US1834578A - Fuse device - Google Patents

Description

N, J. CONRAD Dec. 1, i931.

FUSE DEVICE Filed May 25, 1925 2 Sheets-Sheet 1 Dec. 1, 1931. N J CONRAD 1,834,578

FUSE DEVICE Filed May 25, 1925 2 sheets-sheet 2 l foe 50 720 434e Patented Dee. 1, 1931 l UNITED STATES PATENT OFFICE NICHOLAS J. OONRAD, or WILII'ETTE, ILLINOIS, AssIGNon, BY IIESNE A'ssIGNImNTs, To scnwnrrzna a CONRAD, INC., or CHICAGO, ILLINOIS, A CORPORATION or mma- WARE Application led May 25,

This invention relates to improvements in fuse devices and the like, and is a continuation in part of my prior application, Serial No. 631,263, filed April 1l, 1923, wl,1ich matured into Patent N o. 1,743,322, issued J anuary 14, 1930. l

While it is to be understood that the present invention is not limited to a particular form of device, it relates more especially to fuse devices generally of the Schweitzer and Conrad type such as disclosed, for example, in Schweitzer and Conrad Patent No. 1,135,- 548, granted April 13, 1915.

In the present invention, I provide novel anti-vibration Spacer and vibration damping means for the movable fuse terminal means and for the means for retracting or 'drawing said terminal means to open position.

The present invention further provides a' novel fuse element for mechanically holding the movable terminal means set and which may be rated to break the circuit at the desired point, novel means for assuring the rupture of the mechanical connection when the fuse blows, a novel mounting for the liquid director and novel means 'for attaching the ends of the opening spring to the terminals of the fuse. v f

In Order to acquaint those Skilled in the art with the-manner of constructing and practicing my invention, I shall'now describe, in connections with the accompanying drawings, certain speciic embodiments of the invention.

Fig. 1 is a transverse section through a fuse device embodying my invention, taken on the line 1-1 of Fig. 2;

Fig. 2 is a longitudinal section taken on the line 2,-2 of Fig. 1;

Fig. 3 is a transverse section taken on the line 3-3 of Fig. 2;

Ffg. 4 is a transverse section taken on the line 4-4 of Fig. 2;

Fig 5 is an enlarged fragmentary detail section taken on the line 5-5 of Fig. 1; d

Fig.\6 is a fragmentary elevational vview partially in section of the fuse element;

-Fig. 7 is a longitudinal section showing a moditied arrangement of the'fuse element;

FUSE DEVIUE 1925.y serial Ne. 32,740.

Fig. 8 is a transverse section taken on the line 8 8 of Fig. 7;

Fig. 9 is a longitudinal section through a modication Fig. 10 is a fragmentary longitudinal section through the fuse of Fig. 9 after blowing;

Fig. 11 is a top plan view of the fusev shown in Figs. 9 and 10 with the vent cap removed;

Fig. 12 is a transverse section taken on the line 12-12 of Fig. 9;

Fig. 13 is a longitudinal section through the upper arcing terminal taken on the line 134-13 of Fig. 9; and

Fig. 14 is a side elevational view partially in section-of the lower terminal' member.

The fuse illustrated in Figs. 1 to 6 comprises a hollow Sleeve or tube 5 of insulating material. It may be cylindrical in form and of glass, as shown, or its form may be Otherwise as desired and it may be formed of .any

other suitable or preferred insulating mate# rial, such as for example, with bakelite.

A base 6 is secured 'upon the bottom of the tube 5 and secured upon the upBer or opposite end of the tube 5 is a ferrule 8. The

fiber impregnated base 6 and ferrule 8 are of metal, or othersuitable conducting material, and they form the fuse terminals and areconnected or disconnected by the conducting parts within the tube 5. The base 6 and ferrule 8 may be secured upon the tube 5 in the manner and by means of the sealing means disclosed inf my hereinbefore referred to co-pending application, now Pat. No. r`1,743,322, or otherwise. The means there disclosed is in the nature of a non-drying cement which will not harden or become brittle and it forms proper seals 10 between the tube 5 and base 6 at one end and between the tube 5 and ferrule 8- at the other end.

