US2313364A - Fuse construction - Google Patents

Description

March9, 1943. w. o. scHuLTz 2,313,354

` FUSE CONSTRUCTION Filed March 4, 19:59 4 sums-sheet 2 lNvENToR Wal/,4M 0. Jef/Mrz March 9, 1943.

W. O. SCHULTZ FUSE CONSTRUCTION Filed March 4, l1939 l 4 Shasta-Sheet 4 IN VEN TOR. Wam/n0. Jaffa/rz K BY Patented Mar. 9, 1943 UNITED STATES PATENT GFFICE 2,313,364 FUSE CONSTRUCTION William 0. Schultz, South Milwaukee, Wis., assignor to Line Material Company, South Milwaukee, Wis., a corporation of Delaware Application March 4,' 1939, Serial No. 259,809

t 29 Claims.

This invention relates to fuse constructions. Objects of this invention are to provide a novel form of fuse, preferably a housed type of expulsion fuse, in which the fuse tube remains stationary after it has blown and the door remains closed, and in which the fuse tube is relieved of potential stress between the contacts after it has blown so that there is no danger of burning the fuse tube or the door even though the fuse tube may be left in an unfused condition for a material length of time.

Further objects are to provide a construction in which an indicator or semaphore is provided and is displayed when the fuse has blown, thereby giving an indication that the fuse has blown, and to provide means for mechanically withdrawing the fuse link, such means acting in a direction substantially in line with the fuse tube at the initial portion of its stroke as distin-A guished from pulling the link around the end of the tube, whereby links of less flexibility may be used and whereby a positive extraction of any remaining portion of the fuse link is provided by mechanical meansso that in addition to the expulsion action of the fuse tube there is a mechanical clearing of the fuse tube. A'

Further objects are to provide means for further interrupting the circuit in addition to that produced by the fusing of the fuse link, such means coming into operation only after the fuse linkhas melted and has been expelled or withdrawn from the fuse tube, such additional means operating although the fuse tuberemains stationary.

Further objects are to provide a construction in which the mechanical means for withdrawing any remaining portion of the fuse link and the auxiliary means for further interrupting the circuit, in addition to that provided by the melting` of the fuse link, are supported from the door, in which the entire assembly of fuse tube, door and mechanical link extracting means and circuit interrupting means may be removed from the housing as a unit for refusing so that the device may be refused while it is completely detached from the remaining portion of the apparatus.

In greater detail, a further object of this invention is to provide an automatically acting switch preferably located adjacent the lower end of the fuse tube and controlled by the fuse link, the semaphore indicating means and the fuse extracting means being also controlled by the fuse link, the switch being held closed until the interruption of the circuit has been effected in 'the fuse tube and thereafter the switch moving `tus or any remaining portion of the fuse link,

means independent of the fuse link so that the fuse link is not subjected to stress due to the contact pressure on the switch blade, irrespective of the magnitude of this pressure which may 'for certain types or sizes of the devices be relatively great as compared with the strength of the fuse link itself, and to so organize or relate the parts that the device may be readily refused and the parts positioned in their original position by merely rocking the combinedv extracting and indicating means back to its initial positionand thereafter clamping the leader of the fuse link in place.

Further objectsar'e to provide a fuse construction in which the automatically operating switch separates any projecting portions of the apparaafter the switch has operated, from electrical connection with any live contact of the fuse structure, thereby avoiding hazards. For example, in a construction in which a housing is provided and in which the semaphore or other indicating means is projected outwardly beyond the housing, such semaphore is electrically dead after the operation of the device.

An embodiment of the invention is shown in the accompanying drawings, in which:

Figure 1 is a View partly in vertical section Figure 5 is a view corresponding to Figure 2 showing the parts in the position they occupy after the fuse has blown.

Referring to the drawings, it will be seen that the device comprises a housing I of porceiln or other suitable material which is provided with a door 2 of insulating material. The door may be detachably secured to the housing by means of trunnions 3 which are detachably received in the hooks 4 carried by the housing. I'he door remains closed before and after the fuse has operated but it may be pulled open by means of a suitable handle or eye portion 5.

