US1972958A - Oil fuse - Google Patents

Description

Sept. 11, 1934.

A. G. STEINMAYER ET AL 1,972,958

OIL FUSE Filed June 27, 1930 s sheets-sheet 1 Sept 11, 1934- A. G. sTElNMAYi-:R Er A1. 1,972,958

OIL FUSE Filed June 27, 1930 3 Sheets-Shea?l 2 Sept. 11, 1934.

A. G. sTElNMAYER Err A1. 1,972,958

OIL FUSE Filed June 27, 195o s sheets-sheet 3 Patented Sept. 11, 1934 isizsss OIL FUSE Alwin G. Steinmayer, Milwaukee, and William 0. Schultz, South Milwaukee, Wis., assignors to Line Material Company, Wis., a corporation of Dela South Milwaukee, yare Application June 27, 1930, serial Nu. 464,220

13 Claims.

This invention relates to oil fuses,

In oil fuses, as heretofore constructed, it has usually been necessary for the operator to be relatively close to the fuse when the circuit is closed and it has frequently happened that the closing 0i the circuit occurred when an excessive load eX- isted resulting in immediately blowing the fuse. From actual tests with diiierent types of oil fuses it has been found that the sudden generation of gas produced dangerous pressures which sometimes resulted in a violent explosion of the device, with flying metal fragments and heated or burning oil.

This invention is designed to overcome the defects noted above, and objects of this invention are to provide an oil fuse which may be operated by a switch stick or by remote control to open or close the circuit thereby allowing the operator or lineman to remain at a safe distance, which is so constructed that the device can be used also as a switch to open the circuit even under load, and which is provided with means insuring safety of operation under all conditions.

Further objects are to provide an oil fuse in which a novel arrangement of vents is provided for relieving the gas pressiu'e, in which discharge oi the gases from immediately adjacent the fused portion or from the switch contacts is provided,

n in which a direct path free from constriction is provided for discharging the gases without requiring the gases to pass along a circuitous or round about path, in which means are provided for guiding the gases directly to the vents, and in which double safety means are provided for venting the gases.

Further objects are to provide a construction which, in reality, combines both the features of a switch and fuse, which is positive in its closing 4 and opening action, which is positively locked in closed position, which is fully encased or housed, and which cannot blow open when the fuse blows.

Further objects are to provide a fuse switch in which the cover cannot be opened when the switch is in the locked or closed position, and in which the fuse switch cannot be closed when the cover is in the open position or in the unlocked position, but which can be closed only when the cover is closed and positively locked in closed position'. d0 A further object is to provide a'construction such as outlined immediately above which is so made that a special tool may be inserted to permit the closing of the fuse switch for testing purn poses while the cover .is open although under normal conditions and without the use of the ,(cl. 20o-114) special tool such closing of the fuse switch cannot occur when the cover is either open or unlocked.

Further objects are to provide a toggle action oil fuse switch in which the movable and stationary contacts are held in rm engagement under pressure by means of locking toggle mechanism, and in which a quick motion occurs both in opening and closing.

Further objects are to provide an oil fuse switch in which a block carries both the fuse and the movable contacts, in which the block is removable to permit ready renewal of the fuse while the block is removed from the rest of the mechanism, in which the block may be made of any suitable insulating material, whether brittle or not, as it is free from pressure bearing lugs or projections but is of a simple, easily molded shape, in which barriers carried by the block are so arranged that they guide the gases to the adjacent vents, in which a metallic pin or rod extends through the block and transmits the opening or closing force or pressure directly to the body of the block, in which the block itself has only sliding motion, and in which the pin or rod not only connects the fuse and Contact carrying block to the operating mechanism but also directly interlocks the block with the cover to prevent opening of the cover when the fuse switch is closed.

Further objects are to provide an oil fuse switch in which the pressure of the engaged contacts may be readily adjusted, in which a iitting provided with right and left threads is provided for securing this adjustment, and in which this fitting is readily accessible and may be both adjusted and locked in adjusted position after the fuse switch is completely assembled.

