the cable tending to cause it to slide upwardly in Figure 2, will not engage and lift the plunger to a release position.
Bulging of the cable into the space above the angled ; surface prevents the movement of the lock pin from its locking position shown in Figure 2. Even if one engages the handle 72 and attempts to shift the lock pin away from its locking position shown in Figure 2, there can be no movement of the lock pin because of the engagement thereof by the inwardly bulged cable insulation. The cable thus acts as a stop, when the cable is clamped, limiting movement of the lock pin from its locking position shown in Figure 2.
At such time as it may be desired to disassemble the device from its fully assembled, cable-clamping, use position shown in Figure 2, one merely backs off the screw 32. The cable is now loose in the passage 24, and moves out of the path of movement of the lugs 74. By "path of movement" is meant the paths that the lugs would travel when the lock pin is shifted from the Figure '2 position to its retractéd position shown in Figure 13.
With the cable IGose in the passage, one can now, as shown in Figure 13, operate the plunger to its retracted position i:
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against the restraint of spring 76. This disengages the lock pin from its associated locking recess 84. As a result, with the cable loose in passage 24 and the lock pin temporarily held in retracted position, one merely relatively rotates contact housing support 13 in respect to contact housing 12, in a direc-tion to thread the contact housing out of the body 16 of the housing support.
In this way, an extremely effective, safe device is pro-vided, which will assure that the cable will be securely clamped and strain-relieved in the use condition of the device. Further, the device is especially well adapted for quick assembly and dis-assembly ln situ. The cable itself, responsive to its being clamped and strain-relieved, becomes a means for engaging the locking assembly 14 against movement from its locking position shown in Figure 2, and at the same time, the cable further serves as means cooperating with the swiveled head 34 in engaging the set screw against accidentally backing out from its inwardly advanced, strain-relieving position shown in Figure 2.
The female connector is, of course, identical to the male connector in every respect except for the length of the contact housing, and its modification to receive female rather than male contacts. Beginning at a location designated by thè
cutting plane 10-10 of Figure 2, and for the remainder of the length of the device when one looks toward the cable entrance end thereof, the female and male connectors are identical in every respect.
A modified construction of the strain-relief is illus-; trated in Figures 14 and 15. In the modified arrangement, where-in the strain-relief has been generally designated 30a, the set screw 32a is formed with a deep, annular slot 36a opening upon the inner end of the set screw, and with an axial recess 38a : ~; . ':
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~: ' also opening upon the inner end of the screw as shown in Figure 15. Recess 38a may be formed with a slight enlargement at its inner end, which can be readily achieved in the molding opera-tion by maintaining the required undercut in the mold within parameters permissible in molding techniques where a part has to be stripped from the mold.
In any event, in this form of the invention the outer wall of the annular recess 36a is formed with a continuous series of straight facets 46a, complementing corresponding facets 44_ formed on the outer surface of the body 42a of a swiveled clamp-ing head 34a having a diametrically extending main strain-relief rib 50a and parallel, secondary strain-relief ribs 54a.
Referring to Figure 15, integrally molded with the body of the clamping head is a rearwardly extending stem 48a, having ~
an enlarged head at its distal end. ~-In this arrangement, the swiveled head is first as-embled with the screw, by pressing the stem into the recess 38a.
The head and screw in effect are snapped together, with the head thus being captive on the screw but being freely rotatable in regard thereto.
As the screw is advanced, the facets 44a, 46a will pro-duce a gentle clicking during rotation of the screw relative to the clamping head which, as previou~ly described, does not turn as it moves forwardly within the guide slots 56. This provides ~` a tactile indexing feature, that is, as the user advances the screw, the user feels the gentle ratcheting or clicking action ;
as the screw turns. Eventually, as the swiveled clamping head moves into its full clamping position, the feel becomes more pronounced, and ultimately, the user, by the tactile indexing feature, knows that the screw has heen advanced to the desired ~;~ extent to assure D good clamping and strain-re]ief of the cable.
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In this arrangement, further, in the final position of the screw, facets 44_ would be in registration with facets 46a, and this aids in preventing reverse rotation of the screw. The facets have an interference with each other as the screw rotates rela-tive to the head. Accordingly, the screw would not rotate past the several, uniformly angularly spaced interference points in and of itself, requiring instead a more positive force such as would be exerted by the torque of a screwdriver in the hands of a user.
