US2091453A - Fuse - Google Patents

Description

Aug 31, 1937.

-ZQZzi v2 A. RAMSEY FUSE Filed May gas, 1935 4 SheetsSI 1eet l A. RAMSEY Aug. 31, 1937.

FU S E Filed Mary 18, 1933 4 SheetsSneet 2 I'lllll" J? W72Z 5Ofx $1262)? 1 8627725 Aug. 31, 1937. A. RAMSEY 2,091,453

FUSE

Filed May 18, 1933 4 Sheets-Sheet 3 a /0(9 v, W7

Aug. 31, 1937. RAMSEY 2,091,453

FUSE

Filed May 18, 1953 4 Sheets-Sheet 4 /U j 325125-55: gig-ii; I

Patented Aug. 31, 15337 UNITED STATES PATENT OFFICE FUSE poration of Delaware Application May 18, 1833, Serial No. 671,660

71 Claims. (Cl. 200-117) My present invention relates to electric fuse devices and the instant application is a continuation in part of my copending application Serial No. 559,846, filed August 28, 1931. i Y While the specific embodiments which I shall illustrate are adapted for interrupting high ten- 'sion current and for use in expulsion type fuses and cut-outs of the character shown in my copending application above identified, the inven- 16 tion is not to be limited to such specific application, nor is the invention to be limited to high voltage only. In the fuse element and fuse element assemblies of fuse devices of the type with which my 16 present invention is concerned, certain dimculties have been encountered. One difficulty has been in obtaining the desired original accuracy of the time current blowing characteristics and the matter of permanence of the time current blowing characteristics or, in other words, the maintenance of the desired original accuracy of the time current blowing characteristics over long periods of time has presented another difllculty.

One of the reasons for the difllculties heretow fore encountered lies in the fact that the oxides of the fuse elements or fuse links previously employed are non-conducting or relatively non-con- 'ducting and, furthermoreilake off and thereby reduce or vary the cross-section of the element. Another reason for the prior difliculties lies in the fact that the fuse element has been exposed to atmosphere, gases and moisture.

A still further reason for the difficulties previously encountered lies in the fact that the fuse element and fuse element assemblies have not had the desired rigidity between the parts connected thereby but have been relatively free for movement between such parts. I 1

One of the objects of the present invention 40 is to overcome these difficulties heretofore encountered. A I

Another and more specific object is to improve the original accuracy of the time current blowing characteristics of the fuse element and fuse as element assembly.

Another object is to improve the permanence of the time current blowing characteristics of the fuse element and fuse element assembly, or, in other words, to maintain better the desired no original accuracy of the time current blowing characteristics over long periods of time.

Another object is to construct the fuse element and fuseelement assembly so that same may be used either in the Schweitur and Conrad type 55 spring actuated expulsion fuse or in ordinary air expulsion fuses. This gives the element and element assembly a highl desirable universal charactor.

The fuse element which I employ is preferably formed of a material whose oxide is a conductor. It and the tensile or strain wire are both preferably completely enclosed and shielded from atmosphere, gases and moisture. And the fuse element assembly is held rigidly between the parts between which it is connected, the fuse element being held rigidly and against crimping, and it and the other parts of the fuse element assembly being held rigidly against movement relative to and between the parts connected thereby.

Another feature of the present invention consists in providing the fuse element assembly with a projecting tail part or extension which may be grasped conveniently for the purpose of setting the fuse and which, after the fuse is set, may he cut off or removed.

Another feature consists in providing a secondary enclosure which telescopes or slips off the element assembly. With this secondary enclosure in place and the element assembly connected to the spring system, the element assembly is ready for use with spring type expulsion fuses and, with the secondary enclosure slipped off or removed and the element assembly disconnected from the spring system, it is ready for use with ordinary air expulsion fuses.

I believe that I have or hereinafter shall state with certainty the difficulties heretofore en- .countered, the reasons therefor, as well as the features of the present invention and the mannet in which the previous difllculties are overcome thereby, but I reservethe right to revise the same or propound different theories should I become aware of results or features of which I am not now aware so long as any revisions'or any additional features or results are based upon the following detailed disclosure as to how my inven- Figure 2 is a side elevational view of another 1 form of fuse element assembly embodying the i present invention as it appears before being placed in the fuse casing;

till

Figure 3 is a detailed transverse section taken on the line 3-3 of Figure 2;

Figure 4 is a detailed transverse section taken on the line 4-4 of Figure 2 5 Figure 5 is a view similar to Figure 2 showing another form of fuse element assembly as it appears before being placed in the fuse casing;

Figure 6 is a view of the fuse element assembly shown in Figure 5 and taken at substantially right angles to Figure 5;

Figure '7 is a fragmentary view of the lower end of the insulating casing of the fuse showing a contact ferrule mounted thereon and adapted for use with the fuse element assembly of Figures 5 and 6;

Figure 8 is a side elevational view of a terminal member adapted for attachment to the lower end of the fuse spring and for use with the fuse element assembly shown in Figures 5 and 6;

Figures 9, 10 and 11 are parts of a longitudinal sectional view through another fuse showing another embodiment of the present invention; (Figure 10 is to be laid below Figure 9 with the dot and dash line H of Figure 10 on the dot and dash line a--a of Figure 9, and Figure 11 is to be laid below Figure 10 with the dot and dash line b-b of Figure 11 on the-dot and dash line b--b of Figure 10).

Figure 12 is a lower end view of the lower terminal clip shown in Figure 10;

Figure 13 is a side elevational view of the bushing for the fuse element of Figures 9, 10 and 11;

Figure 14 is a perspective view of the lower contact terminal of the fuse shown in Figures 9, 10

and 11;

Figure 15 is a detailed transverse section through the fuse link assembly taken on the line I5-l5 of Figure 10;

Figure 16 is a detailed transverse section 0 through the tail extension of the fuse element assembly taken on the line iB-ld of Figure 10;

Figure 17 is a longitudinal sectional view showing on a reduced scale and more or less diagrammatically the fuse shown in Figures 9, 10 and 11;

Figure 18 is a view similar to Figure 17 showing the element assembly in place in an ordinary air expulsion fuse of the General Electric type and with the secondary enclosure for the element assembly removed;

I Figure 19 is a detail transverse section taken on the line i9-l9 of Figure 18; and

Figure 20 is a detail transverse section taken on the line 20-20 of Figure 18.

The fuse shown in Figure 1 comprises a casing 5 in the form of a cylindrical tube. This tube is preferably formed of bakelite with a hard insulating fiber liner known as "Conite or as "Horn Fiber which does not carbonize under heat, but it is to be understood that any other suitable or preferred insulating material may be employed. A ferrule 6 of cast hard bronze or other suitable or preferred material fits over the upper end of the tube 5 and is rigidly secured thereto by means of a pair of screws 1 and 8.'

These screws are threaded through diametrically opposite sides of the ferrule t and into the wall of the tube ii, the upper end of which may be reduced to seat the lower end of the ferrule at 8. The upper end of the ferrule 6 has a pair of laterally extending arms it! (only one of which is shown) formed integral with the ferrule, and spaced below the arms it is a second pair of generally parallel arms Ii also formed integral with the ferrule. Extending diametrically oppositely from the arms it and ii and integral with amines the ferrule t is a hook I? provided for the purpose of attachment of the upper end of the fuse to the cover of the cut-out box (not shown).

