US3744008A

US3744008A - Strain relief assembly

Info

Publication number: US3744008A
Application number: US00201324A
Authority: US
Inventors: E Castellani
Original assignee: Thomas and Betts Corp
Current assignee: ABB Installation Products Inc
Priority date: 1971-11-23
Filing date: 1971-11-23
Publication date: 1973-07-03
Anticipated expiration: 1990-07-03

Abstract

An improved strain relief assembly including an apertured, stepped-diameter pressure ring formed preferably of nonmetallic material and which may be selectively structured to partially envelope and nonrotatably grip the adjacent surface of a tapered compressible grommet for linearly urging said grommet into a complementarily tapered receiving orifice in a threaded body member while engaged in slidable relation with the adjacent inner surface of a gland nut threadably securable to the body member. The grommet may thus be tightly and symmetrically compressed about an elongate member such as a portable electric cord inserted therethrough to provide a strain relief and seal thereabout. The gripping feature may be enhanced by the inclusion of selectively disposed pointed protrusions or radially extending ridges or the like on the pressure ring gripping surface. The ring may be peripherally undercut to permit the inward deflection of a portion thereof to provide an additional strain relief and sealing zone.

Description

United States Patent [1 1 Castellani July 3, 1973 STRAIN RELIEF ASSEMBLY [57] ABSTRACT Inventor; w d J ce ie r An improved strain relief assembly including an aper- South Plainfield, NJ. tured, stepped-diameter pressure ring formed prefera- [73] Assisnee: Thomas & Bats Corporation bly of nonmetallic material and which may be selec- Elizabeth tively structured to partially envelope and nonrotatably grip the adjacent surface of a tapered compressible Filedi NOV. 1971 grommet for linearly urging said grommet into a complementarily tapered receiving orifice in a threaded [21] Appl' 201,324 body member while engaged in slidable relation with the adjacent inner surface of a gland nut threadably [52] US. Cl. 339/103 B seem-able to the body member, The grommet may thus [51] Int. Cl H0lr 13/58 be tightly and symmetrically compressed about an [58] Field Of Search 339/89, 94, 103; elongate member uch as a portable electric cord in- 285/ 174/78 serted therethrough to provide a strain relief and seal thereabout. The gripping feature may be enhanced by [56] Ref ence ted the inclusion of selectively disposed pointed protru- UNITED STATES PATENTS sions or radially extending ridges or the like on the 2,882,509 4/1959 Archer et a1 339/103 M x Pressure ring gripping Surface The ring may be I P 2,824,290 2/1958 Archer et 81.... 339/89 M x erally undercut to permit the inward deflection of 8 2,829,358 4/1958 Testori 339 89 M x po ti n th r t pr an t nal ain r l Primary Examiner-Richard E. Moore A ttorney- Davi'dTeschn'er and J esse Woldman and sealing zone.

7 Claims, 9 Drawing Figures 7O 50 7 &

r 4 g :-3Z

STRAIN RELIEF ASSEMBLY BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is directed to the field of strain relief devices and principally to an improved assembly adapted therefore.

