US2462285A - Electrical switch - Google Patents

Description

Feb. 22, 1949. f N. J. REEs 2,462,285

ELECTRICAL SWITCH ATTORNEY Feb. 22, 1949. N. J. REE-S ELECTRICAL SWITCH 2 sheets-sheet 2Y Filed July 20, 1945 mvENToR Neo 'J. Rees zimw ATTORNEY Patented iqeb. 22, 1949 ELECTRICAL SWITCH Ned J. Rees, St. Louis, Mo., assignor to James R.

Kearney Corporation, St. Louis, Mo., a corporation of Missouri Application July 20, 1945, Serial No. 606,144

Claims. l

This invention relates generally to electrical switches, and more specifically to electrical switches of the type comprising movably supported switch blades movable into and out of electrical contact with contact means so as to complete or interrupt electrical circuits in which the switches are interposed, the predominant object of the invention being to provide such an electrical switch with improved, rapid operating means for quickly interrupting or breaking the circuit at a point remote from the contacts of the switch, with which the switch blade makes electrical contact, so as to protect said contacts and the switch blade from the injurious effects which would otherwise result from arcing when the switch blade would be drawn from the closedswitch position to the open-switch position.

Fig. 1 is a side-elevation of the improved electrical switch of the present invention.

Fig. 2 is a front elevation of the switch shown in Fig. 1.

Fig. 3 is a fragmentary plan view of the switch illustrated in Figs. 1 and 2, a part of the switch being shown in section.

Fig. 4 is a fragmentary view, shown partly in vertical section and partly in elevation, of the quick-break mechanism of the improved electrical switch.

Fig. 5 is an enlarged, vertical section of the lower portion of the quick-break mechanism shown in Fig. 4.

Fig. 6 is a perspective view of one of the contacts of the quick-break mechanism, shown in Figs. 4 .and 5.

Fig. '7 is a side elevation of the improved switch, on a reduced scale, showing the switch as it appears during initial movement of the switch blade thereof to the open-switch position.

Fig. 8 is a view similar to Fig. 7 but showing the switch blade of the switch in a more advanced position during opening movement of said switch blade.

In the drawings, wherein is shown for purposes of illustration, merely, one embodiment of the invention A designates the improved switch generally. The switch A comprises a suitable supporting member I on which is mounted a pair of insulators 2 and 3. The insulator 2 has xed thereto a terminal member 4 which is provided with an upwardly projected extension 4' to which an incoming conductor (not shown) may be connected mechanically and electrically by a suitable connector 4a. Also, the insulator 3 has fixed thereto a terminal member 5 having a downwardly projected extension 5' to which an outgoing y 2 electrical conductor (not shown) may be connected mechanically and electrically by a suitable connector 5a. The terminal 4 supports a contact structure i and the terminal 5 supports a similar contact structure 1, said contact structures being each made up of a plurality of resilient rod or wire elements, and said contact structures i and 1 being secured to the terminals 4 and 5 by suitable attaching means l.

The terminal member 5 is provided with spaced, forwardly projected extensions 9 which support a switch blade I0 for pivotal movement into and out of electrical contact `with the contact structures 6 and 1. The switch blade I0 has clamped thereto at its lower end a member II which is provided with a portion through which an opening is formed, a pivot pin I2 being extended through said opening and having opposed, outwardly extended end portions which are disposed in openings formed in the spaced extensions 9 of the terminal member 5. The pivot pin I2 is retained in position by cotter pinsl3 and said pivot pin supports the switch blade I0 for the pivotal movement described above.

The terminal member 4 at the upper end of the switch A is provided with spaced extensions I4 (Figs. l and 3) between which the rear portion of a switch blade latch I5 is disposed, said latch being pivotally attached to said spaced extensions I4 by a pivot pin I8, and a torsional coil spring I1 being provided which embraces the pivot pin I6 and has its opposite ends in engagement with portions of the terminal 4 and the latch so that the forward portion of said latch is urged downwardly by said torsional coil spring. The forward portion of the switch blade latch I5 is bifurcated, being provided with a pair of spaced arms I5' shaped, as shown at I8 in Fig. 1, to engage opposed, outwardly extended end portions of a pin I9 which is flxedly carried by the upper portion of the switch blade Ill. The spaced arms I5 of the latch I5 are joined at their rear ends by a bridge portion I5a, through which the pivot pin I8 extends, said bridge portion being cut away to provide a space in which the torsional coil spring I'l is disposed. Also, the bridge portion lia of the switch blade latch I5 is provided with an inclined cam face 20 which serves a purpose to be hereinafter set forth.

