US2716681A

US2716681A - Circuit interrupting device

Info

Publication number: US2716681A
Application number: US388622A
Authority: US
Inventors: Jr Sidney R Smith
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1953-10-27
Filing date: 1953-10-27
Publication date: 1955-08-30
Anticipated expiration: 1972-08-30

Description

Aug. 30, 1955 s. R. SMITH, JR

CIRCUIT INTERRUPTING DEVICE Filed Oct. 27, 1955 [UL 61770)" Sid 7g ii 15 2 7, 15 17%? Hi5 flfforngg United States Patent Ofifice 2,716,681 Patented Aug. 30, 1955 r. 2,716,681 CIRCUIT INTERRUPTHNG DEVICE Sidney R. Smith, Jr., Stockbridgc, Mass., assignor to General Electric Company, a corporation of New York Application October 27, 19-53, Serial No. 388,622 6 Claims. (Ci. Zlld -Mll) This invention relates to a circuit interrupting device, and more particularly, to a circuit interrupting device or open type cutout having a fusible element adapted to interrupt an overcurrent in an electrical circuit and a load break mechanism whereby said electrical circuit can be manually interrupted without any exposed electrical arcing and without rupture of said fusible element.

In the electrical art it is well known practice to place an open type fuse cutout in the line or circuit of an electrical apparatus to protect said apparatus from overcurrents or the like. One form of said open type fuse cutout comprises an elongated insulator having two spaced terminal contact hardware portions. A fuse tube having two spaced contact portions spans said two spaced terminal contact hardware portions whereby said fuse tube contact portions make electrical contact with said terminal contact portions. A fusible portion positioned within said fuse tube completes the electrical circuit between said spaced terminal contact portions. If an overcurrent or the like occurs in said circuit, said fusible portion will be fused or ruptured whereby said circuit is interrupted.

In some forms of the above described open type fuse cutout the fuse tube is pivoted or hinged with respect to the terminal contact portions. Accordingly, when it is desired to discontinue operation of said apparatus, the line or circuit can be interrupted by manually pivoting or hinging said fuse tube away from said terminal contact portions. However, such a procedure is hazardous to the operator of the cutout and also results in a gradual corrosion and deterioration of said cutout. When the fuse tube is pivoted or hinged away a heavy arc is drawn between the separated fuse tube contacts and terminal contacts endangering the safety of the operator. Also, there is present a danger of a fiashover of said are to other adjacent metal hardware parts thereby causing a short circuit. Furthermore, said are results in a gradual corrosion and deterioration of said fuse tube contacts and terminal contact portions.

Accordingly, it is an object of this invention to provide a circuit interrupting device or open type cutout having a fusible portion adapted to interrupt an electric circuit upon an overcurrent therein and a load break mechanism whereby said electrical circuit can be interrupted manually without any exposed electrical arcing and without rupture of said fusible element.

My invention comprises a circuit interrupting device or open type cutout having two electrical insulating material tubular members, one end of each of said tubular mem: bers having a common metallic contact portion and said tubular members rigidly connected together at said common contact portion, the other end of each of said tubular members having a metallic contact portion thereon, said circuit interrupting device or open type cutout spanning two spaced metallic terminal contact portions and said other end contact portions engageable therewith for completing an electrical circuit therebetween, a fusible element within one of said tubular members electrically connecting said common contact portion to said one tubular member other end contact portion, and a manually actuatable circuit interrupting mechanism within the other of said other tubular members, said mechanism comprising a movable metallic contact disposed within said other tubular member adjacent said common contact portion and adapted to make electrical contact therewith,

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said movable contact electrically connected to said other tubular member other end contact portion and urged for movement ttowards said other tubular member other end contact portion for disassociation with said common contact portion whereby said electrical circuit can be manually interrupted without any exposed electrical arcing and without rupture of said fusible element, said fusible element and said manually actuatable circuit interrupting mechanism connected electrically in series in said electrical circuit.

The invention will be better understood by considering the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, Fig. l is a side view, partly in section, of a preferred form of my invention. Fig. 2 is a sectional view of the device shown in Fig. l, the section being taken along the line 2-2 of Fig. 1.

