US2820123A - Molded switch head - Google Patents

Description

L: w. HIGGINS ETAL. 2,820,123

MOLDED SWITCH HEAD 3 Sheets-Sheet 1 A I V \w i Jan. 14, 1958 Filed May 18, 1956,

Jan. 14, 1958 L. w. HIGGINS ETAL 2,820,123

, MOLDED [SWITCH HEAD I Filed May 18, 1956 s Sheets-Shae z INVENTORS. Jay/y 4. #5001741! passe. 5 0411/5 4 I r I y Laws way/saws United States Patent MOLDED SWITCH HEAD Louis W. Higgins and Russell S. Davis, Detroit, and John A. Herrmanu, Grosse Pointe, Mich., assignors to BullDog Electric Products Company, Detroit, Mich., a corporation of West Virginia Application May 18, 1956, Serial No. 585,890

17 Claims. (Cl. 200149) This invention relates to improvements in molded switch heads of the type seen in Patent No. 2,287,676 to W. H. Frank et al. and Patent No. 2,302,849 to W. H.- Frank et al.

Switches of the above noted type in essence provide a first and second stationary contact which are engaged and disengaged by a movable contact element or slug. The contact slug is positioned within the switch head and the switch head is further constructed so as to move an insulating barrier between the stationary contacts as the contact slug is moved to a disengaged position. The head is further constructed so as to completely surround the area of contact engagement with an insulating means. Hence, as the switch head is moved to a disengaged contact position, arcing between the stationary contacts is decreased, first because of the interposition of the insulating barrier and secondly, because the amount of oxygen or ionizable gas present is restricted in view of the insulated enclosure around the contact area.

In the past, it has been the practice to attach an operating clamp to the top of the insulatnig material of the switch head, which operating clamp provides the means whereby the switch head is moved between the engaged and disengaged positions. This practice, however, places a. tension strain on the material of the switch head, which is not necessarily constructed to withstand this type of strain.

Furthermore, in the event of severe arcing it is possible that this insulating material would be damaged and there would then be no way in which the movable contact slug could be moved to a fully disengaged position with respect to the stationary contacts.

Our novel invention avoids the two disadvantages inherent in the presently used construction as above noted, by so constructing the operating clamp and switch head so that the operating clamp will tend to compress the material between the operating clamp and the contact slug when the switch head is moved to a disengaged position. In a preferred embodiment, this may be accom: plished by providing recesses in the side walls of the interior of the head casing within which the contact slug will be positioned and to provide recesses in the external surface of the head casing, whereby an operating clamp formed in any desirable manner as for example a spring wire may hook under a hollow protrusion in the said outer surface. In this construction, it is therefore seen that the spring wire of the operating clamp will be positioned beneath the protruding end of the slug which fits into the interior recesses of the head casing, and upon operation of this operating clamp to move the switch head to a disengaged position, the operating clamp wire will cause the casing material between the operating clamp and the slug projection to be in compression.

In view of this type construction, two advantages are immediately obtained. The first advantage is that the insulating material will be put into a compression strain during operation of the switch head and secondly, in the event of destruction due to severe arcs of the switch ice head insulation, it will still be possible for the operating clamp to engage the contact slug at its protruding ends and move this contact slug to a fully disengaged position.

Accordingly, a primary object of our invention is to provide a switch head construction wherein the insulated casing is put into a compression strain upon operation of the switch heads.

Another object of our invention is to provide a switch head wherein the operating clamp may engage the contact slug to move this slug to a disengaged position even though the insulating casing may be destroyed or broken.

Another object of our invention is to provide a contact slug for switch heads which has protruding ends positioned to be engaged through an insulating means by an operating clam-p.

Switching heads of the type to which our invention is directed, are usually provided with a spring biasing means for obtaining strong contact engagement between the movable and stationary contacts. Hence, the essentials of a switching head would comprise the insulated casing, the contact slug, the insulating barrier, the spring biasing means and the operating clamp. We have found that these components could be assembled in a novel manner which leads to the desirable features of simplicity, ease of manufacture, and long creepage distance between the current carrying elements, and the operating clamp which might be at a ground potential.