The pin I9, previously mentioned herein as the element whose outer extended portions are engaged by the switch blade latch I5 for latching the switch blade in the closed switch position. serves to pivotally attach to the switch blade a latch operating member 2|. The latch operating member 2| includes a portion having y spaced portions 22, as is shown to good advana. curved cam face 23 which is adapted to engage the cam face 20 of the bridge portion of the switch blade latch |5. The latch operating member 2l includes an eye 24 at its outer end, and when it is desired to operate the latch, the finger of a suitable switch stick is introduced into this eye and the outer end of the latch operating member is drawn downwardly. This causes the curved cam face 23 of the inner end portion of the latch operating member 2| to engage the cam face 20 of the latch -with the result that the outer portion of the latch is moved upwardly so that the spaced arms thereof are disengaged from the outwardly extended end portions of the pin I9. After such disengagement of the latch from the pin I9, downward and outward pull on the eye of the latch operating member with the aid of the switch stick will swing the switch blade on its pivot |2 to the open-switch position where said switch blade is disengaged from and is spaced with respect to the contact structures 6 and 1.

The switch A is provided with a quick-break mechanism which is designated generally by the reference character Q, said quick-break mechanism including a tubular structure 25 which is secured to the blade l0 of the switch A. The tubular structure 25 comprises an outer tube 26 which is attached rigidly to the switch blade I0 by means of a securing structure 21 that includes a portion 21a that embraces and engages the outer tube 26 of the tubular structure 25, and a stud 21h which is secured to the switch blade I0 and to said portion 21a as is shown in Fig. 2. Also, the outer tube 26 of the tubular structure 25 which is formed of suitable electrical insulating material, has fixed to its lower end portion a metallic cap 28 that embraces said lower portion of said outer tube 26. The cap 28 has formed thereon at one side thereof a boss 28' which is provided with a screwthreaded opening, said screwthreaded opening receiving a reduced, screwthreaded extension 29a of a metallic stud 29. At the end of the stud 29 opposite to the end thereof at which the extension 29a is located, another extension of reduced diameter is provided and this latter extension, which is designated by the reference character 29h, extends through the switch blade I0 and has a nut and washer assembly 30 applied thereto so as to mechanically secure the stud 29 and the cap 28 to the switch blade. The stud 29 serves not only to mechanically attach the cap 28 to the switch blade I6 but it also serves to electrically connect the cap 28 to said switch blade.

Secured to the outer tube 26 of the tubular structure 25, at the upper end thereof, is a cap 3| which is provided with a top wall through which a flanged opening is formed. The upper portion oi the outer tube 26 of the tubular structure 25 is embraced by the cap 3l (Fig. 4), and an edge of said outer tube 26` at the lower end thereof, abuts against a shoulder 28h formed within the cap 28. Also, fixed to the cap 28, located at the lower end of the tubular structure 25, is a discharge member 32 through which is formed a discharge passageway 32', said discharge passageway being of curved formation and being directed forwardly with respect to the switch A, with its upper end in communication with an opening 28a formed through the bottom wall of the cap 28, and its lower end open to atmosphere.

The Outer tube 26 of the tubular structure 25 has arranged therein an inner tubular member 33 which is formed of horn ber, or other material which is characterized by the ability to give off gas in the presence of, an electrical arc, the opening through said inner tubular member being of relatively small diameter when compared with the outside diameter of said inner tubular member so that a wall of substantial thickness is provided. The bottom face of the inner tubular member abuts against the shoulder 28' of the cap 28 at the lower end of the tubular structure 25, and the upper end of said inner tubular member is in contact with the top wall of the cap 3|, as is shown in Fig. 4, said inner tubular member being provided with an enlarged opening 34 in its upper portion.

Disposed-Within the opening through the inner tubular member 33 of the tubular structure 25 is a rod 35 which is produced by a plurality of rod sections suitably secured together to provide a continuous, unitary rod. In other words, the rod 35 includes an upper rod section 36 that is formed of metal and which is provided with a screwthreaded extension 36 at its lower end, said extension being screwed into an opening formed at the upper end of a rod section 31 which likewise is formed of metal. The screwthreaded extension 36' extends through a central opening of a disk 38, and said disk is clamped between the bottom edge of the rod section 36 and the top edge of the rod section 31 so as to be securely retained in position with respect to the rod 35.