The housing is provided with upper and lower terminal members 6 and 'I. The upper terminal member is provided with a pair of spring iingers 8 between which the upper terminal 9 of the fuse tube I is yieldingly gripped. Such upper terminal 9 is preferably rectangular to provide flat sides against which the spring fingers 8 bear. Additionally the upper terminal is provided with an upper spring finger I0' which ts over the cap II forming a portion of the upper terminal 9 of the fuse tube. The spring iinger I0 is provided with a downwardly depressed portion I2 and terminates in an upwardly extending bevelled or cam like portion so that the upper cap II of the fuse tube will ride beneath the cam like portion of the spring nger I0' during closing of the door.

The upper terminal is provided with a line receiving clamping member indicated generally at I3 and the housing I'may be provided with a suitable aperture or apertures, not shown, in the customary manner through which the incoming conductors may pass. The lower terminal 1 includes a lower stationary contact I4 against which the switch or brush I5 normaly bears, as will hereinafter be described. It is also provided with a line receiving clamping member I6 and similarly the housing I is provided with an aperture or apertures, not shown, for the incoming line wire in accordance with the usual practice.

The fuse tube I0 is formed of insulating material and carries the upper rectangular contact 9 which may be provided with a projecting ear I'I positioned beneath a stop I8 carried by the upper terminal to limit the upward recoil and to, prevent contact of the upper edge of the door with the casing. This upper contact is also provided with a lug or ear I9 which is secured to a web 20 formed integrally with the door.

The door also carries a lower bracket 2I to which is bolted an outer bracket or member 22. The members 2I and 22 are shaped to conform to the fuse tube IU, as most clearly shown in Figure 4, and the fuse tube is clamped adjacent its lower portion between these members by means of the bolts or screws 23. The member 22 extends downwardly and is provided with an outwardly projecting foot portion 24 which terminates in a pair of spaced ears 25.

A combined fuse link extracting and semaphore or indicating means is provided and may be formed of a pair of sector-shaped side portions 26 which extend rearwardly and are provided with rear ears 2'I and with front and rear transverse bottom webs 28 and 29. The side portions 26 of this indicating means or semaphore are spaced apart and their front edges are normally located on opposite sides of the fuse tube, as shown most clearly in Figure 3. If desired, the fuse tube may be slightly cut away or attened on opposite sides, as shown in Figure 3, to allow the members to be placed closer together than would otherwise be possible. The side members 2B of the semaphore are preferably out of contact with the fuse tube, though this spacing may be extremely close if desired.

The combined fuse link extracting and indicating means is pivctally mounted on a pivot pin 30 supported by the ears 25 of the foot portion 24 of the bottom bracket and is urged towards open or extended position by means of a spring 3| loosely coiled about the pin 30 and bearing against the foot 24 and the web 29. If desired, a sleeve, not shown, may be placed around the pin 30 to provide a seat for the spring 3 I Whether or not a sleeve is used, the spring 3| is not allowed to bind on the pin 3U. When the indicating means is extended as shown in Figure 5, it projects below the bottom outline of the housing and gives a visual indication that the fuse has blown. It may be painted or colored brightly to increase its visibility.

Normally this combined fuse link extracting and indicating means is in the position shown in full lines in Figures 1, 2 and 3 with the web 28 either adjacent to or in contact with the bottom portion of the fuse tube I0. The leader 32 of the fuse link extends outwardly through the open bottom of the expulsion fuse tube and beneath the web 28 and also beneath the web 29. It is secured directly to the switch in a manner hereinafter to appear.

The switch comprises the brush I5 or blade and a body portion 33 which may consist of a pair of spaced arms and transverse front and rear webs 34 and 34 respectively. The rear web 34 extends beyond the outline of the ears 21 of the combined fuse link extracting and indicating means and is adapted to be struck by such ears after the combined fuse link extracting and indicating means has executed its fuse link extracting operation and during the final portion of the stroke of the combined fuse link extracting and indicating means.