Further objects are to provide a construction of oil fuse in which the fuse has a double reduced section, in which the reduced sections are so located and positioned that very little heat conduction can occur, in which the bottom part of the fuse drops down upon fusing at the reduced sections, thereby producing a long gap in addition to that produced by the actual fusing, in which wrapped portions of the fuse link or element are provided to both reduce conduction and provide additional insulation' between the fuse link and the casing or other portions of the device so that even if the fuse is distorted at fusing undesirable contact cannot occur, and to provide such a construction that any suitableY conducting material such as the low melting alloys, aluminum, or any other metal, even copper,

may be employed ior the fuse link.

jon

Further objects are to provide a novel form of oil fuse switch which is so made that the cover can be opened by means of a switch stick, and which may, if desired, be so made that the vent pipes or members may be used as hangers during hoisting, or in another form suitable for underground installation, for instance, may have its vents piped to a common vent pipe provided with a down turned end, the vents being preferably downturned under all conditions to either shed water or to prevent water from rising into the casing.

Further objects are to provide a rugged, simple type of oil fuse switch which will handle large loads at high voltage, which maybe easily produced, and which is easy 'to operate;

While oil is the preferred liquid to belused in the apparatus, it is intended `that the use of the term oil is not to be construed as specifically limiting the invention other than as indicating a suitable insulating liquid.

An embodiment of the invention isshown in the accompanying drawings, in which:-

- Figure 1 is a vertical, sectional view through the device, such View corresponding to a section on the line 1-1 of Figure 2.

Figure 2 is a view of the device with the top sectioned oi and with some other parts of the apparatus in section. y

Figure 3 is a sectional view on theline 3-3 of Figure 2'.

Figure 4 is a fragmentary, Vsomewhat diagrammatic, sectional View corresponding roughly to the vsection line 4 4 of Figure 3, showing the relative position of the vents and of the active current carryingportion of the apparatus.

Figure 5 is an enlarged sectional view through the fuse carrying blocker movable block. y Figure 6 is a view of the fuse link laid out flat. Y

Figure 7 is a sectional view on the line 7-7 of Figure 2 showing the latch mechanism.

Referring to the drawings, it will be seen that the combined oil fuse and switch comprises f a movable block or member 1 which is formed of suitable insulating material andmay, if desired, be formed of porcelain, as no projecting, pressure bearing lugs are necessitated in this construction. This block is slidably mounted approximately j, centrally of the casing 2 and carries the movable Vcontacts 3, which are removably held to metal terminal blocks 4 and which are preferably provided with removable arcing strips 5, as shown most clearly in Figure 1. The terminal blocks 4 f are located on opposite sides of the'movable mem.-v

ber or block 1 and are eachcarried by means of an inwardly projecting metal arm 6, see Figure 3, which extends beneath overhanging shoulders formed 'on the insulating, movable block'l, and which are held in place by means of kscrews 7 accessible through openings 8 formed in the insulating movable blockV 1.V

VThe arms 6 carry downwardly extending lugs 9 which carry threaded stems l() adapted to rej ceive thumb nuts or clamping nuts indicated in dotted lines at 11 in Figure 3.

A removable fuse link'is held in contact with each of the lugs 9 by means of the thumb nuts 11. This removable fuse link is shown in Figures 1, 3,5 and 6, and comprises forked ends 12 adapted to straddle the threaded stems 10, so that the fuse may be readily renewed when needed. The fuse is provided with two reduced sections 13, and

preferably the intermediate portions of the fuseY are wrapped Ywith paper, ber, or other insulating material, which not only prevents inadvertent contact of the fuse with other portions of the apparatus in the event that the fuse blows and becomes distorted, but also prevents rapid con duction of heat from the fuse.

The reduced sections 13 of the fuse are located at the bottom corners of the lower portion 15 of the insulating Yblock 1. The central portion of the fuse is located immediately below the lower central portion of the fuse carrying, insulating block 1. Preferably the block 1 is provided with barriers 16 formed integrally therewith and projecting from opposite faces thereof, as shown in Figures Band 4. These barriers, it will be noted, are adjacent the movable contacts 3 and provide insulating portions located between the adjacent movable contacts and the fuse, as is most clearly shown in Figures 3 and 4. The barriers 16 extend outwardly substantially nush with the faces of the upper rectangular portion of the fuse block, as is apparent from such figures.