Referring now to the drawing, shown therein is a circuit interrupting device or open type cutout comprising an elongated insulator 10 carried by the cross arm of a pole line or the like, not shown, by a support bracket 11 extending from a central portion of insulator 10. Insulator ll) has mounted at opposite ends thereof. spaced terminal contact hardware. The upper terminal contact hardware comprises a U-shaped spring latch contact member 12, a fiat contact strip 13, and a line connecting member 14, said last mentioned three elements being electrically intercoimected. As will be obvious to those skilled in the art, member 12 is adapted to make latching contact with a metallic contact cap 15. Flat contact strip 13 is adapted to make electrical contact with the upper surface of contact cap 15. A spring backing strip 16 is superposed with respect to contact strip 13 and urges strip 13 downwardly for intimate electrical contact with contact cap 15.

The lower terminal contact hardware comprises a hinge contact member 17, a line connecting member 18, and a spring contact finger 19, said last mentioned three elements being electrically interconnected. Formed Within hinge member 17 are opposed bearing slots or apertures 20, only one of which is shown. Said slots or apertures 20 are adapted to receive opposed trunnions or pivot pins 21, only one of which is shown, of a fuse tube lower metallic contact portion 22.

Positioned closely adjacent to insulator 10 and along the side of insulator 10 opposite to the side of insulator 10 to which support bracket 11 is connected are two electrical insulating material electrical arc interrupting casings or

tubes

23 and 24 which span the terminal contact hardware mounted on the opposite ends of insulator 10 whereby an electrical, circuit is completed therebetween.

Tubular members

23 and 24 are constructed out of a material which will evolve a deionizing gas when subjected to an electrical arc or the heat thereof and extend generally parallel to each other whereby their axes lie substantially in only one common plane. The lower end of upper tube 23 is positioned adjacent to the upper end of lower fuse tube 24 with a common metallic contact portion 25 rigidly connecting said tubes together. As seen in the drawing, upper tube 23 is positioned in front of lower fuse tube 24 with the upper end of tube 23 and the lower end of fuse tube 24 extending in opposite directions.

The upper end of lower fuse tube 24 is closed by a contact cap 26 and the lower end of lower fuse tube 24 is open. Contact cap 26 is in electrical contact with common contact portion 25 inasmuch as contact cap 26 is threadably engaged with a metal sleeve 27 which in turn is in electrical contact with common contact portion 25. Positioned within fuse tube 24 is a fuse link 28 having a button head 29 at the upper end thereof clamped between contact cap 26 and a portion of metal sleeve 27. Fuse link 28 has a fusible portion, not shown, disposed within an auxiliary deionizing gas generating tube 30, as is well known in the art. The lower end of fuse link 28 extends out of the lower open end of fuse tube 24.

The tube or are interrupting

casing assembly

23, 24 is hinged or pivoted with respect to the upper and lower terminal contact hardware for hinged or pivotal opening and closing movement with respect thereto.

Tubular member assembly

23, 24 is hinged or pivotally connected at the lower end of fuse tube 24 to the lower terminal contact hardware by a toggle mechanism. Said toggle mechanism comprises a clamping means 31 embracing a lower portion of fuse tube 24 and fuse tube lower contact portion 22. As seen in the drawing, fuse tube contact portion 22 is generally L-shaped with the upright leg portion thereof pivoted to clamping means 31 at pivot point 32 disposed between fuse tube 24 and insulator 10. The opposite end of generally L-shapcd contact 22 is pivoted in bearing slots or apertures 2 3 by virtue of trunnions or pivot pins 25.. The lower end of fuse link 28 is tautly fastened to the lower contact portion 22 of fuse tube 24 whereby the lower end of fuse tube 24 will abut the upright leg portion of lower contact portion 22. If an overcurrent or the like occurs in the electrical circuit between the upper and lower terminal contact hardware the fusible portion, not shown, in fuse link 23 will fuse or rupture. When the fuse link 22 fuses or melts the current

interrupting tube assembly

23, 24 is free to move dou 'nwardly due to the downward pressure of spring backing strip 16 and pivotally away from generally L-shaped contact 22. Simultaneously, the lower contact portion 22 of fuse tube 24 is free to hinge or pivot clockwise away from electrical contact with spring contact finger 19. Downward movement of the

tube assembly

23, 24 with the respect to U-shaped spring latch contact member 12 will disengage contact cap l5 from said member 12 whereby the