The portion of the rod 35 below the rod Section 31 is made up of a plurality of rod sections 39, 40, 4| 42, and 43 which are formed of suitable insulating material, and a plurality of contacts 44, 45, 46, 41, and 48 which are formed of metal, or other suitable electrical conducting material. The plurality of rod sections 39, 40, 4|, 42 and 43, and the plurality of contacts 44, 45, 46, 41, and 48, are of substantially the same diameter as the rod sections 36 and 31, the contact 44 being interposed between adjacent ends of the rod sections 31 and 39, the contact 45 being interposed between adjacent ends of the rod sections 39 and 40, the contact 46 being interposed between adjacent ends of the rod sections 40 and 4I, the contact 41 being interposed between adjacent ends of the rod sections 4| and 42, and the contact 48 being interposed between adjacent ends of the rod sections 42 and 43. The rod sections 39, 40, 4|, and 42 are provided with alined openings which extend therethrough from end to end thereof, and the contacts 44, 45, 46, 41, and 48 are provided with openings formed centrally therethrough which are alined with the openings of said rod sections. The rod sections 39, 46, 4|, 42, and 43 and the contacts 44, 45, 46, 41, and 48, are secured together and to the rod section 31 by a connecting element 49 which is in the form of a slender rod formed of Bakelite, or other suitable electrical insulating material which extends through said rod sections and through said contacts. The connecting element 49 is screwthreaded at its opposite ends, the upper screwthreaded end portion thereof being screwed into a screwthreaded opening formed in the lower portion of the rod section 31, and the lower screwthreaded end portion of said connecting element having screwed thereon the lowermost rod section 43. which is provided with a screwthreaded opening that receives said lower screwthreaded end portion of said connecting element 49.

The inner tubular member 33 is provided with a plurality of cutaway portions which are located alternately at opposite sides of said inner tubular member, said cutaway portions being designated by the reference characters 50, 52, 53, and 54. Arranged in each of the cutaway portions 50, 5|, 52, and 53 is a contact means, the contact means located in the various cutaway portions 5|), 5|, 52, and 53 being designated, respectively, by the reference characters 55, 56, 51, and 58. Each of the contact means 55, 56, 51, and 58, comprises a strip of metal 60 to which are xed at points adjacent to its opposite ends inwardly projected contacts 6| that extend through transverse openings 62 formed in portions of the inner tubular member 33 so that said transverse openings communicate at their outer ends with the cutaway portions 56, 5|, 52, and 53 and at their inner ends with the opening formed through said inner tubular member. The strip of metal 60 of each contact means has associated therewith a leaf spring 63 of bowed formation, said leaf spring contacting at its opposite ends with said strip of metal 60 and having its intermediate portion in contact with a portion of the inner face of the outer tube 26 of the tubular structure 25. The leaf spring 63 of each contact means 55, 56, 51, and 58, forces the strip of metal of the contact means inwardly so as to force the inner end faces of the contacts 6| into close contacting engagement with the outer face of the rod 35 (see Fig. 5).

Additionally, a contact means 64 is arranged within the lowermost cutout portion 54 of the inner tubular member 33, this contact means comprising a strip of metal 65 from the upper end of which is extended a contact 66. The contact 66 of the contact means 64 projects through a transverse opening formed in the inner tubular member 33, and a bowed leaf spring 61, similar to the leaf springs 63 of the contact means 55, 56, 51, and 58, forces the strip of metal 65 of the contact means 64 inwardly so as to cause the inner end of the contact 66 to closely engage the outer face of the rod 35. The strip of metal 65 of the contact means 64 has soldered, or otherwise attached thereto, the upper end of a flexible conductor 68, the lower portion of said conductor 68 being extended through an opening formed through the lower portion of the cap 28, as shown in Fig. 5, and being soldered, or otherwise secured to said cap.

As will presently appear when the operation of the switch of the present invention is described herein, the rod 35 is adapted to move longitudinally of the tubular structure 25 to make and break electrical contact between the contacts 44, 45, 46, 41, and 48 of said rod 35, and the contacts 6| of the contact means 55, 56, 51, and 58 and the contact 66 of the contact means 64. Such movement of the rod 35 in one direction is produced by a coil spring 69 (Fig. 4) which is seated at its lower end against a portion of the inner tubular member 33 and at its upper end against the disk 38, said coil spring being under compression so that it tends to move the rod 35 upwardly. Also, the rod 35 has xed thereto, adjacent to its upper end, an abutment member 10 which embraces said rod, said abutment member being adapted to contact with the flange of the opening formed through the top wall of the cap 3| of the tubular structure 25 so as to limit downward movement of the rod 35.