A rectangular washer 35 is provided and may also overhang `the ears 21 and. be struck thereby if desired. It is provided with a bottom tongue 36 which fits beneath the portion 34 of the switch and prevents the washer from turning when the bolt or screw 31 is tightened, such screw passing through the washer and being threaded into the portion 34 of the switch.

The fuse link may comprise the fusible section 38, see Figure 1, and the usual upper section which may be provided with a notch 39 and an upper buttonhead 40 and the downwardly extending leader 32. The upper buttonhead 40 is clamped by means of the cap I I in the usual manner. The leader is preferably formed of stranded construction to secure flexibility, but it is obvious that inasmuch as the fuse link extracting means pulls substantially directly downwardly in line with the fuse tube for a portion at least of its stroke, that less flexible fuse links can be used if desired. The leader 32 of the fuse link is clamped between the washer 35 and the por tion 34 of the switch and thus the fuse link is electrically connected to the switch, as shown in Figure 2.

It frequently happens that the contact pressure between the switch I5 and the stationary contact I4 is relatively heavy and this invention provides means for preventing transmission of this force to the fuse link. In order to accomplish this, independent latching means is provided which latches the switch closed and which does not allow any force imposed on the switch t0 be transmitted to the fuse link. This latch may comprise a pair of spaced segmental arms 4I which are joined by means of a web 42 and which have curved outer faces 43. The latching member is pivoted upon a pin 44 carried by the foot 24 and is spring urged towards releasing position by means of the spring 45. One of the arms,4I is provided with a cylindrical integral piny 48 projectinglaterally therefrom.

The pin 46 is received in a cam slot 41 formed in one of the arms of the semaphore 26 so that whenffth'efsemaphore is rocked into signalling position,,the latch is withdrawn to the position shown in Figure 5, thus releasing the switch. When thesemaphore is in the non-signalling or normal position as shown in Figure 2, the latch is in its latching position and latches the switch closed. The side arms of the body 33 of the switch are provided with curved faces 48 which contact the faces 43 of the latch when the latch is in latching position, as shown in Figure 2. Both of the faces 43 and 48 are circles concentric with the axis of the pin 44 about which the latch l remaining portion of the fuse link. It is to be noted particularly from Figure 2 that the r'st portion at least of the motion of the semaphore or combined indicating and extracting means is substantially directly downwardly in line with the axis of the fuse tube. Consequently any remaining portion of the fuse link is withdrawn substantially in line with* the fuse link. It is therefore apparent that less flexible leaders need be provided with this type of fuse than if the leader were pulled at right angles to the axis of the fuse tube. The semaphore or signalling device executes its outward motion quickly and quickly withdraws the fuse link, thereby extending the gap in the fuse and quickly interrupting the circuit.

Additionally it is to be noted that the substantially direct downward pull on the fuse link causes the moving parts to acquire considerable velocity and accumulated,V energy before a change in the direction of pull on the fuse link is pronounced enough to cause appreciable friction between the leader and the side walls of the tube. The result is that even where a stiff leader is used, the momentum of the moving parts would overcome any reasonable friction and stiffness, even though a considerable portion of the leader was not destroyed when the fuse blew.

Towards the latter portion of the outward stroke of the semaphore, the latch is rocked to its releasing position, as shown in Figure 5, and the switch is now free to rock towards the tube away from the stationary contact I4. Obviously if desired a spring may be employed to assist this motion of the switch, though the switch is biased towards opening motion both by gravity and by the relatively heavy spring pressure exerted on the switch blade itself, which switch blade is under considerable pressure when in closed .position and tends to straighten out, as may be seen by comparing. Figures 2 and 5. These effects naturally cause the switch to execute a quick opening motion but in addition to this, the ears 21 of the semaphore strike the web 34 of the switch and if desired also strike the washer 35 of the a quick opening stroke. The semaphore,` therefore, affords a positive driving force for'positively driving the switch open, in addition to the tendency of the switch to open as hereinabove described.