The details of the upper spring contact clip are more fully disclosed in my copending application herein identified and form no part of the present invention. Suflice it, therefore, to explain here that t'nis clip comprises a plurality of laterally extending and generally parallel contact wires preferably of copper and preferably with inherent springiness, although this may vary. These contact wires are indicated at I3, there being in the illustrated embodiment four of these wires in superposed relation on each side and between each'arm ill and the underlying arm ii. The ferrule ends of the contact wires l3 are firmly and rigidly anchored in the ferrule and the outerends of these wires iii are looped at l5. Pins it, formed of brass rod or other suitable material, extend through these looped ends i5 and are anchored at their opposite ends in the arms l0 and ii. The looped ends I5 are the contact ends and the pins it hold these ends in place and against undue displacement but, at the same time, fit sufficiently loosely in the looped ends l5 to permit freedom of operation and closing of these ends upon the contact lug (not shown) with which the upper spring contact clip cooperates.

-Washers il on the plus it and between the respective looped ends l5 of the contact wires i3 and between the arms l0 and ii and the uppermost and lowermost contact wires, provide spacers for spacing and maintaining the desired relative positioning of the looped ends of the contact wires.

The lower ferrule 18 of cast hard bronze or other suitable material is split at It and clamped by screws 28 upon the tubular casing 5. This ferrule it has arms and contact wires (not shown) corresponding with the arms and contact wires of the upper spring contact.

The upper end of the ferrule 6 is threaded internally at 22 to receive a cap screw 23. This cap screw 23 has a hexagonal head 24 to facilitate turning the same into and out of the upper end of the ferrule 6. The cap screw 23 closes the top of the tube 5 and this cap screw has an integral axial boss 25 extending into the tube 5. The

boss 25 has a helical groove 26 for receiving the upper end of the spring 21 by threaded engagement therewith.

The boss 25 is reduced at its lower end and has a socket 29 in which one end of a flexible braided conductor 38 is rigidly secured. This braided conductor 30 is made of copper or the like and its opposite end is connected with the lower terminal member 32 by rigidly securing it in, the socket 33. The lower terminal 32 has a helical groove formed therein for threaded engagement with the lower end of the spring 2l and the lower terminal is thus suspended by the spring. This lower terminal 32 has a flattened portion 35 to receive a stud 36 which may be secured in place by means of a pin 37. The fuse element or fuse link 38 extends around the stud 86 and is bolted to the terminal 32 by means of ly projecting tail end of the link 38 and pulling.

the lower terminal 92 downwardly'against the tension of spring 21. It is to be understood that the parts are so proportioned that the lower tail end of the link 39 will project down below the bottom of the fuse casing I when the spring 21 is retracted and the lower terminal 92 raised. Then, with the lower end of the spring 21 pulled down to extended position, the lower end of the link 39 is folded up around the lower end of the casing 5 as shown, and the free end of the-tail projection of the link 98 is secured to the stud 49 by means oi a nut 42 threaded upon the extending end of the stud 49. A circuit is thus established from the terminal 92, through the fuse link 39, to the lower ferrule l9, and with the parts set, as shown, the circuit is completed from the terminal 92, through thebraided conductor 39, and possibly partially through the spring 21, to the upper ferrule 9, through the boss and the cap screw 29. The fuse link 39 is made of suitable fusible material, preferably a fusible, material whose oxide is a conductor as, for example, pure silver wire, and it has a portion 49 of reduced cross- 25 sectional area at a point along its length within the tube 5, said reduced portion 45 being surrounded by a cork disposed within the lower end of the tube 9. It is to be understood that the showing of the fuse link 39 in Figure 1 is more or less diagrammatic. This element may be similar to the'element shown in Nicholas J. Conrad Patent No. 1,818,382, dated August 11, 1931, or it may-consist of a silver wire paralleled by a nickel chromium alloy strain wire. The 36 formation of the fuse link 39 of silver or some other material whose oxide is a conductor provides a fuse link which will not flake off, deteriorate, or become reduced in cross section. This enables making the time current blowing charac- 40 terlstics accurate originally and tends to maintain the desired original accuracy of the time current blowing characteristics over long periods of time. The enclosure of the reduced portion of the fuse link seals the same from at- 45 mosphere, 'gases and moisture, and tends also to maintain the desired original accuracy of the time current blowing characteristics, particularly along the active part of the fuse link.

When thefuselink-blows. it blows at the reduced portion 45 and, theatension of the spring 21 being thereby released, the spring quickly snaps the terminal 92 upwardly and away from the point of blowing of the fuse to draw out quickly and extinguish any are that may form. ,55 The fuse element assembly shown in Figures 2,

3 and 4, comprises a short length of copper tubing 49 and a somewhat longer length of copper tubing 49 flattened and thereby secured upon the opposite ends of the closed loop strain element or tensile wire 59 arranged to bear the mechanical strength and upon the opposite ends of the crimped fuse wire 5|. The fuse wire ii is made of suitable material, preferably a fusible material whose oxide is a conductor, such as pure silver, 5 and the strain element 59 preferably is of "Chromel" A wire. The cork enclosure 4! surrounds the fuse element and strain wire assembly as shown, and this cork member 52 is made up of two half round corks having complementary depressions 59 and surrounded and held together by a water-proofed paper tube 54. The tube 54 may be of gummed paper or it may be a thin fiber tube, or of other suitable or preferred material.

: 75 The cork is compressed and the two halves secured together by forcing them into and enclosing them in the tube The silver fuse element Ii is enclosed in thin sheet mica at 55 to prevent contact with the strain wire 59 and to keep heat from the fuse element from charring the cork. In this manner, I combine a fuse link 9| of silver or other material, whose oxide is a conductor, with a strain wire, and I completely enclose and shield both from atmosphere, gases and moisture.

It will be noted further that the opposite ends of the tightly compressed cork sections project lengthwise sufficiently to fit over and be compressed tightly upon the adjacent end of the copper tubing 49 and upon the copper tubing 49 at the opposite end of the fuse element assembly. The forcing of the cork member 92 into the tube 54 binds the opposite ends of the cork firmly and rigidly to the copper terminals 49 and 49 of the fuse element assembly, holding the terminals 49 and 49 of the fuse element assembly rigidly together, and the entire fuse assembly is a rigid unit so that the fuse element and strain wire will not I have free movement between the parts connected thereby as heretofore. The flattened section of copper tubing 49 has an eye 99 which may be secured to the lower inside and movable terminal 92 by means of a nut 99 threaded upon the extending end of the stud 96 as described in connection with the preceding embodiment, the eye 99 being adap ed to be passed over the stud 99.