Secured to an integral extension 1| of the upper terminal 4 of the switch A is a camming structure 12 which comprises a pair of resilient elements formed of metal. The resilient elements are provided with a curved portion 12a, and an upwardly and outwardly inclined camming portion 12b which serves a purpose to be hereinafter set forth. The resiliency of the resilient elements of the camming structure 12 tends to move the portions of said elements which are located outwardly of the point of attachment of said elements, in a downward direction, said resilient elements being moved upwardly, and being held in an elevated position, by contact with the lowermost resilient element of the upper end of the rod 35 (see Fig. 1).

When, in the use of the improved switch disclosed herein, the switch blade I0 is in the closedswitch position, where said switch blade is in electrical contact with the contact structures 6 and 1, the current path through the switch is made up of the upper terminal 4, the upper contact structure 6, the switch blade I0, the lower contact structure 1, and the lower terminal 5. Also, during such closed-switch condition of the switch, the upper end of the rod 35 is in contact with the camming structure 12 and the contacts 44, 45, 46, 41, and 46, of said rod 35 are in contact with the -contacts 6| of the contact means 55, 56, 51, and 58, and the Contact 66 of the contact means 64.

Let it be assumed now that it is desired to move the switch blade I0 to the open-switch position. To accomplish this the finger of a suitable switch stick is introduced into the eye of the latch operating member 2| and the outer portion of said latch operating member is drawn downwardly so as to elevate the forward portion of the switch blade latch |5 and disengage its spaced arms I5 from the pin I9 of the switch blade. The switch blade is then drawn downwardly and outwardly about its pivot I2. During its initial outward and downward movement the switch blade is` being moved outwardly with respect to the upper contact structure 6 of the switch, and during such initial movement of the switch blade the upper end of the rod 35 travels forwardly of the bottom face of the camming structure 12 in contact therewith, such contact being maintained by the forward portions of the resilient elements of said camming structure 12 moving downwardly so as to prevent upward movement of the rod 35 and thereby maintain the contacts 44, 45, 46, 41, and 48 of said rod in contact with the contacts of the contact means 55, 56, 51, 58, and 64.

When outward and downward movement of the switch blade has progressed a sufficient distance contact between the switch blade l0 and the upper contact structure 6 is broken, and the eiective current path is transferred to the quick-break mechanism Q, whereby no arcing is produced at the upper contact structure 6 when the switch blade is moved out of contact therewith. When the current path through the quick-break mechanism becomes the effective current path through the switch, the current passes from the upper terminal 4 to the camming structure 12 and from said camming structure to the rod sections 36 and 31 of the rod 35, and to the contact 44 of said rod 35. From the contact 44 of the rod 35 the current passes through the contact means 55 to the contact 45 of the rod 35, from the contact 45 of said rod 35-fby way of the contact means 56 to the contact .46 of said rod 35, from said contact 46 by way of the contact means 51 to the contact 41 of the rod 35, from said contact 41 by way of the contact means 58 to the contact 48 of said rod 35, and by way of the contact means 64 to the cap 28. From the cap 28 the current passes by way of the stud 29 to the switch blade I0 and from said switch blade to the lower contact structure 1 and to the lower terminal 5.

As the outward and downward movement of the upper end portion of the switch blade continues the upper end of the rod 35 will eventually y reach, and will travel beyond, the forward end of the curved portion 12a of the camming structure 12, and when this occurs the coil spring 69 will force said rod 35 upwardly with respect to the tubular structure 25. Such upward movement of 4the rod 35 will quickly move the contacts 44, 45,

46, 41, and 48 of said rod 35 out of contact with the contacts of the contact means 55, 56, 51, 58 and 64, whereby the current path through the quick-break mechanism Q will be interrupted at a plurality of points within the tubular structure 25 of said quick-break mechanism. It is to be noted that as the contacts 44, 45, 46, 41, and 48 of the rod 35 move upwardly away from the contacts of the contact means 55, 56, 51, 58, and 64, an arc will be produced between each rod contact and the contact from which it is separating. These arcs are elongated as the rod contacts move upwardly and they are forced, by the outer faces of the insulating rod sections 39, 40, 4l, 42,-and 43 into close contact with the wall of the opening formed through the inner tubular member 33, with the result that the gases produced by action of the arc on the horn fiber of said inner tubular member, will extinguish the arcs, said gases being eventually discharged from the tubular structure through the passageway 32 of the discharge member 32.