The movable contacts 3 are adapted to engage the flat stationary contacts 17, see Figures 1 and 3, when the block 1 is forced downwardly into its lowermost position, as shown in such figures.

The stationary contacts 17 are carried by in-V wardly projecting insulating members 18 which `are rigidly secured by means of screws 19 to in-` wardly projecting lugs 20 formed integrally with the casing 2, as shown most clearly in Figure 3. 1.11

It is Valso preferable to inset the heads of the screws 19 within apertures 21 formed in the'insulating members 18, and to correspondingly inset the heads of the screws 22 which hold the stationary contacts 17 in place within apertures 23 formed in the insulating members 18.V

These insulating members 18 are syrmnetrically placed on opposite sides adjacent the lower portion of the apparatus, and it is to be noted that the entire fuse link and the movable and stationary contacts are located well below the normal oil level, such as indicated at 24 in `Figure 3.

The rear end of each of the stationary contacts 17 is provided with a conductor or cable receiving socket 25, see Figure 3, within which the corresponding conductor or cable 26 is securely fixed.

The conductors or cables 26 extend upwardly adjacent the rear portion of the apparatus and are heavily insulated and pass outwardly through downwardly projecting pipe-like extensions 27, preferably formed integrally with the casing 2 and located on opposite sides thereof, as shown most Yclearly in Figures 2 and 3. If desired, in-

sulating bushings 28 may be provided for the outlet members 27 if the device is to be used out of doors, or else wiped lead joints are formed between the outlet members 27 and suitable lead pipes if the device is used underground.

It is to be noted that the interior of the casing 2 is insulated by means of a ber sheet 29 which lies againstY the interior faces or walls of the casing. Obviously, this ber sheet may be made of one portion orof several portions, as found most expedient in the manufacture of the apparatus. The lower portion of the fiber sheet is provided with a plurality of holes 30 which are spaced from a centrally located hole 31 formed in a bottom fiber sheet 32, see Figure 3. The centrally located hole 31 is immediately over the drain plug 33. The purpose of this construction is to prevent the striking of an arc from the fuse through any of the holes 30 to the metal portion of the casing. These holes 30, formed in the ber sheet, are staggered or spaced with reference to the hole 31 formed in the bottom fiber sheet 32.

The mechanism for operating the movable fuse carrying and contact carrying block l will now be described.

The block 1 is roughly of rectangula1 cross section, as has been previously indicated, and is provided with an aperture therethrough through which a transverse operating pin 34 projects, es shown in Figures 1, 2 and S, suitable washers and cotter pins or split ins being provided for loosely retaining the rod or pin 34 in place. This rod forms the sole means of communicating pressure or force to the movable block l and has a substantial contact area with the block. The block obviously may formed of any suitable insulating material, as previously described, and in View of the fact that it is free from projecting, pressure bearing ears or ugs, it is clear that there is no danger of cracking or breaking the block, even if the block is formed of relatively brittle material, such as porcelain. rlhe block l is loosely guided for vertical reciprocatory motion by means of a rear guide 35, see Figure 1, bolted to an in- 1 wardly projecting lug 36 of the casing 2, and by a forwardly located guide indicated in dotted lines at 37 in Figure 2, which is provided with an integrally formed bracket 3S. The guide 37 and its integrally formed bracket 38 are bolted Ito an inwardly projecting forward lug 39, see

Figures 1 and 2, formed integrally with the cas- Lng. The guides 35 and 37 are 'provided with oppositely located, inwardly turned flanges 4G and 41 respectively, see Figure 2, for preventing latN eral shifting of the slidable or rcciprocatory block 1.

The operating rod or pin 34, see Figure 1, is normally positioned within the forked arms 42 of a yokeshaped, bell. crank lever indicated generally at 43 in Figures 1, 2 and 3. It is to be noted from Figures 2 and 3 that the forked arms 42 are located on opposite sides of the insulating block and insure parallel motion for opposite ends of the pin or rod Se, thus freely lifting or depressing the slidable block 1 without danger of tilting such block.