2. Description of the Prior Art Prior art strain relief assemblies of the type adapted, for example, for a preferably fluid tight interengagement between portable electric cord or line and portable tools, switch boxes, panel boards, and the like generally comprised, in one form or another, a tapered compressible sleeve or grommet positionable intermediate an appropriately bored body member, and a gland nut generally threadably engageable therewith, each of said members being provided with a suitable passageway proportioned to receive therethrough a portable electric cord or the like. The composite strain relief and seal functions were generally accomplished by tightening the gland nut upon the body member previously attached to the mating device after the electric cord had been inserted through the respective passageways and into the mating device, whereby the tapered compressible grommet was forced into a complementarily tapered portion of the body member passageway to cause at least a partial collapsing of the compressible member about the electric cord in an attempt to provide a sufficient seizure thereabout necessary for an adequate strain relief and seal at the zone of seizure. A generally flat metallic retaining ring was often interposed between the inner surface of the gland nut and the adjacent surface of the compressible member in an attempt to reduce the friction between the aforesaid surfaces to prevent the undesirable twisting and accompanying distortion of the compressible member as the gland nut was threadably tightened on the body member. As the gland nut was increasingly tightened, however, the coefficient of friction between the adjacent surfaces of the retaining ring and the gland nut was sufficiently high to cause the ring to twist with the nut, thereby defeating the principle purpose of such arrangement and resulting, in many cases, in an undesirable deformation, distortion, and extrusion of a portion of the compressible member out through the retaining ring aperture and adjacent gland nut passageway thereby seriously reducing the effectiveness of the assembly. Additionally, at least a partial severing of the electric cord often occurred as the generally sharp inner aperture defining surface of the retaining ring was caused to rotate thereabout, resulting in an extremely dangerous and highly undesirable condition.

SUMMARY OF THE INVENTION The invention overcomes the problems and limitations noted above with respect to such prior art devices by providing an improved strain relief assembly which is more effective, reliable, efficient, positive, and safer than such devices. The improvement is directed principally to the inclusion of a preferably nometallic, stepped-diameter pressure ring positionably intermediate a tapered compressible grommet and the inner surface adjacent the restrictive opening in a gland nut threadably engageable with an appropriately apertured body member adapted for attachment to a further device such as a portable electric device, switch box or the like. The end of the body member adapted for threaded mating engagement with the gland nut is provided with an enlarged tapered opening formed substantially complementary to the tapered contour of the compressible member and into which the compressible member is urged as the gland nut is tightened upon the body member. The pressure ring is formed preferably of a rigid or semi-rigid plastic material such as nylon, PVC, Delrin or the like, such materials having the dual advantage of providing an electrical insulation barrier between the electric cord or cable and the metallic gland nut, and furnishing the required frictional characteristics essential to effect the desired result. Where, for example, the compressible grommet is formed of rubber or similar material, a relatively high frictional force is established between the plastic pressure ring and the adjacent surface of the grommet affording essentially non-slipping interengagement therebetween. The coefficient of friction between the plastic pressure ring and the adjacent mating surface of the metallic gland nut, however, is relatively low, resulting in a desirably high degree of slippage therebetween, in direct contrast to the relatively high coefficient of friction exhibited where the mating components are disposed in metal-to-metal contact, as was generally the case in prior art devices where the pressure or retaining ring was formed generally of stainless steel or the like. The reduced diameter portion of the stepped-diameter pressure ring is selectively proportioned to fit closely within the restrictive aperture in the gland nut thereby axially aligning the electric cord orcable generally centrally therewithin. The nonslip feature of the pressure ring may be enhanced by providing a plurality of either outwardly extending protrusions, or radially extending ridges on the surface thereof arranged to bear against the compressible grommet. A selectively formed annular recess may be provided in the same surface to at least partially envelope and contain the mating portion of the grommet therewithin. The enlarged diameter portion of the ring may be planarly disposed in slanted or tilted annular relationship with the reduced diameter portion thereof and an annular recess provided intermediate the enlarged and reduced diameter portions of the ring, whereby the enlarged diameter portion may be readily deflected under pressure, thereby effecting a partial closure or restrition of the ring passageway opening adjacent thereto and advantageously providing an additional strain relief and sealing zone thereat. It is therefore an object of this invention to provide an improved strain relief assembly.

It is another object of this invention to provide means for increasing the reliability of a strain relief assembly.

It is a further object of this invention to provide means for nondistortably urging the compressible grommet member of a strain relief assembly into tight engagement about an elongate article inserted therethrough.

It is still a further object of this invention to provide means for frictionally isolating a gland nut from a compressible grommet in a typical strain relief assembly.

It is yet another object of this invention to provide an improved strain relief assemblywherein frictional isolation between the compressible grommet and the gland nut thereof is accomplished by the interposition of a non-metallic stepped-diameter pressure ring therebetween.