tube assembly

23, 24 can rotate clockwise for dropout action. Accordingly, when an overcurrent. or the like occurs in the electrical circuit between the upper and lower terminal contact hardware portions, the

contact portions

15 and 22 will become disengaged from the upper terminal contact hardware portion and contact finger 19 respectively. During said dropout action or movement the lower fused end of fuse link 28 will be extracted out of the lower open end of fuse tube 24 whereby the electrical arc between the fused ends of fuse link 28 is elongated. The are struck between the fused ends of fuse link 28 will evolve a deionizing gas within auxiliary tube 3% which will aid in extinguishing said electrical arc. On comparatively heavy overcurrents auxiliary tube 31) will burst and said electrical arc will be placed in contact with the interior side walls of fuse tube 24 thereby generating a still larger quantity of deionizing gas to aid in extinguishing an electr cal arc established between the fused ends of fuse link 28. The deionizing gases generated within fuse tube 24 are expelled out of the lower open end of fuse tube 2 Positioned within the upper tube or are interrupting casing 23 is a manually actuatable arc bore follow rod circuit interrupting mechanism comprising a movable cylindrical metallic contact 33. Movable contact 33 is electrically connected with upper contact portion 15 of tubular member 23 and is continuously urged for movement within tube 23 towards the upper closed end of. tube 23. Electrical connection between movable con tact 33 and contact 15 is established by a flexible braided electrical conductor 34 connected at its lower end to an upper portion of movable contact 33 and at its upper end to a button head 35 which is in electrical contact with contact cap 15. The means for urging movable ceniact 33 away from the lower open end of current interrupting casing or tube 23 towards the closed upper end of tube 23 comprises a spring 36 connected at its opposite ends to movable contact 33 and button head 35.

Extending from a front surface of common contact portion 25 in a direction opposite to support bracket 11 are two opposed spaced metallic bearing arms 37. Mounted in bearing arms 37 is a metallic pin 38 pivotally carrying a metallic release lever or trigger finger 39. Lever or finger 3? is biased in a clockwise direction by 2. spring 40.

As seen in Fig. l, the right hand portion of common contact portion 25 is tubular with the lower endmost part of said tubular portion having an inwardly extending annular flange 41. The central aperture in annular flange 41 has a diameter substantially identical to the inner diameter of tube 23. Formed in the front portion of flange 41 or the portion of annular flange 41 most remote from insulator 10 is a radially extending slot 42. Formed in a. central portion of movable cylindrical contact 33 is a circumferentially extending groove 43. Accordingly, when movable contact 33 is disposed adjacent to the common contact portion 25 it is adapted for electrical contact with said common contact portion 25 inasmuch as spring 49 will urge lever or trigger 39 clockr'ise whereby the left hand tip or end of lever 39 will protrude into slot 42 and engage groove 43 to restrain movable contact 33 from being actuated inwardly of tube 23 due to the biasing action of spring 36. Connected to the lower end of cylindrical movable contact 33 is an electrical insulating material rod 44. The outer diameter of movable contact 33 and the outer diameter of insulating material rod 44 are substantially identical. However, the outer diameters of movable contact 33 and insulating material rod 44 are slightly less than the inner diameters of tube 23 and the aperture in annular flange 41 whereby when movable contact 33 and insulating material rod 44 move within tube 23 an annular arc bore or channel is defined between the exterior surface of insulating material rod 4-4 and the interior surface of tube 23. Rod 44 is constructed out of a material which will evolve a deionizing gas when subjected to an electrical are or the heat thereof.

In the closed position of my circuit interrupting device or open type cutout a series electrical circuit is completed from the upper terminal contact hardware through contact cap 15, button head 35', flexible braided conductor 34, movable contact 33, lever 39, common contact portion 35, sleeve 27, button head 29, fuse link 28, and contact portion 22, to the lower terminal contact hardware. 1 he upper end of tube 23 has an eyelet handle 45 adapted to be engaged by a switch stick or the like whereby said electrical circuit can be manually interrupted by pivoting the

tube assembly

23, 24 away from the upper and lower terminal contact hardware. However, if such a procedure is followed to interrupt the electrical circuit between the upper and lower terminal contact hardware as the