The extension 51 of hot rolled copper or other suitable material has the tail end I which, when the spring 21 is retracted, extends down below the lower end of the fuse casing 9 so that it may be gripped conveniently for setting the fuse and placing the spring 21 under tension as described in connection with the preceding embodiment. As before, the fuse is set by grasping the tail extension Ol and pulling the same downwardly, and,

with this tail end 9 I of the extension 91 pulled downwardly and the spring 21 under tension, the extension 51 is folded up over the lower end of the fuse casing 5 and the opening 59 is placed over the stud 49 and secured to the stud 49 by means of the nut 42 threaded upon the extending end of the stud, as before. With the fuse thus set, and the end of the strip 91 with the opening 99 anchored to the lower fuse terminal by means of the stud 49, the circuit is completed from the terminal l9 through the strip 91, the fuse link and strain wire assembly, and the short length of copper tubing 49, to the terminal member 32. After the end of the strip 51, adjacent the opening 99, is secured to the stud 49, the tail end ll of the extension may be removed by cutting or severing it at the dot and dash line 62 in Figure 2, suitable openings 59 being provided to facilitate the cutting or removal of the tail extension 9|.

The fuse element assembly illustrated in Figures 5 and 6 is similar to that shown in Figures 2,

3 and 4, and like or similar parts are indicated by primed reference characters coresponding to the reference characters employed in connection with Figures 2, 3 and 4. This element, however, has looped terminals 99 and 99 made from stranded conducting cable. The loop 69 is of the casing 5, the loop 1 in the looped extenthe lower contact ferrule '12 as shown in Figure 7. The laterally extending arms and contact wires of this ferrule correspond with those described in connection with the upper ferrule of Figure ipand are designated by primed reference characters correspor "ling with the reference characters in Figure l.

A looped extension 16 oi. soft copper wire or other suitable material is secured at to the looped terminal 66, and this tall extension is adapted to be grasped for purposes of setting the fuse in the manner of the preceding embodiment, 15 and may be removed at 75 after the fuse is set.

With the spring El in retracted position, this tall extension extends down from the casing into position to be conveniently grasped.

The inner surface of the button H is inclined 20 or tapered at 16, and the inner surface of the button 61 is inclined or tapered at if. These inclined surfacesgive the spaces 13 and 19 wedgelike formation so that proper contact of the cable loop 65 with the button 61 and proper contact of the cable loop 10 with the button H is obtained by virtue of the wedging action of the cable loops and 10 in the spaces 18 and i9 and with the wedging or inclined surfaces 76 and ll of the respective buttons. The spring tension on the element by the spring corresponding with the spring 21, Figure 1, causes the cable loops to wedge under the buttons.

As before, the opposite ends of the cork 52' and tube 54, which is of water-proofed or gummed paper, fiber, or the like, fit over the terminals 80 and SI of the fuse element assembly and over the adjacent ends of the looped terminals 65 and '66, and the opposite ends of the cork 52' are compressed tightly upon these terminals and upon 49 the adjacent ends of the looped terminalsSE and 65 with the result that the terminals 80 and iii are bound rigidly together, and the fuse element and strain wire are held rigidly between the parts connected thereby and against free move- 5 ment between such parts. Crimping or twisting of the fuse element is-avoided and, as before, the fuse element assembly constituting a rigidunlt,

. with the difficulty of obtaining the desired original accuracy of the time current blowing char- 50 acteristicsand the difllculty of maintaining the desired original accuracy -of the time current blowing characteristics because of movement of the fuse link and strain wire between the parts connected being thereby avoided. The fuse wire 5i is of silver or other material, the oxide of which is a conductor, and is combined with a Chromel or other suitable strain wire 5i), and

both are completely enclosed and shielded from atmosphere, gases and moisture, and the avoid- 59 ance of flaking ofi, deterioration and reducing of the fuse element in cross-section where it is of a material, the oxide of which is non-conducting,

are also all avoided. The cork 52 or 52' which is held within the fiberor wrapper paper tube 55 as or 5% has an important utility upon blowing ofv the fuse in the formation of an arc. The cork when subjected to the action of the are readily evolves by destructive distillation a large amount of gas which assists in extinguishing the arc. 7 This evolution of gas from organic matter, particularly vegetable matter by the heat of the arc,

is now well recognized as a highly beneficial action in fuses of the air expulsion type, and my invention provides means for advantageously employing such action.

sion 66 is adapted to hook over a button ii on The fuse shown in Figures 9 to 14 inclusive comprises a casing in the form of a cylindrical tube formed of insulating material similar to that described in connection with Figure l. The ferrule 88, of cast bronze or other suitable or preferred material, fits over the upper end of the tube 85 and is rigidly secured thereto in any suitable or preferred manner. The ferrule 86 preferably has a round cylindrical outer surface or it may be slabbed along diametrically opposite sides or it may be provided with spring contact means, similar to the spring contact of Figure l, for cooperation with the upper contact clip (not shown). The upper end of the tube 85 may be reduced to seat the lower end of the ferrule 86 at 87.

The upper end of the ferrule 86 is threaded internally as indicated at 88 to receive a cap screw 90. This cap screw 90 has a hexagonal head 9| to facilitate threading the same upon and from the upper end of the ferrule. An upwardly extending axial stud 82 integral with the cap screw 90 is adapted for engagement with a suitable handle (not shown). The cap screw 90 closes the top of the tube 85 and its threaded engagement with the ferrule 86 provides simple and efflcient means for establishing both mechanical and electrical connection between the ferrule and the screw. The cap screw it also I has an integral axial boss 94 extending into the tube 85. .The boss 84 has a helical groove 96 for receiving the upper end of the spring 8% by threaded engagement therewith.

The boss 96 has, at its lower end, a socketed part 98 in which the upper end of a flexible braided conductor H0!) is rigidly secured. This braided conductor MB is made of copper or the like and its lower end is connected with.the lower terminal member 102 by rigidly securing it in the socketed part I 03 thereof. The lower terminal N12 has a helical groove I for threaded engagement with the lower end ofthe spring 96. The lower end of the terminal I02 has an integral axial threaded stud I05 which is threaded into a threaded socket M8 in the upper end of the upper terminal iill of the fuse element assembly. The upper end of this terminal I 01 has an outwardly extending'annular flange I08 upon which the lower end of the terminal Hi2 seats when the stud I05 is threaded into place in the socket I06.

The fuse element assembly comprises the upper terminal l0], which is formed preferably of copper or other suitable or preferred material, and

the lower fuse element assembly terminal lib,

formed of similar material. The terminals l8! and .l ill of the fuse element assembly are connected by a strain wire or tensile element M2 arranged to bear the mechanical strength. The upper end of this wire H2 is inserted in an axial opening H3 in the terminal I01 and is secured rigidly in place by punching at Hi the stock of the terminal ill? at the inner ends of the openings H5 into firm binding engagement with the wire 5 92. The lower end of the wire H2 is inserted in an axial opening lit in the terminal lid and is secured rigidly in place by punching at fit? the stock of the tel lit at the inner ends of the openings its into binding engagement with the wire H2.

The fuse wire are preferably is of pure silver,

and the strain wire i if preferably is of Chromel A wire. The upper end of the fuse wire M0 is inserted in anopening i2i in the terminal Ill? and ls'secured in place therein by punching at 822 the adjacent side of the terminal it! into firm engagement therewith. The lower end of the wire I20 is inserted in an opening I20 in the terminal H and is secured firmly in place therein by punching at I24 the adjacent sides of the terminal 0 into firm engagement therewith.