When the switch disclosed herein `is moved from the open-switch position to the closedswitch position, the sequence of operations described above are reversed. In other words, the outer end portion of the switch blade is moved upwardly and inwardly with the aid of a switch stick to cause the switch blade I to be latched in its closed switch position in engagement with the contact structures 6 and 1. Also, during such I upward and inward movement of the switch blade, the upper end of the rod 35 will engage the inclined portion 12b of the camming structure 12 and said rod will be moved downwardly within the tubular structure 25 so as to bring its contacts 44, 45, 46, 41, and 48, in contact engagement with the contacts of the contact means 55, 56, 51, 58, and 64, the upper end of the rod 35 riding under the curved portion 12a of the camming structure 12 with the result that said rod 35 will be retained in such position.

I claim:

1. An electrical switch assembly comprising a contact structure, a switch blade supported for movement into and out of contact engagement with respect to said contact structure, a quickbreak mechanism comprising a hollow structure supported by and movable with said switch blade. an elongated member arranged for movement within said hollow structure, said elongated member including a plurality of annular contact elements spaced longitudinally of said elongated member, tubular insulating members interposed between said contact elements for insulating said contact elements from each other, means for securing said contact elements and said insulating members together to produce said elongated member, a plurality of contact means associated with said hollow structure and electrically connected to said switch blade and into and out of contact with which said spaced contact elements of said elongated member are movable, each of said contact means comprising a plate having a contact extending therefrom laterally of said hollow structure, and resilient means for urging said plate inwardly toward said elongated member, and a member engaging said elongated member so as to retain said spaced contact elements thereof in,contact engagement with the contacts of said plurality of contact means associated with said hollow structure when said switch blade is in the closed-switch position and during initial opening movement of said switch bla-de, said elongated member being adapted to become disengaged from said member when a predetermined portion of the opening movement of said switch blade has been completed to permit said elongated member to move so as to disengage said spaced contact elements of said elongated member from the contacts of said plurality of contact means associated with said hollow structure.

2. An electrical switch assembly comprising a contact structure, a switch blade supported for movement into and'out of contact engagement with respect to said contact structure, a quickbreak mechanism comprising a hollow structure supported by and movable with said switch blade, an elongated member arranged for movement within said hollow structure, said elongated member including a plurality of annular contact elements spaced longitudinally of said elongated member, tubular insulating members interposed between said contact elements for insulating said contact elements from each other, means comprising a rod extended through said contact elements and said insulating members for securing said contact elements and said insulating members together to produce said elongated member, a plurality of contact means associated with said hollow structure and electrically connected to said `switch blade and into and out of contact with which said spaced contact elements of said elongated member are movable, each of said contact means comprising a plate having contacts extending therefrom laterally of said hollow structure, and a spring for urging said plate inwardly toward said elongated member, and a, rigidly anchored resilient member engaging said elongated member so as to retain said spaced contact elements thereof in contact engagement with the contacts of said plurality of contact means associated with said hollow structure when sai-d switch blade is in the closed-switch position and during initial. opening movement of said switch blade, said elongated member being adapted to become disengaged from said member when a predetermined portion of the opening movement of said switch blade has been completed to permit said elongated member to move so as to disengage said spaced contact elements of Asaid elongated member from the contacts of said plurality of contact means associated with said hollow structure.

3. An electrical switch assembly comprising a contact structure, a switch blade supported for movement into and out of contact engagement with respect to said contact structure, a quickbreak mechanism comprising a hollow structure supported by and movable with said switch blade, an elongated member arranged for movement 9 within said hollow structure, said elongated member including a plurality of annular contact elements spaced longitudinally of said elongated member, tubular insulating members interposed between said contact elements for insulating said contact elements from each other, means comprising a. rod extended through said contact elements and said insulating members for securing said contact elements and said insulating members together, said rod being connected at its opposite ends to end sections of said elongated member, a plurality of contact means associated with said hollow structure and electrically connected to said switch blade and into and out of contact with which said spaced contact elements of said elongated member are movable, each of said contact means comprising a plate having contacts extended therefrom laterally of said hollow structure, and a leaf spring for urging said plate inwardly toward said elongated member, and a rigidly anchored resilient member engaging said elongated member so as to retain said spaced contact elements thereof in contact engagement with the contacts of said plurality of contact means associated with said hollow structure when said switch blade is in the closed-switch position and during initial opening movement of said switch blade, said elongated member being adapted to become disengaged from said member when a predetermined portion of the opening movement of said switch blade has been completed to permit said elongated member to move so as to disengage said spaced contact elements of said elongated member from the contacts of said plurality of contact means associated with said hollow structure, said resilient member being provided with a camming portion which engages said elongated member and moves same within said hollow structure as said switch blade approaches the closed switch position so as to bring the contact elements of said elongated member into contact engagement with the contacts of said contact means within said hollowstructure.