Other objects and features of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings which disclose, by way of example, the principle of the invention and the best mode contemplated for carrying it out.

IN THE DRAWINGS FIG. 1 is a side elevational view, in section, of an improved strain relief assembly constructed in accordance with the concepts of the invention.

FIGS. 2 and 3 are sectional view of other embodiments of pressure rings of an improved strain relief assembly constructed in accordance with the concepts of the invention.

FIG. 4 is a fragmentary sectional view of a strain relief assembly pressure ring constructed in accordance with a further embodiment of the invention.

FIG. 5 is a front elevational view of a strain relief assembly pressure ring constructed in accordance with yet another embodiment of the invention.

FIG. 6 is a fragmentary side elevational view, in section, showing the assembly of FIG. 1 in a substantially fully tightened condition.

FIGS. 7, 8 and 9 are fragmentary front elevational views of further embodiments of a strain relief assembly pressure ring constructed in accordance with the concepts of the invention. Similar elements are given similar reference characters in each of the respective drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to FIG. 1 there is shown a strain relief assembly 20 constructed in accordance with the concepts of the invention. As illustrated, the assembly 20 comprises a body member 22 having first and

second ends

24, 26, respectively, and a preferably enlarged center portion 28 therebetween. External threads 30 are provided adjacent the second end 26 of body member 22 to permit its attachment to a further member such as a portable electric device, switch box or similar receptacle (not shown). It will, of course, be readily apparent that other commonly employed methods of attachment may be conveniently utilized without departing from the spirit of the invention, and may include the use of external clamps, rivets, weld joints and the like. Extending longitudinally through the body member 22 is a passageway 32 terminating expansively in a tapered portion 34 adjacent the body member first end 24 which is externally threaded, as at 36, for threaded engagement with a gland nut 38. The tapered portion 34 of body member 22 is selectively proportioned and contoured to matingly accept therein a preferably complementarily tapered compressible grommet 40 formed either of rubber or other like relatively soft resilient material. Extending longitudinally through the grommet 40 is a selectively proportioned passageway 42 which may be dimensionally varied to receive therethrough one or more sizes of a range of differently sized elongate articles such as a line cord 44 or similar item. A stepped-diameter pressure ring 46, formed preferably of plastic such as nylon, Delrin, polyvinyl chloride, or other similar semi-rigid material, is positioned intermediate the grommet 40 and the gland nut 38, and comprises an enlarged diameter portion 48 adjacent one end thereof and having a first surface 56 arranged to bear against the adjacent surface of the compressible grommet 40, and a reduced diameter portion 50 adjacent its other end and proportioned preferably to fit closely within a restrictive aperture 52 extending through the enclosed end 54 of gland nut 38. Extending longitudinally through the pressure ring 50 is a passageway 58 providing an entry means for an article such as the line cord 44, and may be either uniformly proportioned or where necessary or desirable, selectively contoured to define an enlarged opening or chamfered portion 60 adjacent its communication with the pressure ring first surface 56. As the pressure ring 46 is forced against the adjacent surface of the grommet 40, the chamfered portion 60 of the ring 46 may be effectively employed to provide a pocket into which the adjacent portion of the grommet is caused to flow, effecting at least a partial seal and strain relief about the article 44 thereat. To effect a completed assembly, and to provide the strain relief and sealing features heretofore mentioned, an elongate article such as 44 having preferably a resiliently deformable outer covering in the form of a rubber or plastic insulation coating is inserted through the loosely coupled assembly 20 as far as necessary to provide a sufficient length for manipulation at the free end 62 thereof. The gland nut 38 is then threadably tightened upon the body member 22, urging