Intermediate its ends, the fuse wire I20 is coiled at I25 about the strain wire II2 and a refractory insulating tube I28 formed of glass or other suitable refractory insulating material, such as mica or the like, fits around the strain wire I I2 and within the coiled part of the fuse wire I20 to prevent contact between the fuse wire and the strain wire and to shield and isolate each from the other. The opposite ends of the tube I20 abut the adjacent ends of the terminals I01 and H0. As in the previous embodiment, while the fuse wire I is preferably of silver, as already described, it is to be understood that this wire or fuse element may be of any other suitable 20 fusible conducting material whose oxide is a conductor. The fuse element assembly terminals are preferably of copper or other suitable mate- I rials.

The fuse element I20 of silver, or other fusible conducting material whose oxide is a conductor,

and the comparatively high resistance strain wire II2, both, are completely enclosed and shielded from atmosphere, gases and moisture. by a tube ill of fiber or other insulating material, a surrounding cork I20 and an outer enclosing tube I00 of water-proofed paper, gummed paper or the like. The opposite .ends of the tube Ill fit telescopically over the reduced ends Ill and I00 of the terminals I01 and H0 of the fuse '35 element assembly. This tube I" offers no impairment to free separation of the terminals I01 and III upon blowing of the fuse, yet, at the same time, It is rigid throughout its length and has abutting engagement at its opposite ends 40 with the shoulders I42 and I on the terminals I01 and III which, with its fit over the reduced terminal ends I00 and I00, holds the terminals 1 I01 and III rigi ly together and against relative lateral movement such as otherwise might re- 45 sult in movement or even crimping or twisting of the fuse wire I20 and/or strain wire II2. As shown in Figure 15, the cork member I20 is made up of two half round corks having complementary depressions I00 adapted to receive and conforming to the outer periphery of the tube[ I25 and the outer peripheries of the ad jacent ends of the terminal members I01 and IIO.' 'The opposite ends of the sections of the corkmember iliextend lengthwise sumciently to embrace and fit over the adjacent ends of the terminal members I01 and III, and the two cork sections are held together and compressed relatively tightly about the tube ill and terminals I01 and H0 by forcing them into and enclosing them in the. relatively thin tube I20 which, as

already pointed but, may be of fiber, or may be a tube rolled from gum paper, 'or a cover wrapped tightly about the cork member I36. The tube I35 with the cork member I" and the outer'relatively thin enclosing tube I20 completely encloses and shields the fuse element assembly from atmosphere, gases and moisture, and holds the fuse element assembly rigid and against free lateral movement between the parts.

7 For the purpose of setting the fuse and hoiding the same set, the lower end of the terminal member H0 is provided with an extension I00 formed of stranded conducting cable or other suitable material, three strands of "Depth cable being employed in the illustrated embodiment,

although this may, of com-se, vary widely. The stranded cable Ill is looped through an eye I 02 in the lower end of the terminal H0 and is twisted at I02 aboutthe integral lower portion I of the terminal III. After the cable is looped through the eye I02, a wedge pin I05 is driven into the eye to bind the cable tightlyin place. The opposite ends may be soldered at I00. The lower free ends of the stranded cable I00 are spliced together by a short copper sleeve or ring I00 placed about the same and flattened tightly thereon. Within its length, the stranded conductor I00 is I10 for cooperation with a clip I12 to hold the fuse in set position.

The'bushing I10 has an axial passage I13 ntting-and soldered, or otherwise rigidly secured, upon the cable I00. A wedge pin I12 may be in- Serted or driven as a core between the strands of the cable I00 and into the opening I12 to bind additionally the bushing I10 in place on the cable. The clip I12 is secured to the lower end of the integral tongue I14 depending from the lower ferrule I10, which lower ferrule may be of cast bronze or other'suitable material and fits over the lower end of the tube 00 and is -rigidly secured thereto. The means for'securingthe clip I12 to the tongue I14 may bein the form of a screw I10 sunk at I10 to receive the head of the screw I10. The hooked sides I00 of the clip I12 define a vertical eye III provided with a front opening I02 and. tapered at the bottom at I02 to guide the conicalbushing I10 into place. The lower end of the casing 00 is reduced for shouldered engagement with the upper end of the ferrule I10 at I00, and the lower end of the ferrule I10 is flanged inwardly at I01 for cooperation with the lower end of the casing 00. The extension or stranded cable I00 may be flattened at I00 to facilitate passing'the same through the front opening I02 between the clip I12. -The extension or stranded cable Ill constitutes a tail extmsion which, when the spring" of the fuse casing 00 so that it may be ripped conveniently for setting the fuse and placing the spring 21 under tension. With the spring 00 retracted the setting of the fuse is accomplished by graspingthe tall extension I00 and pulling the same downwardly against the tension of the spring 00 until the conical bushing is positioned below or clear of the bottom of the clip I12.

The cable I00, above the bushing ticulariy the flattened portion I00, is then passed through the opening I02 between the hooked sides of the clip I12. Then upon releasing the tail extension I00. the spring. holds the conical bushing I10 up firmly against the hooked sides of the clip I12, and this cooperation 'of the bushing i 10 with these hooked sides of the clip holds the spring 96 extended and the fuse in set position. A circuit is thus established from the ferrule 00, cap screw 00, stranded conductor I00,v

terminals I02 and I01, fuse link and strain wire assembly I20 and H2, terminal IIO, stranded conductor 0, bushing I10 and clip I12, to the 7 lower ferrule I10. The tail extension I00, below the conical bushing I10 may be cut on or other- I wise removed after the fuse is set, as above described, but it is to be understood that this removalofapartorallofthetailextension for provided with a conical bushing hooked sides ill of the is retracted. extends down below the lower end I". nd W- setting the fuse anchoring the lower end of the fuse element assembly to the lower terminal on the fuse casing is not necessary within the scope of my present invention.

The longitudinal sectional showing of Figure 17 is on a reduced scale and more or le diagrammatic to show in a single view the device illustrated in Figures 9, l0 and 11. This shows the use of the-fuse element assembly in a spring expulsion'fuse. The reference characters are-thesameas in Figures 9 through lfip One end of the fuse elementassembly is detachably secured to the spring system of the fuse. The

flexible tail extension is adapted for setting the.

fuse, and the collar or abutment-means thereon anchors the other end of then-fuse element assembly. Inthistype of fuse the cork enclosurev I38 closes iup the tube Bftoward its open end and increases the 'expulsive efiect. The fuse shown in Figures 18, 19 and 20, is an ordinary air type expulsion fuse, the particular tube and ferrule arrangement being oi the Gen:

' eral Electric type. The insulating tube 2% has themetalferrule 2M threaded upon its upper end; The ferrule 2M has the square part 292 and the reduced tubular extension 268, the lower part of the cylindrical outer surface of which is threaded at 265 forthreadedengagement with a metal capilibwhichclose's the top of the tube 2%. The top of the cap 2% is, closed at res and the cylindricaiouter surface of the cap is knurled or roughened at 201. r At diametrically opposite sides of the inner peripheryof the tubular extension 203 are longitudinal grooves 2bd'whlch open into the bore and extend down no the topfoi the extension 203. I p V The lower metal ferrule 2 i0 is secured upon the tube 208 by a screwiill. This terrule kid has the cylindrical part 282 at the top of which is the part M3 with the square outersrn-iace and at the bottom'of which is the threaded part 225 i.