tube assembly

23, 24 is pivoted away from the upper and lower terminal contact hardware electrical arcing is established between the upper and lower terminal contact hardware and the contact portion on the upper end of tube 23 and the contact portion on the lower end of fuse tube 24. Said electrical arcing is dangerous to the operator of the circuit interrupting device or open type cutout. Also, if such electrical arcing should be permitted to be established, there is present a danger of a short circuit. For instance, as the upper end of tube 23 is withdrawn from the upper terminal contact hardware an electrical are established therebetween is elongated. Said elongated electrical arc may strike over to the support bracket hardware 11 thereby establishing a short circuit condition in the line. Also, electrical arcing between the upper and lower insulating member terminal contact hardware and the

contact portions

15 and 22 of the

tube assembly

23, 24 causes a gradual corrosion and deterioration of said contact portions and hardware.

Said dangers and gradual corrosion, above-mentioned, and discussed heretofore, are avoided by the arc bore follow rod circuit interrupting mechanism associated with upper tube 23. If it is desired to interrupt the electrical circuit an operator need only deflect the right hand portion of trigger or lever 39 upwardly against the clockwise biasing action of spring 4t). Counterclockwise rotation of trigger or lever 39 withdraws the left hand end or tip of trigger or lever 39 from slot 42 and from engagement with the movable contact 33. As soon as the left hand end of lever 39 and the groove 43 of movable contact 33 become disengaged the biasing means or spring 36 snaps the movable contact 33 and the insulating material rod 44 within the tube 33 towards the upper closed end of tube 23. As the movable contact 33 moves inwardly of tube 23 an electrical arc is established between movable contact 33 and the annular flange 4-1 or the left hand tip of trigger 39, or both. This electrical arc is elongated as movable contact 33 progresses inwardly of tube 23. With insulating material rod 44 disposed within tube 23 attendant to release of movable contact 33 said electrical arc is positioned within the annular arc channel or bore defined by the spaced interior surface of tube 23 and exterior surface of insulating material rod 44. Inasmuch as said elongated arc is in contact with the deionizing

gas generating materials

23 and 44 said are besides being elongated will be rapidly extinguished by the deionizing gas liberated from the interior side walls of tube 23 and exterior surface of insulating material rod 44. Accordingly, the electrical circuit between the spaced terminal contact hardware is interrupted within the tube 23 whereby no external or exposed electrical arcing is established attendant to interruption of said circuit.

Another advantage of my circuit interrupting device or open type cutout is that the fuse link 28 is not disturbed when it is desired merely to interrupt the line or electrical circuit of the apparatus protected by my circuit interrupting device or open type cutout, as when it is desired to discontinue operation of said apparatus. Also, in my circuit interrupting device or open type cutout no special fuse links are required. The fuse link 28 is a conventional fuse link commonly used in the form of open type cutout discussed hereinbefore on page 1. Additionally, in my circuit interrupting device or open type fuse cutout provision is made for dropout action of the

tube assembly

23, 24 upon the occurrence of an overcurrent resulting in a rupture of fuse link 28. Dropout action of the

tube assembly

23, 24 upon fusing of the fusible element 28 is desirable inasmuch as without said dropout action there is danger of current leakage along the

tube assembly

23 and 24 between the spaced upper and lower terminal contact hardware portions despite rupture of fuse link 28 whereby a short circuit may eventually be established. Following the same reasoning, after an operator interrupts the electrical circuit between the spaced terminal contact hardware portions the

tube assembly

23, 24 can be dropped open by pulling outwardly on the eyelet handle portion 45 to disassociate the

tube assembly

23, 24 from the terminal contact hardware portions.

While there has been shown and described a particular embodiment of the invention, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention, and that it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. A circuit interrupting device comprising two electrical insulating material electrical arc interruptin tubes, each of said tubes having a metallic contact portion at opposite ends thereof, the contact portion at one end of one of said tubes in electrical contact with the contact portion at one end of the other of said tubes, said tubes rigidly connected together adjacent said one end contact portion of said one member,

portions, the contact portions at the other ends of Said tubes spaced from each other, said tubes adapted to span two spaced metallic terminal contact portions whereby said other end contact portions make electrical contact with said terminal contact portions, said one tube having a fusible element therein electrically connecting the corn tact portions at opposite ends of said one tube, said other tube having a movable metallic contact therein, said movable contact disposed adjacent one of the contact portions of said other tube and adapted to make electrical contact therewith, said movable contact electrically connected by a flexible electrical conductor to another of the contact portions of said other tube and biased for movement inward of said other tube away from said one contact portion towards said another contact portion, said flexible electrical conductor and said fusible element connected in electrical series circuit relationship.

