CA2152419A1 - Strain relief sleeve for cable connectors - Google Patents

Abstract

A strain relief sleeve for use in conjunction with a standard in-line telephone-type modular plug having a multi-wire cable inserted thereinto is disclosed. The strain relief sleeve comprises a main body in the form of a shell having walls of predetermined thickness. The main body has a cable engaging portion and a plug engaging portion, and comprises substantially identical first and second body portions. The first and second body portions have co-operating opposed mating surfaces at the outer end of each of said side wall members that faces the respective outer end of said wall member of the other of said first and second body portions. An internal gripping surface on the cable engaging portion is shaped and dimensioned so as to intimately engage the jacket of the inserted cable in unmoving relation thereto, to thereby cause the cable engaging portion to securely grip the inserted cable in movement precluding relation. An internal engaging surface on the plug engaging portion is shaped and dimensioned so as to intimately engage the exterior surface of the plug in unmoving relation thereto, to thereby cause the plug engaging portion to securely grip the plug in movement precluding relation. When tensile forces are generated in the jacket of the cable from pulling on the cable, the forces are generally transmitted from the cable to the cable engaging portion, through the main body, to the plug engaging portion, and ultimately to the plug.

Description

2152~19 STRAIN RELIEF SLEEVE FOR CABLE CONNECTORS

FIELD OF THE INVENTION:
This invention relates to strain relief sleeves for use in conjunction with standard in-line telephone-type modular plugs having a multi-wire cable inserted thereinto, and more particularly to such strain relief sleeves where the multi-wire cables have in-line telephone-5 type modular plugs at both ends and are in form of a patch cord used for data tr~mi~ionpurposes in conjunction with computers.

BACKGROUND OF THE INVENTION:
Modular plugs and jacks for use in conjunction with telephone cords were originally 10 developed in the late 1950's for use in conjunction with telephone handsets. Accordingly, these in-line telephone-type modular plugs were purposely designed to be small and unobtrusive, which unfortunately also means that they are not overly robust. Such plugs were originally designed to remain plugged into a respective jack in positive latched engagement and to remain plugged into the handset or the telephone set for long periods 15 of time, and to be unplugged from the handset or the telephone set only very occasionally.
In order to remove such a plug from a jack, it is necessary to operate a small release handle on the plug which thereby moves a shoulder portion of the release handle from being in interfering relation with a co-operating abutment portion of the jack. Thus it is difficult to remove such plugs from a respective jack merely by pulling on the telephone cable. If 20 the cable is pulled on with any substantial force whatsoever, it is very likely that the wires within the cable will be damaged or at least separated from their respective contacts.
Subsequently, these modular plugs and jacks came into use with household telephone equipment, replacing the large, bulky, four-pin plugs that preceded them. Soon after, these plugs became the industry standard for household and eventually business 25 telephone connections. Given that these types of plugs were not originally designed for 21~2~19 such widespread general use in telephone equipment, and given that these plugs are not overly robust, it has been found that these types of plugs are somewhat easily damaged during normal use, especially where the telephone cable is pulled from a jack without first operating the release handle.
These in-line telephone-type modular plugs are typically made from polycarbonate, which is a transparent hard plastic (but may also be colored), that is also somewhat flexible so as to provide a resilient living hinge for the release handle. When these types of in-line telephone-type modular plugs are installed on a cable to form a patch cord, the manufacturing process is relatively quick and is automated -- the connection is therefore not necessarily the best. Further, the connections in these types of plugs are contacting type physical connections -- they are not soldered, although they are crimped.
As telephones that are typically used in a business environment have become moreand more complex, the industry standard cables for connecting such telephone sets has become six-wire, instead of two-wire or four-wire as might be used in a home.
Accordingly, a slightly larger industry standard in-line telephone-type modular plug, and co-operating jack, has been developed for such business telephone equipment. The size and shape of the plugs for use with six-wire cables is standardized. These slightly larger six-wire plugs are, however, essentially of the same basic design as are the originally designed two-wire or four-wire plugs. Accordingly, these six-wire plugs are also not overly robust and may be easily damaged in the course of normal use.
In more recent years, with the advent of computerized data-telecommunications equipment, the use of which is now universal and extremely wide-spread throughout the world, it is common to have eight-wire data communication cables for hard wire interconnecting various pieces of data communications equipment within a room or a building. Again, the standard in-line telephone-type modular plug for such eight-wire conductor cables has been developed, and is of a size and shape that is an industry standard. Eight-wire cables having telephone-type modular plugs at each end, arecommonly used in telecommunications applications, or in general computer communications applications, and are commonly known as "patch cords". Patch cords may be only about one foot long in some instances, but may also be about ten feet long, or more, if required.