Integral. withthe ferrule 29d and depending below the threaded part 2M is an extension 2 i 5, the outer surface of which is'of conical form and knurled or roughened at 2 it. The threaded part 2 M has notches 2 ill opening longitudinally there through at diametrically opposite sides, and a clamping ring 2,1 8 threaded removably upon the v 1 threaded part 255 has the knurled or roughened periphery 2i 9 and the reduced extension 2%, the bore 22i ofv which is of conical form conforming generally with but somewhat larger than the knurled conicalpart 2 l5 ofrthe ferrule The fuse element assembly in this case is the same as the fuse element assembly of the embodiment of Figures 9 through 17 except that the surrounding enclosure consisting of the cork enclosure -i36 and the surrounding tube is slipped on the element assembly The reference 6 0 assembly are thesame as in" the embodiment of vFigures Qthrough 17; With the cap 2 6% removed, this assembly is introduced through the top of the upper ferrule 20! into the position shown in 5 Figure 18. The flange 188 of the, upper fuse link terminal m seats upon the top of the reassembly.

characters applied to the various parts of this I the notches 2H. The sleeve or ring I68 may be removed from the tail extension I if desired. The ring M8 is then telescoped or passed up over the lower end of the tube 200 and is threaded into place upon the lower ferrule 'as shown. As it is threaded upwardly into place its conical bore 22l engages and eifectively clamps the tail extension H5 upon the knurled conical periphery 2 [6,01 the extension 2i 5. ,The cooperation of the bonical bore- 22! with Lthe ,knurle'd' surface 2I6 "has a clamping action ofLwedge-lik'e character upon the tail extension lfillto'anchor'the seine securely to the lower terminal, IInfthis'case; thef'g'ener ally conical bushing ill] on the tail extension I" acts as aplug within the tube 2illltendingjto'close ,the tube to increase the expulsive' effect. This assists in the expulsion or the flexible cable where the fuse: element assembly is used in this type of fuse." Itisapparent, of course, thatjin of fuse there is no spring system within the fuse,

and the upper terminal I01 of the fuse link assembly, insteadof being connected .to the. spring system as ,in the previous embodlmentlserves to anchor directly the upper end ofitheelement The present invention is] capable'of a wide range of modifications and] is adapted forfl'a wide range of uses, and Ido notintendptherfore to be limited to? the particular fde'taus n particular use or manner. of sho' scribed. air expulsion fuse, an enclosedfuse elementassembly having a fuse element, a strain wire inparallel with the fuse element and, a rigid sleeve of insulation out of contact'withthe fuse element to prevent fiexingof the fuse' element.

2. In an air expulsion fuse, asilver' fus'linh' a comparatively highjresistance strain element, and means enclosing ,andfcovering both said fuse link and said strain element against contaminating and corrosive agentsgsaid meansfalso preventing bendingfof Saidjf element andj'said mile and being out of contact withthefsame';

3. in an air expulsion fuse, afus'e-link assembly comprising a pair of fuse link. terminals, a silver fuselink and a comparatively high'reslstance strain element connected between said-terminals, and a rigid insulating'tube surrounding and enclosing said fuse link and said strain element andcoop'erating with said fuse link terminals to hold same rigidly in position and limiting the access of atmospheric gases tosald link.

, .4. In a fuse link assembly, a pai'r offfuse-link betwe'enwhich an arc is adapted to be lawn, a "fuse link connected betwee'n said terminalsra strain element'connected between said tenals, a fibrous insulatingitube', surrounding and enclosing said-fuse} llnkifand lsaid strain element and cooperating with the fuse link 'terminals to hold some ri idly in position, means within said tubefor insulating the fuselink from'the n element, a light insulating enclosure surrounding and enclosing said tube and the adjacent ends of .theiuse link terminals, and a covering enclosing said last enclosure.

5. In a fuse .link assembly a pair 01 fuse link erra. between which an arc is adapted to be drawn, a fuse link connected between said ternals, an insulating tube surrounding and enclosing saidfuse link and said strain element and cooperating with said fuse link terminals to hold some rigidly in position, and insulating a strain element connected between said ing and fastened to'the lower terminal on the A means within said tube for separating the link from said strain element.

6. In a fuse link assembly a pair of fuse link terminals betweenwhich an arc is adapted to be drawn, a fuse link connected between said terminals, a strain element connected between said terminals, an insulating tube surrounding and enclosing said fuse link and said strain element andcooperating with said fuse linkterminals fuse to hold some rigidly in position, insulating, means within said tube for separating the fuse link from said strain element, and a tail extension on one.

of-said fuse link te'rminaisand-a contact terminal carriedon said tail oxtension'intermediate isits end. 7 7. Ida fuse link assembly apair of fuse link terminals between which an arc is adapted to'be drawn, a fuse link connected between .said'ter- I minals, a strain element connected between said no terminals, an insulating tube surrounding; and enclosing said fuse link and saidstrain element and cooperating with said fuse link terminals to hold same rigidly in position, insulating means within said tube for separating the fuse link from said strain element, a tail extension on of said fuse link terminals, saidtail extension comprising a stranded conductor, and anchoring means on said stranded conductor for anchoring saidtail extension to'an electrical terminal. l 8. In a fuse device, a fiber tube, a fusible link within said tube, a cork enclosuresurrounding said tube, and a relatively thin paper cover enclosing said cork-enclosure.v 7

9. In a fuse device, a fiber tube, a fusible link 85'within said tube, a sectionalized cork enclosure surrounding said tube, and a relatively thinpaper cover surrounding said cork enclosure and holding the cork enclosure compressed and the sections thereof together. i

10. In a fuse device, a fiber tube, a strain element within said tube, a refractory insulating sleeve surrounding said strain element, a fusible link disposed within said tube and coiled about said sleeve, a cork enclosure surrounding said 4,5 tube and a relatively thin paper cover enclosing saidcork enclosure. 3 g 7,

11. In a fuse device, a pair of fuse terminals between which an arc is adapted to be formed, a fusible link connected between said terminals, 5. a strain element connected between said terminals, a fiber tube surrounding and enclosing said fusible link and said strain element and telescopically engaged at opposite ends with saidtermmals, means within said tube for insulating said 55 fusible link from said strain element, a cork enclosure surroundins said tube and flttingat' opposits ends over said terminals, and a thin insulating tube enclosing said cork enclosure. l 12. In combination, a tubular casing, anupp'er to terminal onsaid casing, a lower terminal onsaid casing, a fuse link assembly adaptedfor disposition within said casing and comprising an terminal'adapted to be .anchored to-theluppei' terminal on the casing and slower torin'inaha fusible link connected between-the ""0:

said fuse link assembm a strain'ele'mentconnected between the of'said fuselink aaembly, an insulating sleeve surroundin'g iand enclosing said fusible link and said strainelement and cooperating with the terminalsof the fuse link assembly to hold the same rigidly in position, and a tail extension on the lowertermi- V nal of the fuse link assembly and extending down 75 through and bent around the bottom of the cascasing.