The bell crank lever 43 is provided with spaced bearings be ween which the head 44 of an operating link is positioned, see Figure 2. This operating link has a forward head 45 pivoted between the ears of a short lever 45. The heads 44 and 45 of the connecting link are joined by means of a fitting consisting of a plug-like member 47 which threaded into the head 45 and which receives the threaded extension 48 of the head 44. Prefer'- ably the external and internal threads oi the fitting or member 47 are right and left hand threads, so that il' such member is rotated, the distance between the heads 45 and 4.4 of the composite connecting link may be readily adjusted. It is preferable to provide the fitting 47 with a nut-shaped portion 49 that may be engaged by a wrench during adjustment, and to provide a lock nut 50 for locking the device in place. This construction is very clearly shown in Figure 2.

The lever 46, see Figures 1 and 2, is rigidly mounted upon an operating rock shaft 51 carried in suitable bearings and projecting outwardly through the wall of the casing. A stuffing box is preferably provided for the shaft 51 and may consist of the packing gland 52 and any suitable packing 53, as shown in Figure 2, to prevent loss of oil. The outer end of the rock shaft 51 is provided with an operating lever 54, which is preferably apertured to receive the hooked end of a switch stick. Very obviously this operating lever may be connected by links and levers with a remete control lever, or with any other suitable remote control device.

It is to be noted from the description thus far given of the operating mechanism, that the levers 43 and 46 and the intermediate link joining such .evers constitute toggle mechanism, so that when the rock shaft 51 is rocked in a clockwise direction, the toggle mechanism is straightened out and slightly passes dead center to thereby force the forked arms 42 of the bell crank lever downwardly, thus carrying the insulating block 1 downwardly and forcing the movable contacts 3 into binding engagement with the stationary contacts 17. In order to prevent the toggle mechanism from passing beyond the predetermined locking position, a screw or stop member 55, see Figure 1, is carried by the lever 46 and engages a lip 56 formed integrally with the head 45 of the connecting link. This holds the toggle mechanism in locked position just past dead center and secures the positive locking of the combined fuse and switch in closed position.

It is preferable to provide some form of spring, such as coiled springs 57, see Figures 1 and 2, for urging the mechanism towards switch open position. These coiled springs 57 are preferably loosely wrapped about the pivot pins 58 which pivotally join the bell crank lever 43 to the bracket 38, the spaced arms of such bell crank lever being positioned between upwardly projecting lugs formed on the bracket 38, as shown in Figure 2. It is preferable to provide the pins 58 with heads at their inner ends, and to provide through remote control mechanism connected to 11."

the lever 54, or else by means of a switch stick, and at all times remain a considerable distance from the apparatus during the opening or closing of the switch.

The casing 2 is provided with a hinged cover L. preferably ribbed for strength, and provided with rearwardly projecting 52 pivoted bee tween ears 63 formed integrally with the casing as shown in Figures l and 2, the lugs 62 con stituting stops to hold the cover in open tion when it is upwardly just past center, as is obvious from an inspection of Figure Th cover Si is provided with a dar-.inwardly openinD channel within which packing 64 is positioned to thus seal against the upper edge of the casing' the cover is closed. The cover is also provided with projecting slotted ears 65, see Figure 1, which are adapted to receive the threaded locking bolts 56 pivot-ally carried by the casing and provided with clamping nuts 57. The clamping nuts 67 may, if desired, be provided with pivoted handles 68 in the usual manner. When the cover is closed. the pivoted bolts S5 are rocked into position. and the cover is clamped tightly to the casing by the nuts S7 in the well known manner.

The cover 6l is provided with a projecting, apertured tongue or ear 69, see Figure 1, which may be engaged by a switch stick when it is dcsired to open or close the cover.

Returning again to the operating mechanism,

it will be seen from Figures l and 2 that the lever 46 is provided' with an extension having an integral tongue or catch 7G which is projected inwardly when the switch is in closed position, but which extends downwardly when the mechanism is rocked to open position. Under certain conditions hereinafter described, the tongue 79 is adapted to be received within a hole 7l formed in a pivoted latch or lever 72, see Figures 2 and 7, which is pressed upwardly by means of a spring 73, see Figures l and 7.