This novel construction comprises the features of making the insulated barrier an integral part of one half of the contact head insulating casing. The recesses above described in conjunction with the feature of allowing the switch head insulation to be in compression, are then further formed not only to side mount the contact slug, but to side mount the contact biasing spring as well. After placing these components in their respective positions, the other half of the insulated casing, which has cooperating recesses for the contact slug and biasing spring is then placed in a telescoping arrangement with the first half.

This second half is further formed to have a slot which will cooperate with the insulating barrier, to thereby decrease distortion and warpage under operating conditions.

Furthermore, the telescoping arrangement will provide a greatly increased creepage distance from the contact elements to the spring clamp which is subsequently fastened to the insulated head in the manner described above, and in a further manner, so as to maintain two telescoping connections in engagement with one another.

Another object of our invention is to provide a novel molded switch head construction which side mounts the components thereof, and physically secures these parts in a simplified manner.

Another object of our invention is to provide a molded switch head in which the insulating casing is formed of a first and second section, which are telescopically connected to one another and are held in their closed position by means of an operating clamp.

A still further object of our invention is to provide a molded switch head constructed of two telescoping halves, whereby the creepage distance between the contact structure and exterior parts of the switch head are relatively large.

In the past, the entire surface of the insulating barrier which follows the movable contact slug is in engagement with the entire surface of the fixed contact members or switch jaws.

A further object of our invention is to provide protrusions on the surface of the insulating barrier, which will maintain a portion of the surfaces of the switch jaws and insulating barrier at a predetermined distance, so

that foreign matter which might result in short circuits and damage to mechanical operating parts of the switch head may be confined within this space.

These and other objects of our invention will become apparent when taken in conjunction with the drawings in' which: I

Figure l shows an exploded perspective view of our novel switch head.

Figure 2' shows a perspective view of one of the tele scoping insulating casing sections of Figure 1.

Figure 3 shows a cross-sectional 'view' of the switch head of Figure 1 when assembled. v

Figure '4' shows a cross section view of Figure 3 when taken across the lines 4-4.

Figure 5 is similar to Figure 4 and shows the switch head in a disengaged position.

Figure 6 is a cross-sectional view of Figure 3 when taken across the lines 66.

Figure 7 is a side view of the assembled switch of Figure 1.

Figure 8 is a front exploded view of a second embodiment of our invention.

Figure 9 is a side view of Figure 8.

The exploded perspective view of Figure 1 clearly shows the five components of the switch head of our novel invention. These components are the first insulated casing section 20, a second insulated casing section 21, a contact slug 22, biasing means 23 and the operating clamp 24. Insulating section 21 is further shown in Figure 2, when seen looking into the interior thereof. It is seen in both of Figures 1 and 2, that the sections 21 and 22 are so molded to provide a ledge 25 and 26 respectively on which the surfaces 27 and 28 of the movable contact slug 22 may be seated. Similarly, each of sections 20 and 21 are provided with ledges such as 29 and 30 to seat portions 31 and 32 of the biasing spring 23 of Figure 1. The ledges 25, 26, 29 and 30 may be further seen in reference to Figure 3, which shows the relative positions of contact slug 22 and spring 23 with respect to these ledges.

As then shown in each of Figures 1, 4 and 5, the insulated casing section 20 contains the insulating barrier 33 as an integral portion thereof. This barrier 33 is provided with protrusions 34 and 35, which as will be shown hereinafter, are effective to prevent dirt or foreign particles from entering the contact area.

It is further seenwith reference to Figures 4 and 5, that the insulating barrier 33, in conjunction with the side surfaces 36- and 37, serves to position and guide the switch head with respect to the switch jaws 38 and 39 when moving the switch head to the on position of Figure 4. In order to achieve a more rigid construction and to allow resistance to distortion and warpage under operating conditions of the barrier 33, the second insu-l'ating. section 21,- which: has a protruding portion 40 which may be telescopically insertedinto the first section 20, is further provided with a notch. 41, which when the sections 20 and 21 are telescopically engaged, will receive aportion of the insulated barrier 33.

As'now seen in Figures 1 and 3, the outer surface of sections 20 and 21 is provided with: projecting abutments 42 and 43, which abutments internally receive the protruding portions of slug 22 which form the ledges 27 and 28. The operating clamp 24 of Figures 1 and 3, which may he formedof spring wire, includes a hook 44 and 45 at each side so as to engage the protruding abutments 42 and 43 in the manner shown in Figures 3 and 7. The top portion 46 of the operating clamp 24 is then so constructed as to be capable of receiving a .bar 47 which may be the common: operating. bar. for a plurality of switch heads.