It'is to be noted particularly that the latching means not only locks theswitch in closed position vbut also keeps the switch closed during the opening operation until the fuse link extracting means has moved a sufficient distance for the arc to be extinguished inside the fuse tube and that thereafter the switch quickly moves to open position. It is to be noted that after the fuse has blown and the device hasoperated, that any parts projecting below the bottom of the casing are electrically dead as the lower portion of the apparatus is electrically disconnected from the stationary lower contact, as shown very clearly in Figure 5, and there is, therefore, no hazard due to vthese projecting partssuchas the semaphore and any remaining portion of the fuse link. This is especially important if 'the semaphore is made of conducting material, which is the form shown switch and positively drive the switch open with and. described though the invention in its broadest `aspect contemplates the making of the semaphore of either conducting or non-conducting material.

When the lineman wishes to refuse the device, he merely unhooks the door from the casing and lifts the door, fuse tube; semaphore, latch and switch as a unit from the casing. He thereafter. may refuse the device. During this refusing, he rocks the semaphore 26 towards non-signalling position and draws the leader of the fuse link beneath the bottom webs 28 and 29 of the semaphore, see Figure 2, and clamps the fuse link directly to the switch as shown. y

It is to be noted that when the semaphore is rocked back into its non-signalling position by the lineman, that the cam slot 41 rocks the latch 4I and this latch in turn bears on the lower portion of the switch and rocks the switch towards closed position until the curved faces 43 ride beneath the curved faces 48 of the switch, thus locking the switch in the position shown in Figure 2. Thereafter the lineman hooks the trunnions 3 of the door in the hooks 4 of the casing and rocks the door to closed position.v The switch then bears firmly against the stationary contact I4 and the upper contact 9 and cap II of the fuse tube respectively, move between the spring jaws 8 and Ibelow the upper spring contactjiinger I0'.

If the lineman wishes to inspect or open the device while the fuse link is intact, he merely pulls the door open and if he so desires, he may unhook the door from the casing. This operation does not place any strain upon the fuse link. Also during the closing ofthe door no strain is placed on the fuse link by the engagement of the switch I5 with the stationary contact. 1 It will be seen that an expulsion type fuse ccnstruction has been provided in which the circuit is first opened Within the fuse tube itself, and that thereafter although the fuse tube does not move, nevertheless the automatic switch moves to open position and therefore opens the circuit at an additional point. This relieves the fuse tube of any potential stressesbetween its upper and lower Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variousliy embodied and is to be interpreted as claimed.

I claim:

l. A fuse construction comprising a pair of contacts, a fuse tube, a switch movable independently of said fuse tube, a fuse link within said fuse tube connected in series with said switch between said contacts, means for moving said switch to open position upon rupture of said fuse link, and mechanism controlled by said fuse link for locking said switch in closed position without imposing strain on said fuse link from said switch, said mechanism releasing said switch upon rupture of said fuse link.

2. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, a resilient switch normally yieldingly bearing i against one of said contacts, said switch being movable independently of said fuse tube, mechanism controlled by said fuse link and released when said fuse link is ruptured, said mechanism directly resisting the thrust from said switch when said switch is closed without transmitting the force due to the thrust of said switch to said fuse link.

3. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, a resilient switch normally yieldingly bearing against one of said contacts, said switch being movable independently of said fuse tube, mechanism controlled by said fuse link and released when said fuse link is ruptured, said mechanism including latching means directly resisting the thrust from said switch when said switch is closed without transmitting the force due to the thrust of said switch to said fuse link.

4. A fuse constructionfcomprising a pair of contacts, a fuse tube having a fuse link therein, a resilient switch normally yieldingly bearing against one of said contacts. said switch being movable independently of said fuse tube, mechanism controlled by said fuse link and released when said fuse link is ruptured, said mechanism resisting the thrust from said switch when said switch is closed without transmitting the force due to the thrust of said switch to said fuse link.