While particular embodiments of this invention have been shown in the drawings and described above, it will be apparent, that many changes may be made in the form, arrangement and positioning of the various elements of the combination. In con~sideration thereof it should be understood that preferred embodiments of this invention disclosed herein are intended to be illustrative only and not intended to limit the scope of the invention.
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An axial passage 24 (Figures 2, 3, and 6) is formed in end portion 20, receiving an insulated power cable or conductor C. Formed in the passage 24, inwardly from the end thereof, is a strain-relief rib 26, molded integrally in the wall of the passage, and extending, in a preferred embodiment, through approximately 180. At its ends, strain-relief rib 26 merges smoothly into the surface of the passage wall. A similar strain-relief rib 26a is formed in the inner wall of sleeve or skirt 18 (see Figures 2 and 6).
Diametrically opposite the strain-relif ribs 26, 26a, there is formed in the two piece body 16 a laterally inwardly extending, threaded opening 28 in which the strain-relief means ~'l 30 is mounted. Referring to Figùre 6, it may be noted that the opening 28 is defined by confrontingl semi-circular recesses 28a, 28b of rear end portion 20 and skirt 18 respectively. The confronting recesses are formed with mating threads, so that in the assembled relationship of the skirt 18 and the rear end portion 20,'said recesses cooperate to define the threaded opening 28 in which is engaged the strain-relief 30.
! ~ - Strain-relief 30 comprises a screw 32 which, as is true also of the skirt 18 and rear end portion 20, may be of molded plastic material. Screw 32 (see Figure 5) is assembled with a swiveled clamping head generally designated 34. Head 34 is swivelly mounted upon the leading or inner end of the screw, and~extends into the passage is confronting relation to the I permanently molded strain~relief ribs 26, 26a.
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Since both screw 32 and head 34 may be molded of plastic material, they may also be transparent. This transparency of the two elements in combination with their large diameters, facilitates inspection of the clamped portion of the cord after it has been installed in the device. Thus, initial misplacement of the cord or possible slippage of the cord when the device is in use can readily be detected.
Referring to Figure 5, it will be seen that the screw 32 is formed with a deep recess 36 extending inwardly from the inner end thereof. Centrally disposed in the recess 36 is a molded boss 38 (Figures 2 and 5), which projects toward the open inner end Gf recess 36, and which is molded with an elongated I axial p~ojection 39 having a tapered inner end portion 39a centered upon and molded integrally with the boss 38.
Head 34 is also of molded plastic, and is formed with a circular, flat, disc-like base 40 integral with a reduced, "
circular, rearwardly extending portion 42 rotatably, snugly engaged in the inner end of recess 37 of screw 32. A center opening 44 of head 34 receives the distal end of projection 39 which, after extension through the center opening, is staked or otherwise expanded as shown at 46 in Figure 2 to hold the head and screw assembled. This may be achieved by ultrasonic, mechanical, or~thermal staking, all of these methods being known i in the art. In staking the end of the projection, a knurled or ¦ roughened surface may be imparted to the staked-over portion, to ; increase the frictional binding of the projection against the I insulation of the conductor or cable C, when the conductor is ! .
clamped. This enhanced frictional engagement of the projection with the cable inhibits rotational movement of the screw in a reverse direction after it has been advanced to a position in which the swiveled clamping head is fully engaged against the .
; ' ' 8 ~-cable insulation in a strain-relieving relationship to the cable.
On the front surface of the head 34, there is integrally formed a center strain-relief rib 50 extending diametrically across and molded integrally with the base, midway between a pair of like, side strain-relief ribs 54 laterally spaced from and parallel with the rib 50. In the preferred embodiment, the rib 50 projects forwardly a greater distance than do the side ribs 54. Rib 50 has, at the center of the head, an open area 52 communicating with the projection-receiving opening 44, the projection extending through the opening and being staked over the portion of the head surrounding the projection-receiving opening.
The rlb 50 is formed in halves respectively disposed at opposite sides of projection 39 and extending forwardly beyond the staked end 46 thereof. Frictional engagement of the con-ductor insulation by end 46, is thus promoted while destructive penetration of the cable jacket by the end 46 is prevented by the adjacent rib halves.
-Rib 50 projects, at its ends, beyond the periphery of the base 40, and the projecting ends of the rib engage in dia-metrically opposed, elongated, parallel guide slots 56 formed in the wall of threaded opening 28. The rib ends are freely slidable within the guide slots, which engage the head against rotation, during advancement or retraction of the screw.
