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Publication numberUS2724736 A
Publication typeGrant
Publication dateNov 22, 1955
Filing dateFeb 27, 1953
Priority dateFeb 27, 1953
Publication numberUS 2724736 A, US 2724736A, US-A-2724736, US2724736 A, US2724736A
InventorsJr Ferdinand Klumpp
Original AssigneeJr Ferdinand Klumpp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Spring type strain-relief bushing
US 2724736 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

Nov. 22, 1955 F. KLUMPP, JR 2,724,736

SPRING TYPE STRAIN-RELIEF BUSHING Filed Feb. 27, 1955 %Wz;@ Eat b24271] warm ya c771 United States Patent SPRING TYPE STRAIN-RELIEF BUSHING Ferdinand Klumpp, Jr., Union, N. J.

Application February 27, 1953, Serial No. 339,420

7 Claims. (Cl. 174-153) In my Patent 2,424,758, July 29, 1947, I have shown and described a self-locking strain-relief bushing for the purpose of securing an electrical conductor or cable in the bushing when the same is moved into position into a support of the plate type. I have also made a strainrelief device in which one end of a circular elongated metal spring is mounted. The spring embraces a cable or conductor coming to the strain-relief device for the purpose of taking much of the strain off the cable or conductor if the same is bent at a substantial angle closely adjacent the strain-relief device. It has been found from practice that in some uses the metallic spring will wear into the insulation around the cable or conductor and may cause trouble such as a short circuit.

To overcome this trouble I have developed a strainrelief structure in which the main body thereof is formed with an elongated integral part formed like a spring, it being understood that this main part of the strain-relief device is made of suitable insulating material such as nylon.

By the construction to be hereinafter described I have eliminated the metal spring entirely and have simplified the key used for locking the cable or conductor in place within the holder or body portion of the strainrelief device.

In the drawing:

Figure 1 is a plan view of the strain-relief device applied to a cable and showing one position in broken lines which the spring end may take during its use.

Figure 2 is a side view of Figure 1.

Figure 3 is a part sectional and part elevational view on the center line of Figure 1.

Figure 4 is a sectional view on the line 4--4 of Figure 1.

Figure 5 is a view of the main part of the strain-relief device without the grip lock, the position of the cable being indicated in broken lines.

Figure 6 is a plan view of the inner portion of the grip lock.

Figure 7 is a side view of the grip lock.

Figure 8 is a section on the line 88 of Figure 7.

Figure 9 is a view on the line 9-9 of Figure 1.

Figure 10 is a view on the line 1010 of Figure 2.

In the drawing the various views are made full size of the working device or model. In drawings 1 is the body or main part of the strain-relief structure. Extending longitudinally from the body portion 1 are a plurality of spaced parts 2 corresponding to the convolutions of a spring. These convolutions terminate in a circular flange 3. I have found that where the convolutions 2 are arranged in three parts resembling screw threads, the flexibility of a suitable molded material, such as nylon, will give excellent flexibility so that the cable may be bent at a considerable angle without injuring it or the turns 2. The body portion 1 has a flange 4 which is adapted to engage a mounting plate 5 as shown in Figures 1 and 2. Projecting from the flange 4 is a hub 6 having flat surfaces on opposite sides ending in tapered surfaces 7 on "ice each side for assistance in assembling the strain-relief device into its mounting plate 5. The interior part of hub 6 has grooves 8 extending downwardly toward a bottom recess 9. These grooves 8 are adapted to receive fingers 10 which project from the key member 11. Between the fingers 10 is a circular portion 12 that'is adapt ed to engage the cable C when the key 11 is forced into locking position by pushing the strain-relief device into a cooperating hole in the mounting plate 5. The key has an arcuately shaped groove 13 on its outer surface to engage the mounting plate 5 and to hold the key in its locking position, forcing the cable into the recess 9 as shown in Figure 3. After the cable or conductor has been inserted through the spaced parts, 2 into the body portion 1, the key member 11 is placed into position and then the assembled device is forced into the support plate 5 which causes the key 11 to move into the locking position as shown.

From the foregoing it will be seen that I have provided a two piece strain'relief structure in a new and novel manner.

Having thus described my invention, what I claim is:

l. A strain relief bushing having a main portion to receive a cable or conductor and a locking key slidably carried by the main portion which has an integral extension composed of spaced parts resembling and acting as a spring as and for the purpose described.

2. A strain relief bushing having a main portion and a locking key slidably carried by and at right angles to the horizontal axis of said main portion which has an integral extension composed of spaced parts resembling and acting as a spring and having an interior diameter 10 receive a cable or conductor.

3. A strain relief bushing of suitable insulating material for holding an electrical conductor in a mounting plate hole, said bushing having a body portion with a flange to engage a mounting plate, said body portion having a hollow integral extension at its other end, said extension being composed of spaced resilient parts resembling a spring and serving as a flexible support for said conductor, said body portion having a transverse opening through one side of its wall at the end opposite said spring portion, the body portion having a recess opposite said opening and below the main hollow part of the bushing and a grip-key positioned in said opening and adapted to be engaged by said plate, when the bushing is forced into the plate hole, to bend the conductor into said recess and lock it securely in the bushing.