The cover 6l is provided witha downwardly projecting iinger 74, see Figures l and 2, which, when the cover is locked in closed position, engages and dcpresses the latch or lever 72 and holds such latch out of engagement with the tongue 70, thereby permitting the switch to be readily closed. However, assuming that the switch is open and the cover is open, it is apparent that the switch cannot be closed, as the tongue is held by the latch 72 and motion of the switch operating mechanism is thereby prevented. However, when the cover is closed, the switch operating mechanism is free andmay be rocked to closed position.

It is also apparent that it is undesirable to open the cover while the switch is in closed position. This is readily prevented by providing the cover with hook-shaped downwardly and rearwardly projecting arms 75 which are in the path of the pinV Sli, see Figure l, when the cover is in closed position. In view of the fact that the switch is locked in closed position by the toggle mechanism, it is apparent that the cover is also locked closed due to the engagement of the hooked arms 75 with the pin 34, and consequently such cover cannot be opened until the switch is moved to open position. I

When the switch is moved to open position, it is clear that the pin 34 is suiciently raised to permit the cover to be rocked upwardly, the arms 75 being free of the pin.

It will be seen, therefore, that simple and reliable means have been provided for preventing the closing of the oil fuse switch when the cover is opened, for preventing opening of the cover when the oil fuse switch is closed,

lt is apparent, however, that :for testing piuposes a special tool may be used to depress the latch or lever 72 and permit the closing of the switch for testing purposes while the cover is open.- This, however, is not the normal operation of the apparatus, as is apparent from the immediately preceding description.

It is apparent that whatever liquid is used, as the insulating liquid within the combined fuse and switch apparatus, that gases will be generated either when the contacts are separated and the current iiowing or when the fuse blows under load. From actual experience with oil fuses, it has been found that the generation of gas is extremely sudden and that with certain designs oi oil fuses dangerous and even explosive pressures sometimes occur. This generation of pressure occurs with the utmost rapidity and is somewhat in the nature of'an explosion.

This invention provides an unrestricted, direct and free venting of the gases when the fuse blows.

The casing 2 is provided with upwardly slanting projections 75, see Figures 2 and 3, which form upwardly opening side chambers 77 which open directly into the fuse casing from opposite sides thereof and directly above the contacts, as may be seen from Figure 3. The location ci these vent chambers 77 is diagrammatically shown in Figure 4, and it will be seen from such gure that the gases generated by the blowing of the fuse, or the opening of the switch, pass directly into these chambers, the barriers or bailies 16, see

Figures 3 and 4, serving to somewhat separate the gases into two streams directed towards the venting chambers 77. From Figure 3 it is apparent that the-gases have a free passage upwardly to the vent-ing chambers and outwardly through the vent pipes 78. These vent pipes are arched and bent downwardly so as to shed water, and they may be turned either as shown in the drawings or laterally to each side o the apparatus, or, in fact, in any direction desired.

In view of the fact that the gases are provided free passage outwardly from adjacent each contracted portion 13 of the fuse link, it is apparent that, although the fuse may blow under heavy load, nevertheless no damage whatsoever can occur.

The construction illustrated in the drawings and described immediately above is the preferred construction for outdoor mounting. It is obvious that for underground mounting the vent pipes may communicate with a common pipe which may connect to other oil fuses of a similar construction. At all events, the end of the vent pipe or vent pipes is always turned downwardly so that, if water should collect in the manhole where the apparatus is positioned, air will be trapped within the casing and the water cannot rise upwardly through the downwardly extending vent pipes. This construction is not shown specically in the drawings, but it is obvious from the construction actually shown and described. v

Assume that the switch is in closed position and that the fuse blows or melts under load. It is apparent, from reference to Figure 5, that the contracted portions 13, which are only in contact with the insulating block at the extreme lower corners, will melt and allow the central portion to drop downwardly,. thereby materially increasing the length of the gap. The evolution of gases is readily taken care of by the vents described above, as free passage is aiorded on each side of the main or slidable block.