By reason of this arrangement, when the screw is threaded inwardly, ultimately the head will be forced against the insulation of cable C, and will be pressed into said insula-tion, effectively deforming or crimping the insulation about the ribs in the manner shown to particular advantage in Figure 2.
The cable is forced by the head against the opposite side of the cable passage 24, where it is further deformed and hence -~
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strain-relieved by the integral ribs 26, 26a. Ribs 26, 26a are offset longitudinally of the passage 24 from the center rib 50 and the ribs 54. The ribs 26, 26a occur between the center rib 50 and the respective ribs 54 as shown to best advantage in Figure 2.
Further strain-relieving of the connection of the cable to its associated terminals, and clamping of the cable, is -achieved by the lock means 14, in a manner to be discussed in further detail herein.
When the strain-relief screw 32 is advanced, as for example to the Figure 2 position, the head 34, as it is forced into the insulation of the cable, exerts a reverse or rearwardly directed pressure against the screw. This pressure is exerted by the periphery of the base 40, against the adjacent, open end of the screw. The thread, as a consequence, is caused to bind at the location of its threads, against the female threads of the opening 28. This locks the screw frictionally against reverse rotation from a full, cable-clamping position.
At the same time, the cable engages the roughened end 46 of the projection 39, and this engagement further serves to inhibit rotational movement of the screw from its advanced, opera-tive position. As previously noted herein, pressure of the end 46 of projection 39 against the cable jacket is limited by the rib 50 to inhibit rotation of the screw while avoiding penetra-tion of the jacket.
Referring to Figure 2, in the forward end of skirt 18, there is formed a bottom recess or counter bore 60, in communi-cation with the axial passage 24, and integrally molded in the wall of the recess 60 are female threads or slots 62. The par-ticular form of these slots is shown to best advantage in Figure- 6, from which it is seen that the slots are steeply pitched and .:
are widely spaced. In a preferred embodiment, three, uniformly angularaly spaced slots are utilized. As a result, when the contact housing 12 is to be assembled with the skirt 18, they are simply brought together without need for aligning the male and female threads. A pilot section of the contact housing less than or equal to the minor diameter of the male thread facili-tates axial alignment of the contact housing and skirt. A
simple, partial rotation of the skirt and contact housing rela-tive to one another is effective to register the male and female threads and thereafter quickly couple the contact housing and skirt in a position in which they are fully assembled as in Figure 2, the dead front of the contact housing having a knurled portion protruding from the leading or forward edge of the skirt 18 to facilitate grasping thereof during assembly or disassembly.
Also formed in the skirt 18 of the body 16 (see Figures 2 and 6), in parallel relation to the centrally disposed con-ductor passage or bore 24, is a plunger or lock pin bore 64, aligned axially with a recess 66 (Figure 2) formed in the inner face of the end portion 20. Communicating with the plunger bore 64, and opening through the side wall of the skirt 18, is a plunger handle guide slot 68.
Locking Assembly A locking assembly or lock means generally designated 14 includes (Figure 2) a molded, plastic, elongated locking plunger 70 formed to include a one-piece plunger element or lock pin 71 having flat sides so as to be non-rotatable in the com-plementarily shaped plunger bore 64 while being freely slidable in the bore in the direction of the plunger length. Projecting laterally outwardly from the lock pin 71, and molded integrally therewith, is an elongated handle 72 projecting laterally out-~ wardly through and shiftable longitudinally within the handle :
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guide slot 68. To save material and to shorten cure time in the mold, recesses or openings 73 are formed in the lock pin.
The lock pin is molded integrally with triangular clamping lugs 74 at opposite sides of a coil-spring-receiving, longitudinally extending recess 75 opening upon one end of the lock pin and adapted to receive a coil spring 76 held under com-pression (Figure 2) between the lock pin and a projection 76a extending from the end wall of recess 66. The clamping lugs extend laterally inwardly, adjacent the spring-receiving end of the lock pin, through orifice 77 communicating between the cable - or conductor passage 24, and the plunger bore 64.
Spring 76 normally biases the lock pin 71 in an axial direction, to the position shown in Figure 2, in which position it is adapted, as will be described in full detail hereinafter, to releasably interlock the contact housing 12 and the contact housing support 13 against relative separation from their assembled, Figure 2 position.
Contac* Hoùsing The contact housing 12 is illustrated to best advantage in Figures 2, 4, ~, and 11. In its fully assembled condition it appears as in Figure 11.
