US3450855A - Sealed limit switch - Google Patents

Description

June 17, 1969 w. J. RUSSELL SEALED LIMIT SWITCH Filed Sept. 2 1966 Sheet of s FIG-I INVENTOR. 5 I WILLIAM J. RUSSELL- HIS ATTORNEYS June 17, 1969 RUSSELL 3,450,855

SEALED LIMIT SWITCH Filed Sept. 2, 1966 Sheet Of 6 I62 I60 I58 I64 FIG-5 /7 42 I I60 I58 NVENTOR.

24 32 2 WILLIAM J. RUSSELL EXAM/M H IS ATTORNEYS W. J. RUSSELL SEALED LIMIT SWITCH June 17, 1969 I Sheet Fi led Sept. 2, 1966 I N VENTOR. WILLIAM J. RUSSELL HIS ATTORNEYS June 17, 1969 w. .1 RUSSELL 7 3,450,855

SEALED LIMIT SWITCH Filed Sept. 2, 1966 Sheet 4 ore INVENTOR. WILLIAM J. RUSSELL HIS ATTORNEYS June 17, 1969 W. J.. us5

SEALED LIMIT SWITCH INVENTOR. WILLIAM J. RUSSELL Filed Sept. 2, 1966 HIS ATTORNEYS US. Cl. 200-168 13 Claims ABSTRACT OF THE DISCLOSURE This application discloses a switch casing construction with a switch therein. Switch power line-s are connected to connecting means or screws on the switch to connect switch power lines for control of one or more circuits by the switch. A switch access opening is provided on the casing for access to the switch line connecting means, for attaching the switch power lines to the switch. A cover is provided for the access opening, which will be used when the switch casing construction is to be used alone without any plug-in casing. Such switch casing construction can be mounted on any support desired, and may operate in the usual manner. A plug-in casing has prong interlock means in the casing and plug-in power line connecting means for connection of the plug-in power lines to the interlock means. A plug-in access opening is provided for access for the prong interlock means in the plug-in casing. A plug-in change prong interlock means or construction is provided to replace the switch power line connecting means, so that the switch casing may be changed to be connected to the plug-in casing. This is accomplished by omitting the cover and securing the switch casing and the plug-in casing together at the access openings and with power lines connected to the plug-in power line connecting means.

This invention relates to a sealed limit switch with plug in change means and a plug-in receptacle.

A switch construction, according to this invention, may include a switch casing with a switch in the casing. A power line switch connector means may be provided inside of the casing, with a switch connector access opening means on the casing for access to such connector means. Such switch construction may be used by itself, to be attached to a support in any suitable manner, as desired.

Additionally, such switch construction may also be used with a plug-in casing and with a plug-in change means, so that the switch construction may be plugged into the plug-in casing or receptacle, after the plug-in receptacle has been connected to a power line.

The construction is such that the plug-in receptacle may be mounted on a supporting surface or board, with the power line or power lines connected to a connector, or connectors in the plug-in receptacle. Thereafter the switch construction may be plugged in to the plug-in receptacle, or unplugged therefrom, in an efficient manner.

Further, this invention may include a name plate or cover which may be used with the switch construction alone over the access opening of the switch construction, and such name plate or cover may be transferred to another position on the switch casing.

Plug-in change prong means may replace the power line switch connectors of the switch construction. Then the switch casing and plug-in casing may be united in a plugged-in manner.

A gasket construction may be used in connection with the name plate or cover on the switch construction when used alone. Additionally, such gasket may be used benited States Patent 6 F Patented June 17, 1969 tween the two casings, when they are united, hermetically to seal both the switch casing and the plug-in casing.

Other features of this invention are apparent from this description, the appended claimed subject matter, and/or the accompanying drawings, in which:

FIGURE 1 is a perspective view of the switch construction when used alone, without the plug-in casing construction.

FIGURE 2 is a front view of the switch construction of FIGURE 1, in enlarged scale, with the name plate, or cover, and the gasket construction removed.

FIGURE 3 is a vertical cross section generally transverse to FIGURE 2, and taken along the line 33 of FIGURE 1.

FIGURE 4 is a vertaical cross section taken generally along the line 4-4 of FIGURE 3.

FIGURE 5 is a cross section taken line 55 of FIGURE 4.

