US2318817A - Fuse construction - Google Patents

Description

y 11, 1943- H. A. TRIPLETT 2,318,817

FUSE CONSTRUCTION Filed Nov. 13, 1939 3 Sheets-Sheet l flfgj 2 20 I NJ'ULATION IUBBEK ,BU/HFKE May 11, 9 3- H. A. TRIPLETT FUSE CONSTRUCTION File d Nov. 13, 1939 3 Sheets-Sheet 2 May 11, 1943. 'H. A. TRIPLETT FUSE CONSTRUCTION Filed Nov. 1:, 1939 3 Sheets-Sheet 3 w W W4 A Patented May 11, 1943 FUSE CONSTRUCTION Hu h A. Triplett, Wilmette, 111., assignor to Schweitzer & Conrad, Inc., Chi

poratlon of Delaware cago, 111., a cor- Application November 13, 1939, Serial No. 304,035

13 Claims.

My invention relates, generally, to circuit interrupters and it has particular relation to fuse devices of the dropout type.

This application is a continuation in part of my application, Serial No. 223,175, filed August 5, 1938, now Patent No. 2,226,838.

The present invention constitutes an improvement over the dropout fuse construction shown in the copending application of Allan Ramsey, Serial No. 740,057, filed August 16, 1934, now Patent No. 2,247,700, and assigned to the assignee of this application. It also provides a fuse construction that has a greater range of current interrupting capacity and greater interrupting capacity. It is adapted for use on higher system voltages, i. e., up to 46,000 volts. However, this figure is not intended to represent the limit of system voltage to which the invention may be applied but is merely illustrative of its range of application.

In said patent of Ramsey a fuse tube is provided that is hinged on a lower stationary terminal and is latched at the top to another stationary terminal. The stationary terminals, are, of course, connected to the circuit to be protected. The fuse tube has positioned therein a fuse link containing a fusible element that blows under predetermined conditions of overload on the circuit. As long as the fuse link remains intact, the fuse tube is held in position because of the latch at the upper end. On blowing of the fuse link, the latch is released and the tube is permitted to rotate about its lower end to an open circuit position, thereby placing an air gap in the circuit in addition to that formed by blowing of the fusible element. The upper terminal assembly is provided with a pair of contact fingers that are rigidly secured to the upper stationary terminal and are flared outwardly and upwardly at their outer ends for contact engagement with opposite sides of the upper terminal of the fuse tube. This construction requires that there be fairly close alignment'betwcen the fuse tube or its lower support and the upper contact assembly. One of the objects of my invention is to provide for receiving the upper terminal of the fuse tube of a hinged type of dropout in order to accommodate a fairly wide range of misalignment between the upper contact assembly and the fuse tube support.

The lower contact assembly shown in said patof shape or otherwise distorted by accidental ens dement by a switch stick or the like. It is an object of my invention to protect the movable contact engaging portions of the lower contact s y 01' a hing d ype of fuse dropout and at the same time provide a relatively high degree of contact pressure between it and the lower terminal of the fuse tube.

The fuse link shown in said copending application is provided with a fiber tube that is se- .cured to a terminal which, in turn, is connected to a tension spring in the fuse tube. When the fusible element in the fuse link blows, the terminal and the fiber sleeve of the fuse link are drawn into the fuse tube by the spring. In some cases the are is first formed within the sleeve of the fuse link and then is drawn into the bore of the fus tube which is of considerably larger diameter. Under certain operating conditions difliculties may be encountered in quickly extinguishing the arc. It is an object of my invention to automatically latch and hold the sleeve of a fuse link or fuse cartridge with its lining of arc extinguishing material stationary relative to the fuse tube when the fusible element blows in an improved manner.

Another object of my invention is to provide for latching the fuse cartridge in place by interaction with the same of a single spring biased latch pin which is movable transversely of the longitudinal axis of the cartridge.

Other objects of my invention will, in part, be obvious and in part appear hereinafter.