2152~19 Such patch cords are commonly used in computer networks, such as local area networks or wide area networks, to interconnect computers and other equipment with network servers, in telecommunications or colnpu~el network equipment in rack mounted distribution centres to interconnect the various equipment components in the rack, and also 5 in industry settings in computer aided manufacturing equipment, or other related robotic equipment. Again, these larger eight-wire plugs are essentially of the same basic design as are the originally designed two-wire or four-wire plugs and accordingly are also not overly robust and may be easily damaged in the course of normal use.
It is comrnon in these applications, especially in data-tr~n.~mi~ion and 10 telecommunication systems, to have the patch cords plugged in and unplugged very frequently, perhaps as much as several times per day under certain circumstances, such as in~t~lling or testing equipment. Further, such frequent plugging in and unplugging tends to be done under hurried conditions, which means that frequently the patch cord is removed without fully operating the release handle. The tensile forces generated as a result of the 15 pulling on the cable are transmitted to the plug; however, the strain relief that is an inherent part of the plug is not adequate enough to ensure that all of these tensile forces are transmitted to the body of the plug, since the strain relief mechanism was designed for use with telephone handsets. Accordingly, the tensile forces from the cable are often transmitted to the location where the wires of the cable are attached to the electrical 20 contacts of the plug, which connections are only contacting type physical connections --they are not soldered, and they are only crimped, but not necessarily well connected. It is therefore common for the wires in such telecommunication data cables to separate from the contacts, thus causing the electrical connection to be broken, or the cable joint can separate from the wires, thus causing the delicate data wires to be exposed or broken, or the cable 25 can even become entirely removed from the plug. In any event, it is therefore necessary to replace the entire patch cord.
It may actually be preferable to have the cable pull out of the jack as opposed to having one of the wires become physically separated from its respective contact, since a separated cable is obvious; but a cable having a wire that is not making proper electrical 30 connection is very difficult to detect and locate. In any case, it is highly desirable that the patch cord not be damaged, even in the event that the cable of the patch cord may be pulled on in an attempt to hurriedly remove it from its plug, or even in the event that the patch cord is accidentally caught by another object, or perhaps a person's hand or foot, and pulled on with perhaps a great deal of force.
What is needed is a proper strain relief mechanism for use in conjunction with standard in-line telephone-type modular plugs having a multi-wire cable inserted thereinto.
Strain relief mech~ni~m.~ for standard l l0 VAC electrical plugs and cords are well known;
however, they are not suitable whatsoever for use with standard in-line telephone-type modular plugs and cables. Such strain relief mech:~ni~m.c need to be relatively small and unobtrusive, especially since such patch cords are often plugged in side-by-side relation, typically known as a batch wherein the plugs are centred on spacings of about l/2" and are separated one from the other by about 1/~".

SUMMARY OF THE INVENTION:
In accordance with one aspect of the present invention, there is provided a strain relief sleeve for use in conjunction with a standard in-line telephone-type modular plug having a multi-wire cable inserted thereinto, the plug having a pre-determined exterior surface configuration, and the cable comprising a plurality of wires within a jacket. The strain relief sleeve comprises a main body having a centrally disposed longitudinal axis and being in the form of a shell having walls of a predetermined wall thickness that defines the shell. The main body having a cable eng~ging portion at a first end thereof and a plug engaging portion at an opposite second end thereof. An internal gripping surface is located on the cable eng~ging portion, the internal gripping surface being shaped and dimensioned so as to intimately engage the jacket of the inserted cable in unmoving relation thereto, to thereby cause the cable çng:~ging portion to securely grip the inserted cable in movement precluding relation. An internal eng~ging surface is found on the plug eng~ging portion, the internal eng~ging surface being shaped and dimensioned so as to intim~tely engage the exterior surface of the plug in unmoving relation thereto, to thereby cause the plug engaging portion to securely grip the plug in movement precluding relation. When tensile forces are generated in the jacket of the cable from pulling on the cable, the forces are - 21~2419 -generally transmitted from the cable to the cable eng~ging portion, through the main body, to the plug engaging portion, and ultimately to the plug.