5. A fuse construction comprising stationary contacts, a fuse tube having an open end, a fuse link within said fuse tube and projecting from the open end, a switch adjacent the open end of said fuse tube, said switch Aand said fuse link being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, and mechanism controlled by said fuse link for locking said switch in closed position without straining said fuse link by any force imposed on said switch when said switch is closed, said mechanism being released upon rupture of said fuse link.

6. A fuse construction comprising stationary contacts, a fuse tube having an open end, a fuse link within said fuse tube and projecting from the open end, a switch adjacent the open end of said fuse tube, said switch and said fuse link being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, and mechanism controlled by said fuse link and including latch means for locking said switch in closed position without straining said fuse link by any force imposed on said switch when said switch is closed, said mechincluding cam actuated latching means directly` anism being released upon rupture of said fuse link 7. A fuse construction comprising stationary contacts, a fuse tube having an open end, a fuse link within said fuse tube and projecting from the open end, a switch adjacent the open end of said fuse tube, said switch and said fuse link being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, and mechanism controlled by said fuse link and including cam actuated latch means for locking said switch in closed position without straining said fuse link by any force imposed on said switch when said switch is closed, said mechanism being released upon rupture of said fuse link.

8. A fuse construction comprising contacts, a fuse tube, a fuse link within said fuse tube, a switch, said fuse link and said switch being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, a latch for locking said switch in closed position, and means controlled by said fuse link and distinct and separate from said latch for releasing said 'latch upon rupture of said fuse link.

9. A fuse construction comprising contacts, a fuse tube, a fue link within said fuse tube, a switch, said fuse link and said switch being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, a latch for locking said switch in closed position, and fuse link extracting means controlled by said fuse link and controlling said latch.

vl0. A fuse construction comprising contacts, a fuse tube, a fuse link within said fuse tube, a switch, said lfuse link and said switch being normally connected in series between said contacts, means for opening said switch upon rupture of said iuse link, a latch for locking said switch in I closed position, and fuse link extracting means biased towards fuse link extracting motion and controlled by said fuse link and controlling said latch.

11. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, a switch, said switch and fuse link being normally connected in series between said contacts, a latch for locking said switch in closed position, and sign-ailing means normally held in a nonsignaliing position by said fuse link and biased towards signalling -position and controlling said latch.

12. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, a switch, said switch and fuse link .being normally connected in series between said contacts, a latch for locking said switch in closed position, and signalling means normally held in a nonsignalling position by said fuse link -and biased towards signalling position, said signalling means when in non-signalling posiiton holding said latch against releasing and when in signalling position releasing said latch.

13. A fuse construction comprising a pair of contacts, a fuse tube having an open end, a fuse link within said fuse tube and p.ojecting from said open end, a switch, said switch and fuse link being normally connected in series between said contacts, latch means for latching said switch in closed position, and a combined fuse extracting and signalling means biased towards fuse link extracting motion and normally restrained by said fuse link and holding said latch means against releasing motion when in nonsignalling position.

14. A fuse construction comprising a pair of contacts, a fuse tube having an .open end, a fuse link within said fuse tube and projecting from said open end, a switch, said switch and fuselink being normally connected in series between said contacts, latch means for latching said switch in closed position, and a combined fuse extracting and signalling means biased towards fuse link extracting motion and normally restrained by said fuse link and holding ysaid latch means against releasing motion when in non-signalling position, said .combined fuse link extracting and signalling means being distinct and separate from said latch means.

15. A fuse construction comprising a housing having an open bottomha pair of contacts within said housing, a fuseftubewithin said housing, said fuse tube having an open end adjacent the open bottom of said housing, a fuse link withinl saidfuse tube projecting from the open end thereof, a switch, said switch and said fuse link being normally connected'in series between said contacts, latch means for latching said switch in closed position, and signalling means' norm-ally holding said latch in latching position,v said signailing means having -fuse link extracting means and being biased towards fuse link extracting and signalling position.