The contact housing in the male connector 10 includes male contacts that project forwardly in the manner shown in Figures 1, 2, and 11. If the contact housing is of the type that receives female contacts, it would be elongated downwardly in Figure 2, for recessing of the female contacts entirely within the body of the housing, as distinguished from the Figure 2 arrangement in which the male contacts project beyond the -insulative, plastic carrier provided therefor. ~ ~
In Figure 1, the contact housing has been generally -designated 12a and except for elongation thereof to receive .' .
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female contacts that are fully recessed, is identical in con-struction and use to the housing 12. Accordingly, the housing 12 description will be regarded herein as applying to the housing 12a except, of course, for the difference in lengths and the recessing of the contact housing 12a to receive female contacts, rather than projecting male contacts.
Contact housing 12 includes (see Figure 8) a circular, flanged, preferably transparent contact carrier cover 78 of a plastic, electrically insulative material, formed as a flat, circular body 79 integral with a central, molded boss formed with side-by-side wireways 80. A three-wire connector is illus-trated purely by way of example. Obviously, the number of wire-ways would depend upon whether the device is being made as a two-wire, three-wire, four-wire! or five-wire device, all of which are variations of the inventive concept disclosed.
; Referring to Figure 8, uniformly, angularly spaced about the periphery of the contact carrier cover body 79 are outwardly opening, shallow locking recesses 84, corresponding in number to the threads and thread grooves provided upon the contact housing and the interior of the skirt 18, respectively. The locking recesses are so disposed angularly upon the circumference of the carrier cover body that upon turning of the contact housing into the skirt, one of the recesses will move into axial align-ment with the plunger element 71, when the contact housing reaches its innermost, final position in respect to the support body 16. This position is shown in Figure 2. As the contact carrier cover nears the inner end wall of bottom recess 60 of skirt 18, it will slidably engage the projecting end of the spring biased lock pin or plunger element 71. Further rotatable advancement of the contact housing into the recess 60 will initially force the lock pin 71 inwardly, as shown in Figure 12.
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When, however, a locking recess 84 moves into full alignment with the plunger element 71 (this will occur when the contact housing has been rotatably, inwardly advanced 'co its full extent), the spring 76 will now be free to expand, and will bias the plunger element into the recess 84 aligned therewith. This interlocks the contact housing 12 with the contact housing support 13, in their assembled relation shown in Figure 2. When so interlocked, they cannot be relatively rotated from their fully assembled relationship shown in Figure 2.
The flat top surface of the carrier cover body 79 has been designated at 82, and recesses 84 are formed in said top - ;
surface, the bottoms of the recesses terminating short of the underside of the carrier cover. Molded integrally with the under-side of the carrier cover, and extending downwardly therefrom in alignment with the respective recesses 84, are downwardly tapering projections 90. These extend into upwardly opening recesses 88 of a contact carrier 86 also of molded plastic material. Recesses 88 and projections 90 provide for accurate orientation of the contact carrier cover 79 in respect to its associated, underlying contact carrier 86, not only for the purpose of properly locating the stripped ends E of the con-ductor in respect to terminals carried by the carrier 86, but also, for the important purpose of properly orienting the locking recesses 84 in relation to male threads integrally molded upon the exterior of the carrier 86 for engagement in grooves 60 of skirt 18.
In a preferred embodiment (see Figure 10) contact car-rier 86, unlike the carrier cover 79, is not transparent, but is nevertheless formed of molded plastic, electrically insulative material. As shown in Figure 10, the carrier 86 is molded integrally with a series of radial partitions 92 integrally . ~.
~ -17-: - , ~ ,: .
joined at the center of the carrier and extending outwardly to an integral connection to the side wall 93 of the contact carrier.
The partitions 92 are also integral with a front wall 94 of the contact carrier, which constitutes the "dead front" of the cord connector. The term "dead front" is understood as meaning a front end construction, in an electrical connector, wherein the molded housing material extends fully across the front, with all terminal connections disposed in back of it and without access to the interior. In a "dead front" device such as that illus-trated, the only electrically conductive elements accessible atthe front are the male or female contacts themselves.
The partitions 92, side wall 93, and the dead front 94 cooperate to define rearwardly opening contact cavities 96 which ~ -~in the present instance, the connectors being a three-wire device, are three in number as shown in Figure 10, each receiving a contact and its associated terminal, in a manner to completely insulate the same electrically from contacts and terminals adjacent thereto.