The lower end of the base 6 is closed at 12 and it may have a tapered shoulder 13 for centering the tube 5 in the base 6 and providing minimum engagement between the lower end of the tube 5 and the base 6.` A boss 14 projects upwardly from the center of the closed end or bottom 12 and is bored and internally threaded to receive the threaded end15 of the lower terminal member 16. The terminal member 16 is secured upon the lower end of the flexible stranded conductor or cable 17, which conductor or cable extends longitudinally through the tube 5 and is connected mechanically and electrically at its opposite or upper end tothe upper arcing terminal 25.

The terminal member 16 comprises a stud member or post, the lower end of which is threaded into the boss 14 and above the boss the shank of this post is secured in a collar 18 as by means of a screw 20. Above the collar 18 the post is socketed as shown. The threads at the lower end may be suiiciently larger than the portion of the post lying within the collar 18 to additionally retain the terminal member against displacement through the collar in one direction and the flaring or enlargement of the upper socketed end may additionally retain the post against displacement through the collar in the opposite direction.

The lower end of the stranded conductor 17 is inserted in the upper socketed or boredout end of the terminal member 16 and union between the lower end of the strand and said terminal member may be produced by crushing or pressing the wall of the socketed portion of the terminal member inwardly at opposite sides to compress them upon the fibers of the stranded conductor and firmly and securely grip the conductor in the terminal member. A simple, eective and inexpensive mechanical and electrical connection is thereby produced. The flat faces formed in the terminal member 16 thereby permit engagement by a suitable tool for screwing the lower end of the terminal member into and out of the boss 14, as more clearly shown in the embodiment illustrated in Figs. 9 to 14.l At the same time, the swedging or crushing out of the upper end of the terminal member 16 forms the enlarged upper portion or retention shoulders for preventing displacement of the terminal member through the collar 18 in the opposite direction.

The upper end of the conductor 17 is secured in a movable or arcing terminal 25. vThe terminal member 25 comprises a stem or post, the lower end of which may be bored out or socketed and crushed upon-the upper inserted end of the conductor 17 to form a good mechanical and electrical connection therebetween, as described in connection with the lower terminal member 16. The upward- 1y extending shank of the terminal member 25 projects through a collar -26 mounted thereon and secured against longitudinal movement and rotation relative thereto as by means of a suitable screw 28. In addition, the crushing of the lower socketed end of the terminal member 25 enlarges the same and L additionally prevents displacement in one direction through the collar. Above the collar 26 the terminal member 25 may be enlarged or shouldered, if desired. v

Connected between the lower relatively stationary terminal member 16 and the upper movable or arcing terminal member 25, for the purpose of retractin'g or drawing said arcing terminal member 25 to open position when the use blows, is a coil tension spring 30. The coil spring 3() is wound helically about the stranded conductor 17. The lower end of the spring 30 is wrapped about the collar 18 with one or more of its lower convolutions engaging with and held by pins 32 mounted in and projecting radially from the collar 18. This anchors the lower end of the spring and prevents its pulling olii o the collar 18 when the spring is distended. The screw 20 by being inserted below the lower convolution of the spring may Aprevent the lower end of the same from dropping or being sprung down below the collar, thereby functioning with the pins 32 to anchor'the lower end of the spring against displacement in either direction.

Like the lower collar 18, the upper collar 26 may be provided with one or more radially projecting pins 35, preferably a pair arranged diametrically opposite. One or more of the upper convolutions of the springBO is threaded around the pins 35 or wrapped circumferentially thereabove whereby the upper end of the spring is anchored against downward displacement from the collar. The screw 28 may be arranged above the up-` per convolution of the spring to prevent upper displacement of the upper end of the spring, thereby cooperating with the pins 35 to anchor the upper end of the spring against displacement from the collar 26 in either direction.