13. In combination, a tubular casing, an upper, terminal on said casing, a lower terminal on said casing, a fuse link assembly adapted for disposition within said casing and comprising an upper terminal adapted to be anchored to the upper terminal on the casing and-a lower terminal, a fusible link connected between 'the'termi'nals of said fuse link assembly, a strain element connectedbetween the terminals of said fuse link assembly, an insulating sleeve surrounding and enclosing said fusible link and said strain element and I cooperating with'the terminalsof the fuse link assembly to'hold the same rigidly in position,'and

'a tailextension extending from the lower termi nal 0f the fuse link assembly and'adapted to be fastened to the lower terminal on the casing. 14.. In combination, a tubular casing-an upper terminal on .said casing, alower terminal on said casing, a fuse link assembly adaptedfor dispositioniwithin said casing and adapted to be an- "chored at its upper end to the upper "terminal on v the casing,: a clip on na rower-mammal on the casinggatall extensionon lower'terminal of the fuse link assembly and adapted to be placed 'saidclip,"and-'"an mchoring element on said tail extension and adapted'to cooperate with said clip tosanchor said extension to thelower terminal-on the-casing when said extension is placed in said clips '1 v 15; In combination, a tubular casing, an upper "i terminal-on said casing, alower'terminal on said -casing, a fuse link fordlsposi- .tion within said casing and comprising an upper terminaladapted to beanchored to the upper terminal on the casing and a lower terminalfa fusiblelink terminals of said fuse. link: assenfiiy, a strain eiementconnected between the terminals of thefuse-link assembly, a-fibrous-insuhting tubesurroundin'g and enclosing said fusible linkand said strain aleme'nt,' refractory insulating material disposedwithin said tube and insulating thefmible link from the strain element, ia' lia ht porous insulating enclosure surroundingandenclosing said tube and the adjacent endsiof'fthe terminais of the fuse link ..-assembly; ran tube surrounding.

said last enclosure,}and a.tail extenlon extend- "ingifromthe loner terminal-' ofthefuselink assembly and adapted to be to the-lower 16. In combination; a tiiular casing, an upper onsaid casing; a" lower terminal-en said a fuse. link aamblyiadapted for disposition within said casing and comprising an upper vterminal adapted to: bO 'lllOhOl'Qdi-O the upper terminal on thecasing and a loam-terminals "fusible link connected-between the terminals of .the fuse linkassembly and formed of material -whose'oxideis aconduotor, s'relatively'high renuance-strum element connected between the terminals of -fuse link-assembly, a fibrous insulating tube and enclosing said fusible link and said strain element and cooperat- Jing withthe-terminal's of'the fuse link assembly :tohold the-same rigidlyin posltion, a refractory insulating sleeve surrounding said strain element and insulating-it from the fusible link, a cork enclosure surrounding and enclosing said fibrousinsulating tube and the adiacent ends of the terminals ofthe fuse link' assembly, a paper covering surrounding and enclosing said cork enclosure, and a tail extension extending from the lower terminal of the fuse link assembly and adapted to be fastened to the lower terminal 'on- .ia nci 17. A fuse element comprising a strain element 'rinytheriormiota clo ed lq pre fu eelemen s ledsand ispo d wit in said qo .e.nd an insula -ins enc osu e.a cun i hefu e e e en e i /er :po d ;between it and; the strain elemen v 8;- Ai-Iuse elemen ;c p is svavstm elemen .z nil he;lO I tOZB-E O QG 913;;31 le tfoldio' ediandadisp sed ,with nr sa d 1. op,- n, n a in euclosuresround. the; s me ten in e p ed netweeinit". a d hei r n el me t. en: a e t s conduct n ube.:.su 0 nd nszone nd v the astr ine emen an jthe adj t en -0 th fuse inclement; and flattened ther qn, aiconducting tube -surmun ins theio here n e strain em he adjacent end of the fuse element and flattene thv eQn;.- ndva n .1 e. e rm saidlas be; 1

insertionteaming a strain assemeri svrmi m sed op. e use l me f d fand dismsedwithin saidloop, 'an insulating. en-

closure-around the fuse element and interposed ,between it, and the strain element, a pair of half ro un d corkssurrounding said fuse and strain element-ands wa e -m w d pap t ine a ound and strain elements.

, v 21. In combination, a fuse element vassembly jconsisting-ofrasilver fuse wire'paralleledb'y a 40f'nickel chromium alloy strain wire, a rlgldenclosure surrounding said wires and a secondary enclosure surrounding said first enclosure for use .with said assemblyinione type of expulsion fuse, z-said secondary enclosure being adapted to be ;,slipped: oflisaid element assembly for use of said assembly inanother type of iuse. a a 7' a 22. In combination, a pair of fuse link terminals between which anarc-is adapted to be drawn,

A a. fuse-link connected between said terminals, a strain element connected between said terminals, an insulating enclosure surrounding said fuse link and said strain element, a flexible stranded wire tail extension on one-ofsaid fuse link terminals, "andpmeans'on the other fuse link terminal for anchoring one end of said fuse link assembly and means-for holding said stranded wire extension, said means having a wedging contact engagement energized by tension on the stranded wire. 23. In combination, a pair of fuse link terminals Lbetweenwhich an arc is adapted to be drawn, a lfuse link connected. between said terminals, a strain element connectedbetween said terminals, fan insulating enclosure surrounding said fuse link andsaid strain element, a flexible tail extension sfi'on-ione'of said fuse link-terminals, and an abut- -menton said flexible tail extension, v

' -24.; In combination, a pair of fuse link terminals between which an arc is adapted to be; drawn, a fuse: link connected between said, terminals, 9.

strain element connected between said terminals, an insulating enclosure surrounding said fuselink and said strain element, and a flanged head on one of said fuse link terminals for anchoring one .end of said fuse link assembly in an ordinary air expulsionv fuse. said head having an axial socket 'con ti itnl id'en s dsiand sh e n ille e aenvelopeembracing said terminalsiand said en- S f ib e ;m m ers..-a dan aii s nesls e relefil 'sm m ln -eevec t i e qs nss id? fe b in u po s n t w ht am a d h in its ends substantiallyclosed bysaid ,terminals at terminals, a tension sustaining connectionQ be.-

ifor e ilns a d e m na s ie ee i selly each other, and astiif insulating sleeve oflsrnall 'necting element and forming, a strut endwise be:

enclosed in the" other of Said l'conn'ectiattachment is suture; stationary-"terminal; pair of 'conce'ntricsleeves of dnsulation disposed threaded for detachable connection to the spring velope at least one of said terminals being,- freely/ {retractible from saidenvelope'upon melting of class descr edjfltermi least ne o mi m naltmem r e e ns' freely retractible iromsaid sleeve-uponnielting of v fuse- Q52: 1 -':1:. w a 28. In a fuse pi -the class described a pair of tween said terminals andadapted-to resist separa tion of said terminals a fusible link of greater length than the I distance v-between-said terminals aid connection and said linkbeingout of cont t with 35 internal diameter-enclosing said link and ,con-:

tween saidterminalsm 29. In'aAuse-ohthes as d scr aib substantially rigid terminais having;-eacha;p r as oL longitudinal i bores extending from their. end

l a stra n: wi aha ns i zen s di n ediin and gri'pp dby: one artic e-b es ea h t m nal. aifusible. wire; havin itswa nds d p sedii and ipped by the, other oil-the boresofe ch terminal,

'andconnectingjsaidterminalsirandf other of which has a 'f flexible stranded 'le in axial alignment between' athe ends a of =said terminalsm strain wirewlthirf'one oi'ithesleeves,

and a fuse wire' withinrthemtlrer o1'-.said'sl,eeves, I

, 5 and arigid tube-of insulation embracing the ends J n ni one of said sleeves and strain wire holding said terminals in spaced alignment.