'When it is desired to renew the fuse, the cover cannot be opened until the mechanism is rocked to open position. This may be readily accomplished by a switch stick or by remote control, as previously described, and the cover may be opened by a switch stick, if desired. Thereafter the slidably mounted insulating block may be lifted directly upwardly, as it will clear all portions of the mechanism and as the pin or rod 34 will then pass directly upwardly from the upwardly positioned forked arms 42, see Figure 1, of the bell crank lever 43. This block may, therefore, be freely removed from the apparatus and a new fuse link substituted for the used link. Thereafter the block l is dropped back into place, the guides 35 and 37, see Figure 2, guiding the block downwardly into correct position, with ilhe pin or transverse rod 34 seating itself within the forkedV arms 42. However, the witch cannot be closed to put the fuse into circuit until the cover is locked in closed position, thereby holding the latch 72, see Figures l and 7, depressed. Under these conditions, however, the switch may be rocked to closed position.

When the device is initially assembled and adjusted, any desired pressure may be secured between the movable contacts 3 and the stationary contacts 17 after assembling the device by merely adjusting the tting 47, see Figures l and 2, thereafter locking such fitting with the lock nut 50.

Also, it is to be noted that when 'the toggle mechanism moves past dead center during opening motion, that the switch opens with a quick movement due to the springs 57, and consequently a quick break or quick opening movement is cured.

rEhe casing 2 may be obviously supported in any suitable manner, as by means of apertured brackets 79, see Figures l and 2, formed integrally with the casing. It is also apparent t-hat the device may be easily hoisted into position, the curved vent pipes 78 being used as hangers to facilitate this operation.

t is to be noted particularly that every active portion of the combined switch and oil fuse is adequately and fully insulated, and that no estrnctive arcing can occur.

The device is very simple, is eminently practical, and may be most easily manufactured, assembled and adjusted.

Although this invention has been described in considerable detail, it is to be understood that such description intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

We claim:

1. A fuse construction comprising a closed casing provided with a cover and adapted to receive oil, stationary contacts mounted within said casing, a block slidably mounted within said casing, movable contacts carried by said block and adapted to engage said stationary contacts, a fuse carried by said block and electrically `joining said movable contacts, and operating mechanism for longitudinally sliding said block with reference to said casing, said operating mechanism having a portion passing through said casing and maintaining an oil tight joint with said casing, said operating mechanism being operatively connected to said block and in one position permitting the direct removal of said block from said casing, said block at all times retaining its longitudinal axis in a iixed relation to said casing,

whether said cover is open or closed.

2. A fuse construction comprising a slidable block, a body portion, relatively stationary means carried by said body portion for guiding said block, stationary contacts carried by said body portion, a fuse carried by said block, movable contacts carried by said block and adapted to engage said stationary contacts and connected to opposite ends of said fuse, operating mechanism for sliding said block, said operating mechanism comprising a lever provided with forked ends, and means projecting from said block and normally seated within the forked ends of said lever, said lever in one position permitting the ready withdrawal of said block.

3. A fuse construction comprising a casing, guides carried within said casing, a pair of spaced stationary contacts carried within said casing, a block slidably guided by said guides, said block being adapted to move between said stationary contacts, movable contacts carried by said block for engaging said stationary contacts, a fuse carried by said block and connected at opposite ends to said movable contacts, a pin extending through said block, and operating mechanism comprising a lever provided with open forked end portions normally engaging said pin for sliding said block, said lever in one position having the open forked portions directed outwardly to permit the ready withdrawal of said block.

4. An oil fuse switch comprising a casing adapted to receive oil, stationary contacts mounted within said casing, a movable member provided with movable contacts adapted to engage said stationary contacts, a fuse carried by said mov-- able member, operating mechanism for moving the movable contacts into engagement with said stationary contacts, said operating mechanism including a pair of toggle links, said toggle links transmitting the force for initiating the opening and closing of said switch, and means bia g aid switch towards open position, said toggle links moving past dead center when said switch is closed.

5. An oil fuse switch comprising a casing adapted to contain oil, stationary contacts mounted within said casing, a movable member provided with movable contacts adapted to engage said stationary contacts, a fuse carried by said movable member and electrically joining said movable contacts, a pair of toggle links for operating sai-l movable member to force said movable contacts into engagement with said stationary contacts, said toggle links transmitting the force for initiating the opening and closing of said switch, and means biasing said switch towards open position, said toggle links moving past dead center when said switch is closed.