FIGURE 6 is a diagrammatic exploded perspective view of the switch construction, and the plug-in construction, before they are united into the assembly condition shown in FIGURE 7.

FIGURE 7 is a vertical cross section, partly in elevation, showing the switch construction and the plug-in construction of FIGURE 6 in united form, and in enlarged scale.

FIGURE 8 is an elevation of the p1ug-in receptacle, along the line 8-8 of FIGURE 7.

FIGURE 9 is a cross section taken line 99 of FIGURE 8.

FIGURE 10 is a view somewhat similar to FIGURE 2, with the plug-in change means or prongs having replaced the power line connector means of FIGURE 2.

FIGURE 11 is a cross section taken along the line 11-11 of FIGURE 10.

FIGURE 11A is a view of a portion of FIGURE 11, before the plug-in prong construction has replaced the power line connector means of FIGURES 2 and 3.

FIGURE 12 is a diagrammatic, exploded, perspective generally along the generally along the .view of the plug-in receptacle construction before it is assembled.

FIGURE 13 is an exploded rear view of the insulating plug-in cup construction shown in the central part of FIGURE 12.

FIGURE 14 is a perspective view of the connector holding wall taken along line 14-14 of FIGURE 12.

FIGURE 15 is a plan view of another embodiment of a plug-in receptacle.

FIGURE 16 is a cross section along line 1616 FIGURE 13.

FIGURE 17 is a perspective exploded view of the lower right hand corner of a portion of FIGURE 13 and looking in the opposite direction.

Certain words may be used in this specification and claimed subject matter which indicate direction, relative position, and the like. Such words are used for the sake of brevity and clearness. However, it is to be understood that such words are intended to be used in connection with the views of the drawings, and that in actual use, parts so described may be in a different direction, relative position, and the like. Examples of such words are verti cal, horizontal, upper, lower, etc.

A switch casing means or construction is generally indicated at 20 in the various figures. A plug-in casing means or construction is generally indicated at 22 in the various views. Such switch casing or construction 20 may be used independently of the plug-in casing or construction 22, as shown in FIGURES 15. However, certain parts of the switch casing or construction 20 may be changed, as hereinafter described, and such switch casing or construction 20 may then be used in combination with the plug-in casing or construction 22, as shown in FIG- URES 6-14, as will become apparent.

The switch casing or construction 20, as shown in FIG- URES 1-5 may have any type of suitable switch means 24 inside the casing 20. Switch actuating means or actuator means 26 may actuate the switch inside the casing and may have operable or operating means 28 outside the casing. Said operating means 28 is mounted on said switch casing 20 and connected on said casing so that the operating means may be mounted in any one of four different horizontal directions. The operating means 28 is mounted on the casing in any suitable manner. For example, screws 29 extend through the casing of the operating means and into the casing 20 to hold the casing of the operating means 28 firmly on the casing 20.

A switch power supply or power line connector, connectors, or connecting means 30 may be provided on the switch 24. Such connecting means may include one or more screws with screw heads. Switch power lines 32 may be connected to the power line connecting means 30, when the switch construction 20 is to be used alone, as shown in FIGURES 1-5. Such power lines 32 may enter the switch casing 20 through a power line conduit 34, which may be inserted and sealed in the conduit or switch power line receiving opening means 36. For example, the conduit 34 may be threaded into the opening 36, and sealed by a gasket at 38. However, the opening 36, and the end of conduit 34 may be smooth and may be secured together by epoxy adhesive or the like, if desired. The power lines 32 may be inserted in the casing 20 from the conduit 34 and may be secured to the power line connectors or screws 30 in any well known manner.

A substantially fiat switch access opening means may be provided on one wall of the switch casing 20. Such opening means 40 may be covered by a flexible gasket means 42 and by a cover, means such as a name plate or cover plate 44. The gasket 42, and name plate or cover 44 may be secured over the opening means 40 by means of the screws 46. The screws 46 may pass through openings 97 in the gasket, FIGURE 12, and into threaded holes 47 in casing 20, shown in FIGURE 2. The cover 44 and gasket 42 may be removed from their positions shown in FIGURES 1 and 3 by removing the screws 46, and then the power lines 32 may be secured to the connector means 30, or may be removed from such connector means 30, as desired. The gasket 42 and cover 44 may then be replaced after removal, as desired.