33. In a fuse of the class described, a fuse sleeve having permanent terminals for the at- 5 tachment of a replaceable fuse link, a spring for tensloning the link, a replaceable fuse link comprising two terminal portions connected by a fusible conductor and a flexible stranded wire conductor in series, one of said permanent l terminals and said last mentioned terminal portion having self-tightening wedging engagement under the action of the spring.

34. In a fuse of the class described, a fuse sleeve having permanent terminals for the at- 16 tachment of a replaceable fuse link, a spring for tensioning the link, a replaceable fuse link comprising two terminal portions connected by a fusible conductor and a flexible stranded wire conductor in series, said flexible stranded con 20 ductor having a portion extending beyond the adjacent terminal portion, one of said permanent terminals and said last mentioned terminal portiori having self-tightening wedging engagement under the action of the spring.

25 35. In combination, a sleeve, a fusible link in the sleeve, a spring in the sleeve for tensioning the link, said link comprising a fusible portion and a flexible stranded wire lead provided with a contact portion, and said sleeve having a sta- 30 tionary terminal engageable with the contact portion of said lead to provide a wedging contact engagement which is self-tightening under the action of said spring. I

36. In combination, a fuse sleeve having permanent terminals for a renewable fuse link, a renewable link comprising a fusible portion and a flexible stranded lead provided with a terminal portion, a spring for tensioning said link.

said terminal portion and one of said perma- 0 nent terminals having a wedging engagement is improved 37-1n n n, a fuse sleeve having providing electrical contact which by the action of the spring.

permanent terminal which is movable, a perma- 5 nent hooked terminal which is stationary, a spring for the movable terminal, and a fuse link having a fusible portion and a pliant loop for hooking over and being tensioned by said spring upon said hooked terminal said hooked terminal providing a V-shaped .wedging portion for receiving said pliant loop.

38. In combination, a fuse sleeve having a permanent button-like terminal which is movable, a permanent button-like terminal which is 55 stationary, a spring for said movable terminal, and a fuse link having a fusible portion and looped pliant ends for buttoning upon said button-like terminals, said spring holding said pliant loops in good contact with said terminals.

0 39. A fuse link comprising a fusible portion including a fusible wire and a strain wire for relieving the fusible wire of tension and pliant stranded wire loops forming terminals for said fusible portion. a

'5 40. In a fuse link, a pair of terminals, a silver fuse wire connecting said terminals, a small tubular enclosure for the silver fuse wire for shielding it from atmosphere, said enclosure being capable of withstanding a relatively high 70 temperature and being out of contact with said wire anda high tensile strength connection for resisting tension between said terminals, said connection being symmetrically disposed to avoid cocking of the terminals.

strain wire adapted to stand normally under spring tension, a fuse wire, a surrounding tubular insulating member, and means to prevent the fuse wire from contacting the strain wire or insulating member.

42. A refill for an expulsion fuse, a pair of terminals, a metallic tension resisting member constituting' an electrical connection between said terminals adapted to stand normally under tension, and a compression resisting member of insulation surrounding the tension resisting mernbet and being disposed in engagement with at least one of the terminals, the other of said pair of terminals being capable of withdrawal freely from said member of insulation upon melting of the tension resisting element.

43. In a fuse link for an air expulsion type fuse a pair of terminals, a sleeve of, insulation supported on and surrounding the terminalaa fusible link connecting the terminals, and means between the link and the sleeve to protect said sleeve from injury by the heat of the link at least one of said pair of terminals being capable of withdrawal freely from said sleeve upon melting of the fusible link.

44. In a fuse link for an air expulsion type fuse, a pair of substantially cylindrical terminals, a rigid tubular sleeve of insulation telescopically supported on and centered by at least one of said terminals, 9. strain wire and'a link connecting said terminals and being disposed in concentric relation out of contact with each other within the sleeve.

45. In a fuse link for an air expulsion type fuse,

1 apair of terminals, a fuse link, and a strain wire disposed out of contact with each other, a tubular sleeve supported telescopically with at least one of said terminals and being out of contact with the fuse link, means for connecting one terminal to-a cooperating conductor, and a flexible lead extending from the other terminal.

46. In a fuse link for an air expulsion type fuse, a pairof terminals, a fuse link, and a strain wire disposed out of contact with each other, a tubular sleeve supported telescopically with at least one of said terminals and being out of contact with the fuse link, means for connecting one terminal to a cooperating conductor, a flexible lead extending from the other terminal, and spring means for tensioning the strain wire.

47. In a fuse link for an air expulsion type fuse, a pair of terminals, a fuse link, and a strain wire disposed out of contact with each other, a tu- .bular sleeve supported telescopically with at least one of said terminals, means for connecting one terminal to a cooperating conductor, and a flexible lead extending from the other terminal, said connecting means having a longitudinally threaded end portion.

48. In an air expulsion fuse, an enclosed fuse element assembly having a fuse element, a protective sleeve of insulation to limit the access of atmospheric gases, and means between said element and said sleeve to protect said sleeve of insulation from deterioration.

49. In an air expulsion fuse, an enclosed fuse element assembly having a silver fuse element and a high tensile strength strain wire, a surrounding tubular sleeve of insulation, and means between said element and said sleeve to protect said sleeve of insulation from deterioration by the heat of the element at its working temperature.

50. In an air expulsion fuse, a pair of termi- 75 41. A refill for an expulsion fuse comprising a nals, a fusible link connecting said terminals, a

51. In an air expulsion fuse, a pair of terminals, a fusible link connecting said terminals, 9; strain link connecting said terminals, and a rigid 10 sleeve of insulation centered on said terminals to hold the terminals substantially in alignment i and to prevent injury to said links.

52; In a fuse device, the combination of a tube of insulation adapted to be closed at one end, a terminal member at said end, the other end of the tube permitting the escape of gases when the fusible portion blows, a conductor extending through the tube, one end of the conductor being joined to the terminal member, said conductor having a pair of substantially rigid infusible terminals joined by a fusible portion comprising a fusible element and a tension element in parallel between said infusible terminals. said fusible portion being disposed within the tube and adapted to be melted upon excessive current flow through the conductor, said tension element being adapted to stand normally under spring tension, and a spring connected to the conductor at one side of the fusible portion for extending the gap made by fusing of the fusible portion, the reaction of the spring being supported on said first named terminal member and upon the second end of the tube, said conductor having a fiexible stranded wire portion extending outside the tube for connection with a second terminal remote from the second end.

i 53. In a fuse device, the combination of a tube of insulation adapted to be closed; at one end, a terminal member at said end, the other end of the tube permitting the escape of gases when the fusible portion blows, a conductor extending in the tube and adapted to be melted upon excessive current flow through the conductor, said tension element being adapted to stand normally under spring tension, a spring connected to the conductor at one side of the fusible portion for extendingthe gap made by fusing of the fusible portion, the reaction of the spring being supported on said first named terminal member and upon the second end of the tube, said conductor having a flexible stranded wire portion extending outside the tube for connection with a second terminal remote from the second end, and a tubular organic insulating sleeve embracing but being out of contact with the fusible element.