BRIEF DESCRIPTION OF THE DRAWINGS:
Embodiments of this invention will now be described by way of example in association with the accompanying drawings, in which:
Figure 1 is a side elevational view of the strain relief sleeve of Figure 1, assembled onto a standard eight conductor patch cord, and about to be plugged into a co-operating jack in a telecommunications equipment component in a rack mounted distribution centre;
Figure 2 is a side elevational view similar to Figure 1, with the plug of the patch cord plugged into the co-operating jack in the telecommunications equipment component;
Figure 3 is a perspective view of the strain relief sleeve of the present invention, with the patch cord omitted for the sake of clarity;
Figure 4 is an enlarged side elevational view of the strain relief sleeve of Figure 3 assembled on a patch cord, with various internal surfaces shown in ghost outline;
Figure 5 is a perspective view of one half of the main body;
Figure 6 is a top plan view of the half of the main body of Figure 5;
Figure 7 is a bottom plan view of the half of the main body of Figure 5; and Figure 8 is a cut-away side view of the half of the main body of Figure 5, takenalong section line 8-8, as indicated in Figure 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
Reference will now be made to Figures 1 and 2, to describe the strain relief sleeve 20 of the present invention. The strain relief sleeve 20 is for use in conjunction with a standard in-line telephone type modular plug 22 having a multi-wire cable 24 inserted therein, thereby forming a patch cord 26. As can best be seen in Figures 1 and 2, there is a co-operating jack 28 at the exterior of a telecommunications equipment component 30 in - 21~2419 a rack mounted distribution center 32. The patch cord 26 is inserted into and removed from the jack 28 through manipulation of the release handle 23 -- in the direction indicated by arrow "R" for releasing the latching function and in the direction indicated by arrow "E"
for eng~ging the latching function The modular plug 22 has a predetermined exterior surface configuration, at least for any of the three standard cable sizes -- four wire cable; six wire cable; or eight wire cable, which cable 24 comprises in plurality of wires, either four, six, or eight, within an outer protective jacket 25. The fact that each standard size modular plug 22 has a pre-determined exterior surface configuration -- that is to say that the exterior surface is of a pre-determined shape and dimensions -- is used advantageously in the present invention so as to permit secure attachment of the strain relief sleeve 20 to the modular plug 22, as will be discussed in greater detail subsequently.
Reference will now be made to Figures 3 through 8 to describe the strain relief sleeve 20 of the present invention in detail. An entire assembled strain relief sleeve 20 is shown in Figure 1. The patch cord 26 -- the modular plug 22 and multi-wire cable 24 inserted thereinto -- are not shown, for the sake of clarity. It should be understood, however, that in normal use, the strain relief sleeve 20 would not exist in an assembled form without being on a plug 22. The strain relief sleeve 20 is assembled directly onto a modular plug 22, as will be discussed in greater detail subsequently.
The strain relief sleeve 20 comprises a main body 40 having a first end 41, a second end 42, a centrally disposed longitudinal axis "A", and being in the form of a shell having walls 44 of a predetermined wall thickness, preferably of about 0.040", that defines the shell. Such thin walls 44 are necessary in order to permit a plurality of plugs 22 to be used in close side-by-side relation. It is common in telecommunications equipment to have modular jacks 28 located in a row in juxtaposed relation one to another and spaced about l/8" apart. Since the eight wire modular plugs 22 used in conjunction with such jacks 28 are about 3/81' wide, it is necessary that the walls 44 of the strain relief sleeve 20 be quite thin.