The upper ferrule 8 is provided with an internal flange 40, which lia-nge 40 is formed with an annular shoulder 42 for the reception or" the vent cap 43, a second annular shoulder 44, and an upwardly flared or tapered surface 45. An annular ring 46 mounted in the ferrule 8 upon the shoulder 44, supports a washer y48 of bakelite or other suitable non-conducting material. The washer 48 rests upon an annular shoulder extending inwardly at the lower end of the ring 46, and this washer 48 has an axial opening 50. The upper end of the terminal member 2 5 extends into the axial opening 50 and is held properly disposed centrally within the tube 5 by engagement therein.

The arcing terminal 25 is held in its distended set position, as shown in Fig. 2,.and electrical connection is made between it and the terminal ferrule 8 by the fuse element 52. As shown in Fig. 6, the fuse element 52 comprises a fusible wire 53 which is enclosedy within a non-conducting strain sheath 54, or wrapped with a non-conducting strain element, which is preferably of fishing cord, suitable fabric, or suitable combustible material, although this, of course, may be varled. The fuse wire 53 is usually so line or its structureotherwise such that it cannot take any of the tension or strain of the spring 30. The metal actually used in this vwire is nickelchromium, although this may be varied. The wrapping or sheath 54 is therefore employed to withstand the strain and give the fuse link 52 the necessary mechanical strength to hold the upper terminal and other parts in their set position, as shown in Fig. 2.

Intermediate or between the ends of the fuse link 52, the fusible wire 53 is led out through the wrapping or mechanical strength imparting means 54 and is wrapped externally thereaboutat 55 to provide for electrical contact with the terminal member 25. At the opposite ends of the link 52 the fusible wire 53 is also led out and wrapped externally about the wrapping or mechanical strength imparting material 54, as indicated at'56.

Diametrically through the upper end of the shank of the terminal member 25 is an opening 60. The fuse link 52 is passed through this opening and is drawn taut and the exposed ends 56 of the fuse wire 53 are secured under the heads of screws 62 threaded into the ferrule 8 at diametrically opposite points in the flared or tapered surface 45. The intermediate exposed portion 55 of the fuse wire 53 lies in the opening 60 anden-l gages with the shank of the terminal member 25. This exposed portion 55 may be wrapped with tin-foil to assure good Vcontact with the arcing terminal 25 and to offer such mechanical protection for the exposed portion of the wire 53 as it may. The tin-foil wrapping is indicated at 65 in Figs. 2, 5 and 6.

By this construction of ther fuse element, the fuse wire 53 is connected electrically between the terminal member 25 and the ferrule 8, and at the same time the wrapping 54 is connected mechanically between the terminal member 25 and the ferrule through the screws y 62 which provide the v electrical connection.

Consequently, the wrapping 54 holds the upper terminal 25 and other parts set and the fuse wire 53 provides a sensitive electrical connection between the upper terminal and the upper ferrule which may be accurately rated to blow at the desired point.

en the fuse wire 53 is melt-ed or fused,

the wrapping 54 is subjected to the resulting arc. It at once burns and ruptures the mechanical holding connection, freeing the terminal member 25, whereupon said terminal member 25 is drawn downwardly to open position by the spring 30, the liquid director or sprayer projecting a stream of the arc extinguishing liquid 72 within the tube l5 upwardly, upon the space where the arc tends to form.

To assure burning' and rupture of the cord for wrapping 54, I mount a radial conducting adjacent screw 62 and it lies radially across thetop' of the ring 46 and washer 48 beneath one side of the fuse element 52 and its inner end may be turned down slightly/in the opening 50 toward the upper end of the shank of the Y terminal member 25. Consequently, when the fuse wire 53 blows, a more or less concentrated arc will be produced between the inner end of the linger 75 and the upper end of the terminal member 25 immediately adjacent one side of the fuse element, so as to subject the winding or strain element 54 thereof to this arc and assure burning and rupture of said element 54, to permit proper release and opening of the fuse.

The vent cap 43 has a marginal flange 78 and may be bulged centrally to be sprung i tightly in place into the upper end of the ferrule 8 and down upon the shoulder 42. .The vent cap with an application of nondrying cement 79, such as disclosed in my hereinbefore referred to Clo-pending application, now Pat. N o. 1 ,7 43,322, is pressed into place and the fuse hermetically sealed.