Communicating with each contact cavity, as shown in Figures 2 and 10, are laterally opening, generally semi-circular terminal-screw-receiving notches or side openings 98. ~lso communicating with each contact cavity through the dead front, are contact-receiving slots. In the present instance, in a three-wire device of the type illustrated, there are two line contact slots 100, and one grounding contact slot 102, which differs from the line contact slots by reason of having a special lateral extension or extensions at its ends, according I to contact configurations that are standard in the wiring device j industry.
At this point it may be noted that the particular cord connector illustrated is of the locking type in which the male .
~ -18-1:
, , . . - .
and female cord connectors are relatively rotated to join the same, and move into a relationship in which they are inter-locked against accidental separation. The invention could, of course, be applied equally well to connectors of the straight blade type.
In the illustrated example, each contact is engaged in the associated contact cavity, at the inner end of the contact, through the provision of a terminal collar 104, which may be as shown, a wholly conventional type capable of being purchased on the open market. As shown in Figure 9, terminal 104 includes, in the illustrated example, a rectangular yoke 106, seeding in the associated cavity, and having a threaded opening 118 in one end adapted to receive a machine screw 120 which, in the illus-trated example, is of the washer head type.
It will be understood that the cover body 79 is ultra-sonically welded or otherwise permanently secured, during manu-facture, to the contact carrier 86. By making the cover trans-parent, the user can observe whether the terminals are in clamped -or open position and whether the inserted wires are properly located and fully inserted in the terminals.
In the illustrated example the line contacts have been designated 122, and as shown include laterally outwardly pro-jecting, curved lugs 124 which seat within the slots 100 to close the slots over the full length thereof in the assembled relation-ship of the contacts and carrier. Immediately adjacent the lugs 124 there are provided laterally outwardly extending stop shoulders 125, which are extended straight outwardly from the body of the contact, and as shown in Figure 2 are offset inwardly from the slots 100 so as to bear against the bottom surfaces of the contact cavities.
.~ -19-. . ~ . .
At their inner ends, the contacts as noted above are slightly offset radially inwardly of the contact carrier (Figure 2), and extend into the terminal yokes 106, being formed at their inner ends with inwardly offset tabs 126 for this purpose.
Tabs 126 have partly-spherical projections 127 to improve the quality of the electrical connection between the terminals and the cable ends.
The stripped ends of the conductor, as shown in Figure 2, are extended into the yokes, and responsive to advancement of the screws, are effectively clamped between tabs 126 and the yoke walls remote from the screws.
The ground contact in the illustrated example has been designated 128 and of course has a standard configuration at its distal end, for ground contacts of the type and electrical rating illustrated by way of example. At its inner end, the ground contact is formed similarly to the line contacts. The contact carrier cover, as shown in Figure 8, may have a marking "G" adjacent one of the wireways to assure connection of the ground wire of conductor C to the ground contact 128.
Referring to Figure 1, in the female connector 11, terminals 104 are identical to those already described. In this form of the invention, however, the female contacts have been designated 122a, and at their distal ends are of well-known, -standard configuration adapted to receive the line contacts 122 or the grounding contact 128 as the case may be. At their inner ends, the contacts 122a would be formed similarly to the contacts 122, 128, that is, they would have the stop shoulders 125 and the tabs 126 extending into their associated yokes 104. In this -form of the invention, as previously noted, the contact slots lOOà are elongated in the axial direction, to accommodate the full length of the female contacts and assure their being wholly recessed within the material of the contact carrier 96a.
,: , , . . - . .
- : : : , ,:: ., ~ . , :
Molded upon the exterior surface of the carrler side wall 93 (see Figures 6 and 11) is a series of uniformly, angu-larly spaced quick threads 130 corresponding in number to the thread grooves 60. In the form of the contact carrier used for the female connector 11, the quick threads would be identical to those shown in Figure 6 for the male connector, and it will be also understood that the female thread grooves 60 of skirt 18 would similarly be identical in length and location in both the -male and female connector structure.
Operation In use of the device, it will be understood that the contact housing 12 will be factory-assembled in the form shown in Figure 11. The same is true of the contact housing support 13 illustrated in its fully assembled form in Figure 11.
The user of the device first strips ends E of the conductor or power cable C, after e~tending the power cable through the conductor passage 24 to the position shown in Figure 11. The stripped ends E are then inserted through wire-ways 80, moving into the yokes 106 to the position shown in Figure 2. Screws 120 are then turned home, to tightly clamp the stripped ends in the yokes.