Hence, the first feature of our novel switch head of 'simplicitpof manufacture is now'apparent since one need only insert the contact slug 22 and the spring biasing means 23 in their respective positions with respect to the first section 20 and thereafter'bring the second section 21 into its telescopic engagement with the first section 20. The operating clamp 24 is then brought into position as seen in Figures 3 and 7, so that it will serve the dual function of an operating means and a means to maintain the assembly fixed.

Figures 3 and 7 specifically illustrate our novel feature of constructing the operating clamp and switch head in such a manner that the insulating material of the switch head will be put in compression responsive. to operation of the operating means, and furthermore that although the insulating body of the switch head be destroyed, that operation of the operating means 24 will still be efiective to remove the contact slug 22. to a completely disengaged position with respect to the stationary contact members 38 and 39.

That is to say, the operating clamp 24 of Figures 3 and 7 is shown as being positioned beneath the abutments 42 and 43 of section 20, where protrusions 27 and 28 of contact slug 22 project into the abutments 42 and 43. Hence, if the switch head is to be moved to a disengaged or off position, spring portions 44 and 45 will operate on the contact slug portions 27 and 28 through the insulating material of section 20, to thereby place this insulating material in compression.

When moving the switch to the engaged or on position, the bar or bale 47 engages the top of member 20 and through surfaces 29 and 30 imparts a force to the biasing means 23 and contact slug 22, to the on position of Figure 4. Hence, in moving the switch head to the on position it is seen that the entire assembly is put into compression strain.

Furthermore, if the insulating material of the switch head section 20 be destroyed by severe arcing in the con.- tact area or breakage, it is seen that upon moving the operating member 24 to a disengaged position that portions 44 and 45 of the operating member 24 will come into physical contact with projections 27 and 28 of the contact slug 22 to thereby move this contact slug 22 to a completely engaged position with respect to the stationary contact 38 and 39.

Our novel switch head further provides a greater creepage distance from the contact area to the outer portions of the insulating body, such as the operating, clamp 24 by virtue of our novel telescoping arrangement. This may be seen with reference to Figure 6, which specifically shows the creepage distance as comprising a. path. across the surface of protusion 40 of the second insulatinghead section 21, and thereafter, to the outermost portions of the switch head. It is to be noted, that in past. arrangements, that the creepage due to telescoping. section was not provided and the creepage was merely that of one thickness of the insulation.

The operation of our novel switch head may be. seen in conjunction with Figures 4 and 5, wherein. Figure-4 shows the contact slug 22 in its engaged position. with respect to stationary conductors 38'and 39'.

When moving the contact engaged position, in. view of the enclosed construction around the area of contact disengagement, the amount of oxygen or ionized gases entering the enclosure will be restricted since the internal pressure caused by these gases will be higher than the external pressure and arcs will rapidly extinguish.

' Figures 4 and. 5 show a further novel feature of our invention which is based on the provision of the en.- larged sections 34 and 35 of the barrier member 33. it is clearly seen in Figures 4 and 5, that these enlargedsections provide spaces 50 and 51 between the surfaceof the barrier 33' and the surface of conductors '38 and .39. These spaces 50 and 51. are so positioned as to receive foreignmatter which would otherwise .act to gall, thecons tact surfaces of conductors '33 and '39 and contact slug 22 or result in short circuits between the various conductors. These spaces also allow for blistering or warping of barrier 33 under excessive heat conditions which would otherwise fracture the insulating material.

A second embodiment of this novel invention may be seen in the exploded front and side views of Figures 8 and 9 respectively. The embodiments of Figures 8 and 9 differs from that of the previous figure in that the insulating barrier following the contact slug is an integral part of the casing 61 while the contact slug 62 and biasing means 63 are side mounted in the casing 61 at the top of the housing. Hence, surfaces 64 and 65 of contact slug 62 are seated on ledges 66 and 67 of housing 61 while surfaces 68 and 69 of spring 63 are positioned on ledges 70 and 71 of housing 61.

The insertable head 72 is then connected in telescoping relationship with respect to the housing 61 so that when the unit is assembled surface 73 of insert 72 will be flush with the upper surface of the housing 61.