the pressure ring 46 to the right of FIG. 1 and causing the pressure ring first surface 56 to bear against the adjacent surface of the grommet 40, forcing the grommet 40 into thecomplementarily tapered opening 34 in the body member 22. The coefficient of friction between the plastic pressure ring 46 and the rubber grommet 40 has generally been found to be of sufficient magnitude to prevent slippage therebetween as the gland nut is threadably tightened on the body member 22. Where, however, it is either necessary or desirable to further enhance the gripping action between the ring 46 and the grommet 40, protrusions such as 64 (FIG. 9) or radially extending ridges formed either straight, as at 66 (FIG. 7), or arcuate, as at 68 (FIG. 8), may be conveniently provided on the first surface 56 of pressure ring 46. Rearward of the first surface 56 of ring 46 is an opposing or second surface 70 arranged for intimate engagement with the adjacent portion of the inner surface 72 of gland nut 38. Because of the relatively low coefficient of friction existing between the plastic pressure ring second surface 70 and the metallic gland nut surface 72, these surfaces tend to engage in sliding relationship as the gland nut 38 is rotatably tightened on the body member 22, thereby resulting in little more than a slight torsional force being imparted to the pressure ring 46 during the assembly. The ring 46 and grommet 40 are thus advanced towards the body member 22 in substantially linear fashion, free from the distorting rotational force heretofore described with respect to prior art devices. The sliding relationship between the adjacent surfaces 70 and 72 may be enhanced by including on the former one or more generally annular ridges 74, as shown in FIG. 4, thereby effectively reducing the area of contact between said surfaces 70 and 72. The enlarged diameter portion 48 of pressure ring 46, although shown as planarly oriented substantially normal to the longitudinal axis of ring 46, may be formed or bowed at an oblique angular relationship therewith, as shown for example at 76 in FIG. 2. As illustrated, the enlarged portion 76 is bowed towards the reduced diameter portion 78 of the ring a predetermined angle a which may be in the range of approximately a degree or two upwards to approximately 30. A circumferentially disposed recess 80 may be further provided intermediate the enlarged and reduced diameter portions 76 and 78, respectively, to provide increased flexibility of the enlarged diameter portion 76 as the gland nut 38 is tightened thereagainst. In the embodiment shown in FIG. 2, the enlarged diameter portion 76 of the pressure ring is substantially symmetrically deflected forwardly or to the right of FIG. 2 under the influence of the pressure exerted by the gland nut 38 during the assembly operation, causing a partial restriction of the chamfered opening 84 with the consequent closure thereof about the cord (not shown) positioned within the passageway 82. The aforementioned closure thus advantageously provides an additional strain relief and seal zone supplementary to the primary seal and strain relief described below. It will, of course, be readily apparent to those skilled in the art that the chamfer defining the chamfered opening 84 may be readily eliminated in the arrangement shown, and the passageway 82 formed with a uniform diameter throughout its length without departing from the spirit of the invention and within the concepts herein disclosed. Slots 86 (FIG. 5) may be provided at the juncture of the passageway 82 and the enlarged diameter portion 76 to further enhance the deflectability of portion 76 where necessary or desirable.

Referring now to FIG. 3 there is shown a further em bodiment of an improved strain relief assembly pressure ring 88 constructed in accordance with the concepts of the invention, in which the ring 88 is provided with a generally annular recessed portion 90 formed within its enlarged diameter portion outer or first surface 92. This arrangement may be advantageously employed to at least partially contain the adjacent portion of the grommet 40 therewithin during assembly. The tapered shoulder 94 forming the inner edge of the recess 90 is forced at least partially into the grommet passageway 42 during the assembly, thereby tending to cause the grommet wall adjacent thereto to deform or roll inwardly tightly about the contained elongate article or cord 44, affording additional sealing and strain relief thereaft.