Accordingly, my invention is disclosed in the embodiment thereof shown in the accompanying drawings and it comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description, taken in connection with the accompanying drawings in which:

Figure 1 is a view. in side elevation, of a dropout fuse device constructed in accordance with my invention;

Figure 2 is a view, in front elevation, of the fuse device shown in Figure 1;

Figure 3 is a view, in side elevation, of the lower contact assembly for the fuse device shown in Figure 1;

Figure 4 is a View, in front elevation, of the contact assembly shown in Figure 3;

Figure 5 is a view, partly in side elevation and partly in section, of the upper contact assembly for the fuse device shown in Figure 1;

Figure 6 is a view, in bottom plan, of the contact assembly shown in Figure 5; and

Figures 7A and 7B, taken together, show the construction of the dropout fuse tube and associated parts, certain portions being broken away in order to more clearly illustrate the details of construction.

Referring now particularly to Figures 1 and 2 of the drawings, it will be observed that the reference character H designates, generally, adropout fuse having a channel base |2-on which are mounted insulators 3 and I4. Upper and lower contact assemblies l5 and I6 are mounted on the insulators l3 and I4 and they are provided, respectively, with circuit terminal members l1 and |8 to permit clamping thereto of the line conductors. A fuse tube, shown generally at 20, is provided with upper and lower terminal assemblies 2| and 22. The upper terminal assembly 2| is arranged to have contact engagement with the upper stationary contact assembly l5 while the lower terminal assembly 22 is arranged not only to have contact engagement with the lower contact assembly IE but is also hingedly mounted thereon. When a fuse link or fuse cartridge within the fuse tube blows, as will be described hereinafter, the upper terminal assembly 2| is no longer held in the position shown in Figures 1 and 2 of the drawings but is released therefrom to permit the fuse 20 to rotate to the alternate position shown by the broken lines. This provides a definite air gap between the circuit terminals formed by the contact assemblies l5 and I6 so that it is unnecessary to rely upon the gap which is provided by blowing of the fuse link or fuse cartridge itself.

In Figures 5 and 6 of the drawings the details of construction of the upper contact assembly l5 are more clearly shown. The upper contact assembly I5 is provided with a frame member 25 that is arranged to be suitably mounted on the insulator I3. It has integrally formed therewith a sleet hood 26 which serves to protect the mechanism underneath including the upper terminal assembly 2| of the fuse tube 20 from the elements.' Guide clips 21 are secured, as illustrated, to the opposite side walls of the sleet hood 26 for guiding the fuse tube 20 to the circuit closed position. i

Flexible and resilient contact fingers 28 are provided with out and upwardly turned end portions 29 for contact engagement with the spaced apart contact surfaces on contact bosses 30. Figure 7A, forming a part of the upper terminal 2| of the fuse tube 20. As will hereinafter appear, a portion of this upper terminal assembly 2| moves upwardly when the device is called upon to interrupt the circuit and, therefore, the outer ends 29 of the contact fingers 28 and the contact surfaces of the contact bosses 30 are shaped as described to facilitate this movement. At their inner ends the contact fingers 28 are secured, as by rivets, 3|, to the depending sides 32 of a backing member, shown generally at 33. A hinge pin 34 extending through the depending sides 32 of the backing member 33 and into the depending side walls'of the sleet hood 26 serves to rockably mount the backing member 33 and the 28 is thereby provided which is not present in the construction referred to hereinbefore in the copending application of Ramsey in which the contact fingers are secured directly to the depending walls of the sleet hood. It will be observed that the outer end portions 35 of the sides 32 of the backing member 33 are turned outwardly and upwardly to correspond to the outer end portions 29 of the contact fingers 28. Coil compres sion springs 36 are provided therebetween for biasing the end portions 29 into contact engagement with the contact surfaces of the contact bosses 30, Figure 7A, of the upper terminal assembly 2|.

It will now be apparent that the contact fingers 28 have two degrees of freedom. Because of their being rockably mounted on the pin 34, they are movable in a vertical plane. resiliency of the contact fingers 28 and the springs 36 permit movement in a horizontal plane. As a result close alignment isnot required to be maintained between the fuse tube 20 or its mounting in the lower contact assembly l6 and the upper contact assembly I 5. This is of considerable advantage not only from a manufacturing but also from an operating standpoint. It is not necessary to provide for mounting the lower terminal assembly 22 of the fuse tube 20 in the lower contact assembly IS with close tolerances. In the field it is unnecessary to hold the insulators l3 and I4 within close limits of tolerance nor must a great deal of care be exercised in operating the fuse tube 20 to the circuit closed position. When it is recalled that fuse devices of the type disclosed herein are mounted overhead and are intended to be operated by means of switch hooks from a considerable distance, the advantages of these features will be readily apparent.