The contact housing is then assembled with the housing support 13 in the manner previously described herein, that is, the housing support 13 is merely moved downwardly along the cable after the cable ends have been secured within the yokes, until the pilot portion of the contact housing 12 ~or 12a in the case of the female connector) enters skirt 18. Then the skirt is rotated relative to the contact housing. This requires use - only of the tactile sense, rather than a conscious requirement of visual orientation of the skirt and housing relative to each other. Relative rotation through a few degrees will cause thread ; :
l8 grooves 62 to align with the inner ends of the male quick thréads 130 of the contact housing. It is immaterial which thread grooves align with which threads. Further relative rotation of the housing support 13 relative to the contact housing~ thrf~ugh per-haps 90, more or less, causes the housing and the housing sup-port to move into their fully assembled relationship shown in Figure 2. As previously noted herein, during this assembly the lock pin 71 is initially pressed back by the flat top surface of the carrier cover 78, but is biased forwardly into one of the locking recesses 84 in the fully assembled relationship of the contact housing and its associated support. The final position of the parts is shown in Figure 4, and also in Figure 2.
The strain-relief 30 is now operated, screw 32 being advanced until the cable is tightly engaged by and between strain-relief ribs 26, 26a and the ribs 50, 54 of the strain-relief head 34. In these circumstances the insulation of the cable is pressed inwardly and is deformed in the manner shown in Figure 2, at diametrically opposite locations on the cable, by the ribs 26, 26a, 50, 54.
When the cable is forced to its clamped, strain-relieved position shown in Figure 2, as previously noted the cable itself acts as a means (though not the only means) for locking the strain-relief screw against retrograd~ movement. Very important-ly, however, and as clearly shown in Figure 2, at a location ; ~ diametri~ally opposite the swiveled clamping head the cable insulation is forced into the clamping orifice 77, against the clamping lugs 74. The cable insulation bulges into the space between the angled surface of the lugs 74 and the wall of .
orifice 77 spaced from the lugs. ~ -The angled surface of lugs 74 serves a three-fold purpose. First, if plunger 70 does not seat fully in bore 64, ::
: .
f 8 ~
the cable jacket when forced against the lugs will exert a cam action against the angled surface and will bias the plunger to a fully seated position. Second, on disassembly the cable insula-tion tends to remain deformed with its bulge remaining in the space above the lugs. The angled surface will cammingly bias the jacket material out of the path of the lugs as the plunger is ~' lifted, to free the contact housing for release. Third, because `
the angled surface is angled away from the cable and is recessed in respect to rib 26a (see Figure 2) any excessive, extremely heavy pull on the cable tending to cause it to slide upwardly in Figure 2, will not engage and lift the plunger to a release position.
Bulging of the cable into the space above the angled ; surface prevents the movement of the lock pin from its locking position shown in Figure 2. Even if one engages the handle 72 and attempts to shift the lock pin away from its locking position shown in Figure 2, there can be no movement of the lock pin because of the engagement thereof by the inwardly bulged cable insulation. The cable thus acts as a stop, when the cable is clamped, limiting movement of the lock pin from its locking position shown in Figure 2.
At such time as it may be desired to disassemble the device from its fully assembled, cable-clamping, use position shown in Figure 2, one merely backs off the screw 32. The cable is now loose in the passage 24, and moves out of the path of movement of the lugs 74. By "path of movement" is meant the paths that the lugs would travel when the lock pin is shifted from the Figure '2 position to its retractéd position shown in Figure 13.
With the cable IGose in the passage, one can now, as shown in Figure 13, operate the plunger to its retracted position i:
8 ~
against the restraint of spring 76. This disengages the lock pin from its associated locking recess 84. As a result, with the cable loose in passage 24 and the lock pin temporarily held in retracted position, one merely relatively rotates contact housing support 13 in respect to contact housing 12, in a direc-tion to thread the contact housing out of the body 16 of the housing support.
In this way, an extremely effective, safe device is pro-vided, which will assure that the cable will be securely clamped and strain-relieved in the use condition of the device. Further, the device is especially well adapted for quick assembly and dis-assembly ln situ. The cable itself, responsive to its being clamped and strain-relieved, becomes a means for engaging the locking assembly 14 against movement from its locking position shown in Figure 2, and at the same time, the cable further serves as means cooperating with the swiveled head 34 in engaging the set screw against accidentally backing out from its inwardly advanced, strain-relieving position shown in Figure 2.