2. A circuit interrupting device comprising two electrical arc interrupting electrical insulating material tubes, one end of each of said tubes connected together by a common metallic contact portion and the other end of each of said tubes having a metallic contact portion thereon, said other end contact portions spaced from each other, said tubes adapted to span two spaced metallic terminal contact portions whereby said other end contact portions make electrical contact therewith, a fuse link within one of said tubes, said fuse link electrically connected at opposite ends thereof to said common contact portion and said other end contact portion of said one tube, a movable metallic contact within the other of said tubes disposed adjacent said common contact portion and adapted to make electrical contact therewith, said movable contact electrically connected to said other end contact portion of said other tube by a flexible electrical conductor, and means urging said movable contact inward of said other tube away from said common contact portion towards said other tube other end contact portion.

3. A circuit interrupting device comprising two electrical insulating material tubular members, one end of one of said members positioned behind one end of the other of said members and said members positioned substantially parallel to each other whereby the axes of said members lie substantially in only one common plane, said one ends rigidly connected together by a common metallic contact portion, the other ends of said members having a metallic contact portion thereon, said other ends extending in opposite directions from said one ends, said other end contact portions adapted to make electrical contact with two spaced metallic terminal contact portions, said two members having electrically conductive means therein for completing an electrical circuit between said terminal contact portions comprising a fuse link within one of said members electrically connected to said common contact portion and said other end contact said fuse link having a fusible portion fusible in response to an overcurrent in said electrical circuit, and said electrically conductive means comprising means within another of said members for manually interrupting said electrical circuit comprising a movable metallic contact within said another memher, said movable contact disposed adjacent said common contact portion and in electrical contact therewith, said movable contact electrically connected by a flexible electrical conductor to said other end contact portion of said another member, means biasing said movable contact for movement inward of said another member away from said common contact portion towards said other end contact portion of said another member whereby said movable contact is removed from electrical contact with said common contact portion, and means retaining said movable contact in electrical contact with said common con tact portion against the biasing action of said biasing means, said retaining means manually actuatable to release said movable contact for said inward movement by said biasing means.

4-. A circuit interrupting de ice comprising a generally upright upper electrical insulating material tube and a generally upright lower electrical insulating material tube, the lower end of said upper tube positioned behind the upper end of said lower tube, said ends rigidly connected together by a common metallic contact, said tubes disposed substantially parallel to each other, the axes of said tubes lying substantially in only one common plane, the upper end of said upper tube and the lower end of said lower tube having a metallic contact thereon, said upper tube upper end and said lower t ibe lower rid extending in opposite directions, two generally vertically spaced upper and lower metallic terminal contacts spanned by said tubes whereby said upper tube upper and lower tube lower contacts malie electrical contact with said two terminal contacts and said tubes having electrically conductive means therein to comp ete an electrical circuit between said terminal contacts, said tub -.ingcd to said lower terminal contact at said lower tube l er coutact for opening and closing movement with resvcct to said terminal contacts for opening and closing said electrical circuit. said electrically conductive means comprising a fuse link within said lower tube electrically con nected to said cot, on contact and said lower tube lower contact, said it link nav' g a fusible portion fusible in response to an evcrcurrent in said electrical circuit where by said tubes will be automatically hinged open with respect to said terminal contacts to open said electrical circuit upon the occurrence of an overcurrent therein, and said electrically conductive means comprising means within said upper tube for manually interrupting said electrical circuit without rupture of said fuse link comprising a move le metallic contact within said upper tube disposed adjacent said common contact and in electrical contact thc'ewith, said movable contact electrically connected by a flexible electrical conductor to said upper tube upper contact, means biasing said movable contact for movement inward of said upper tube towards said upper tube upper contact and away from electrical contact with said common contact, and means retaining said movable contact in electrical contact with said common contact against the biasing action of said biasing means, said retaining means manually actuatable to release of said movable contact for said inward movement by said biasing means,

