US2201213A

US2201213A - Strain relief

Info

Publication number: US2201213A
Application number: US183766A
Authority: US
Inventors: Holtz Charles Theodore Von
Original assignee: Harvey Hubbell Inc
Current assignee: Harvey Hubbell Inc
Priority date: 1938-01-07
Filing date: 1938-01-07
Publication date: 1940-05-21
Anticipated expiration: 1957-05-21

Description

y 1940. c. T. VON HOLTZ 2,201,213

STRAIN RELIEF Filed Jan. 7. 1938 Patented May 21,1940

UNITED STATES s'rnsnv anus!" Charles Theodore. Von

assignor to Harvey Bridgeport, Conn., necticnt Application January 7,

2 Claims.

This invention relates to new and usefulimprovements in electrical devices, and has particular relation to a strain reliever for small attachment plug caps. although it may be used for various devices.

An object of the invention is to provide a relatively small and':inexpensive attachment plug cap including a strain reliever for the lead connections to the binding screws, and which strain reliever is mounted on the cap without the aid of an extra metal shell or other part.

Other objects and advantages will become apparent from a consideration of the following detailed description taken in connection with the accompanying drawing wherein a satisfactory embodiment of the invention is shown. However, it is to be understood that the invention is not limited to the details disclosed but includes all such variations and modifications as fall within the scope of the invention.

In the drawing: t

Fig. 1 is a top plan view showing the improved plug cap on an enlarged scale;

.Fig. 2 is a side elevational view thereof with 'parts broken away to. show interior construction;

Fig. 3 is a bottom plan view of the cap;

Fig. 4 is a sectional view as along the line H of Fig. l, but with the connecting cable omitted, and with the strain reliever shown in elevation, the dotted lines in the figure indicating the mannerof applying and removing the strain reliever; 1

Fig. 5 is a sectional 'view as of along the line 8-5 of Fig. 1;

Fig. 6 is a top plan view of the strain reliever alone; and

Fig. 7 is a side elevational view of the strain reliever alone.

While the invention may be applied in connection with other electrical devices, it is herein disclosed as embodied in a plug cap.

Referring in detail to the drawing, at It is shown a moulded one piece body of insulating material, such for example as fBakelite" or similar material, open at its under side as at H, and through its upper side provided with an opening i2 for the passage of av cable l3 containing the lead wires. Within the body and facing the lower open end thereof are shoulders it against which are secured the inner or base portions ii of contact elements or blades it, each such contact element being providedwith a binding post screw II, by means of which, the wires it of cable I! are connected with the contact elements.

Holtz, Bridgeport, Coma. Hubbell, Incorporated, a corporation of Conisss, Serial No. 183,766

The base portions I 5 are provided'with extensions Ila forced into the body material to anchor the contacts to the body.

Recesses is are provided in the body between the shoulder portions I4. and such recesses extend radially in opposite directions from the inher end of the opening l2 andsare open at their inner sides, being in the nature'of. radially extending channels. The strain reliever of the invention comprises a cable clamp generallydesignated 20 and including sheet metal elements 2| and 22 formed to the proper shape and each including a cable clamping portion and a foot 24 at the inner end of and at right angles to the portion 22.

Strain reliever 20 is mounted on the body .II with cable clamping portions 23 of the reliever extending outwardly through vtheopening i2 of the body and with the feet 24 within the body and extending opposite one another and located in the recesses i9. Ears 25 are formed with and extend laterally from the-edges of clamping portions 23. They are located at the outer side of the body and are connected by-screws or the like 28 adapted to be tightened to draw the elements 2i and 22 toward one another whereby to have the Iportions 23 of such elements clamp the cable 3.

As the feet 24 of the clamping element extend radially with respect to the opening l2 in the same manner as the recesses it, it will be apparent that the elements 2| and 22 may be moved toward and from one another to clamp and release a cable and to accommodate different sizes of cables. The feet 24 are substantially as wide as the recesses It and therefore while the clamping elements may be moved toward and from one another they may not turn relative to the body I 0 and therefore any twist on the cable It beyond the clamping means will not be transmitted to the binding post connections.