When the switch construction 20 is to be used by itself, as shown in FIGURES 15, the casing 20 may be mounted on a supporting surface or board by means of the mounting screws 48, which may be inserted in the internally smooth corner openings 50, which extend completely through the casing 20, so that the mounting screws 48 may be inserted into and secured to the mounting board or surface, not shown.

When the switch construction 20 is to be used in combination with the plug-in casing means or construction 22, the parts may be assembled or arranged as shown in FIGURES 6-14.

The plug-in casing or construction 22 may have a permanent prong interlock means 52 which may be plugin connector, connectors, or connector means or prong receiving fork members 52. Such connector, connectors, or connector means 52 may be spaced, prong receiving fork members somewhat similar to the usual prong-receiving fork connectors or members of a usual plug-in receptacle construction. According to this invention the fork members 52 may be loosely mounted in the casing 22 to accommodate themselves to variations in the assembly of the prong points 66.

The plug-in casing or plug-in construction 22 may be provided with a substantially flat plug-in connector access opening means 54, FIGURES 6, 7 and 8 which may include the gasket receiving and sealing head 56.

Plug-in change prong interlock means or prongs 58, FIGURES 7 and 11, may replace the power line switch connectors 30 of FIGURE 11A. The power supply connectors or screws 30 may be removed or unscrewed from the switch construction at 11A, and the plug-in change prong interlock means or prongs 58, of FIGURE 11, may be screwed in to the receiving sleeve connectors 158 of the switch construction 20. The prong means 58 may include a screw or threaded portion 62 at one end, an intermediate turning or wrench-receiving portion or hexagonal portion 64, and a prong point 66 at the other end. The prong point 66 is insertable into the power line plugin connector or connectors or prong interlock members 52. It is therefore to be seen that the plug-in change prong means of FIGURE 11 replaces the power line switch connector 30 of FIGURE llA.

After the change means or prongs 58 have replaced the switch connectors 30, the switch casing construction 20 and the plug-in construction 22 may be secured together, as shown in FIGURE 7 with both the access opening means 40 and 54 aligned with each other. The gasket 42 covers the main part of the access openings or opening means 40 and 54 as shown in FIGURE 7, and may be screwed or bolted together by the uniting screws 68, which pass through smooth openings 50 and enter the threaded openings 70 in the switch casing 22. Previously, the mounting screws 72 may have been inserted into the internally smooth openings 74 in the plug-in casing 22. The openings 74 are not internally threaded, but the openings 70 are internally threaded, to receive the threaded ends of the uniting screws 68 which pass through the internally smooth openings 50. The mounting screws 72 are insertable in the openings 74, and the threaded ends 76 thereof may be screwed or bolted to the mounting board or surface, not shown. In this manner the plug-in receptacle 22 may be mounted on a board by the screws 72, and thereafter the switch casing 20 may be secured to the plug-in casing construction 22 by the uniting screws 68. During this process of uniting the switch construction 20 and plug-in construction 22, the prong points 66 are inserted through gasket openings 76 in gasket 42 and into the power line plug-in connectors or prong receiving members 52 which are further to be described. While this uniting operation is being performed, the casing means securing means or screws 68 secure the casings together. The switch connector access opening means 40 and the plug-in access opening means 54 are aligned and held together with the plug-in change means or prongs 58 passing through both of such access openings.

The plug-in casing 22 may also have internally smooth mounting openings 75, FIGURES 6 and 12 through which mounting screws, similar to screws 72, may be inserted, to secure the plug-in construction 22 by its side against the supporting surface.

The switch casing 20, and the plug-in casing 22 may be substantially parallelepipeds with respective access opening means 40 and 54 on respective sides of such parallelepipeds.

The switch casing 20 may have a switch power line opening means or conduit opening 36 and the plug-in casing 22 may have a plug-in power line opening 78, FIG- URES 3 and 7. When the casings 20 and 22 are to be united, as shown in FIGURES 6 and 7, a removable closure member or plug means 80, FIGURE 7, may be inserted and sealed in the switch opening 36. Such plug may be sealed by the gasket 38 or by a suitable sealing compound. At this time, plug-in power line or lines 82, which may be carried by power line conduit 84, may enter the casing 22 through means opening 78 and may be connected to plug-in power line connectors, connector means, or screws 86, which may be screwed into the bases 88, which are integral with the plug-in connectors or connector means 52 in a manner to be more fully described.