Referring now to FIG. 6 there is shown the improved strain relief assembly in substantially fully assembled relationship. The gland nut 38 has been sufficiently tightened upon the body member 22 to force the pressure ring 46 tightly against the grommet 40 which is thereby urged into the tapered opening 34 in body member 22. The grommet 40 is thus subjected to sufficient radial force to cause at least a partial collapse of its passageway 42 about the cord 44 as generally indicated at 96. The resiliently deformable outer covering of cord 44 is thus compressed inwardly somewhat, substantially as illustrated, resulting in a tight seizure and interengagement between the grommet 40 and the cord 44 thereat, and providing a strain relief and seal thereabout wherein the cord 44 is essentially locked in place and prevented from further movement within the confines of the assembly 20. Where the pressure ring 46 is provided with a chamfered portion 60, and auxiliary strain relief and seal is provided as shown at 98 in a manner essentially as described heretofore. It will, of course, be readily apparent to those skilled in the art that the auxiliary strain relief and seal indicated at 98 is not essential to effect an assembly adequate for the purposes set forth herein and that the pressure ring chamfered portion 60 may be readily eliminated, where necessary or desirable. The aforementioned seal established within the region indicated generally at 96 has been found to be essentially fluid tight and adequate for those applications wherein a fluid tight seal is either necessary or desirable. It will also be readily appreciated that the assembly described heretofore and the embodiments set forth herein may be equally as effective for providing a seal and retaining means for use in conjunction with rigid or semi-rigid tubing or pipe having either a rigid or resilient outer covering or layer.

The embodiments of the invention in which an exclusivie property or privilege is claimed are defined as follows:

I claim:

1. In a strain relief assembly for use with an elongate article having a resiliently deformable outer covering and of the type having a body member having a first end, a second end, a center portion therebetween, threads disposed about at least a portion of the periphery of said body member adjacent at least said first end thereof, and a passageway extending between said first and second ends of said body member and terminating in a tapered portion adjacent said body member first end; a gland nut having a first end, a second end, a restrictive aperture extending axially through said second end, and internal threads adjacent said first end for threadable engagement with said first end of said body member; a compressible member having a passageway extending generally longitudinally therethrough, and having a selectively tapered portion contoured to fit within said tapered portion of said body member passageway, the improvement comprising: a nonmetallic pressure ring positionable intermediate said compressible member and said gland nut second end, said pressure ring having an enlarged diameter portion adjacent one end thereof, a reduced diameter portion adjacent its opposite end, and a selectively proportioned passageway extending generally longitudinally through said pressure ring between said ends thereof, said enlaged diameter portion being at least partially defined by a first surface remote from said reduced diameter portion, and a second surface generally adjacent said reduced diameter portion, said pressure ring first surface being selectively formed for nonrotatable engagement with said compressible member, said pressure ring second surface being selectively contoured for sliding engagement with the surface of said gland nut adjacent said second end as said gland nut is threadably engaged with and tightened upon said body member; the wall defining said compressible member passageway being proportioned to at least partially collapse about, and seize the adjacent resiliently deformable outer covering of a generally elongate member inserted therethrough to provide a strain relief and a seal thereat as said gland nut is tightened upon said body member and said pressure ring is urged against said compressive member, said pressure ring being provided with gripping means disposed on at least a portion of said first surface thereof, said gripping means comprising a plurality of discrete protrusions extending outwardly from at least a portion of said pressure ring first surface.