6. An oil fuse switch comprising a casing adapted to contain oil, stationary contacts mounted within said casing, a movable member provided with movable contacts adapted to engage said stationary contacts, a fuse carried by said movable member and electrically joinin aid movable contacts, and toggle links for operati able member to force said movable contacts into engagement with said stationary contacts, .said toggle links being adapted to pass dead center when said movable contacts engage said stationary contacts to cause binding action between said stationary and movable contacts, said toggle links transmitting the force for initiating the opening and closing motion of said switch.

7. An oil fuse comprising a casing adapted to contain oil, a pair of stationary contacts mounted within said casing in spaced relation to each other, a block of insulating material adapted to slide between said stationary contacts, a pair of movable contacts mounted on opposite sides of said block for engaging said stationary contacts when said block is slid between said stationary contacts, said `movable contacts being positioned above the bottom of said block, a fuse link joining said movable contacts and extending around the bottom of said block, toggle mechanism for sliding said block to cause engagement between said stationary and movable contacts, and means for adjusting the pressure exerted by said movable contacts upon said stationary contacts.

8. An oil fuse comprising a casing adapted to contain oil, a pair of stationary contacts mounted within said casing in spaced relation to each other, a block of insulating material adapted to slide between said stationary contacts, a pair of movable contacts mounted on opposite sides of said block for engaging said stationary contacts when said block is slid between said stationary contacts, said movable contacts being positioned above the bottom of said block, a fuse link joining said movable contacts and extending around the bottom of said block, toggle mechanism ior sliding said block to cause engagement between said stationary and movable contacts, and means for adjusting the pressure exerted by said movg said movj able contacts upon said stationary contacts, said means being carried by said toggle mechanism.

9. A fuse construction comprising a casing, stationary contacts mounted Within said casing, a block slidable With reference to said stationary contacts, movable contacts carried by said block, a fuse carried by said block and joining said movable contacts, toggle mechanism for moving said block to cause engagement between said movable and stationary contacts; and an adjustable ntting carried by said toggle mechanism and having right and left hand threads for adjusting the 'pressure exerted by said movable contacts upon said stationary contacts.

l0. A fuse construction comprising a casing, stationary contacts mounted within said casing, a movable member, movable contacts carried by said movable member and adapted to engage said stationary contacts, a fuse carried by said movable member and electrically joining said movable contacts, operating mechanism including toggle mechanism for moving said movable member, said operating mechanism having a rock shaft projecting through said casing, means positioned exteriorly of said casing -for rocking Said rock shait, said toggle mechanism being movable past dead center to lock said movable contacts in circuit closed position, said toggle mechanism transmitting the force from said rock shaft to said movable member.

11. An oil fuse comprising a casing adapted to contain oil, a block formed of insulating material and provided with barriers on opposite sides thereof, Contact means located on opposite sides of said block and mounted Within said casing, a fuse joining said contact means, and venting means formed in said casing on opposite sides thereof and adjacent said barriers, whereby two, free, unrestricted paths are provided for the'passage of gases from adjacent each barrier and on opposite sides of the said block.

12. An oil fuse comprising a casing adapted to contain oil, stationary contacts mounted within said casing adjacent opposite sides thereof, a movable member, movable contacts carried by said movable member for engaging said stationary contacts, a :fuse link having portions located on opposite sides oi said movable member and electrically joining said movable contacts, means for causing. engagement and disengagement of said movable and stationary contacts, and freely open venting means formed in opposite sides of said casing and openinginto said casing directly adjacent the sides of said movable member upon which the portions of said fuse are located.

13. An oil fuse comprising a casing adapted to contain oil, stationary contacts mounted Within said casing adjacent opposite sidesk thereo'an insulating blo-ck. movably mounted Within said casing, movable contacts carried by said block for engaging said stationary contacts, a fuse link joining said movable contacts and extending from opposite sides of said bloei: around the bottom of said block, means for moving said block to place said stationarj and movable contacts in engagement, said casing having vents opening on opposite sides thereof substantially directly above said contacts, and downwardly curved pipes communicating with said vents and projecting from opposite sides of said casing.

ALWIN G. STEINMAYER. WILLIAM O. SCHULTZ.

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