The gasket 42 and the cover or name plate 44 are used over the access means or opening 40 when the switch construction 20 is used alone without the plug-in construction 22 as illustrated in FIGURES 1-5.

When the switch construction 20 and the plug-in construction 22 are to be used together, the name plate 44 is transferred to the side wall 90, FIGURE 7, of the switch construction 20 and is secured thereto by the screws 92, or by screws 46 which have been removed from their position in FIGURE 2. The gasket 42 in FIGURE 7, remains against the access opening 40 of switch construction 20, or is caused to engage such access opening 40 in the same manner that it engaged such access opening in the construction of FIGURES l-5. The access opening 40, FIGURE 2, has a continuous outward bead 94, FIGURE 2, which is substantially of the same size and contour as the bead 56, FIGURES 8 and 12, of the access opening '54 of the plug-in construction 22.

When the switch construction 20 and the plug-in construction 22 are brought together, as shown in FIGURES 6 and 7, the beads 56 and 94 are aligned, and tightly seal. or engage the gasket 42 as is shown in FIGURE 7. The permanent prong interlock or electrical interconnector means 52 and the plug-in change prong interlock or electrical interconnector means 62, 64 and 66 are in engagement with each other in the plug-in casing means 22 with the plug-in change prong interlock or electrical interconnector means 62, 64, 66 passing through both of said access opening means 40- and 54.

In order to align the gasket 42 between the openings 40 and 54, the openings 54, FIGURES 6 and 12, is provided with pegs 96 over which the openings 97 in the gasket 42 are mounted, as shown in FIGURE 6. The pegs 96 are of sufficiently small diameter so that they may be inserted in the threaded openings 4 The plug-in casing 22, FIGURES 1214, receives a molded insulative cup 98, which has an integral molded insulative bottom 100. The bottom 100 has connector receiving openings 102 which receive the bases 88 of the connecting pieces shown in FIGURE 13. The bases 88 and the prong receiving members 52 are parts of one unitary or integral piece. The openings 102 each have an intermediate wall 104 which prevents the bases 88 from passing completely through the openings 102 in bottom 100, of FIGURE 13. The intermediate wall 104 has screw-receiving openings 106 to receive the screw heads of screws 86 and prong-receiving openings or connector-receiving opening 107 to receive the prong receiving members 52. The prong receiving members or connectors 52, and the heads of the screws 86 may be inserted respectively in the openings 107 and 106, so that the connectors 52 and the screw heads of screws 86 extend into the cup 98 as shown in FIGURE 12.

In FIGURE 13, the two upper bases 88 have been inserted in the openings 102 and are pressed against the wall 104. The two lower bases 88 of FIGURE 13 have not been inserted in the openings 102, but they will be inserted therein, as shown by the dotted lines in FIG- URE 13. After all the bases 88 have been inserted in the openings 102, the connector holding wall 108, FIG- URE 13, is moved diagonally upward, to engage and hold the bases 88 in place. The protrusions 110, FIG- URE 14, will engage the bases 88, and hold the bases 88 in place.

The retaining wall 108 has forwardly directed ears 112, which have openings 114. The openings 114 lock over the slanting tongues 116, which are shown in FIGURES 12 and 13. This connector holding engagement of ears 112 and tongues 116 will hold wall 108 in position, as shown in FIGURE 12.

In this manner, the complete insulative cup assembly 98, 108 of FIGURE 12 is produced, so that the power line plug-in connectors 52 extend outwardly toward the rim 117 of the cup 98, and are ready to receive the plugin prongs 58 with the prong points 66 entering the connectors 52, as is apparent from FIGURE 6 where the 6 connectors 52 are exposed in the openings 76 in the gasket 42. Also, the power lines 82, FIGURES 7 and 8, can be attached under the heads of screws 86.

The outside wall of the cup 98 has internally smooth screw-receiving openings 118, FIGURE 12, which are exposed by the olTset curls 120, so that the cup-mounting screws 122 may be inserted into the openings 118, and can pass through the openings 124 in the wall 108 and may be inserted into the threaded screw-receiving openings 126, in the casing 22, FIGURE 12.