Fastened to the insert 72 is the plate 74 having the hook end 75 as an integral portion thereof which may be utilized for moving the switch head to a disengaged position.

A spring shaped clamp 76 is then connected to the plate 74 in any desired manner and is positioned under the protruding hollow portions 77 and 78 of the housing 61 when the insert 72 is in its closed telescoping relation with respect to the housing 61.

Hence, it is seen that in the case of Figures 8 and 9 as well as in the preceding figures, that when the switch head is moved to a disengaged position, the clamp 76 will place the material between it and the contact slug 62 in compression. Similarly, the embodiment of Figures 8 and 9 present the advantages of side mounting and the telescoping engagement between the two portions of the switch head housing.

In the foregoing, we have described our invention solely in connection with specific illustrative embodiments thereof. Since many variations and modifications of the invention will now be obvious to those skilled in the art, we prefer to be bound not by the specific disclosure herein contained but only by the appended claims.

We claim:

1. A switch head having an operating means for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section; a biasing means and a contact slug; said first insulating head section having depressions therein for receiving and positioning one end of said contact slug and biasing means; said second insulating head section being connectible to said first insulating head section; said second insulating head section having depressions therein for receiving and positioning the other end of said contact slug and biasing means when said first and second insulating head sections are connected; said biasing means being positioned to move stationary conductors into engagement with said contact slug when said switch head is moved to the engaged position; said operating means being connected to said switch head adjacent said depressions to place the portion of said switch head between said operating means and said contact slug in compression when said operating means moves said contact slug out of engagement with said first and second stationary conductors.

2. A switch head having an operating means for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section and a contact slug; said first insulating head section having depressions therein for receiving and positioning one end of said contact slug; said second insulating head section being connectible to said first insulating head section; said second insulating head section having depressions therein for receiving and positioning the other end of said contact slug when said first and second insulating head sections are connected; said operating means being connected to said switch head adjacent said depressions to place the portion of said switch head between said' operating means and said contact sing in compression when said operating means moves said contact slug out of engagement with said first and second stationary conductors.

3. A switch head for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section; an operating spring clamp, and a contact slug; said first insulating head section having depressions therein for receiving and positioning one end of said contact slug; said second insulating head section having depressions therein for receiving and positioning the other end of said contact slug when said first and second insulating head sections are connected; said operating spring clamp being constructed to move said switch head into and out of engagement; said operating spring clamp being connected to said switch head adjacent said depressions to thereby place the portion of said switch head between said operating spring clamp and said contact slug in compression when said operating spring clamp moves said contact slug'out of engagement with said first and second stationary conductor; said operating spring clamp being further constructed to maintain said first and second insulating head sections connected to one another.

4. A switch head having an operating means for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section and a contact slug; said first insulating head section having depressions therein for receiving and positioning one end of said contact slug; said second insulating head section being connectible to said first insulating head section; said second insulating head section having depressions therein for receiving and positioning the other end of said contact slug when said first and second insulating head sections are connected in telescoping relationship with respect to one another; said operating means being connected to said switch head adjacent said depressions to place the portion of said switch head between said operating means and said contact slug in compression when said operating means moves said contact slug out of engagement with said first and second stationary conductors.

5. A switch head having an operating means for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section, an insulating barrier and a contact slug; said first insulating head section having depressions therein for receiving and positioning said contact slug; said second insulating head section being connectible to said first insulating head section; said insulating barrier being constructed to follow said contact slug when said contact slug is moved to a disengaged position; said insulating barrier being an integral portion of said first insulating head section; said second insulating head section being constructed to have .a depression therein for receiving a portion of said insulating barrier when said first and second head sections are connected to one another; said'operating means being connected to said switch head adjacent said depressions to place the portion of said switch head between said operating means and said contact slug in compression when said operating means moves said contact slug out of engagement with said first and second stationary conductors.

6. A switch head having an operating means for mov ing a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section, an insulating barrier and a contact slug; said first insulating head section having depressions therein for receiving and positioning said contact slug; said second insulating head section being connectible in telescoping relationship to:.saidtfirst insulating head section; said insulating barrier beingconstructed to. follow said contact slug when said contact: slug is moved to a disengagedposition; said insulating barrier being an integral portion of said first insulating head section; said second insulating head section being constructed to have a depression therein for receiving a portion of said insulatingbarrier whensaid first and second head sections are connected to oneanother; said operating means being connected to said switch head adjacent said depressions to place the POI:- tionof said switch head between said operating'means and said contact slug in compression when said operating means .moves said contact slug out of engagement with said .first and. second stationary conductors.