54. In a fuse device, the combination of a tube of insulation adapted to be closed at one end, a terminal member at said end, the other end of the tube permitting the escape of gases when the fusible portion blows, a conductor extending through the tube, one end of the conductor being joined to the terminal member, said conductor having a pair of substantially rigid infusible terminals joined by a fusible portion comprising a fusible element and a tension element in parallel between said infusible terminals, said fusible portion being disposed within the tube and adapted to be melted upon excessive current fiow through the conductor, said tension element being adapted to stand normally under spring tension, a spring connected to the conductor at one side of the fusible portion for extending the gap made by fusing of the fusible portion, the reaction of the spring being supported on said first named terminal member and upon the second end of the tube, said conductor having a flexible stranded wire portion extending outside the tube for connection with a second terminal remote from the second .end, and a fiber tube closely embracing but being out of contact with the fusible element.

55; In a fuse device, the combination of a tube of insulation adapted to be closed at one end, a terminal member at said end, the other end of the tube permitting the escape of gases when the fusible portion blows, a conductor extending through the tube, one end of the conductor being joined to the terminal member, said conductor having a fusible portion comprising a fusible element and a tension element in parallel disposed within the tube and adapted to be melted upon excessive current flow through the conductor, said tension element being adapted to stand normally under spring tension, a spring connected to the conductor at one side of the fusible portion for extending the gap made by fusing of the fusible portion, the reaction of the spring being supported on said terminal and upon the second end of the tube, a second terminal associated with but spaced from the second end of the tube, said conductor having a flexible stranded wire portion extending outside the tube for connection with said second terminal, and a wedging contact between said second terminal and said flexible wire portion, which wedging contact is improved by the force of the spring.

56. A fuse link comprising a pair of substantially rigid terminals, a fusible conductor and a strain wire secured to and extending between said terminals, insulating means engaging said terminals and holding them substantially in alinement to protect the fusible conductor and strain wire against injury by flexure, said means lying out of contact with said fusible conductor and strain wire.

57. The combination with claim 56 of conductors joined to said terminals for extending the circuit thereof, one of said last named conductors being a flexible lead, the terminal to which said flexible lead is connected being free to separate from said insulating means by motion endwise thereof upon melting of the fusible conductor and said strain wire.

58. A fuse link comprising a pair of substantially rigid terminals, a fusible conductor of relatively high melting point joining said terminals, an insulating sleeve engaging said terminals and holding them substantially in alinement to protect the fusible conductor against injury by flexure, said insulating sleeve comprising insulation of vegetable origin which would tend to be charred by the working temperature of the fusible conductor, said sleeve being out of thermal contact with said fusible conductor and at least one of said terminals being freely movable endwise out of engagement with said sleeve upon melting of said conductor.

tact with said sleeve, and a flexible stranded lead extending from one of said terminals, said one of the terminals being free to be expelled from the sleeve.

60. A fuse link comprising a pair of terminals, fusible conducting means connected between said terminals, a tubular insulating sleeve consisting chiefly of material of vegetable origin surrounding the fusible conducting means loosel0 ly and telescoping with said terminals, one of said terminals being free to move out of the adjacent end of the sleeve upon melting of the fusible conducting means, and a flexible stranded conductor connected to said one terminal for extending the circuit thereof.

61. In a fuse link having detachable terminal portions, one of which is a flexible stranded lead,

- a pair of relatively heavy and relatively infusible fuse terminals carried between said detachable terminal portions, a fusible section connecting the fuse terminals, said section comprising a strain element and a fusible element connected in parallel between said fuse terminals and a tubular insulating member surrounding the adjacent ends of the fuse terminals to give the fusible section mechanical support against bending.

62. A fuse link for use as a.replacement in a reusable fuse tube comprising the combination of a pair of terminals which are relatively heavy and infusible, the first one of said terminals having a coupling by which the link is supportable in the reusable fuse tube, the second one of said 3 terminals having a flexible lead connected to it adapted to be anchored outside the bore of the reusable fuse tube, said flexible lead permitting the second fuse terminal to be expelled from the reusable fuse tube upon the occurrence of a heavy current are between the fuse terminals, a fusible element electrically connected between the fuse terminals, a stress sustaining element connecting said fuse terminals whereby in the event tha the fuse link is subjected to tension the fusible element will be relieved of tension, and an insulating pressure resisting tube telescoped with said fuse terminals, said tube trapping sufflcient pressure between said fuse terminals upon the blowing of the fusible element and stress sustaining element to; produce an expulsion effect upon said second terminal sufficient to drive it out of said pressure resisting tube.

63. The fuse link of claim 62 wherein the 55 pressure resisting tube has means for securing a substantially gas tight seal with at least one of said fuse terminals.

64. A replaceable fuse link for breaking circuit in air comprising cylindrical fuse terminals of relatively large diameter, a stress sustaining wire of small diameter connecting said terminals and disposed substantially coaxially of the terminals, a fusible element of relatively small diameter wire disposed in a helical coil of relatively large diameter substantially coaxially about said stress sustaining wire and connecting said terminals, a flexible lead wire attached at its inner end to one of the fuse terminals and having its opposite end free for making a desired connection at any intermediate point, and a sleeve of insulation carried by said link, said sleeve being telescopically disposed with respect to said fuse terand extending therefrom, which flexible'lead is minals and enclosing but lying out of contact with said helically coiled fusible wire.

65. For use with a pair of spring separated mounting terminals, a renewable link comprising a pair of fuss terminals, a fusible element connecting said terminals, a tube of insulation telescoped with said terminals and carried by said link, at least one of said terminals being freely movable out of said tube, said terminals having flexible extensions terminating in anchoring members, and a rigid loop connected to one of said extensions for facilitating the mounting of said link upon said mounting terminals.

66. In a fuse, a pair of fuse terminals, a fusible element connected between said terminals, spring means tending to separate said terminals, a strain element also interconnecting said terminals for relieving said fusible element of the stress imposed by said spring, and a fiber tube surrounding said fusible and strain elements and being telescoped with said terminals and supported upon at least one of them, said tube having a lining being exposed to an arc in extinguishing the arc.

67. In a fuse, a pair of fuse terminals, 9. fusible element connected between said terminals, a tube of waterproofed insulation surrounding said fusible element and being telescoped with said terminals and supported out of contact with said fusible element, the ends of said tube being closed and said tube having a lining of a material which upon being exposed to the are formed between said terminals on blowing of said fusible element evolves a gaseous medium which assists in extinguishing it.

68. A fuse link comprising a pair of fuse terminals, a fusible element and a strain element interconnecting said terminals, a tube of waterproofed insulation surrounding said fusible and strain elements and said fuse terminals, flexible leads connected to said terminals and extending out of the ends of said tube, said tube being supported out of contact with said fusible and strain elements, and a lining in said tube formed of a material which evolves a gaseous medium on being exposed to the arc formed between said terminals on blowing of said fusible and strain elements for assisting in extinguishing it.

69. A fuse link comprising a pair of terminals having shoulder portions facing each other, a flexible conductor connected to one of said terminals, fusible means interconnecting said terminals, and a fiber tube surrounding said fusible means and spaced therefrom and interfltting with said shoulders.

70. In a fuse link, in combination, a fusible element,

adapted to prevent separation thereof by fric-- tional engagement therewith.

ALLAN RAMSEY.

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