16. A fuse construction comprising aghousing having a pair of contacts, a fuse tube mounted within said housing and having an open end, a switch normally engaging one of said contacts,

a fuse link normally connecting said switch and the other of said contacts and being located within said fuse tube and projecting from the open end thereof, l-atch means for latching said switch y in closed position, combined signalling and fuse link extracting means biased towards motion outwardly of said housing and restrained by said fuse link, said combined signalling and fuse link extracting means and said latch having cooperating cam parts whereby when' said combined signalling and fuse link extracting means moves to signalling position said latch moves to releasing position.

17. A fuse construction comprising a housing having an upper and a lower contact, a. fuse tube located within said housing and having an `upper contact normally engaging the upper contact of said housing, said fuse tube having an open lower` end, a fuse link extending from the upper -contact of said fuse tube through said fuse tube and projecting from the lower end thereof, a switch normally engaging the lower contact of said housing, said fuse link being electrically connected to said switch, latching means biased towards releasing position for latching said switch in closed position, and combined signalling and f-use link extracting means biased towards outward motion to signalling position outwardly of said housing and normally restrained -by said fuse link, said combined signalling and fuse link extracting means holding said latch against releasing motion until after said combined signalling and fuse link extracting means has moved towards signalling position.

18. A fuse construction comprising a housing having upper and lower contacts and having an open bottom, a fuse tube within said housing having an open lower end, a fuse link within said fuse tube, said fuse link projecting outwardly through the open end of said fuse tube, a switch normally engaging thelower contact, said fuse link and said switch being connected in series between said upper and lower contacts, a pivoted semaphore adjacent the lower end of said fuse tube, said semaphore being normally housed within said 'housing and being biased for pivotal motiongoutwardly from said housing, said semaphore having fuse link extracting means over which the lower projecting end of said fuse link passes and having a cam slot, and a latch biased towards releasing motion and normally locking said switch in closed position, said latch having a projecting member tting within said cam slot.

19. A fuse construction comprising a housing having upper and lower contacts and having an open bottom, a fuse tube within said housing having an open lower end, a fuse link within said fuse tube, said fuse link projecting outwardly through the open end of said fuse tube, a switch normally engaging the lower contact, said fuse link and said 'switch being connected in series between said upper and lower contacts, a pivoted semaphore adjacent the lower end of said fuse tube, said semaphore being normally housed within said housing and being biased for pivotal motion outwardly from said housing, said semaphore having fuse link extracting means over which the lower projecting end of said fuse link pa'sses Yand having a cam slot, and a latch biased towards releasing motion and normally locking said switch in closed position, said latch having a projecting member iitting within said cam slot, said switch having a portion in the line of travel of said semaphore whereby said semaphore will strike a part of said switch.

20. A fuse construction comprising a housing, ak pair of contacts within said housing, a fuse tube within said housing, a fuse link within said fuse tube, a switch, said switch and said fuse link being normally connected in series between said contacts, latching means for latching said switch in closed position, and signalling means biased towards signalling position outwardly of said housing, said fuse link controlling the operation of said signalling means and said latching means, said switch when in open position separating said signalling means electrically from any live portion of said construction, whereby said signalling means is electrically dead when said switch is open.

2 1. A fuse construction comprising a housing, a pair of contacts within said housing, a fuse tube mounted within said housing and having an open end, a switch normally engaging one of said contacts, a fuse link normally connecting said switch and the other of said contacts and being located within said fuse tube and projecting from the open end thereof, latch means for latching said switch in closed position, combined signalling -and fuse link extracting means biased towards motion outwardly of said housing and restrained by said fuse link, said switch being movable to open position when released by said latch means and said combined signalling and fuse link extracting means being electrically dead when said switch is in open position.