The prong-receiving fork members 52 and bases 88, of FIGURES 12-14 are loosely mounted in the cup 98, so that a slight moving action can take place. This insures that the prong points 66 can enter the prong-receiving members 52 without any binding action. The electrical connection is very good, however, since the current travels from the power lines 82, FIGURE 7, through the screws and screw heads 86, to the bases 88, and to the prong-receiving members 52. The members 52 and 88 are integral so that the current is easily carried.

The protrusions 110, FIGURE 14, have the same general shape as the members 88, so that these protrusions push the members 88 toward the cup 98, when the wall 88 is snapped into position. The protrusions 110 have openings 111, which receive the ends of the screws 86 loosely therein. The protrusions 110 fit in the openings 102 fairly snugly, to center the plate or wall 108 against the bottom 100 of the cup 98.

The button 123 engages the bottom 100 of the cup 98 and cooperates with the ears 112 in maintaining a tight fit between the ears 112 and the slanting tongues 116.

The differently slanted bases 88 aid in maintaining effective contact between the prong points 66 and the prong receiving members 52.

Another embodiment of a plug-in receptacle or casing is shown in FIGURE 15. In this construction, the metal casing 130 may have the general function and shape of the plug-in casing 22, and may have openings 132 to receive screws corresponding to screws 68 of FIGURE 6 and may have openings 134 to receive screws corresponding to screws 72 of FIGURE 6. That is, openings 132 correspond to openings 70 of FIGURE 6, and openings 134 correspond to openings 74 of FIGURE 6. An opening 136 may correspond to power line opening 78, of FIGURE 7, through which power lines 82 may pass to be attached to the retaining screws 86A which are inserted in the prong-carrying plate 138. The plate 138 may be riveted at 140 into the bottom 142 of the insulative cup 144. The prong-carrying plate 138 may have attached thereto prong receiving fork members 52A, which correspond to connectors 52 of the previous figures. The fork members 52A are carried sufiiciently loosely by the prong carrying plate 138 to accommodate slight variations in the assembly of the prong points 66. Three similar prong receiving members 52A may be connected and carried by similar prong-carrying plates similar to plate 138. In this manner, power lines corresponding to power lines 82 of FIGURE 7 may be attached to the power line connectors or screws 86A, in the same manner that power lines 82, FIGURE 7, are attached to the power line connectors or screws 86 of the bases 88 of FIGURE 7. A gasket 44A may be placed over the access opening of the casing 130. The gasket 44A may have openings 76A through which the prong points 66 may pass.

Any type of switch construction may be placed in the casing 20. However, merely by way of example, the switch construction disclosed in the application of Werner Robert Bauer, Ser. No. 493,108, filed'Oct. 5, 1965, now Patent No. 3,317,697, patented May 2, 1967, may be used. Reference is made to such application, if necessary, for further description of the switch construction per so. In general, the switch may have a snap-acting blade construction 150, FIGURE 4, which has double movable contacts 152 at each end of the blade 150. These contacts 152 engage the stationary contacts 154. The stationary contacts 154 are carried by sheet metal angle members 156, which are riveted to metal conductors 158, FIGURE 5. These metal conductors 158 have threaded openings 160, which receive the screws 162, which have the screw heads 30 to which the power lines 32 are connected. The metal conductors 158 are embedded in the insulative switch casing 164. The casing 164 has the downward extension 166 through which a mounting screw 168 may be inserted and may be secured to the rear wall 90 of the casing 20. The casing 164 has a cover 170, which is hermetically sealed to the casing 164 by the flexible gasket 172. The cover 170 has an extension 173 which matches extension 166 and through which the screw 168 passes. The entire switch casing 20 may be hermetically sealed, as more fully described in said copending application Ser. No. 493,108.

The operating means 28 may be of the character more fully described and disclosed in the application of William J. Russell, Ser. No. 299,612, filed Aug. 2, 1963, now Patent No. 3,252,345, patented May 24, 1966, to which reference is made, if necessary, for a further description of the operating means extending from the casing 20.