5. A circuit interrupting device comprising an upright upper electrical insulating material tube and an upright lower electrical insulating material tube, the lower end of said upper tube positioned behind the upper end of said lower tube and a common metallic contact immovably uniting said tubes together at said ends, said tubes posi tioned substantially parallel to each other and having their axes lying substantially in only one common plane, the upper end of said upper tube and the lower end of said lower tube having a metallic contact thereon, said upper tube upper end and said lower tube lower end extending in opposite directions, fuse link within said lower tube connected at its opposite ends to said common contact and said lower tube lower end contact, said fuse link having a fusible portion, said upper tube having manually actuatable circuit interrupting means comprising a movable metallic contact disposed therein adjacent said common contact, said movable contact electrically connected by an electrical conductor to said upper tube upper end contact, means continuously urging said movable contact for movement within said upper tube towards said upper tube upper end, said common contact having a metallic trigger finger mounted thereon, a portion of said trigger finger cngageable with said movable contact whereby said movable contact is in electrical contact with said common contact and whereby said movable contact is restrained from movement within said upper tube towards said upper tube upper end by said urging means, said trigger linger manually actuatable to release said movable contact for movement towards said upper tube upper end.

6. A circuit interrupting device comprising an upright upper electrical insulating material tube and an upright lower electrical insulating material tube, the lower end of said upper tube positioned behind the upper end of said 5 lower tube and said tubes rigidly united together by a common metall c contact at said ends, the upper end of said upper tube and the lower end of said lower tube having metallic contact thereon, said tubes disposed parallel to each other and their axes lying in only one common plane,

it) said upper tube upper end and said lower tube lower end extending in opposite directions, said tubes spanning two vertically spaced metallic terminal contacts, said tubes pivoted to a. vertically lowermost of said terminal contacts at said lower tube lower end contact for engagement and 13 disengagement of said upper tube upper end contact with a vertically uppermost of said terminal contacts, said lower tube having its upper end closed and its lower end open, a fuse linl; within said lower tube connected at its opposite ends to said common contact and said lower tube ti l end contact, said fuse link having a rupturable fusible portion therein rupturable in response to an overcurrent in an electrical circuit, said tubes pivoted to said lowermost terminal contact by a toggle mechanism comprising said lower tube lower end contact whereby said upper 3 tube upper end contact will be automatically disengaged from said uppermost terminal contact upon rupture of said fusible portion, the upper end of said upper tube being closed and the lower end of said upper tube being open, d upper tube having a manually actuatable arc bore rollow red circuit interrupting mechanism cooperative therewith for manually interrupting said electrical circuit without rupture of said fusible portion and without disengagement of said upper tube upper end contact from said uppermost terminal contact comprising a cylindrical 5 movable metallic contact within said upper tube disposed adjacent said upper tube lower end, an electrical connection between an upper portion of said cylindrical movable contact and said upper tube upper end contact, a

cylindrical electrical insulating material rod rigidly connected to a lower portion of said cylindrical movable contact, said tubes and said rod constructed out of a material which will evolve a deionizing gas when subject to an electrical are or the heat thereof, said rod protruding out of said upper tube open end, said rod and cylindrical movable contact having an outer diameter slightly less than the internal diameter of said upper tube, biasing means urging said cylindrical movable contact and said rod for movement within said upper tube towards said upper tube closed end whereby an annular arc bore is defined between the interior surface of said upper tube and the exterior surface of said rod, metallic latch means mounted on said common contact and engageable with said cylindrical movable contact for placing said cylindrical movable contact in electrical contact with said common contact and for restraining movement of said cylindrical movable contact and rod within said upper tube towards said upper tube closed end, said latch means manually operable for releasing said cylindrical movable contact and rod for movement within said upper tube toln'l wards said upper tube closed end by said biasing means whereby an electrical are drawn between said movable contact and said common contact is confined within said annular bore whereby said electrical circuit is interrupted m without exposed electrical arcing.

References Cited in the file of this patent UNlTED STA. ES PATENTS 7n 22:9,084 Mosley Oct. 21, 1941 2,362,314 Schultz et al. Nov. 7, 1944 2,429,347 Earle et al. Oct. 2], 1947 1671342 Lindell Mar. 2, 1954 2,671,145 Lindell Mar. 2, 1954 2,709,736 Schneider May 31, 1955