The sleeve or tube 5 contains an arc extinguishing liquid, the level of which is prefalthough this may be varied as desired. The arc extinguishing liquid employed is preferably a derivative of a suitable hydro-carbon. It may be any one of the liquids disclosed in Patent No. 1,319,907, dated October 28, 1919, or any preferred arc extinguishing liquid. The fuseelement 52 is plosion chamber in the ferrule 8 above the bakelite, lava, or other insulating washer 4S. Consequently, if the fuse blows on Very heavy overload or short-circuit, the resultin explosive etl'ect is confined to the chamber above the washer 48 and below the safety pressure Vent 43. The result is, that on shortcircuit or very heavy overload, the vent cap blows off before any extensive pressure can develop in the glass tube, and breakage of the glass tube is thus avoided. After the strain element 54 has burned or` ruptured, the washer 48 is also free to rise and thus prevents any excessive pressure within the glass tube when the arcing terminal 25 is drawn down in the liquid.

The lower end of the ferrule 8 may be splayed on diametrically opposite-sides to provide generally parallel flat contact surfaces and the lower ferrule or base 6 may be similarly splayed to provide substantially parallel flat contact surfaces 82. The ferrule 8 may be sealed upon the`l tube 5 at 83 similar to the sealing of the base 6; and it also preferably has a tapered shoulder 84 for cenin a separate ex-V yerably up to or just below thepwasher 48,

tering the tubeitherein and providing minikmum contact therewith. A

preferably three equally spaced, in which fit' pins of bakelite or other suitable insulation 86. The pins 86 project radially, and as the screw 85 is threaded in, the cone point thereof, forces said pins out into engagement with suitable sockets or recesses in the liquid director 70, thereby securing the liquid director securely against axial movement or rotationon the terminal member 25. The liquid director may be of lava, bakelite or other suitable material and it tends to direct or squirt liquid upon the place where the are is drawn when the fuse blows. It is, in fact, a plunger fitting more or less closely in the tube 5 and having a central opening, the lower end of which is flared or tapered outwardly to the lower end of the director, as shown.

For the purpose of dam-ping vibration of the terminal member 25 and spacing and guiding the same, I provide a plurality of anti-vibration spacing prongs or members 90. Three equally spaced about the terminal 25 as shown, are preferable, and these prongs 90 may be of fiber, bakelite or other suitable insulating material. Suitably secured upon the shank of the-terminal 25 is a washer 92 having a sharp edge orfrelatively sharp spaced portions along its edge which engage in notches 93 in the prongs 90. The prongs 90 are thereby fulcrumed upon the edge of the washer 92 and their upper ends are tied together and normally contracted by means of an annularly arranged coiled spring 94, secured through suitable openings to the upper end of each prong. TheV contraction of the upper ends of the prongs spreads the, lower ends outwardly about the washer-92 as a fulcrum into engagement with the tube 5, thereby yieldingly holding the terminal mem'- ber 25 properly positioned and yieldingly damping any vibration that occurs. This re-l lieves the fuse element and other parts of the strain which would otherwise bey caused by such vibration. Each prong 90 is preferably provided with a plurality of notches 93, as shown in Fig. 2, to adjust the .amount of projection produced by the spreading o'f the lower ends of the prongs, by changing the position of the fulcrum along said prongs. In some instances, especially where the conductor 17 and spring 30 are relatively long, I find that it may be desirable to damp vibration of the spring 30 within its length.

' For this purpose I provide within the length of the spring 30 a spring vibration damper comprising an anti-vibration collar 96 which is also preferably of insulating material. EX-

tending radially through this, are three circumferentially spaced studs or anti-vibration pins 97. The inner reduced ends of these pins engage between convolutions ofthe spring 30 and hold the anti-vibration means roperly positioned longitudinally thereof.

he outer ends of the pins 97 are headed and these headed ends engage the tube 5 and damp vibration of the spring 30. This anti-vibration means moves with the spring as it is distended or retracted and I find that it is desirable to place it at the center of the fuse spring, although if additional devices o'f this sort are desired, they may be spaced along the spring in any suitable manner.