- 21~2419 The main body 40 has a cable eng~ging portion 50 at a first end 41 thereof and aplug engaging portion 60 at an opposite second end 42 thereof. The cable eng~gin~ portion 50 of the strain relief sleeve 20 engages the jacket 25 of the cable 24 that is part of the patch cord 26. The plug eng~ging portion 60 engages the exterior surface of the modular plug 22 of the patch cord 26.
As can be best seen in Figures 5, 6, and 8, the cable en~ging portion 50 has an internal gripping surface 52 that is shaped and dimensioned so as to intim~tely engage the jacket 25 of the inserted cable 24 in a moving relation thereto. In this manner, the cable eng~ging portion 50 is caused to securely grip the jacket 25 of the inserted cable 24 in movement precluding relation. The internal gripping surface 52 further comprises at least one projecting member 54 that is shaped and dimensioned to intim~tely engage the jacket 25 of the inserted cable 24 in movement precluding relation, and thereby so as to augment the gripping action on the jacket 25 of the cable eng~gin~ portion 50 of the main body 40 of the strain relief sleeve 20. The internal gripping surface 52 of the cable eng~ging portion 50 is flared outwardly at its first end 41 so as to accommodate sideways directed pulling of the cable 24 of the patch cord 26, without causing the cable 24 to bend at a severe angle, but to be able to bend at a more shallow angle, which therefore is less likely to damage the wires in the cable 24.
As can also be best seen in Figures 5, 6, and 8, the plug engaging portion 60 has an internal eng~ging surface 62 that is shaped and dimensioned so as to intim~tely engage the exterior surface of the plug 22 in unmoving relation thereto. Essentially, the internal eng~ging surface 62 of the plug eng~ging portion 60 is generally very close to the overall size and shape of the exterior surface of the modular plug 22, and is perhaps a couple of a thousandths of an inch larger, at least before assembly. In this manner, the plug eng~ging portion 60 of the main body 40 of the strain relief sleeve 20 is caused to securely grip the plug 22 in movement precluding relation.
The main body 40 comprises discrete first and second body portions 46 and 48 that are substantially identical one to the other, and are joinable one to the other to form the main body 40. In this manner, the first and second body portions 46 and 48 are hermaphroditic -- that is to say that two of the same entities mate together to form a single entity. It is also possible to join the first and second body portions 46 and 48 by way of a living hinge, since polycarbonate is flexible, so as to make the first and second body portions 46 and 48 one integral monolith. Such an embodiment of the present invention would be more complicated to mold.
At the plug eng~ging portion 60, each of the first and second body portions 46 and 48 comprise a base wall member 64 and a pair of side wall members 66 that are joined to the base wall member 64, so as to have a generally rectilinear "U"-shaped configuration along the centrally disposed longitudinal axis "A". Each of the side wall members 66 has an open edge 68 remote from the base wall member 64. Preferably, the open edges 68 of each of the first and second body portions 46 and 48 face in the same direction as each other, and are parallel one to the other. When the strain relief sleeve 20 is assembled, the open edges 68 of the first body portion 46 are opposed to the open edges 68 of the second body portion 48, so as to provide co-operating mating surfaces when the first and second body portions 46 and 48 are joined to one another. The base wall member 64 and the side wall members 66 define the internal en~;~ging surface 62.
Similarly, at the cable en~ging portion 50, each of the first and second body portions 46 and 48 comprise a generally semi-cylindrically curved peripheral wall member 51, which peripheral wall member is adjoined to the base wall member 64 and the two side wall members 66. The peripheral wall member terrnin~tes in a pair of open edges 53, which open edges 53 face in the same direction as each other, and are parallel one to the other. Each of these open edges 53 is continuous with a respective open edge 68 on an adjoined side wall member of the plug eng~ging portion 60.
Preferably, there is a notch 65 in the base wall member 64 of the plug eng~ging portion 60, which notch 65 is positioned and dimensioned to accommodate the release handle 23 of the modular plug 22 that the strain relief sleeve 20 is attached to. When the release handle 23 of the modular plug 22 is depressed, it moves toward the modular plug 22 so as to contact it. Without the notch 65, the release handle 23 would abut against the base wall member 64 of the plug eng~ging portion 60 of the strain relief sleeve 20, and might not move far enough to allow for proper disengagement of the modular plug 22 from its respective jack.