7. A switch head having an operating spring clamp for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section and a contact slug; said first and second insulating head sections being connectible in-telescoping relationship to one another; said contact slug being mountedwithinsaid first and second insulating head section; said first and second insulating head sections being constructed to allow access of said contact slug to stationary contact members, said operating spring clamp being operatively connected to said. switch head to place theportion of said switch head between said operating spring clamp and said contact slug in compression when said operating spring clamp moves said contact slug out. of engagement withsaid first and secondstationary conductor.

8. A switch head for moving a contact slug intoand out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section, an operating springclamp and acontact slug; said first and second insulating head sections being connectible to one another; said contact slugv being mounted within said first and second insulating head section; said first and second insulating head sec tions being constructed to allow access of said contact slug-to stationary contact members; said operating spring clamp being. constructed to. move said switch head into and out of engagement; said operating spring clamp being operativelyconnected to. said switch head to place the portion of said switch head between said operating spring clamp. and said contact slug in compression when said operating. spring. clamp moves said contact slug out of engagement with said first and second stationary conductor; said operating spring clamp being further constructed to maintain said first and second insulating head sections connected to one another.

7 9. A. switch head for moving a. contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section, an operating spring clamp and. a: contact slug; said first and second insulating head sections being. connectible in telescoping relationship to one another; said contact slug being mounted within said first and second insulating head section; said first and secondinsulating head sections. being constructed to allow access of said contact. slug to: stationary contact members; said operating spring clamp being constructed to move said switch head into and out of engagement; said operating spring clamp being operatively connected to said switch head to place the portion of said switch head between said operating spring clamp and said contact sing in compression when said operating spring clamp moves said contact slug out of engagement with said first and second stationary conductor; said operating spring clamp being further constructed to maintain said first and second insulating head sections connected toone another.

101 A switch head 'for moving a contact slug intov and out. 'ofi engagement with a first and second stationary conductor; said? switch head comprising an insulating casing, an operating; means and a. contact slug; said contact slug being mounted within said insulated casing;

8 saidxinsulated casing being constructed to allow said contact slug access. to cooperating stationary conductors; said insulating. casing having anexternal protrusion; a portionof'saidcontact sing being positioned within said external protrusion;.saidoperating means being connected to said protrusion to, place the material of said insulating casing betweensaid operating means andsaid portion of said. contact slug in compression when said operating meansmoves. said switch head to a disengaged position.

ll. .A-tswitch head for moving a contact slug into and out of engagement with a firstandsecond stationary conductorasaid switchvhead comprising an-insulating casing, an operating means and a contact slug; said contact slug being mounted within said insulated: casing; said insulated: casing being constructed to allow said contact slug accessto cooperatingsta-tionary conductors; said insulating casing having-an external protrusion; a portion of said contact slug; being positioned within said external protrusiomsa-idioperating-meansbeing connected to said protrusion-to place the materialof said insulating casing between saidwoperating means and said portion of said contact: slug incompression when said operating means moves. said switch head to a disengaged position; said operating-means; being engageable with said. portion of said contact slug in the absenceof said insulating material between saidtoperating means and saidcontact slug portion.

12. Aswitchhead'for moving a contact slug into and out of, engagement with a first and second stationary conductor; said switchzheadcomprising an insulating casing, an operatingspring clamp andia contact slug; said conitactxslug being mounted within said insulating casing; said insulating casing being constructed to allow said contact slugaccess tolcooperating stationary conductors;

said insulating; casing having. a: first andisecond external protrusion; a first. and second portion of said contact slug' being positioned. within said first and second protrusions respectively; said operating spring clamp being operatively connected to said first and second protrusions to place the material of said insulating casing between said contact slug. and; said. operating spring clamp in compression when said operating, spring clamp moves said switch head toua disengaged position.