4. A strain relief bushing as set forth in claim 3 further defined in that said spring-like end is formed by a plurality of spirally arranged parts terminating in a collar at the outer end for receiving a conductor.

5. A strain relief bushing as set forth in claim 3 further defined in that said spring-like end is formed by three spirally arranged parts which terminate in an integral collar to receive a conductor.

6. The combination of a mounting plate having a hole therein to receive a strain-relief bushing of suitable insulating material, the bushing being composed of two parts to grip an electrical conductor or cable placed between them, one part having a recess therein while the other part is slidable as a whole toward a longitudinal axis of said one part, said slidable part having an arcuately formed projection for engaging said conductor or cable, each part having at least a slight tapered end to assist in entering the parts into said hole, the two parts being forced toward each other by the wall of the hole so said projection will force the conductor or cable downwardly into said recess, both parts having co-operative arcuate grooves to lock the parts to the mounting plate, said part having the recess therein having an integral circular ex Patented Nov. 22, 5

tension composed of spaced parts resembling and acting as a spring as and for the purpose described.

7. In combination with a mounting plate having a hole therein to non-rotatably receive a strain-relief bushing, a bushing of strong insulating material to fit said hole, the. bushing having a transverse side opening at one end with a recess opposite said opening and a passageway spaced longitudinally away from said recess, said passageway terminating in an integral elongated circular springlike formed section of insulating material through which a cable or conductor may pass through the bushing, a locking key of strong insulating material transversely carried by said bushing opposite said recess and adapted to be. moved toward said recess to grip the conductor and force it into said recess and means on the bushing and key to lock the two of them in the plate hole.

References Cited in the file of this patent UNITED STATES PATENTS McCatchie Apr. 29, 1924 Preston Mar. 6, 1934 Klumpp July 29, 1947 Reder June 14, 1949 Hultgren Aug. 7, 1951 FOREIGN PATENTS France Jan. 25, 1932 (First addition to No; 695,525)

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1492335 *Mar 21, 1919Apr 29, 1924Benjamin Electric Mfg CoAttachment device
US1950036 *May 29, 1929Mar 6, 1934Black & Decker Mfg CoCord clamp for portable electric tools
US2424758 *Jun 14, 1945Jul 29, 1947Heyman Mfg CompanyStrain-relief bushing
US2472986 *May 23, 1946Jun 14, 1949Reder Jr Emil ECord protector and strain reliever for use with electrical connectors
US2563604 *Nov 5, 1949Aug 7, 1951 Strain belief bushing
FR40162E * Title not available
FR695525A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2820209 *Feb 28, 1956Jan 14, 1958Whitso IncInsulated electrical terminal
US2922836 *Feb 20, 1956Jan 26, 1960Chrysler CorpGrommet
US3156514 *Nov 21, 1961Nov 10, 1964Hi Shear CorpConnector
US3258234 *May 21, 1964Jun 28, 1966United Carr IncStrain-relief device
US3749818 *Sep 30, 1971Jul 31, 1973Heyman Mfg CoElectric cord stress relief combined with a strain relief grommet
US4137558 *Jan 10, 1977Jan 30, 1979Robertshaw Controls CompanyInstrument probe assembly having continuous probe insulation
US4568047 *Aug 16, 1984Feb 4, 1986Kitagawa Industries Co., Ltd.Cord bushing
US4632488 *Jun 8, 1984Dec 30, 1986Switchcraft, Inc.Cord strain relief device
US4734055 *Dec 30, 1981Mar 29, 1988Kitagawa Industries Co., Ltd.Cord bushing
US5375523 *Apr 26, 1993Dec 27, 1994J.E.M. Smoke Machine Company, Ltd.Pyrotechnic device
US5390272 *Aug 31, 1993Feb 14, 1995Amphenol CorporationFiber optic cable connector with strain relief boot
US5823817 *Oct 24, 1996Oct 20, 1998Hamilton Beach/Proctor-Silex, Inc.For use in an electrical appliance
US5874709 *Apr 14, 1997Feb 23, 1999Tweco Products, Inc.Strain relief assembly for welding cable
US7794255Feb 23, 2009Sep 14, 2010Melni Mark LElectrical connectors and methods of manufacturing and using same
US7901233Aug 30, 2010Mar 8, 2011Melni Mark LElectrical connectors and methods of manufacturing and using same
US8066525Nov 3, 2010Nov 29, 2011Melni Mark LElectrical connectors and methods of manufacturing and using same
US8246370Nov 29, 2011Aug 21, 2012Melni Mark LElectrical connectors and methods of manufacturing and using same
US8771000Aug 21, 2012Jul 8, 2014Melni, LlcElectrical connectors and methods of manufacturing and using same
DE2714225A1 *Mar 30, 1977Dec 29, 1977Heyman Mfg CoAus einem dielektrischen kunststoff geformte, selbstsichernde biege- und zugentlastungsbuechse oder -huelse
WO2011056901A2Nov 3, 2010May 12, 2011Mark L MelniElectrical connectors and methods of manufacturing and using same
U.S. Classification174/153.00G, 248/56, 439/448, 439/449, 178/23.00A, 248/49
International ClassificationH01B17/58, H01R13/58
Cooperative ClassificationH01R13/5816, H01B17/58
European ClassificationH01B17/58, H01R13/58B6