Thus a switch construction 20 is provided with an access opening 40 which is hermetically closed by name plate or cover 44 and gasket 42. Also, a plug-in receptacle 22 is provided with an access opening 54. The name plate or cover 44 may be removed from opening 40 and may be mounted n the rear wall 90 of the switch casing 20. Then the switch construction and the plug-in casing 22 may be united with the access openings 40 and 54 aligned and sealed by the gasket 42. The switch actuator 26 is flexibly hermetically sealed as disclosed in said copending aplication 493,108. The opening 36 is sealed either by the conduit 34 or the plug 80. The opening 78 is sealed by the conduit 84 and the operating means 28 is sealed where it connects the actuating means 26. Hence the switch casing 20 is sealed when used alone, and the casings 20 and 22 are sealed when they are used together.

Thus the switch construction 20 may be used by itself with the cover over the access opening 40 or it may be plugged in to the plug-in receptacle 22 with plug-in change means or prongs electrically uniting the receptacles 20 and 22, in a very efficient manner.

While the form of the invention now preferred has been disclosed as required by statute, other forms may be used, all coming within the scope of the claimed subject matter which follows.

What is claimed is:

1. In combination: a switch casing means to cooperate in said combination; a switch means in said switch casing means to operate in said switch casing means; switch access opening means on said switch casing means, said switch access opening means being subtantially flat, and said switch means being entirely inside said switch casing means; a plug-in casing means to be connected with said switch casing means; permanent prong interlock means in said plug-in casing means receiving and connecting with plug-in change prong interlock means; plug-in power line connecting means on said permanent prong interlock means to connect said permanent prong interlock means to said plug-in power lines; substantially flat plug-in access opening means on said plug-in casing means for plugin access to said permanent prong interlock means in said plug-in casing; plug-in change prong interlock means connecting with said permanent prong interlock means; and switch casing means and plug-in casing means securing means securing said switch casing means and said plug-in casing means together with said switch access opening means and said plug-in access opening means aligned together, and with said plug-in change prong interlock means and said permanent prong interlock means in engagement with each other in said plug-in casing means and with said plug-in change prong interlock means passing through both of said access opening means to cause said plug-in power lines to be controlled by said switch means.

2. A combination according to claim 1 in which'said plug-in change prong interlock means includes at least one prong construction, each with a threaded portion at one end, a prong point at the other end, and an intermediate turning means between said threaded portion and said prong point.

3. A combination according to claim 1 in which said plug-in casing means has mounting screw receiving opening means for mounting said plug-in casing means on a supporting surface by means of mounting screws; and said switch casing means has mounting screw receiving opening means for mounting said switch casing means on said plug-in casing.

4. A combination according to claim 1 in which said permanent interlock means in said plug-in casing means includes prong receiving fork members loosely mounted in said plug-in casing.

5. In combination:

a plug-in casing means (22) to cooperate in said combination;

permanent prong interlock means (52) in said plug-in casing means (22) to connect with plug-in change prong interlock means;

plug-in power line connecting means (86) on said permanent prong interlock means (52) electrically to connect plug-in power lines (82) to said permanent prong interlock means;

substantially fiat plug-in access opening means (54) on said plug-in casing means (22) for plug-in access to said permanent prong interlock means (52);

a switch casing means (20) to cooperate in said combination;

a switch means (24) in said switch casing means (20) having electrical contacts (152, 154) to open and close an electrical circuit;

a plurality of power conductor connecting means (158) on said switch means (24) electrically connected to said contacts (152, 154);

a plurality of plug-in change prong interlock means (58) removably connected to said plurality of conductor connecting means (158) and insertable into and connecting with said permanent prong interlock means (52);

substantially fiat switch access opening means (40) on said switch casing means (20) for access to said change prong interlock means (58) and for interengagement with said plug-in access opening means and casing means securing means (68) to secure said switch casing means (20) and said plug-in casing means (22) together with said substantially fiat switch access opening means (40) and said substantially flat plug-in access opening means (54) aligned together, and with said plug-in change prong interlock means (58) and said permanent prong interlock means (52) in engagement with each other in said plug-in casing means through both of said access opening means to cause said plug-in power lines (82) to be controlled by said switch means.

6. A combination according to claim 5 in which a cover means (44) is to be used as a name plate (44) on a side wall of said switch casing means.

7. A combination according to claim 5 in which each of said conductive connecting means (153) is an internally threaded opening means (160) and in which each of said plug-in change prong interlock means (58) has a threaded portion means (62) atone end inserted in said internally threaded means (160) an intermediate turning portion means (64) to be turned by a tool, and prong point means (66) at the other end, so that said prong point means (66) is inserted in said permanent prong interlock means (52) when said casing are secured together.