The female connector is, of course, identical to the male connector in every respect except for the length of the contact housing, and its modification to receive female rather than male contacts. Beginning at a location designated by thè
cutting plane 10-10 of Figure 2, and for the remainder of the length of the device when one looks toward the cable entrance end thereof, the female and male connectors are identical in every respect.
A modified construction of the strain-relief is illus-; trated in Figures 14 and 15. In the modified arrangement, where-in the strain-relief has been generally designated 30a, the set screw 32a is formed with a deep, annular slot 36a opening upon the inner end of the set screw, and with an axial recess 38a : ~; . ':
~' : . ,:
~: ' also opening upon the inner end of the screw as shown in Figure 15. Recess 38a may be formed with a slight enlargement at its inner end, which can be readily achieved in the molding opera-tion by maintaining the required undercut in the mold within parameters permissible in molding techniques where a part has to be stripped from the mold.
In any event, in this form of the invention the outer wall of the annular recess 36a is formed with a continuous series of straight facets 46a, complementing corresponding facets 44_ formed on the outer surface of the body 42a of a swiveled clamp-ing head 34a having a diametrically extending main strain-relief rib 50a and parallel, secondary strain-relief ribs 54a.
Referring to Figure 15, integrally molded with the body of the clamping head is a rearwardly extending stem 48a, having ~
an enlarged head at its distal end. ~-In this arrangement, the swiveled head is first as-embled with the screw, by pressing the stem into the recess 38a.
The head and screw in effect are snapped together, with the head thus being captive on the screw but being freely rotatable in regard thereto.
As the screw is advanced, the facets 44a, 46a will pro-duce a gentle clicking during rotation of the screw relative to the clamping head which, as previou~ly described, does not turn as it moves forwardly within the guide slots 56. This provides ~` a tactile indexing feature, that is, as the user advances the screw, the user feels the gentle ratcheting or clicking action ;
as the screw turns. Eventually, as the swiveled clamping head moves into its full clamping position, the feel becomes more pronounced, and ultimately, the user, by the tactile indexing feature, knows that the screw has heen advanced to the desired ~;~ extent to assure D good clamping and strain-re]ief of the cable.
:
~ 25-: : :
In this arrangement, further, in the final position of the screw, facets 44_ would be in registration with facets 46a, and this aids in preventing reverse rotation of the screw. The facets have an interference with each other as the screw rotates rela-tive to the head. Accordingly, the screw would not rotate past the several, uniformly angularly spaced interference points in and of itself, requiring instead a more positive force such as would be exerted by the torque of a screwdriver in the hands of a user.
While particular embodiments of this invention have been shown in the drawings and described above, it will be apparent, that many changes may be made in the form, arrangement and positioning of the various elements of the combination. In con~sideration thereof it should be understood that preferred embodiments of this invention disclosed herein are intended to be illustrative only and not intended to limit the scope of the invention.
.;` ' .
~', :. . .
!
~, :
Claims (12)
1. In a wiring device of the type that includes a body of electrically insulative material having an axial passage for an electrical conductor, the improvement comprising:
1. a screw threadedly engaged in the body for advancement transversely of and into the passage, the body having a laterally inwardly extending opening entering upon the passage and formed with threads engaging the threads of the screw; and 2. a clamping head swivelled on the screw for advancement therewith into and transversely of the passage and having a clamping surface facing away from the screw adapted for exerting pressure on the conductor effective to clampingly engage it against the wall of the passage at a location diametrically opposite that at which said opening enters upon the passage, when the screw is advanced.
2. The wiring device improvement of claim 1 in which the body has guide slots formed in the wall of said opening and continuing into the passage, said slots paralleling the screw axis and slidably engaging portions of the head to prevent the head from rotating with the screw.
3. The wiring device improvement of claim 2 in which the head has ears extending radially, outwardly therefrom beyond the major diameter of the screw and comprising the portions of the head engaged in the slots.
4. The wiring device improvement of claim 2 in which said clamping surface of the head is formed with at least one rib projecting forwardly therefrom in a direction away from the screw and facing into the passage to deform and thereby strain-relieve the conductor when the head exerts pressure thereon.
5. The wiring device improvement of claim 4 in which the rib extends diametrically of the head and projects radially outwardly therefrom at its ends to define the ears.
6. The wiring device improvement of claim 5 in which said clamping surface of the head includes a pair of forwardly projecting secondary ribs paralleling the first named rib at opposite sides thereof and also facing into the passage in a direction away from the screw, said secondary ribs cooperating with the first named rib in deforming and strain-relieving the cable.