It is desirable to automatically align the contact fingers 28 with the contact bosses 38, Figure 7A. For this purpose a centering arm 38 is integrally formed with one of the sides 32 of the backing member 33 and is provided with a slotted opening 40, the outer ends of which are flared outwardly, as illustrated in Figure 5, for receiving a guide pin 4|, Figure 7A, that is carried by a guide arm 42 forming a part of the upper terminal assembly 2| of the fuse tube 20. When the fuse tube 20 is operated toward the closed circuit position, the guide pin 4| first enters the flared out end portion of the slot 49 and then enters the slot 40 itself to lift the backing member 33 to the extent that may possibly be required. Since there is a definite relationship between the positions of the guide pin 4| and the contact bosses 30 and also between the slot 40 and the contact fingers 28, it will be readily apparent that proper contact engagement will be made between the outer end portions 29 of the contact fingers 28 and the contact surfaces of the contact bosses 30 despite the fact that they might otherwise be considerably out of alignment. The contact surfaces of the outer end portions 29 which are inclined from straight vertical surfaces have a tendency, when pushed in, or as a result of standing in a closed position over a long period of time and being subjected to vibration, etc., to change their relation to each other in a vertical direction. This tendency becomes greater, of course,as the insulation stacks l3 and I4 become higher. It will be noted that the centering arm 39 holds the two contactfingers 28 in a fixed vertical relation with respect to each other after the fuse tube 20 is pushed into place.

With a view to holding the fuse tube 20 in the The inherent circuit closed position, a latch arm 66 is provided, Figure 5, that is secured at its rear end by rivets 66 to a bridging member 66 between the sides 62 of the backing member 66. The forward end of the latch arm 66 is split and the two portions thereof are turned at right angles to the remainder of the latch arm 66 as indicated at 66 for receiving therebetween a roller 61. A spring strip 66, secured in position by the rivets 66 which also hold the latch arm 66, serves to bias the roller 61 upwardly, its upward movement being limited by a stop 66 formed by a depending flange of the backing member 66. It will be understood that the roller 61 is adapted to be engaged by a latch hook 66, Figure 7A, forming a part of the upper terminal assembly 2| of the fuse tube 26. Since the latch arm 66 and the roller 61 carried thereby move with the backing member 66, the roller 61 is automatically centered with the latch hook 66 when the guide pin 6| enters the slot 66 in the centering arm 66. I

In order to provide a good electrical connection between the backing member 66 and the .frame 26 a flexible shunt II is provided comprising several layers of flexible copper strips. The flexible shunt 6| is secured at one end by rivets 62 to a bridging member 66 between the sides 62 of the backing member 66. At its other end it is secured to the frame 25 by rivets 66.

The downward movement of the backing member 66 and the parts carried thereby about the hinge pin 36 is limited by awstop 66. It will be noted that the stop 66 is provided by a lug that may be cast integrally with one of the side walls of the sleet hood 26.

In Figures 3 and 4 of the drawings the details of construction of the lower contact and hinge assembly |6 are illustrated. The assembly comprises a housing 66 that is open at the front and has a wall 6| closing the top and side walls 62 depending therefrom. A rear wall 66 joins the walls 6| and 62, as shown. The assembly l6 serves not only to rockably mount the fuse tube 26 but also to conduct current to the lower terminal assembly 22.