The ears 2! (see Fig. 5) engage or are adjacent the outer surface of the body as at 21 and thus limit movement of the elements 2| and 22 inwardly through the opening I 2, and serve to maintain the feet 24 in engagement or substantially in engagement with the upper walls or surfaces 28 of the recesses l9, whereby there is no chance of such feet engaging any portion of the elements it.

The'clamping elements 2| and 22 are of such size with relation to the opening l2that bytilting such elements (see the dotted lines, Fig. 4) and inserting them with the free endsof their feet 24 foremost and then after the feet begin to enter the recesses l9, straightening the elements or bringing the clamping portions 23 toward each other to substantially parallel relation, they may be easily and quickly mounted on the body. After the connecting screws 28 are in place, the elements 2| and 22 being connected, the strain reliever cannot be removed from the body except by first removing the screws 26.

While the elements are connected, the feet 24 extend laterally or radially of the opening l2 in any position of the strain reliever and therefore these elements cannot be removed from the body so long as one or both of the screws are in place.

This is fully illustrated in Fig. 4, wherein the screws 26 have been tightened as far as possible and the reliever has been moved as far as possible toward the left. Yet in such figure .it will be noted that the foot 24 projecting toward the right has its free end disposed laterally of or beyond the edge of the opening I2. This is the most contracted position of the elements but it will be seen they cannot be removed from the body as the diameter of the opening I2 is less than the dis tance from the outer surface of the clamping portion 23 of one element to the free end of the leg portion 24 of the other element.

From the foregoing description it will be clear that the strain reliever has been mounted on the plug cap without the use of an outer metal shell or the like. Thus, the expense of an extra mounting means is avoided, and, in addition, the usual ornamental surface of the moulded body is fully exposed whereby the appearance of the device is not detracted from. These features are of a special importance in connection with a small plug cap.

Having thus set forth the nature of my invention, what I claim is:

1. In a device of the character described, an integral moulded one-piece body of insulating material, lead wire connections carried by said body, said body having an opening leading to said connections, a cable clamp including a pair of elements extending through said opening and each comprising a cable clamping portion and an angularly related foot within said body and extending radially relative to said opening, means connecting said clamping portions for causing them to clamp a cable passing through said opening, said body having internal recesses extending radially from said opening having bottom walls spaced inwardly from the outer wall through which the opening enters and facing in the opposite direction from this wall, said recesses being open at their inner sides and receiving said feet to cooperate with said bottom walls whereby the clamping elements may move toward and from one another but are held against removal from necting portion of one element and the free end of the foot of the other element when saidclamping portions are connected and of a size to permit each element to be rocked about the edge of the opening to permit insertion and removal of the foot through the opening when the elements are disconnected.

2. In a device of the character described, a connector cap comprising a molded one-piece body of insulating material open at one side and pro vided withshoulders spaced inwardly from said open side and facing said open side, contact elements comprising base portions mounted on said shoulders and blade portions projecting from. said open side of the body and means for connecting lead wires to said elements, said body being provided with an opening leading therethrough from the opposite side to said shoulders for passage of a cable containing lead wires for connection to said elements, said body having a pair of recesses extending inwardly from said shoulders and laterally in opposite directions from said opening and having bottom walls spaced inwardly from said shoulders, a pair of clamping elements mounted in said opening and each comprising a curved body adapted to be clamped against the cable and an angularly related substantially fiat foot at its inner end extending radially in one of said recesses relative to said opening to engage the bottom wall of the recess and slide thereon with the side walls of the recesses cooperating with the edges of the foot portions to prevent turning of the clamping elements in the body, cooperating means on the clamping elements and the body to limit inward movement of said elements in the opening, means connecting the body portions of the clamping elements to clamp them against a cable, and said feet being of such a size with respect to the, opening that when said connecting meansare disconnected the elements may be tilted about the edges of the opening and the feet passed through the opening to or from a position in the recesses and when the elements are connected by said means said feet extend laterally beyond the edges of the opening to engage the bottom walls of the recesses in all positions of the elements to prevent their removal from the opening.

CHARLES THEODORE VON HOLTZ.