22. A fuse construction comprising contacts, a fuse tube, a fuse link within said fuse tube, a switch, said fuse link and said switch being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, a latch for locking said switch in closed position, and fuse link extracting means controlled by said fuse link and controlling said latci'y, said fuse link extracting means withdrawing any remaining portion of said fuse link substantially in line with said fuse tube during the initial portion of the motion of said fuse link extracting means, whereby any remaining portion of said fuse link and said fuse link extracting means acquires momentum while any remaining portion of said fuse link is traveling in a direction substantially in line with said fuse tube.

23. A fuse construction comprising contacts, a fuse tube, a fuse link within said fuse tube, a switch, said fuse link and said switch being normally connected in series between said contacts, means for opening said switch upon rupture of said fuse link, a latch for locking said switch in closed position, and fuse link extracting means biased towards fuse link extracting motion and controlled by said fuse link and controlling said latch, said fuse link extracting means withdrawing any remaining portion of said fuse link substantially in line with said fuse tube during the initial portion of the motion of said fuse link extracting means, whereby any remaining portion of said fuse link and said fuse link extracting means acquires momentum while any remaining portion of said fuse link is traveling in a direction substantially in line with said fuse tube.

24. A fuse construction comprising a pair of contacts, a fuse tube, a switch movable independently of said fuse tube, a fuse link within said fuse tube connected in series with said switch between said contacts, means for moving said switch to open position upon rupture of said fuse link, and mechanism controlled by said fuse link for locking said switch in closed position without imposing strain on said fuse link from said switch, said mechanism releasing said switch upon rupture of said fuse link, said mechanism including fuse link extracting means for moving any remaining portion of said fuse link upon rupture of said fuse link a sufcient distance to insure opening of the circuit within said fuse tube prior to the opening of said switch.

25. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein. a resilient switch normally yieldingly bearing against one of said contacts, said switch being movable independently of said fuse tube, mechanism controlled by said fuse link and released when said fuse link is ruptured, said mechanism directly resisting the thrust from said switch when said switch is closed without transmitting the force due to the thrust of said switch to said :fuse link, said mechanism including fuse link extracting means for moving any remaining portion of said fuse link upon rupture of said fuse `link a sufficient distan-ce to insure opening of the circuit within said fuse tube prior to the opening of said switch.

26. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, a switch normally engaging one of said contacts, said switch being movable'independently of said fuse tube, mechanism controlled by said fuse link and released when said fuse link is ruptured, said mechanism including latch means directly resisting the thrust of said switch when said switch is closed without transmitting the force due to the thrust of said switch to said fuse link, said mechanism also including fuse link extracting means for .moving any remaining portion of said fuse link upon rupture of said fuse link a sufficient distance to insure interruption of the circuit within said fuse tube prior to the opening of said switch.

27. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, a switch, said switch and fuse link being normally connected in series between said contacts, a latch for locking said switch in closed position, and signalling means normally held in a nonsignalling position by said fuse link and biased towards signalling position and controlling said latch, said signalling means forming a permanent portion of said fuse construction.

28. A fuse construction comprising a pair of contacts, a fuse tube having a fuse link therein, resilient switch means having a movable portion movable independently of said fuse tube, the movable portion of said switch means being held in closed position when said fuse link is unfused, and means for opening said switch means upon rupture of said fuse link, said fuse construction including means directly resisting the thrust from the movable portion of said switch means when said switch means is closed without transmitting the force due to the said thrust to the said fuse link.

29. A fuse construction comprising a pair of contacts, a xed fuse tube having a permanently open end, a switch movable independently of said fuse tube, a fuse link within said fuse tube extending out of the open end of said fuse tube. said fuse link being electrically connected in series with said switch through the agency of the outwardly extending end of said fuse link, said switch being held in closed position when said fuse link is unfused without imposing any strain on said fuse link from said switch, and means olrk opening said switch upon rupture of said fuse WILLIAM O. SCHULTZ.

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