4. An electrical switch assembly comprising a contact structure, a switch blade supported for movement into and out of contact engagement with respect to said contact structure, a quickbreak mechanism comprising a hollow structure supported by and movable with said switch blade, an elongated member arranged for movement within said hollow structure, said elongated member including a plurality of annular contact elements spaced longitudinally of said elongated member, tubular insulating members interposed between said contact elements for insulating said contact elements from each other, means comprising a rod extended through said contact elements and said insulating members for securing said contact elements and said insulating members together, said rod being screw-threadedly connected at its opposite ends to end sections of said elongated member, a plurality of contact means associated with said hollow structure and electrically connected to said switch blade and into and out of contact with which said spaced contact elements of said elongated member are movable, said plurality of contact means being disposed alternately at opposite sides of said hollow structure, said hollow structure comprising an outer tube an-d an inner tubular member supported within said outer tube, and each of said contact means comprising a plate having contacts extending therefrom laterally of said hollow structure through openings formed through said inner tubular member, and resilient means for urging said plate inwardly toward said elongated member, and a rigidly anchored resilient member engaging said elongated member so as to retain said spaced contact elements thereof in contact engagement with the contacts of said plurality of contact means associated with said hollow structure when said switch blade is in the closedswitch position and during initial opening movement of said switch blade, said elongated member being adapted to become disengaged from said member when a predetermined portion oi' the opening movement of said switch blade has been completed to permit said elongated member to move so as to disengage said spaced contact elements of said elongated member from the contacts of said plurality of contact means associated with said hollow structure, said resilient member being provided with a camming portion which engages said elongated member and moves same within said hollow structure as said switch blade approaches the closed switch position so as to bring the contact elements of said elongated member into contact engagement with the contacts of said contact means within said hollow structure.

5. An electrical switch assembly comprising a contact structure, a switch blade supported for movement into and out of contact engagement with respect to said contact structure, a quickbreak mechanism comprising a hollow structure supported by and movable with said switch blade, an elongated member arranged for movement within said hollow structure, said elongated member including a plurality of annular contact elements spaced longitudinally of said elongated member, tubular insulating members interposed between said contact elements for insulating said contact elements from each other, means for securing said contact elements and said insulating members together to produce said elongated member` a plurality of contact means associated with said hollow structure and electrically connected to said switch blade, and into and out oi' contact with which said spaced contact elements of said elongated member are movable, leaf springs for moving said contact means toward the outer face of said elongated member, said plurality of contact means being disposed alternately at opposite sides of said hollow structure and each of said plurality of contact means being in contact engagement with two of the contact elements of said elongated member, said hollow structure comprising an outer tube and an inner tubular member supported within said outer tube, and each of said contact means comprising a plate having contacts extending therefrom laterally of said hollow structure through openings formed through said inner tubular member, and a leaf spring for urging said plate inwardly toward said elongated member, and a, rigidly anchored resilient member engaging said elongated member so as to retain said spaced contact elements thereof in contact engagement with the contacts of said plurality of contact means associated with said hollow structure when said switch blade is in the closed-switch position and during initial opening movement of said switch blade, said elongated member being adapted to become disengaged from said member when a predetermined portion of the opening movement of said switch blade has been completed to permit said elongated member to move so as to disengage said spaced contact elements of said elongated member from the contacts of said plurality of contact means associated with said hollow structure, said said'elongated member into contact engagement with the contacts of said contact means within said hollow structure.

NED J. REES.

l2 REFERENCES CITED The following references are of record inthe file of this patent:

UNITED STATES PATENTS Number Name Date 649,554 Schwedtmann May 15, 1900 1,360,047 Stirling Nov. l23, 1920 1,706,158 Hendricks, Jr. Mar. 19, 1929

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