In order to rockably mount the fuse tube 26, the side walls 62 are provided with slotted openlugs 66 for receiving therein trunnions, one of which is shown by a broken line at 66 in Figure 7B of the drawings as forming a part of the lower terminal assembly 22. When the fuse link or cartridge within the fuse tube 26 blows, the fuse tube 26 is unlatched at its upper end, as previously described, and rotates downwardly with the trunnions 66 turning in the bottoms of the slots 66. A rubber bumper 66 is provided for cushioning the inward swing of the fuse tube 26. Disengagement between the fuse tube 26 and the hinge and contact assembly I6 is prevented by interfitting flanges 61 and 66. The flanges 61 are formed integrally with the side walls 62 and project inwardly therefrom while the flanges 66, one of which is shown by broken lines in Figure 7B, are integrally formed with the lower terminal assembly 22. It will be understood that, when the fuse tube 26 is in the circuit-closed position, the flanges 61 and 66 overlap, thereby preventing the recoil resulting from the blowing of the fuse link or cartridge causing the fuse tube 26 to move upwardly and possibly carry the trunnions 66 out of the slots 66. It is only when the fuse tube 26 has rotated to the broken line position shown in Figure 1 that it is possible to lift it out of the slots 66. Likewise, it can only be inserted therein by being initially placed substantially in this position.

Contact engagement with the lower terminal assembly 22 is provided by an inverted U-shaped contact finger 66 that may be secured by rivets 16 to the rear wall 66 of the housing 66, which pass through one leg thereof. As shown, theouter end of the other leg of the U-shaped contact finger 69 is turned back on itself as'indicated at 1| to provide a curved surface for contact engagement with a contact shoe 12, Figure 73, that is part of a contact arm 16 which extends from the lower terminal assembly 22 into the housing 66 when the fuse tube 26 is in the circuit closed position. An inverted U-shaped spring strip 16, conforming generally to the shape of the contact finger 69 and having one leg commonly secured to the rear wall 66 therewith by the rivets 16, is provided for biasing the other leg of the contact finger 69 outwardly into contact engagement with the contact shoe 12. While the contact finger 69 itself is resilient, the added resiliency of the spring strip 16 serves to bias the portion 1| into high pressure contact engagement with the contact shoe 12.

While it is desirable to bias the contact finger 69 into high pressure contact engagement with the contact shoe 12, it is desirable that there be little movement of the turned back portion 1| required for eflecting this high pressure contact engagement. Therefore, a pin 16 is provided through the turned back portion 1|, its ends being secured in the side walls 62. The contact finger 66 and the spring strip 16 are then held in a prestressed condition when the contact shoe 12 is out of engagement therewith. In order to obtain the full biasing effect of the contact finger 69 and of the spring strip 16, it is only necessary for the contact shoe 12 to move the turned back portion 1| out of engagement with the pin 16. Despite the fact that only a slight movement of the contact fin er 69 takes place. yet. as soon as it is moved away from the pin 16, the full biasing force of the contact finger 69 and of the sprin strip 16 is available for providing the desired high pressure contact engagement. With a view to increasing the flexibility of the contact finger 66 and of the spring strip 16 they are split as indicated at 11 in Figure 4 of the drawings.

In Figures 7A and 7B of the drawings the details of construction of the fuse tube 26 are shown. It will be observed that it comprises an outer sleeve 66 and a lining or inner sleeve 6|. Preferably, the outer sleeve 66 is formed of a weather resisting material, such as phenolic condensation product, while the liner or inner sleeve 6| is formed of fiber for reasons now well known to those skilled in the art. If desired, the liner or inner sleeve 6| may be omitted and the outer sleeve 66 alone used. A replaceable fuse cart ridge, shown generally at 62, and described in detail in the application of which this is a continuation-in-part, is provided at the lower end of the fuse tube 26 and connection thereto is provided by a flexible cable 83. A coil tension spring 66 is provided for tensioning the fuse cartridge 62 and withdrawing a terminal therefrom as will presently appear.

At their upper ends the flexible cable 66 and the spring 66 are secured to a cable and spring fastener having a flanged head 65, the under surface of which engages a flange 66 of a sleeve 61 that is slidably mounted on a ferrule 66. A cap 66 is threaded on the sleeve, as shown, for clamping the flanged head to the sleeve 61 for securing good electrical contact engagement therebetween. A spring 90, around the upper end of the fuse tube 20 and interposed between the sleeve 81 and the ferrule 88 serves to bias the former upwardly.