Located on one of the two opposed mating surfaces of each of the first and second body portions 46 and 48, is a pair of elongate locating protrusions 70, one elongate locating protrusion 70 on the plug engaging portion 60 and one elongate locating protrusion 70 on the cable eng~ging portion 50. Correspondingly, located on the other of the two opposed 5 mating surfaces of each of the first and second body portions 46 and 48, is a pair of co-opelaLillg locating recesses 72, one co-operating locating recess 72 on the plug eng~ging portion 60 and one co-operating locating recess 72 on the cable engaging portion 50. The locating recesses 72 are located in mirrored relation, with respect to the centrally disposed longitudinal axis "A", to the corresponding of the locating protrusions 70. The locating 10 protrusions 70 fit into the respective co-operating recesses 72 so as to allow the first and second body portions 46 and 48 to readily be properly aligned one with the other during assembly.
In order to mate the plug eng~ging portion 60 with the modular plug 22 as strongly as possible, the internal eng~ging surface 62 of each of the plug eng~ging portions 60 is 15 designed such that, during assembly, the strain relief sleeve 20 is ultrasonically weldable to the exterior surface of the modular plug 22. A pair of energy concentrators 80 have been included on a portion of each of the internal engaging surfaces 62. Each area energy concentrator 80 is in the form of an upstanding narrow ridge formed as part of the base wall member 64, with each of the upstanding narrow ridges having a greater length than 20 height. Further, the height of the ridge is substantially less than the wall thickness of the walls 44 of the main body 40 and the plug eng~ging portion 60, which thickness is about 0.040". It is believed to be unknown in the prior art to have energy concentrators 80 on material that is of a thickness of less than 0.120".
During assembly of the strain relief sleeve 20 to the modular plug 22, these energy 25 concentrators 80 are melted by way of ultrasonic welding. During ultrasonic welding, the energy concentrators 80 melt first, before the remainder of the material of the first and second body portions 46 and 48 and before the material of the plug 22. The melted polycarbonate material of the energy concentrators 80 flows generally over the entire surface of the internal engaging surface 62 and also over the entire outer surface of the plug 30 22, thus melting outer layers of molecules of the internal eng~ging surface 62 and of the plug 22. The polycarbonate molecules of the plug 22 and the strain relief sleeve 20 migrate, so as to ultimately mix together, and subsequently re-crystallize, thereby to permanently fuse the plug 22 and the strain relief sleeve 20 into a unitary structure. Such ultrasonic welding is typically performed in a factory setting, but may alternatively be preformed "on site" using portable ultrasonic welding equipment.
There are also energy concentrators 82 in the form of upstanding narrow ridges, located on each of the locating protrusions 70. Each of these energy concentrators 82 has greater length than height, and has a height substantially less than the width of the locating protrusions 70. These energy concentrators 82 work in the same manner as the energy concentrators 82 on the internal engAging surface 62, as discussed above, so as to melt during the assembly process when the strain relief sleeve 20 of the present invention is assembled onto the patch cord 26.
In the above described manner, the first and second body portions 46 and 48 are strongly welded to each other at their respective outer edges of the side wall members 66 and of the outer edges.
In use, after the strain relief sleeve 20 of the present invention has been assembled in place on a modular plug 22, and the cable 24 of the patch cord 26 contAining the modular plug 22 is pulled on, the tensile forces that are generated in the jacket 25 of the cable 24 are generally transmitted from the cable 24 to the cable engAging portion 50 of the main body 40, through the main body 40, and into the plug engAging portion 60 of the main body 40, and ultimately to the plug 22. In this manner, the forces are not transmitted to the portions of the wires of the cable 24 that are internally connected to the electrical connectors within the modular plug 22.
In order to be able to easily and quickly identify the strain relief sleeve 20 of the present invention installed on a patch cord 26, the polycarbonate material that is used to manufacture the strain relief sleeve 20 may be colored. It has been found that green is an easily identifiable color and contrasts well against the colors that are used for various types of telecommunications connectors.

2152~19 In one alternative embodiment, it is envisioned that the strain relief sleeve of the present invention could have a protrusion on the second body portion, which protrusion fits into a cavity in the underside of a modular plug, so as to provide a stop means to further preclude the strain relief sleeve from being pulled from the modular plug. Such a strain 5 relief sleeve would not be hermaphroditic, however.
In another alternative embodiment, it is envisioned that the strain relief sleeve of the present invention could be secured to the modular plug by way of a suitable adhesive, such as cyanoacylate or epoxy. It has been found, however, that using such adhesives is undesirable as it is messy, requires specific ventilation, can seep into the modular plug, and 10 generally increases production problems and costs.
In yet another alternative embodiment, it is envisioned that the strain relief sleeve of the present invention could be made from a heat shrink material and be heat shrunk onto the modular plug. It has been found, however, that heat shrinking is a poor alternative as it requires jigging during the assembly process, and the strain relief sleeve may shrink too 15 much and crack the modular plug. Further, the jacket on the cable of the patch cord is a heat shrink material and may be shrunk further, which is undesirable.
Other modifications and alterations may be used in the design and manufacture ofthe a~paldlus of the present invention without departing from the spirit and scope of the accompanying claims.