13. A switchtlreadfor-moving acontact slug into and out of engagementwitlr a first and'second stationary conductor; said switch head. comprising an insulating casing, an operating spring clamp and a. contact slug; said contact slug being mounted Wlii'llfi said insulating casing; said insulating-casing: having a first and second external protrusion; a first andseccnd. portion of said contact slug being. positionediwithin said first and second protrusions respectively;said2operatingspring clamp being operatively connected to said first and second protrusions to place the material. of said insulating. casing between said contact slug. and said, operating spring clamp in compression when said operating spring clamp moves said switch head to a disengaged positiomsaid. insulating casing comprising a first andsecond: section connected in telescoping relationship;.said operatingspring clamp being further constructed to maintain said first and second sections in their sai-dtelescoping relationship.

14. A switch head for movinga, contact slug into and out of engagement with: a first and second stationary conductor; said switch head comprising a first and second insulating head section and a contact slug; said first insulating head section having depressions therein for receiving and positioning one end of said contact slug; said second insulating head section being connectible to said first insulating head section; said second insulating head section having depressions therein for receiving and positioning the other end of said contact slug when said first and second insulating head sections are connected; said. first and second insulating head sections having a first and secondv protrusion respectively; a first and second portion of said contact slug being positioned within said first and second protrusions respectively; an operating spring clamp; said operating spring clamp being operatively connected to said first and second protrusions to place the material of said insulating casing between said contact slug and said operating spring clamp in compression when said operating spring clamp moves said switch head to a disengaged position.

15. A switch head for moving a contact slug into and out of engagement with a first and sec-ond stationary conductor; said switch head comprising a first and second insulating head section and a contact slug; said first insulating head section having depressions therein for receiving and positioning one end of said contact slug; said second insulating head section being connectible to said first insulating head section; said second insulating head section having depressions therein for receiving and positioning the other end of said contact slug when said first and second insulating head sections are connected; said first and second insulating head sections having a first and second protrusion respectively; a first and second portion of said contact slug being positioned within said first and second protrusions respectively; an operating spring clamp; said operating spring clamp being operatively connected to said first and second protrusions to place the material of said insulating casing between said contact slug and said operating spring clamp in compression when said operating spring clamp moves said switch head to a disengaged position; said operating spring clamp being constructed to move said switch head into and out of engagement; said operating spring clamp being further constructed to maintain said first and second insulating head sections connected to one another.

16. A switch head for moving a contact slug into and out of engagement with a first and second conductor; said switch head comprising an insulating .casing having a contact slug and an insulating barrier mounted therein; said insulating barrier being positioned with respect to said contact slug to follow said contact slug when said contact slug is moved to a disengaged position; said insulating barrier having a first surface adjacent to the area to be filled by said first conductor and a second surface adjacent to the area to be filled by said second conductor; said first and second surfaces of said insulating barrier having depressions therein to provide spacing of at least a portion of said first and second surface of said insulating barrier and at least a portion of conductors moved into said area to be filled by first and second conductors; said contact slug being moved into and out of engagement with said first and second conductors without said first and second conductors entering said spacing.

17. A switch head for moving a contact slug into and out of engagement with a first and second stationary conductor; said switch head comprising a first and second insulating head section, an insulating barrier and a contact slug; said first insulating head section having depressions therein for receiving and positioning said contact slug; said second insulating head being connectible to said first insulating head section; said insulating barrier being constructed to follow said contact slug when said contact slug is moved to a disengaged position; said insulating barrier being an integral portion of said first insulating head section; said second insulating head section being constructed to have a depression therein for receiving a portion of said insulating barrier when said first and second head sections are connected to one another; said insulating barrier having a first surface adjacent to the area to be filled by said first conductor and a second surface adjacent to the area to be filled by said second conductor; said first and second surfaces of said insulating barrier having depressions therein to provide spacing of at least a portion of said first and second surface of said insulating barrier and at least a portion of conductors moved into said area to be filled by first and second conductors; said contact slug being moved into and out of engagement with said first and second conductors without said first and second conductors entering said spacing.

References Cited in the file of this patent UNITED STATES PATENTS 1,951,297 Von Norman Mar. 13, 1934 2,130,589 Lantz Sept. 20, 1938 2,230,428 Frank Feb. 4, 1941 2,287,676 Frank et a1. June 23, 1942 2,393,385 Lankmeier Jan. 22, 1946 2,561,450 Russell July 24, 1951

Images