7. In a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising:
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, the body having guide slots paralleling the screw axis and slidably engaging portions of the head to prevent the head from rotating with the screw, the head and screw having complementary means producing interference between the screw and head at predetermined intervals during rotation of the screw relative to the head to provide at least a tactile reference to a user in the form of step-by-step indexing of the advancing screw.
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, the body having guide slots paralleling the screw axis and slidably engaging portions of the head to prevent the head from rotating with the screw, the head and screw having complementary means producing interference between the screw and head at predetermined intervals during rotation of the screw relative to the head to provide at least a tactile reference to a user in the form of step-by-step indexing of the advancing screw.
8. The wiring device improvement of claim 7 in which the complementary means comprises facets arranged in a circumferential series upon the screw and head respectively and slidably contacting one another when the screw is rotated.
9. The wiring device improvement of claim 8 in which the screw has an annular recess and the head has a mating annular flange extending into the recess, the facets being formed on confronting faces of the flange and recess respectively.
10. In a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising:
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passages when the screw is advanced, the screw including a projection extending through the clamping head, the clamping head being rotatable upon said projection, said projection extending forwardly through the clamping head for frictional, binding engagement against the conductor whereby to assist in clamping the conductor within said passage, while being retained frictionally by the conductor against rotation of the screw from selected positions to which it is advanced.
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passages when the screw is advanced, the screw including a projection extending through the clamping head, the clamping head being rotatable upon said projection, said projection extending forwardly through the clamping head for frictional, binding engagement against the conductor whereby to assist in clamping the conductor within said passage, while being retained frictionally by the conductor against rotation of the screw from selected positions to which it is advanced.
11. In a wiring device of the type that includes a body having a passage for an electrical conductor, the improve-ment comprising:
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, said clamping head being formed with a plurality of parallel, forwardly projecting strain relief ribs adapted to bear against the conductor at selected locations longitudinally spaced along the conductor, for strain relief of the conductor responsive to threaded advancement of the screw.
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, said clamping head being formed with a plurality of parallel, forwardly projecting strain relief ribs adapted to bear against the conductor at selected locations longitudinally spaced along the conductor, for strain relief of the conductor responsive to threaded advancement of the screw.
12. In a wiring device of the type that includes a body having a passage for an electrical conductor, the improvement comprising:
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, said clamping head having a center opening, the screw including an axial projection extendable through the center opening for rotatable movement of the clamping head upon the projection, said clamping head including a plurality of forwardly projecting, generally parallel, spaced strain relief ribs, one of said ribs extending diametrically of the head and being interrupted by said opening, the axial projection extending through the opening and being staked over said diametrically extending rib, for holding the head and screw assembled, the projection being formed at the location where it is staked, with a roughened surface engageable against the conductor, whereby to frictionally interengage the conductor and the axial projection, to inhibit rotation of the screw in a reverse direction from a selected position to which the screw is advanced.
1) a screw threadedly engaged in the body for advancement into the passage; and 2) a clamping head swivelled on the screw and adapted for exerting pressure on the conductor effective to clampingly engage it in the passage when the screw is advanced, said clamping head having a center opening, the screw including an axial projection extendable through the center opening for rotatable movement of the clamping head upon the projection, said clamping head including a plurality of forwardly projecting, generally parallel, spaced strain relief ribs, one of said ribs extending diametrically of the head and being interrupted by said opening, the axial projection extending through the opening and being staked over said diametrically extending rib, for holding the head and screw assembled, the projection being formed at the location where it is staked, with a roughened surface engageable against the conductor, whereby to frictionally interengage the conductor and the axial projection, to inhibit rotation of the screw in a reverse direction from a selected position to which the screw is advanced.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA366,181A CA1111118A (en) | 1978-05-30 | 1980-12-04 | Strain relief |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US910,569 | 1978-05-30 | ||
| US05/910,569 US4213667A (en) | 1978-05-30 | 1978-05-30 | Dead front connector |
| CA309,609A CA1112318A (en) | 1978-05-30 | 1978-08-18 | Electrical connector attachable to an end portion of a power cable |
| CA366,181A CA1111118A (en) | 1978-05-30 | 1980-12-04 | Strain relief |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1111118A true CA1111118A (en) | 1981-10-20 |
Family
ID=27165807
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA366,181A Expired CA1111118A (en) | 1978-05-30 | 1980-12-04 | Strain relief |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1111118A (en) |
-
1980
- 1980-12-04 CA CA366,181A patent/CA1111118A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |