US3499126A - Electrical contact assembly with ramp guide - Google Patents

Description

(PRIOR ART) March 3, 1970 JONES ETAL 3,499,125

ELECTRICAL CONTACT ASSEMBLY WITH RAMP GUIDE Filed July 24, 1968 2 Sheets-Sheet 1 Fig.1

JN VE IV 7035 E DWARD A. JONES JAMES A. KRUSE ATTORNEY yE/VT H SCOPACK BY 7,! W

March 3, 1970 E. A. JONES ETA!- 3,499,126

I ELECTRICAL CONTACT ASSEMBLY WITH RAMP GUIDE Filed July 24, 1968 2 Sheets-Sheet 2 Fig. 5

. 3 o o 52 90 I TZ [1%, 44' A 46' 9O 48' A [E 42' i! 36' 7 7e 40' 38' 80 M Q INVENTOES EDWARD A. JONES JAMES A. KRUSE V/NCENT H SCOPACK ATTORNEY United States Patent O 3,499,126 ELECTRICAL CONTACT ASSEMBLY WITH RAMP GUIDE Edward A. Jones, Sylmar, Calif., Vincent H. Scopack,

Colorado Springs, Colo., and James A. Kruse, Woodland Hills, Calif., assignors to Litton Precision Products, Inc., Beverly Hills, Calif., a corporation of Delaware Filed July 24, 1968, Ser. No. 747,280 Int. Cl. H01h 15/00 US. Cl. 200-16 9 Claims ABSTRACT OF THE DISCLOSURE An improved electrical contact assembly is disclosed. The assembly comprises three fixed contact elements positioned in two grooves; two of the fixed contact elements have portions aligned with one of the grooves while the third fixed contact is positioned Within the other groove. Two slidable contact elements move within the grooves, one in each groove for making and breaking electrical contact with the fixed contact elements. A guide ramp is provided adjacent the groove containing the two fixed contact elements for supporting that grooves slidable contact element between electrical contact with either fixed contact element and for providing positive disengagement of the slidable contact element from the fixed contact elements.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to electrical contact assemblies for use in electrical switches and more particularly to electrical contact assemblies wherein camming' action provides for positive contact element disengagement.

Description of the prior art Electrical switch assemblies of the multi-circuit type employing a plurality of fixed contact elements supported on an insulative base and cooperating with a plurality of slidable spring finger contact elements have been used in the electrical and electronic fields to provide multicircuit switching and are usually manually actuated, as for example, by a pushbutton. Such a device is shown and described in US. Patent No. 3,329,792 to E. A. Jones, et al. and assigned to the assignee of the present invention. This particular switch includes a contact assembly having a plurality of fixed contact elements on a cylindrical insulative base, the base having a plurality of longitudinal peripheral grooves. Disposed about the fixed contact is a plurality of slidable spring finger contact elements. The spring finger contact elements are longitudinally moveable from a first or extended position to a second or contracted position; in each of the first and second positions the slidable spring finger contact elements engage a different set of fixed contact elements thereby providing a switching function by changes between the two positions.

While the switch described and illustrated in the abovementioned patent has performed well after extended usage, certain problems have been found that must be overcome to provide a more universally adaptable switch. For instance, when the switch is connected to an energized external circuit electrical arcing may result when the slidable spring finger contact element are removed from the fixed contact element in order to open the circuit. Arcing causes pitting of the fixed contact elements at the edge where the sliding contact element separates from the fixed contact element when the sliding contact element breaks connection. The pitting may cause an earlier break in the circuit which may be, in certain situations, intolerable.

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Another problem of concern has been the migration of the material comprising the fixed contact onto a normally insulated area due to a smearing action of the slidable contact elements and due to electrical arcing. Thus, under the migration situation the electrical contact elements tend to remain electrically closed longer than desirable since electrically conductive material has been deposited'on the formerly all insulative material. Such an extension of the electrical engagement period may be undesirable when a break before make switching condition is required, i.e., the opening of one circuit must occur before the closing of a second circuit.

An additional concern which relates to any manufactured device is its complexity and hence its manufacturing costs. In the above-mentioned patent the method of manufacturing the switch required that the fixed contacts be installed in a mold and held in place during the molding operation of the cylindrical insulative base. Since the contact elements may be relatively small and relativelynumerous a mislocation or misalignment of the contact elements necessitated a rejection of the entire subassembly.

SUMMARY OF THE INVENTION The foregoing problems and disadvantages of the prior art contact assemblies have been overcome with the present invention by providing an electrical switch contact assembly comprising first, second and third fixed contact elements, first and second connected slidable contact elements, a nonconductive base for supporting the first, second and third fixed contact elements wherein the first and second fixed contact elements are aligned to be alternately contacted by the first slidable contact element and the third fixed contact element is disposed to be contacted by the second slidable contact element, means for guiding and supporting the first slidable contact element between alternate contact with the first and second fixed contact elements and surface means for contacting said guiding and supporting means, said surface means connected to said first slidable contact element supported by the base support means and covering at least a portion of the base means, a slidable electrical contact for selectively engaging the fixed contact and a guide means for selectively supporting the slidable contact whereby the slidable contact is moveable along the guide means for selectively making and breaking engagement with the fixed contact.

An object of the present invention is to provide a new and improved electrical contact assembly which is relatively simple to construct and exceedingly reliable in making and/or breaking electrical engagement.

Another object of the subject invention is to provide a new and improved electrical contact assembly which provides for positive removal of the slidable contact element from contact with the fixed contact element so as to prevent migration problems.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective View of a prior art arrangement of fixed contact elements in contact with an array of slidable contact elements.

FIG. 2 is a perspective view of a preferred embodiment and illustrates fixed contact elements in contact with slidable contact elements and including a guide means or ramp.

FIG. 3 is a perspective view of another preferred embodiment illustrating one fixed contact element, one slidable contact element and a corresponding guide means.

FIG. 4 is a perspective view of an embodiment very similar in structure to that shown in FIG. 3 except illustrating a fixed contact element providing the opposite electrical make-break sequence.

3 FIG. 5 is a side view of a fully assembled switch with a pushbutton actuator.

FIG. 6 is an enlarged partially broken away side view of a portion of a switch as shown in FIG. 5 illustrating the fixed and slidable contact elements shown in FIG. 2.

FIG. 7 is an enlarged partially broken away side view of a portion of a switch as shown in FIG. 5 illustrating the fixed and slidable contact elements shown in FIGS. 3 and 4.

FIG. 8 is an exploded side view of the portion of the switch illustrated in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 there is shown a prior art array of contact elements comprising three fixed contact elements 10, 12 and 14 and three slidable contact elements 16, 18 and 20 that are constructed of strips of spring material, commonly referred to as spring finger contact elements which are connected by a common lateral arm 22. The fixed contact elements 10, 12 and 14 are mounted upon an insulative support, portions of which are designated 24 and 26 with which the fixed contact elements and 14 are respectively aligned so as to form a flush surface. The slidable contact elements 16, 18 and 20 are movable along a longitudinal path from a first position as shown in FIG. 1 where the slidable contact elements 16, 18 and 20 contact respectively insulative portion 24, fixed contant element 12 and fixed contact element 14, to a second position (not shown) in which the slidable contact elements 16, 18 and 20 contact respectively, fixed contact element 10, fixed contact element 12 and insulative portion 26. It is to be understood that the slidable contact elements move from their first position to their second position simply by sliding longitudinally; i.e. in the direction of extension of each slidable contact element.

It is seen that slidable contact elements 16 and 20 make and break electrical contact during their movement from the first position to the second position; essentially, it is the breaking of electrical contact that causes the problem of electrical arcing. For example, as slidable contact element 20 is moved from the first position wherein it engages fixed contact element 14 to the second position wherein it engages the insulative portion 26, an electrical arc may develop between the edge portion 28 of contact element 14 and the slidable contact element 20. The arcing will cause a minute area on the fixed contact to reach an extremely high temperature which results in the pitting of that'area. Pitting is a major problem because of the slow deterioration of the fixed contact; good electrical engagement becomes uncertain as does the point of electrical break.

Additionally, the electrical arcing and sliding movement of the slidable contact element cause migration of the material of the fixed contact element along the path traversed by the slidable contact element. In the embodiment of FIG. 1 (when moving from the first position to the second position) the slidable contact element 20 breaks contact with the fixed contact element 14 before the slidable contact element 16 contacts fixed contact element 10. A shorthand expression for the above mentioned switching sequence is break-before-make. It becomes apparent that migration of the material of the fixed contact element 14 beyond the edge portion 28 onto the insulative portion 26 will cause an extension of electrical contact time of the slidable contact element 20 and the fixed contact element 14. Hence, after a period of usage the switch will change to a makebefore-break arrangement and thus go into a failure mode. In a like fashion, movement of the slidable contact element 16 from the second position to the first position will cause migration of the material of the fixed contact element 10 onto the insulative portion 24.

Structurally, the fixed contact element 10 is embedded in the in ulative base (which may be a cylindrical supporting body having a plurality of fixed contact elements embedded within grooves extending along its periphery) so that its top surface and the surface of insulative portion 24 are substantially flush, enabling an easy sliding motion of the slidable contact element 16. When the insulative base is made of a moldable plastic, the usual method of manufacturing requires that the fixed contact element positioned before and maintained in that position during the molding of the base. Since the fixed and slidable contact elements are usually relatively small and since positioning items in a molding process inherently causes manufacturing difficulties, the structure shown in FIG. 1 is difficult to produce, causes higher manufacturing costs and is responsible for an undesirably high rejection rate, since a misplaced, mislocated or misaligned fixed contact element causes rejection of the entire molded structure.

Referring now to FIG. 2 an array of cooperating fixed and slidable contact elements is illustrated to overcome the problems'of the prior art and comprises three fixed contact elements 36, 38 and 40 and two slidable contact elements 30 and 32 which are connected by an arm 34. It is to be noted that fixed contact element 36 has a hook portion 42 (better seen in FIG. 8, designated 42) so that the fixed contact element 38 and the hook portion 42 of the fixed elongated element 36 are longitudinally aligned along the elongated path that the slidable contact element 30 traverses from a first position to a second position as explained above in connection with FIG. 1.

However, unlike the FIG. 1 embodiment the improved contact assembly of FIG. 2 includes a cam in the form of a guide ramp 44 which may comprise a level surface 46 and two sloping surfaces 48 and 50 and is adapted to support the slidable contact element 30 during a portion of its movement from its first to second positions. To conveniently achieve the support of the slidable contact element 30 a lateral portion 52 preforming the function of a cam follower is connected to the slidable contact element 30. The cam follower 52 extends like an outstretched arm to slide along the guide ramp 44 so as to cause positive disengagement of the slidable contact element 30 from the hook portion 42 when the slidable contact element is moving from its first position to its second position and to cause positive disengagement of the slidable contact element from the fixed contact 38 when the slidable contact element is moving from its second position to its first position. The positive disenagement will eliminate fixed contact element material migration and greatly reduce the effects of electrical arcing.

Referring now to FIG. 5 there is illustrated a common cylindrical switch configuration. The switch is mounted to a panel 60 and comprises a spring biased pushbutton actuator 62 which is directly connected to the slidable contact elements (not shown in FIG. 5) causing the slidable contact elements to be moveable between their first and second positions.

The engagement of the fixed and slidable contact elements takes place within housing 64 with the electrical signals being passed from the fixed contact elements to pins 66 which may be integral extensions of'the fixed contact elements. As shown the switch may be adapted to be plugged into a socket receptacle 68 having terminal pins 70' which may be adapted to connect to a Wiring harness (not shown).

Referring now to FIG. 6 there is shown an enlarged partially broken away portion of a switch configuration as shown in FIG. 5 and located within the housing 64. Briefly, pins 66 are shown supported by a base support 76 with three of the pins integral with the three fixed contact elements 36, 38' and 40'. (The prime numbers in FIG. 6 designate elements which correspond to the elements shown in FIG. 2.) It is noted that the fixed contact element 36' has a hook portion 42' which is ali ned longitudinally with the fixed contact element 38'. Slidably disposed on the fixed contact elements are two slidable contact elements 30' and 32' with slidable contact element 30' having a lateral portion 52 for slidably engaging and being supported by a guide ramp 44.

In more detail, and referring to FIG. 8 in addition to FIG. 6, the base support 76 comprises a generally cylindrical body of insulative material such as moldable plastic having two portions. A first portion includes a shoulder 78 and a cylindrical plate 80 each having an annular array of apertures (not shown) while the second portion comprises a cylindrical body 82 having a plurality of longitudinal grooves 83 about its periphery extending from a first end 84 to the shoulder 78 and in alignment with the apertures through the shoulder 78 and the plate 80. The grooves form elongated paths which define and confine the movement of the slidable contact elements 30 and 32'. As exemplified by the fixed contact elements 36', 38 and 40', a plurality of such fixed contact elements are disposed in the grooves about the body 82 and are organized to form groups of three. In a like fashion the slidable contact elements and disposed about the body 82 and are grouped in pairs, each pair to correspond to a group of three fixed contact elements. This gives the switch its multi-circuit characteristics.

It is to be noted that a large number of various combinations of fixed and slidable contact elements may be used, for example, if the fixed contact elements form groups of two, a single-pole, single-throw switch operation is achieved. If, as shown in FIG. 2, the fixed contact elements form a single group of three, a singlepole double-throw switch operation is achieved. If a pair of the three-group fixed contact elements is used, as well as a pair of two-group slidable contact elements, a double-pole, double-throw switch arrangement is achieved. A variety of other combinations of fixed and slidable contact elements may be included and as the number of contact elements increase or decrease, so may the diameter of the body 82. By adjusting the relative longitudinal lengths or positions of the fixed contact elements switching action may be multipolar break-before-make or make-before-break or any other desired arrangement.

Disposed immediately adjacent and paralleling the grooves 83 in which accommodates the fixed contact elements of each group corresponding to fixed contact element 38' and hook portion 42 of fixed contact element 36 are cams exemplified by the guide ramp 44. The guide ramp may be formed about the periphery of body 82 and located between selected grooves (not shown) or may be formed on a second element as shown in FIGS. 6 and 8 such as a cylindrical shaped base cap 90 of insulative material having a plurality of longitudinal slots 91 and a plurality of guide ramps 44'. The base cap 90 may be positioned about the body 82 with the longitudinal slots 91 aligned over or opposite the grooves 83 containing the fixed contact elements while the guide ramps 44 are psitioned adjacent the grooves in which hook portions 42' and fixed contact elements 38 are situated.

In operation of the switch the pushbutton actuator 62, FIG. 5, is usually spring biased in the position as shown in FIG. so that the slidable contact elements 30' and 32, FIG. 6 are located in their first position with slidable contact elements 30' and 32 engaging or contacting respectively hook portion 42' and fixed contact element 40 providing an electrical connection between the fixed contact elements 36 and 40 by way of the slidable contact elements and the arm 34. When the pushbutton actuator 62 (FIG. 5) is depressed the slidable contact elements 30 and 32' assume their second position shown in dashed lines with slidable contact elements 30 and 32' engaging respectively fixed contacts 38' and 40 wherein electrical connection is made between the fixed contact elements 38' and 40. It is to be noted that during the movement of the slidable contact elements between the first and second positions the lateral portion 52' will engage the guide ramp 44' causing a positive disengagement of the slidable contact element 30' from either the fixed contact element 38' or the hook portion 42 of the fixed contact element 36'. During movement from the first to the second positions the lateral portion 52' slides up sloping surface 50 along level surface 46' and down sloping surface 48. When moving from the second to the first positions, the sliding motion of the lateral portion 52 is reversed.

A preferred method of manufacturing the electrical switch of the embodiment shown in FIG. 6 may best be viewed in FIG. 8 and comprises forming the base sup port means 76 of plastic which may be injection molded into a configuration including the plate 80 having a plurality of apertures, the shoulder 78 integral therewith and the aperture extending therethrough and the body portion 82 having the plurality of longitudinal peripheral grooves 83. The fixed contact elements 36, 38 and 40 of FIG. 2 may be stamped from sheet metal and inserted into their respective grooves. As shown in FIGS. 2 and 6 the fixed contact elements and the pins 66 are made integral. Union is achieved by slidably inserting each contact-pin stamping into a groove and through the aligned apertures in the shoulder 78 and the plate 80. It is noted in FIG. 2 that the contact-pin stampings have a slight bend 92 which is formed to abut an interior angular flange (not shown) formed in the plate 80 so as to prevent further longitudinal movement of the fixed contact-pin stamping in the direction of the plate 80. Next, the base cap having its plurality of longitudinal slots 91 and plurality of guide ramps such as exemplified by 44 is positioned about the body 82 with the slots aligning opposite the grooves for exposing the fixed contact elements and with the guide ramps aligning adjacent the grooves having the fixed contact elements 38' and hook portion 42 disposed therein.

Referring now to FIG. 3 there is shown a portion of an embodiment which differs from that described above and comprises a fixed contact element similar in structure to the fixed contact element 40 of FIG. 2 but having an opening 102 through a portion remote from a bend 103 of the fixed contact element 100. Located adjacent to the opening and parallel thereto is a guide ra-mp 104 having a level surface 106 and a sloped surface 108. A slidable contact element 110 is supported by the surface 106 of the guide ramp 104 and is shown oppositely disposed from the opening 102 of the fixed contact element so that no electrical engagement is made with the fixed contact 100'. The slidable contact element 110 is movable from a first position as shown in FIG. 3 in which it is supported by the guide ramp 104 and out of engagement with the fixed contact element 100 to a second position as shown in dashed lines and designated 112 wherein the slidable contact element makes electrical contact with the fixed contact element 100.

Referring now to FIG. 4 there is illustrated a fixed Contact element 114 having an opening 116 which is adjacent a bend 117. A guide ramp 118 having a level surface 119 and a sloped surface 121 is oppositely arranged from that shown in FIG. 3 so that when a slidable contact element (not shown) is in its first position it is in electrical contact with the fixed contact element 114; when the slidable contact element is in its second position it is supported by the guide ramp 118, and is oppositely disposed from the opening 116 and thus out of electrical contact with the fixed contact element 114. It is noted that in FIGS. 3 and 4, the flat surfaces 106 and 119 are adjacent the openings 102 and 116 respectively though the surface 119 is nearer the bend 117 than is the surface 106 to the bend 103. Thus, the fixed contact element 100 is roughly analogous to the fixed contact element 38 in the FIG. 2 embodiment while the fixed contact element 114 is roughly analogous to the fixed contact element 36.

Referring now to FIG. 7 there is shown the slidable and fixed contacts of FIGS. 3 and 4 in the form of an array so as to provide the same switching characteristics as explained for the embodiment shown in FIG. 6. The switch comprises a group of three fixed contact elements 100, 120' and 114. (Note that the prime numbers in FIG. 7 correspond to corresponding numbers in FIGS. 3 and 4.) Fixed contact element 114' has an elongated opening 116 While fixed contact element 100 has an elongated opening 102; the openings 102 and 116 are longitudinally misaligned as will be more fully explained below. Moveably disposed to selectively engage the fixed contacts are three slidable contact elements 121, 122 and 124 all of which are electrically connected to each other by an arm 126. As illustrated, the array of slidable contact elements are moveable between first and second positions so that in a first position slidable contact element 124 engages fixed contact element 114 thereby making electrical connection, slidable contact element 122 electrically engages fixed contact element 120 while slidable contact element 121 is disposed opposite aperture 102' and is supported by the guide ramp 118'; hence, when the slidable contact elements are in their first position electrical engagement is made between the fixed contact element 120 and the fixed contact element 114'. In the second position as shown in dashed lines the slideable contact element 124 is supported by a guide ramp 104' and is located opposite the aperture 116 so as to be out of engagement with the fixed contact element 114 while slidable contact element 122 electrically engages the fixed contact element 120 and the slidable contact element 121 electrically engages fixed contact element 100 so that the fixed contact element 120 is electrically connected to the fixed contact element 100'. The location of the openings, one in each of the positions of the slidable contact elements, illustrates the meaning of the term longitudinally misaligned. As is explained above with regard to the FIG. 6 embodiment the guide ramps shown in FIG. 7 selectively support the respective slidable contact elemerits so as to positively disengage the slidable contact elements from the fixed contact elements thereby preventing fixed contact element material migration and reducing the effects of electrical arcing.

In more detail, the FIG. 7 embodiment comprises a base support means 130 similar in structure to the base support means 76 of the FIG. 6 embodiment having a plate 132, a shoulder 134 both having aligned apertures therethrough, and an upper body 136 having a plurality of longitudinal peripheral grooves which receive the fixed contact elements.

In manufacturing the FIG. 7 embodiment it may be preferable to form the guide ramps adjacent to and parallel with the grooves receiving the fixed contacts 100 and 114' in one molding operation so as toobviate the need for a base cap as was disclosed for the FIG. 6 embodiment (though a base cap may be used if desired), The fixed contact elements may be stamped as was described for the FIG. 6 embodiment so as to form a contact-pin combination which may be inserted into the respective grooves and through the apertures of the plate 132 and the shoulder 134 as explained above in regard to the FIG. 6 embodiment.

, It is to be understood that while a limited number of embodiments have been disclosed herein for purposes of illustration, various changes can be made in the various parts of the embodiments without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. An electrical contact assembly comprising:

(a) first, second and third fixed electrical contact elements;

(b) first and second connected slidable electrical contact elements disposed to move parallel to one another;

(c) a non-conductive base for supporting said first, second and third fixed electrical contact elements wherein said first and second fixed electrical contact elements are aligned to be alternately contacted by said first slidable electrical contact element and said third fixed electrical contact element is disposed to be contacted by said second slidable electrical contact element;

((1) means for guiding and supporting said first slidable contact element between alternate contact with said first and second fixed contact elements, said means disposed adjacent said aligned first and second fixed contact elements; and

(e) surface means for contacting said guiding and supporting means, said surface means connected to said first slidable contact element.

2. An electrical contact assembly as claimed in claim 1, including:

(a) first and second parallel groves formed in said base; and

(b) said first and second fixed contact elements are aligned in said first groove and said third fixed contact element is disposed in said second groove,

3. An electrical contact assembly as claimed in claim 2 wherein:

(a) said guiding and supporting means is positioned adjacent and parallel to said first groove.

4. An improved electrical contact assembly of the type having fixed and slidable contact elements comprising:

(a) a supporting base;

(b) a slidable electrical contact element disposed to move along an elongated path on said base, said lidable contact element having a laterally extending arm;

(c) a first fixed electrical contact element supported by said base and positioned in said elongated path;

(d) a second fixed electrical contact element positioned in said elongated path spaced from said first fixed contact; and

(e) means, including a sloped portion, for guiding and supporting said slidable contact element, said sloped portion being disposed along said elongated path wherein said slidable contact element is movable along said elongated path to contact alternately said first fixed contact element and said second fixed contact element and said guiding and supporting means cooperates with said laterally extending arm to guide and support said slidable contact element out of electrical contact with said first and second fixed contact elements.

5. An improved electrical contact assembly as claimed in claim 4 including:

(a) a third fixed contact element located along a second elongated path, said second path being parallel to said first mentioned elongated path;

(b) a second slidable contact element connected to and moving parallel with said first mentioned slidable contact element, said second slidable contact element movable along said elongated path; and

(c) wherein said first mentioned and said second slidable contact elements are movable along said first mentioned and said second elongated paths respectively to electrically connect when in a first position said third fixed contact element and said first fixed contact element and when in a second position said third fixed contact element and said second fixed contact element.

6. An improved electrical contact assembly of the type having fixed and slidable contact elements comprising:

(a) a supporting base;

(b) a slidable electrical contact element movable along an elongated path on said base;

(c) a fixed electrical contact element supported by said base, and positioned in said elongated path, said fixed contact element having an aperture therein;

(d) means, including a sloped portion, for guiding and supporting said slidable contact element, said sloped portion being disposed a ong said elongated path; and

(e) said slidable contact element having a lateral portion for slidably contacting said sloped portion of said guiding and supporting means for moving said slidable contact element into and out of electrical contact with said fixed contact element.

pair of said first and second fixed contact elements are disposed and each one of said second slidable contact elements is movable in the corresponding (d) a plurality of means, including sloped portions,

for guiding and supporting said plurality of first slidable contact elements, each of said supporting and guiding means is positioned adjacent and parallel to a corresponding groove in which a pair of said first 7. An improved electrical contact assembly as claimed in and second fixed contact elements are disposed, said claim 6 including: plurality of guiding and supporting means supporting (a) second and third fixed contact elements supported said plurality of first slidable contact elements when by said base positioned along second and third elonsaid first slidable contact elements are disposed begated paths, respectively, said second and said third 10 tween said first and second positions; and elongated paths being parallel to said first men- (e) each of said plurality of slidable contact elements tioned elongated path; has a lateral portion thereof for slidably engaging a (b) second and third slidable contact elements consloped portion of a corresponding supporting and nected to and moving parallel with first mentioned guiding means. slidable contact element, said second and third slid- 9. An improved electrical contact assembly comprisable contact elements being moveable along said ing: second and third elongated paths respectively; (a) an insulative cylindrical base support having a (c) a second means for guiding and supporting said plurality of longitudinally extending parallel grooves third slidable contact element, located adjacent and disposed about the periphery of said base; parallel to said third elongated path; and wherein (b) a plurality of first, second and third fixed contact (d) said third fixed contact element has an aperture elements supported by said base and disposed in said therein; and grooves, each of said elements is received by one of (e) said first mentioned, second and third slidable conthree adjacent grooves, each of said first and third tact elements are moveable from a first position to fixed contact elements has an aperture therein; a second position so that when in said first position (c) a plurality of first, second and third slidable consaid first mentioned slidable contact element engages tact elements longitudinally movable along said said first mentioned fixed contact element, said second grooves for contacting the fixed contact elements; slidable contact element engages said second fixed (d) a plurality of means for guiding and supporting the contact element and said third slidable contact eleplurality of first and third slidable contact elements, ment is supported by said second guiding and supsaid plurality of guiding and supporting means inporting means adjacent said aperture in said third eluding a plurality of sloped portions positioned adjafixed contact element whereby said first mentioned cent selected grooves; and and said second fixed contact elements are connected (e) said plurality of first, second and third slidable conto form an electrical path, and when in said second tact elements are movable between first and second position said first mentioned slidable contact elepositions so that in said first positions each one of said ment is adjacent said aperture in said first mentioned plurality of first slidable contact elements engages a fixed contact element, and supported by said first corresponding one of said plurality of first fixed conmentioned guiding and supporting means, said second tact elements, each one of said plurality of second slidable contact element engages said second fixed slidable contact elements engages a corresponding one contact element and said third slidable contact eleof said plurality of second fixed contact elements and ment engages said third fixed contact element whereeach one of said plurality of third slidable contact by said second and third fixed contact elements are elements is supported by a corresponding one of said connected to form an electrical path. supporting and guiding means adjacent said aper- 8. An improved electrical contact assembly of the type ture in one of said third fixed contact elements wherehaving fixed and slidable contact elements comprising: by an electrical path is created between one of said (a) an insulative cylindrical base support having a first fixed contact elements and the corresponding plurality of longitudinally extending parallel grooves one of second fixed contact elements, and in said disposed about the periphery of said base; second position each one of said first slidable con- (b) a plurality of first, second and third fixed contact tact elements is supported by a corresponding one of elements supported by said base and disposed in said said guiding and supporting means adjacent an apergrooves, one pair of said first and second fixed conture of one of said first fixed contact elements and tact elements are disposed in the same groove with each one of said second slidable contact elements said first fixed contact element being longitudinally engages a corresponding one of said second fixed conspaced from said second fixed contact element and tact elements and each one of said third slidable coneach of said third fixed contact elements are disposed tact elements engages a corresponding one of said in a groove adjacent the groove in which the first third fixed contact elements whereby an electrical and second fixed contact elements are disposed; path is created between each one of said second con- (c) a plurality of first and second slidable contact eletact elements and the corresponding one of said third ments, each one of said first slidable contact elements fixed contact elements. is movable in the corresponding grooves in which a 0 References Cited UNITED STATES PATENTS grooves in which one of said third fixed contact ele- 3,299,226 1/1967 Edwards 200'16 ments is disposed, said plurality of first and second 3,319,016 5/1967 et a1 200 16 slidable contact elements are movable between a 3,329,792 7/1967 Jones et first position and a second position so as to create 3,378,654 4/1968 Y at an electrical path between corresponding first and ROBERT A O p i Examiner third fixed contact elements when in said first position and to create an electrical path between corre- 7 SCOTT Assistant Examiner sponding second and third fixed contact elements U,S (1 X3, when in said second position; 200 167

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