It will be noted that the contact bosses 30 and the latch hook 50 are formed integrally with the sleeve 81. As long as the fuse cartridge 82 remains intact, the sleeve 81 is prevented from moving upwardly under the influence of the coil spring 90. However, as soon as the fuse cartridge 82 blows, the sleeve 81 is no longer restrained but moves upwardly carrying with it the latch hook 50. As previously described, when it moves out of engagement with the roller 41, Figure 6, the fuse tube 20 is then free to swing downwardly to the circuit open position.' The upward movement of the sleeve 81 relative to the ferrule 88 is limited by screws 8| which project into suitable slots, not shown, in the ferrule 88. The ferrule 88 is fastened on to the upper end of the fuse tube 20 so that it is rigid therewith. For this purpose transverse pins, one of which is shown at 94. are provided on opposite sides. Thus the guide arm 42, which is integrally formed with the ferrule 88, and the guide pin 4| are rigid with the fuse tube 20.

In order to lift the latch hook 50 from engagement with the roller 41 for the purpose of manually removing the fuse tube 20, a pair of arms are provided, one of which is shown at 95, on opposite sides of the ferrule 88 as a part of an operating lever 96 which is pivoted on a pin 91 that extends through a portion of the ferrule 88, as shown. An eye 98 is formed integrally with the operating arm 96 and is adapted to be engaged by the prong of a switch hook, as will be readily understood. A stop 98, forming a part of the eye 98, on engaging a flange I extending from the sleeve 81, serves to prevent upward movement of the latter when the fuse tube 20 is moved to the closed circuit position.

In Figure 7B the details of construction of the lower terminal assembly 22 are more clearly illustrated. This terminal assembly includes a ferrule I03 that is fixedly secured to the lower end of the fuse tube 20 by suitable means. An eye I05 is integrally formed with the ferrule I03 to receive the prong of a switch hook for placing the fuse 20 in position with the trunnions 65 in the slots 64. It will be understood that the fuse tube is first positioned as shown by the broken lines in Figure 1. The prong of the switch stick is then removed from the eye I05, and placed in the eye 98. The fuse tube 20 is then swung upwardly to the circuit closed position.

It will be observed that the lower end of the fuse cartridge 82 is provided with a recess in the form of a peripheral groove I01 with which a latch pin I08'cooperates to hold the fuse cartridge 82 in place in the lower end of the fuse tube 20 and within the ferrule I03 against the tension force of the coiled spring 84. The latch pin I08 is slidably mounted in an opening I09 which extends downwardly and through the lower end of the ferrule I03 in a suitably integrally formed boss. A fitting H0 is threaded in the lower end of the opening I09 to provide for guiding the latch pin I08 in its movement. The latch pin I08 is biased inwardly so that the inner end interflts with the groove I01 by a coil compression spring III which reacts between the inner end of the fitting H0 and a flange H2 which may be integrally formed with the latch pin I08. A head III is provided on the outer end of the latch pin I08 to provide a hold whereby it may be withdrawn to release the fuse cartridge 82.

The lower end of the fuse cartridge 8215 provided with a slight taper Ill so that, when the fuse cartridge is drawn downwardly through the fuse tube 20 to the position shown in the drawings it can readily depress the latch pin I08 until the groove I01 is placed in registry therewith. When the fuse cartridge 82 has been drawn to this position, the latch pin I08 snaps into place and securely holds the fuse cartridge 82 in the position shown.

At its lower end the fuse cartridge 82 is provided with a terminal II5 that is connected by a short length flexible lead Il6 to the ferrule I03. As shown, the flexible lead H6 is provided with a metallic terminal I I1 having a suitable aperture which permits it to be placed over a stud II8 extending from the ferrule I03. A nut IIS threaded on the stud I I8 serves to securely clamp the terminal II 1 in place.

It will be observed that, once the fuse cartridge 82 is drawn into the latched position, as by exerting a pull on the flexible lead H6, as is more fully described in my Patent No. 2,226,838, there is no further tension stress applied to the flexible lead II6. This facilitates the connection of the flexible lead II6 to the ferrule I03.

When it is desired to remove the fuse cartridge 82, it is only necessary to grasp the head H3 and withdraw the latch pin I08 slightly against the biasing force of the spring III. If the fuse cartridge 82 is unblown, the tension spring 84 will immediately ten-d to retract the fuse cartridge 82 toward the other end of the fuse tube 20. After the fuse cartridge 82 has blown the outer shell thereof can be readily removed after the flexible lead H6 is disconnected from the stud I I8 merely by removing the cap 88 and turning the fuse tube 20 up side down and withdrawing the latch pin I08.

In the patent of Ramsey, referred to hereinbefore, three fuse tubes are provided which are arranged to be repeatedly connected into the circuit. That is, on the blowing of the fuse tube that is connected in the circuit, it drops out, as described, and in so doing closes a transfer switch which connects the next fuse tube into the circuit.

When the second fuse blows, it drops out and operates a transfer switch to connect the last fuse tube into the circuit. When the last fuse tube drops out, the circuit is not again reclosed. It will be understood that the present invention may be employed in connection with a repeating fuse structure, as disclosed in this patent of Ramsey, merely by the provision of two or more units with transfer switches arranged as required for completing the circuit through the next fuse when the preceding fuse blows.

Since certain further changes may be made in the foregoing construction and different embodiments 0f the invention may be made without departing from the scope thereof; it is intended that all matter shown in'the accompanying drawings or described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. A contact assembly for engagement with a terminal of a dropout fuse device comprising, in

carried by said backing member for contact engagement with said terminal, means biasing said contact fingers relative to said backing member,

means rockably supporting said backing member whereby close alignment is not required between the contact assembly and said dropout fuse device, a slotted arm carried by said backing member, and a guide arm carried by said fuse device having a portion for entering the slot in said arm for automatically centering said contact fingers with respect to said terminal on movement of the fuse device to the closed position.

2. A contact assembly for engagement with a terminal of a dropout fuse device comprising, in combination, a backing member, contact fingers carried by said backing member for contact engagement with said terminal, means biasing said contact fingers relative to said backing member,

a slotted arm carried by said backing member, and a guide arm carried by said fuse device having a portion for entering the slot in said arm for automatically centering said contact fingers with respect to said terminal in movement of the fuse device to the closed position.

3. A fuse switch comprising, in combination; a fuse tube having a terminal at its upper end; means for rockably mounting said fuse tube at its lower end; a contact assembly positioned adiacent the upper end of said fuse tube including a backing member, contact fingers carried by said backing member for contact engagement with spaced parts of said terminal, and spring means biasing said contact fingers relative to said backing member; means rockably supporting said backing member whereby close alignment is not required between said mounting means for said fuse tube and said contact assembly, a slotted arm carried by said backing member, and a guide arm carried by said terminal having a pin for entering the slot in said arm for automatically centering said contact fingers with respect to the terminal on movement of the fuse tube to the closed position.

4. A unitary hinge and contact assembly for supporting a fuse tube and establishing a circuit to a terminal thereon comprising, in combination, metallic support means rockably mounting said fuse tube, a fiexible resilient contact member carried by said support means and adapted to be engaged by said terminal, and means limiting the free movement of said contact member. 5. A unitary hinge and contact assembly for supporting a fuse tube and establishing a circuit to a terminal thereon comprising, in combination, metallic support means rockably mounting said fuse tube, a contact finger carried by said support means and adapted to be engaged by said terminal, resilient means biasing said contact finger, and stop means limiting the free movement of said contact finger under the infiuence of said biasing means.

6. A unitary hinge and contact assembly for supporting a fuse tube and establishing a circuit to a terminal thereon having trunnions extending from opposite sides and a contact arm extending therefrom comprising, in combination, a metallic housing open at the front for receiving said contact arm therein and having slotted openings in the side walls for receiving said trunnions, a contact finger carried by the rear wall of said housing for engaging said contact arm, resilient means biasing said contact finger, and stop means carried by said housing for limiting the free movement of said contact finge under the influence of said biasirg means.

7. A hinge and contact assembly for supporting a fuse tube and establishing a circuit to a terminal thereon having trunnions extending from opposite sides and a contact arm extending therefrom comprising in combination, a housing open at the front for receiving said contact arm therein and having slotted openings in the side walls for receiving said trunnions, an inverted U-shaped flexible contact finger having one leg secured to the rear wall of said housing and the other leg turned back on itself to provide a curved surface for engaging said contact arms, an inverted U-shaped leaf spring having one leg commonly secured with said one leg of said contact finger to said rear wall and the other leg engaging and biasing said other leg of said contact finger outwardly. and a stop pin extending between said side walls of said housing and through the opening formed by said turned back portion of said contact finger for limiting its free movement under the influence of said biasing means.

8. A fuse switch comprising, in combination, a fuse tube having terminals at its ends and adapted to be normally located in an upright position, support means for rockably mounting said fuse tube at its lower end, a flexible resilient contact member carried by said support means and adapted to be engaged by the lower terminal of said fuse tube, means limiting the free movement of said contact member, a backing member and means for supporting the same in insulated spaced 4 relation above said contact member, contact fingers carried by said backing member for contact engagement with the upper terminal of said fuse tube, means biasing said contact fingers relative to said backing member, and means rockably mounting said backing member on its support means whereby close alignment is not required between said contact fingers and said fuse tube.

9. A fuse switch comprising, in combination, a fuse tube having terminals at its ends and adapted to be normally located in an upright position, support means for rockably mounting said fuse tube at its lower end, a contact member carried by said support means, resilient means biasing said contact member into contact engagement with the lower terminal of said fuse tube when it occupies said upright position, stop means limiting the free movement of said contact member under the influence of said biasing means so that relatively small movement thereof takes place when said fuse tube moves from its upright position, a backing member and means for supporting the same in insulated spaced relation above said contact member, contact fingers carried by said backing member along its outer end portions for contact engagement with' spaced parts of the upper terminal of said fuse tube.

spring means biasing said contactfingers relative to said backing member, and means rockably mounting said backing member at its inner end on its support means whereby close alignment is not required between said support means.

10. A fuse switch comprising, in combination, a fuse tube having terminals at its ends and adapted to be normally located in an upright position, support means for rockably mounting said fuse tube at its lower end, a contact member carried by said support means, resilient means biasing said contact member into contact engagement with the lower terminal of said fuse tube when it occupies said upright position, stop means limiting the free movement of said contact member under the influence of said biasing means so that relatively small movement thereof takes place when said fuse tube moves from its upright position, a backing member and means for supporting the same in insulated spaced relation above said contact member, contact fingers carried by said backing member along its outer end portions for contact engagement with spaced parts of the upper terminal of said fuse tube, spring means biasing said contact fingers relative to said backing member, means rockably mounting said backing member at its inner end on its support means whereby close alignment is not required between said support means, and means carried by said backing member cooperating with means carried by said fuse tube for automatically centering said upper terminal with respect to said contact fingers on movement of said fuse tube to its upright position.

11. A fuse switch comprising, in combination, a

. fuse tube having terminals at its ends and adapted to be normally located in an upright position, support means for rockably mounting said fuse tube at its lower end, contact means movably mounted in insulated spaced relation above said support means for contact engagement with the upper terminal of said fuse tube, a slotted arm carried by said contact means, and a guide arm carried by said i'use tube having a portion for entering the slot in' said arm for automatically centering said contact means with respect to said upper terminal on movement of said fuse tube to the closed position.

12. A fuse switch comprising, in combination, a

fuse tube having terminals at its ends and adapted to be normally located in an upright position, support means for rockably mounting said fuse tube at its lower end, a backing member and means for supporting the same in insulated spaced relation above said support means, contact fingers carried by said backing member for contact engagement with the upper terminal of said fuse tube, a slotted arm carried by said backing member, and a guide arm carried by said fuse tube having a portion for entering the slot in said arm for automatically centering said contact fingers with respect to said upper terminal on movement of said fuse tube to the closed position.

13. A fuse switch comprising, in combination, a fuse tube having terminals at its ends and adapted to be normally located in an upright position, support means for rockably mounting said fuse tube at its lower end, a backing member and means for supporting the same in insulated spaced relation above said support means, contact fingers carried by said backing member for contact engagement with the upper terminal of said fuse tube, means biasing said contact fingers relative to said backing member, means rockably supporting said backing member whereby close alignment is not required between said backing member and said fuse tube, a slotted arm carried by said backing member, and a guide arm carried by said fuse tube having a portion for entering the slot in said arm for automatically centering said contact fingers with respect to said upper terminal on movement of said fuse tube to the closed position.

HUGH A. 'I'RIPLETT.

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