2. In a strain relief assembly for use with an elongate article having a resiliently deformable outer covering and of the type having a body member having a first end, a second end, a center portion therebetween, threads disposed about at least a portion of the periphery of said body member adjacent at least said first end thereof, and a passageway extending between said first and second ends of said body member and terminating in a tapered portion adjacent said body member first end; a gland nut having a first end, a second end, a restrictive aperture extending axially through said second end, and internal threads adjacent said first end for threadable engagement with said first end of said body member; a compressible member having a passageway extending generally longitudinally therethrough, and having a selectively tapered portion contoured to fit within said tapered portion of said body member passageway, the improvement comprising: a nonmetallic pressure ring positionable intermediate said compressible member and said gland nut second end, said pressure ring having an enlarged diameter portion adjacent one end thereof, a reduced diameter portion adjacent its opposite end, and selectively proportioned passageway extending generally longitudinally through said pressure ring between said ends thereof, said enlarged diameter portion being at least partially defined by a first surface remote from said reduced diameter portion, and a second surface generally adjacent said reduced diameter portion, said pressure ring first surface being selectively formed for nonrotatable engagement with said compressible member, said pressure ring second surface being selectively contoured for sliding engagement with the surface of said gland nut adjacent said second end as said gland nut is threadably engaged with and tightened upon said body member; the wall defining said compressible member passageway being proportioned to at least partially collapse about, and seize the adjacent resiliently deformable outer covering of a generally elongated member inserted therethrough to provide a strain relief and a seal thereat as said gland nut is tightened upon said body member and said pressure ring is urged against said compressible member, said pressure ring being provided with gripping means is disposed on at least a portion of said first surface thereof, said gripping means comprising a plurality of generally radially extending ridges.

3. The improvement as defined in claim 2 wherein said ridges are substantially linear.

4. The improvement as defined in claim 2 wherein said ridges are substantially arcuate.

5. In a strain relief assembly for use with an elongate article having a resiliently deformable outer covering and of the type having a body member having a first end, a second end, a center portion therebetween, threads disposed about at least a portion of the periphery of said body member adjacent at least said first end thereof, and a passageway extending between said first and second ends of said body member and terminating in a tapered portion adjacent said body member first end; a gland nut having a first end, a second end, a restrictive aperture extending axially through said second end, and internal threads adjacent said first end for threadable engagement with said first end of said body member; a compressible member having a passageway extending generally longitudinally therethrough, and having a selectively tapered portion contoured to fit within said tapered portion of said body member passageway, the improvement comprising: a nonmetallic pressure ring positionble intermediate said compressible member and said gland nut second end, said pressure ring having an enlarged diameter portion adjacent one end thereof, a reduced diameter portion adjacent its opposite end, and a selectively proportioned passageway extending generally longitudinally through said pressure ring between said ends thereof, said enlarged diameter portion being at least partially defined by a first surface remote from said reduced diameter portion, and a second surface generally adjacent said reduced diameter portion, said pressure ring first surface being selectively formed for nonrotatable engagement with said compressible member, said pressure ring second surface being selectively contoured for sliding engagement with the surface of said gland nut adjacent said second end as said gland nut is threadably engaged with and tightened upon said body member; the wall defining said compressible member passageway being proportioned to at least partially collapse about, and seize the adjacent resiliently deformable outer covering of a generally elongate member inserted therethrough to provide a strain relief and a seal thereat as said gland nut is tightened upon said body member and said pressure ring is urged against said compressible member, said pressure ring further comprising a recessed portion peripherally disposed generally intermediate said pressure ring enlarged diameter and reduced diameter portions and proportioned to permit said enlarged diameter portion to flex thereabout.

6. In a strain relief assembly for use with an elongate article having a resiliently deformable outer covering and of the type having a body member having a first end, a second end, a center portion therebetween, threads disposed about at least a portion of the periphery of said body member adjacent at least said first end thereof, and a passageway extending between said first and second ends of said body member and terminating in a tapered portion adjacent said body member first end; a gland nut having a first end, a second end, a restrictive aperture extending axially through said second end, and internal threads adjacent said first end for threadable engagement with said first end of said body member; a compressible member having a passageway extending generally longitudinally therethrough, and having a selectively tapered portion contoured to fit within said tapered portion of said body member passageway, the improvement comprising: a nonmetallic pressure ring positionable intermediate said compressible member-and said gland nut second end, said pressure ring having an enlarged diameter portion adjacent one end thereof, a reduced diameter portion adjacent its opposite end, and a selectively proportioned passageway extending generally longitudinally through said pressure ring between said ends thereof, said enlarged diameter portion being at least partially defined by a first surface remote from said reduced diameter portion, and a second surface generally adjacent said reduced diameter portion, said pressure ring first surface being selectively formed for nonrotatable engagement with said compressible member, saidpressure ring second surface being selectively contoured for sliding engagement with the surface of said gland nut adjacent said second end as said gland nut is threadably engaged with and tightened upon said body member; the wall defining said compressible member passageway being proportioned to at least partially collapse about, and seize the adjacent resiliently deformable outer covering of a generally elongate member inserted therethrough to provide a strain relief and a seal thereat as said gland nut is tightened upon said body member and said pressure ring is urged against said compressible member, said pressure ring first surface further having a generally annular recess therein.