In Figs. 7 and 8 I have shown the fuse link of the present invention embodied in a device in which the upper arcing terminal comprises a pair of longitudinally spaced terminal members 100 and 102. rIhe opposing ends, at least of these terminal members, are socketed or tubular. The fuse link 103 is wrapped, as before, and the ends of the fuse wire of said link are exposed, as before. The bared ends of the fuse link 103 are inserted into the socketed ends of the terminal members 100 and I102, respectively, and said socketed ends are then crushed or fiattened thereupon, as shown in Fig. 8. The fuse link 103 is thereby firmly gripped and mechanically held at its opposite end to the terminal members 100 and 102, and the exposed ends of the fuse wire make contact with said termial members and connect the same electrica y. The wrapping of the fuse link is held -in the socketed ends of the terminal members with the fuse wire and takes the strain and mechanically sustains the lower terminal 102 from the upper terminal 100 when the fuse is set. The adjacent ends of the terminal members'lOO and 102 and the uselink 103, are preferably confined in an envelope or covering preferably inthe form of a block or plug 105 of material such as cork.

In the embodiment of the invention shown in Figs. 9 to 14, the tube 5f has sealed upon its lower end `a base 6 similar to the base 6 of the previous embodiment, and sealed upon the upper end is the ferrule 8 similar to the ferrule 8 of the previous embodiment.

In this embodiment the lower terminal 16 is formed similar to the terminal 16 of the previous embodiment, and is similarly provided with a collar 18. lThe opposite ends of the conductor 17 are, as before, secured in the upper socketed end of the terminal 16 and in the lower socketed end of the upper arcing terminal 25 and is provided with some slack, even when the spring 30 is distended. The substantially parallel fiat faces 106 of this and the previous embodiment, are probably shown more clearly in Figs. 9, 12 and 14. The screws 28 and 20 hold the collars in place, or additionally hold them as before, and, as before, the opposite ends of the spring 30 are attached to the respective collars by reti-active effort means of radial pins 32 and 35', which may be staggeredvto facilitate winding of the end convolution of the helical coil spring thereabout. I

The upper ferrule 8 is provided with an internal flange 40', which lange 40 is formed with an annular shoulder 42 for the reception of the vent cap 43, a second annular shoulder 44 and an upwardly flared or tapered surface 45. An annular ring 46 mounted upon the shoulder -44 supports a non-conducting washer 48 having a central or axial opening 50', through which the upwardly extending shank of the arcing terminal 25 projects. The terminal 25 is held in its upper set position against the tension or vof the spring by means of a tension or strain wire 108, which passes diametrically through the shank 109 of theupper terminal 25 and is secured at each end under the heads of suitable screws 112 mount- .ed at diametrically opposite points in the flared or tapered surface 45. The upper end of the shank 109 terminates just above the washer 48 and is drilled axially and` tapped at 114 (Fig. 13) to receive a removable screw 115 under which the intermediate portion of a fuse link 116 is secured. The link 116 is shown as extending l comprising, in this case, a pluralit at right angles to thestrain wire 108, and the opposite ends of this fuse link 116 .are mechanically and electrically connected to the ferrule 8 by screws 120 threaded into the sur- ,y face 45 at diametrically opposite i pointsf a5 -fIhe liquid directing or spraying member 121 1s mounted in this case upon the shank 109 by means of three screws 122, the heads of n which are preferably countersunk in the director, as shown.

Vibration of the movable system of this fuse is damped by an anti-vibration device of spring lingers 125. To obtain a simple, e ective and inexpensive scheme of formin these fingers and securing them in place, lghave devised the arrangement shown. One pair of lingers is formed of a single length of wire which passes through an opening 126 (Fig. 13)V in the shank of the terminal 25 and is then bent around the periphery of the shank 109, 90 degrees in the particular embodiment shown, and passed through an opening 127 at substantially right angles or normal to the opening 126.` The other pair of fingers are formed of a similar length of wire passed through an opening 128, bent around the periphery of the shank 109, 9 0 degrees, and then passed through an opening 130 substantially l, normal to the opening `128. vvThis provides a also guides the movable working parts of the i fuse, and by damping the vibrat1on,relieves the fuse element, strain wire and other parts of destructive stresses that might otherwise be imposed.