Claims (18)

1. A strain relief sleeve for use in conjunction with a standard in-line telephone-type modular plug having a multi-wire cable inserted thereinto, said plug having a pre-determined exterior surface configuration, and said cable comprising a plurality of wires within a jacket; wherein said strain relief sleeve comprises:
a main body having a centrally disposed longitudinal axis and being in the form of a shell having walls of predetermined wall thickness that defines said shell;
said main body having a cable engaging portion at a first end thereof and a plug engaging portion at an opposite second end thereof;
an internal gripping surface on said cable engaging portion, said internal gripping surface being shaped and dimensioned so as to intimately engage the jacket of the inserted cable in unmoving relation thereto, to thereby cause said cable engaging portion to securely grip said inserted cable in movement precluding relation;
an internal engaging surface on said plug engaging portion, said internal engaging surface being shaped and dimensioned so as to intimately engage the exterior surface of said plug in unmoving relation thereto, to thereby cause said plug engaging portion to securely grip said plug in movement precluding relation;
whereby, when tensile forces are generated in the jacket of said cable from pulling on said cable, said forces are generally transmitted from said cable to said cable engaging portion, through said main body, to said plug engaging portion, and ultimately to said plug.

2. The strain relief sleeve of claim 1, wherein said internal gripping surface further comprises at least one projecting member that is shaped and dimensioned to intimately engage the jacket of the inserted cable in movement precluding relation, so as to augment the gripping action on said cable jacket of said cable engaging portion.

3. The strain relief sleeve of claim 1, wherein said main body comprises first and second body portions that are joinable one to the other to form said main body.

4. The strain relief sleeve of claim 3, wherein said first and second body portions are discrete one from the other.

5. The strain relief sleeve of claim 4, wherein said first and second body portions are substantially identical one to the other.

6. The strain relief sleeve of claim 5, wherein each of said first and second body portions of said main body comprises a base wall member and a pair of side wall members joined to said base wall member, so as to have a generally rectilinear "U"-shaped configuration along said centrally disposed longitudinal axis, said base wall member and said side wall members defining said internal engaging surface.

7. The strain relief sleeve of claim 6, wherein said internal engaging surface of each of said first and second body portions includes at least one upstanding narrow ridge formed as part of said base wall member, with each of said upstanding narrow ridges having greater length than height, and wherein the height of said ridge is substantially less than the wall thickness of the walls of said main body at said plug engaging portion.

8. The strain relief sleeve of claim 7, wherein each of said side wall members has an open edge remote from said base wall member, with the open edges of said first and second body portions being opposed one to another so as to provide co-operating mating surfaces when said first and second body portions are joined one to the other.

9. The strain relief sleeve of claim 8, wherein said co-operating opposed mating surfaces on said first and second body portions each have at least one elongate locating protrusion thereon and at least one co-operating locating recess thereon, said recess positioned in mirrored relation, with respect to said centrally disposed longitudinal axis, to said at least one locating protrusion.

10. The strain relief sleeve of claim 9, wherein said at least one locating protrusion and said at least one co-operating matching recess are situated on the co-operating opposed mating surfaces of said first and second body portions at said plug engaging portion.

11. The strain relief sleeve of claim 9, wherein said at least one locating protrusion and said at least one co-operating matching recess are situated on the co-operating opposed mating surfaces of said first and second body portions at the cable engaging portion.

12. The strain relief sleeve of claim 9, wherein each of said at least one locating protrusion and at least one co-operating matching recess are elongate.

13. The strain relief sleeve of claim 9, wherein each of said at least one locating protrusion includes at least one upstanding narrow ridge, with each of said upstanding narrow ridges having greater length than height, and wherein the height of said ridge is substantially less than the wall thickness of the walls of said main body.

14. The strain relief sleeve of claim 13, wherein the height of said ridge is substantially less than the width of the respective of said at least one locating protrusion.

15. The strain relief sleeve of claim 2, wherein each of said at least one projecting member is elongate along said centrally disposed longitudinal axis.

16. The strain relief sleeve of claim 1, further comprising a notch in said base wall member of said plug engaging portion, said notch being positioned and dimensioned to accommodate the release handle of said plug.

17. The strain relief sleeve of claim 1, wherein said internal gripping surface of said cable engaging portion is flared outwardly at its said first end.

18. The strain relief sleeve of claim 1, wherein the walls of said main body are about 0.040" thick.