8. A combination according to claim 7 in which each of said permanent prong interlock means (52) is a prong receiving fork member means :with a power line connector screw head (86) accessible from said plug-in access opening means (54) to receive said prong point means (66).

9. A combination according to claim in which said plug-in casing means (22) and said switch casing means (20) are each substantially parallelepipeds with abutting, substantially equal parallelogram sides with respective abutting relatively large plug-in access opening means (54) and switch access opening means (40) and in which screw receiving opening means (50), (70), (74) proyided adjacent the corners of said parallelepipeds to receive screws to attach said plug-in casing means (22) and said switch casing means (20) together, to mount said plug-in casing (22) to a support, and mount said switch casing (20) to a support.

10. In combination:

a plug-in casing means to cooperate in said combination;

permanent electrical interconnector means in said plugin casing means to connect with plug-in change electrical interconnector means;

plug-in power line connecting means on said permanent electrical interconnector means electrically to connect plug-in power lines to said permanent electrical interconnector means;

substantially flat plug-in access opening means on said plug-in casing means for plug-in access to said permanent electrical interconnector means;

a switch casing means .to cooperate in said combination;

a switch means in said switch casing means having electrical contacts to open and close an electrical circuit;

a plurality of power conductor connecting means on said switch means electrically connected to said contacts;

a plurality of plug-in change electrical interconnection means removably connected to said plurality of conductor connecting means and insertable into and connecting with said permanent electrical interconector means;

substantially flat switch access opening means on said switch casing means for access to said change electrical interconnector means and for inter-engagement with said substantially flat plug-in access opening means;

and casing means securing means securing said switch casing means and said plug-in casing means together with said substantially flat switch access opening means and said substantially flat plug-in access opening means aligned together, and with said plug-in change electrical interconnector means and said permanent electrical interconnector means in engagement with each other in said plug-in casing means and with said plug-in change electrical interconnector means passing through both of said access opening means to cause said plug-in power lines to be controlled by said switch means.

11. In combination:

a switch construction; a plug-in casing; plug-in prong interlock means in said plug-in casing; plug-in power supply connecting means on said plug-in prong interlock means; plug-in access opening means on said plug-in casing providing access to said plug-in prong interlock means, said plug-in casing being in the form of a plugin casing cup bottom and a plug-in casing cup side wall construction forming a plug-in casing rim which forms said plug-in access opening means receiving a mating switch casing access opennig means of said switch construction which has a switch casing which is similarly shaped in the form of a switch casing cup bottom and a switch casing cup side wall construction forming said mating switch casing access opening means, and which said switch construction has a switch means entirely within said switch casing opening means and with mating interchangeable switch prong interlock means interlocking with said plug-in prong interlock means, said switch casing has a flat name plate secured on the outside of said switch cup bottom by plate fastening means attached to said switch casing cup bottom, said interchangeable prong interlock means having removable screw means which are removable from said switch construction said plug-in access opening means also providing access to said plug-in power supply connecting means for connecting and disconnecting said power supply to said power supply connecting means on said plug-in interlock means, said plug-in casing having a second access opening means to introduce plug-in power supply'conductor means for connection to said plug-in power supply connecting means on said plug-in prong interlock means, and securing means securing said switch construction and said plug-in casing together.

12. A combination according to claim 11 in which a resilient flat sheet cover seal member is placed over said access opening means of said plug-in casing to be engaged by said casing access opening means of said switch construction.

13. A combination according to claim 12 in which each of said respective access opening means has a mating flat head to engage and hold said resilient sheet cover seal member.

References Cited UNITED STATES PATENTS 3,317,697 5/ 1967 Bauer.

2,494,428 1/1950 Buck 339-- 2,806,912 9/1957 Pearson et al 200-468 2,916,591 12/1959 Benn 200-168 2,942,227 6/1960 Hjelseth 339-120 3,067,362 12/1962. Patton 317-120 3,122,681 2/1964 Pusch 317--120 3,158,703 11/ 1964 De Smidt 20051 ROBERT K. SCHAEFER, Primary Examiner. H. O. JONES, Assistant Examiner.

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