When the fuse link 116 blows or is melted or fused, the tension wire 108 is subjected to a heavy current and to the heat generated by the fusing of the link 116. While it has the mechanical strength for holding the fuse set, it is fused at once by the are and heat generated by the blowing of the fuse 116,'-and releases .the spring 30 -which draws theupper arcing terminal 25', director 121, and anti-vibration device 125 downwardly, the director 121 projecting a stream of thel arc extinguishing liquid 150, contained within the tube 5 as before upon the space where the are tends to form. As in the previous embodiment, blowing on very heavy overload or short circuit occurs in the explosion chamber above the washer 48 and between it and the vent cap 43. The result is, as before, that on short-circuit or very heavy overload, the vent cap 43 blows 0E before any extensive pressure can develop in the glass tube, and breakage of the glass tube is thus avoided. After the strain wire 108 `has melted, the washer 48 is, as before, also free to rise and thus prevents any excessive pressure within the glass tube when the arcing terminal is drawn down into the liquid.

I claim mik v1. In a device of the class described, the I i combination of a tubular casing, a movable system within the casing including a movable terminal member anda coil spring normally under tension connected to said terminal member, and means fulcrumed to swing on a part ofthe movable system for dampingv vibration of said movable system.

2. In a device of the class described, the combination of a tubular casing, a movable system within the casing including a movable terminal member and a coil spring normally under tension connected to said terminal member, land means comprising a plurality of arms carried by and fulcrumed to swing on a part of the movable system and cooperable with the casing for spacing the system therein and damping vibration thereof.

3. In a device of the class described, the combination of a relatively stationary termina-l, a movable system including a movable. terminaland anti-vibration. means swingably lfulcrumed and operable to damp vibration of the movable system of the device.

4. In a device of the class described,.the combination of a tubular casing, a movable terminal therein, .and anti-vibration spacer means swingably fulcrumed on said movable terminal and cooperable with said casing for spacing the movablelterminal in the casing and-for damping vibijation of said terminal.

5. In al device of the class described, the

.39 prongs spaced circumferentially and fulder tension and connected to saidmovable terminal, and means on the spring and cooperable with the casing for damping vibration of the spring.

6. In a device of the class described, the combination of a tubular casing, a movable terminal therein, a coil spring normally under tension and connected tothe movable terminal member, anti-vibration spacer means on the movable terminal and cooperable with the casing for spacing the movable terminal and damping vibration thereoi", and a vibrationJdamper orthe spring connected thereto and cooperable lWith the casing.

7., In a device of the class described, the combination of Va tubular casing, a terminal thereon, a movable terminal in the casing, means tending to separate said movable terminal from said Erst terminal, a collar carried by the movable terminal, anti-vibration prongs fulcrumed on the collar, and spring means connected to said prongs adj acent one end and normally contracting them at that end to swin the opposite ends out into cooperation with the tube.

Y 8. In combination, a terminal member, a collar thereon, a plurality of insulating crumed on said collar, and springmeans connectmg said prongs at one end and tending to contract them at that end to swing the oppo-y site ends of the prongs out into expanded position. f

9. Ina device of the'class described, the combination of a tubular casing, a coil spring therein, a collar surrounding said spring, and studs mounted in said collar and pr0- jectin at their inner ends into cooperation with t e spring and attheir outer ends into cooperation with the casing todamp vibration of the spring. I

10. In combination, separable terminal means, means tending to separate said terminal means, a fusible conductor electrically connecting said terminal means, and a nonconductor of greater tensile strength than the fusible conductor mechanicallyconnectedI to restrain said separating means, the conductor being enclosed within the non-con ductor and led out and wrapped externally on the non-conductor to form a terminal thereof.