7. In a strain relief assembly for use with an elongate article having a resiliently deformable outer covering and of the type having a body member having a first end, a second end, a center portion therebetween, threads disposed about at least a portion of the periphery of said body member adjacent at least said first end thereof, and a passageway extending between said first and second ends of said body member and terminating in a tapered portion adjacent said body member first end; a gland nut having a first end, a second end, a restrictive aperture extending axially through said second end, and internal threads adjacent said first end for threadable engagement with said first end of said body member; a compressible member having a passageway extending generally longitudinally therethrough, and having a selectively tapered portion contoured to fit within said tapered portion of said body member passageway, the improvement comprising: a nonmetallic pressure ring positionable intermediate said compressible member and said gland nut second end, said pressure ring having an enlarged diameter portion adjacent one end thereof, a reduced diameter portion adjacent its opposite end, and a selectively proportioned passageway extending generally longitudinally through said pressure ring between said ends thereof, said enlarged diameter portion being at least partially defined by a first surface remote from said reduced diameter portion, and a second surface generally adjacent said reduced diameter portion, said pressure ring first surface being selectively formed for nonrotatable engagement with said compressible member, said pressure ring second surface being selectively contoured for sliding engagement with the surface of said gland nut adjacent said second end as said gland nut is threadably engaged with and tightened upon said body member; the wall defining said compressible member passageway being proportioned to at least partially collapse about, and seize the adjacent resiliently deformable outer covering of a generally elongate member inserted therethrough to provide a strain relief and a seal thereat as said gland nut is tightened upon said body member and said pressure ring is urged against said compressible member, there being at least one substantially annularly formed raised portion disposed on said pressure ring second surface.

Claims

6. In a strain relief assembly for use with an elongate article having a resiliently deformable outer covering and of the type having a body member having a first end, a second end, a center portion therebetween, threads disposed about at least a portion of the periphery of said body member adjacent at least said first end thereof, and a passageway extending between said first and second ends of said body member and terminating in a tapered portion adjacent said body member first end; a gland nut having a first end, a second end, a restrictive aperture extending axially through said second end, and internal threads adjacent said first end for threadable engagement with said first end of said body member; a compressible member having a passageway extending generally longitudinally therethrough, and having a selectively tapered portion contoured to fit within said tapered portion of said body member passageway, the improvement comprising: a nonmetallic pressure ring positionable intermediate said compressible member and said gland nut secOnd end, said pressure ring having an enlarged diameter portion adjacent one end thereof, a reduced diameter portion adjacent its opposite end, and a selectively proportioned passageway extending generally longitudinally through said pressure ring between said ends thereof, said enlarged diameter portion being at least partially defined by a first surface remote from said reduced diameter portion, and a second surface generally adjacent said reduced diameter portion, said pressure ring first surface being selectively formed for nonrotatable engagement with said compressible member, said pressure ring second surface being selectively contoured for sliding engagement with the surface of said gland nut adjacent said second end as said gland nut is threadably engaged with and tightened upon said body member; the wall defining said compressible member passageway being proportioned to at least partially collapse about, and seize the adjacent resiliently deformable outer covering of a generally elongate member inserted therethrough to provide a strain relief and a seal thereat as said gland nut is tightened upon said body member and said pressure ring is urged against said compressible member, said pressure ring first surface further having a generally annular recess therein.