11. In combination, separable terminal means, means tending to separate said terminal means, a fuse link including a fusible conductor electrically connecting said terminal means, and a non-conductor of greater tensile strength than the` fusible conductor mechanically connected to restrain said separatingmeans, said non-conductor enclosin a. portion of the usible conductor and the conductor being led out and wrapped exsaid pins being odset to ternally of the non-conductor to form a terminal for the link.

12. In a device of the class described, the combination of a tubular casing, a terminal ferrule on said casing, a movable terminal member, a coil spring normally under tension connected to the movable terminal member, a fuse element electrically connecting the movable terminal member and the terminal errule and mechanically restraining the spring, said fuse element comprising a fusible link, andra non-conductor of greater tensile strength than said link, said link having electrical contact With the movable terminal and the non-conductor having mechanical connection therewith, said link also being eX- posed adjacent the terminal ferrule, and means for connecting the fuse element electrically and the non-conductor mechanically to the ferrule.

13. In a device of the class described, theing of theterminal for forcing said pin means out and securing same in cooperation With'the director to secure the director upon the terminal.

15. In a device of the class described, the combination of a terminal member, a conductor connected thereto, a collar thereon, a coil spring having convolutions Wrapped about said collar, and pin means projectmg radially vfrom the collar between convolutions bf said spring for attaching same to the co1- 16. In a fuse device, a terminal member, a conductor connected to said terminal mem ber,.a collar on said terminal member, pin means projecting from said collar and an operating spring connected to said collar' by .cooperation with said pin means.

member, a pair of pins projecting from said collar, andan operating spring connected to Said collar by cooperation With said pins, ermit threading of the spring into cooperation therewith.

18. In a device of the class described, the

g combination of a tubular casing, a ferrule on the end of said casing, a first shoulder in said ferrule, a separate ring seated on said fitting within the end of the ferrule, and

means connected electrically and mechanically between said terminal member and the i ferrule between the washer andv said vent cap.

19. In a device of the class described, the combination of a tubular casing, a terminal ferrule on said casing, a movable terminal member in the casing, a coil spring normally under tension, and connected to the movable terminal, a fuse link connected between the movable terminal and the ferrule, and an arcing terminal connected to the ferrule and extending along the fuse into position for cooperation with said movable terminal member.

20. In a device of the class described, the combination of a casing, relatively ixed terminal means, a movable terminal in the casing, a normally restrained spring adapted upon release to operate said movable termi- 24. In a fuse device, a terminal member, a conductor connected to said terminal member, pin means projecting from said terminal member, and an operating spring having separated coils threaded onto said terminal member by cooperation with said pin means.

25. In a device of the class described, the combination of a terminal member, a conductor connected to said terminal member, pin means disposed radially relative said terminal member, and an operating spring threadedly connected to said terminal member and anchored thereto by cooperation with said pin means.

In witness whereof, I hereunto subscribe my name this 22nd day of May, 1925.

NICHOLAS J CONRAD.

nal from said relatively fixed terminal means and means for damping vibration of said spring. y n 2l. In a device of the class described, the combination of a tubular casing, a terminal ferrule on said casing, a'movable terminal member in the casing, normally restrained means 4for separating the movable terminal p from the ferrule, a fuse link connected between the movable terminal and the errule, and an arcing terminal underlying thefuse link and extending into position for cooperation with the movable terminal.

22. In a device of the class described, the

combination of a tubular casing, a movable terminal therein, a liquid director on said terminal and a plurality of radial securing elements engaging thevdirector and entering the terminal for securin the director thereon, said radial securing e ements having their inner ends separated along the center of said terminal member.

23.l VIn a device of the class described, the

`Combination of a tubular casing, a movablel terminal therein, said terminal having an axial threaded opening, a liquid director on said terminal, a plurality of radial securing elements engaging the director and entering the terminal for securing the director thereon, said radial securing elements having their inner ends separated along the center of said terminal member, and a stud element threaded into the axial threaded opening of saidl terminal member, the separation ofthe inner ends of the radial securing elements accom-A modating the axial threaded opening and the threaded stud between them.

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