US3792402A

US3792402A - Electrical circuit controller

Info

Publication number: US3792402A
Application number: US00195433A
Authority: US
Inventors: J Peluchiwski; D Walstad
Original assignee: Furnas Electric Co
Current assignee: Siemens Energy and Automation Inc
Priority date: 1971-11-03
Filing date: 1971-11-03
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: CA983077A

Abstract

A manually operated switching device which includes a pivotally mounted actuating bracket carrying a cross bar which advances toward and away from a set of fixed contacts as the bracket is rotated. A set of movable contacts on the cross bar make or break the circuit as the bar is moved. A thermal overload device including a plunger normally held in a fixed position by a pawl and detent arrangement but in response to excess heat caused by excessive current in a controlled conductor the detent may rotate permitting a spring to drive the plunger to a position where it operates a reset bracket which in turn operates the actuating bracket opening the circuit and prevents its operation until the thermal overload has been removed.

Description

United States Patent Peluchiwski et al.

52] 11.8. CI 337/59, 337/102, 337/148, able contacts on the cross bar make or break the 337/151 cuit as the bar is moved. A thermal overload device r 511 1 ci. H0lh 61/02 inqluding a. p u ge normally held in a fixed position Field of Search ..337/42, 53, 56, 59, 102, by a pawl and detent arrangement but in response to 337/() 154 14 excess heat caused by excessive current in a controlled conductor the detent may rotate permitting a spring to drive the plunger to a position where it oper- [56] References cued ates a reset bracket which in turn operates the actuat-' UNITED STATES PATENTS ing bracket opening the circuit and prevents its opera 2,664,482 12/1953 Goudy et al. 337/148 X tion until the thermal overload has been removed. 2,006,954 7/l935 Kuhn 337/153 X 23 Claims 27 Drawing Figures i 38- I 42 4a 46 44 34 gg/ ll A k Z2 2 \1 I f Q 116 8 142 w 735 134 g 2 34- 2'74- 161 26 '63 5- 162"" w 32 I 36 82 H U i 78 28 H.

ELECTRICAL CIRCUIT CONTROLLER Inventors: John J. Peluchiwski, Medinah; I Dennis C. Walstad, Winfield, both of lll.

Assignee: Furnas Electric Company, Batavia,

lll.

Filed: Nov. 3, 1971 Appl. No.: 195,433

l2/l942 ll/l957 Butler 337/59 X Kolh et a]. 337/151 X Primary Examiner'Bernard A. Gilheany Assistant Examiner-F. E. Bell [57] ABSTRACT A manually operated switching device which includes a pivotally mounted actuating bracket carrying a cross bar which advances toward and away from a set of fixed contacts as the bracket is rotated. A set of mov- PATENTEBFEBIZIBM v 3,792,402

sum 1 or 4 FIGZ g PM rms 1 PATENTEDFEBI 2 3.792.402

saw a or 4 y FIG. 25

ELECTRICAL CIRCUIT CONTROLLER BACKGROUND OF THE INVENTION This invention relates generally to apparatus for controlling electrical circuits. More specifically, it relates to improvements in switching apparatus.

It is an object of this invention to provide a novel electrical circuit controller which while economical to construct by virtue of its design is nevertheless reliable and capable of a long life while switching relatively large currents.

It is another object of this invention to provide a novel electrical circuit control apparatus which is safe in use and affords a maximum of protection to an operator.

It is a further object of this invention to provide a novel electrical switching apparatus which may be mechanically interlocked with a similar switching apparatus so that only one of two circuits supplying a common load may be completed at a time.

It is still a further object of this invention to provide a novel electrical switching apparatus which is constructed of relatively inexpensive stamped parts so that the cost of producing such apparatus is significantly reduced.

It is a still further object of this invention to provide a novel electrical switching apparatus which while constructed using relatively inexpensive stamped and molded parts nevertheless provides all of the functional capability, reliability and safety features required in such devices.

SUMMARY OF THE INVENTION The foregoing and other objects of this invention are achieved in one embodiment including a terminal supporting block on which are mounted stationary contacts and in which movable contacts are actuated by a snap action mechanism in response to a rockertype actuator and which includes a reusable thermal overload means to provide protection for a load being supplied through the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS The invention itself is set forth in the claims appended hereto and forming a part of this application while an understanding of the structure and operation of an embodiment thereof may be derived from the detailed description taken in conjunction with the following drawings in which:

FIG. 1 is a front view of apparatus in accordance with the invention;

FIG. 2 is a top view along the lines 22 of FIG. 1;

FIG. 3 is a side view of the apparatus illustrated in FIG. 1;

FIG. 4 is a side view similar to FIG. 3 showing, for purposes of clarity, some of the components in an exploded position;

FIG. 5 is a bottom view along the lines 55 of FIG.

FIG. 6 is a back view along the lines 66 of FIG. 4; FIG. 7 is a view along the lines 77 of FIG. 4;

FIG. 8 is a view along the lines 88 of FIG. 4;

FIG. 9 is a sectional view along the lines 99 of FIG.

FIG. 10 is a sectional view along the lines 1010 of FIG. 1;

FIG. 11 is a partial sectional view similar to FIG. 9 showing the switch in accordance with the invention in one possible condition of its operation;

FIG. 12 is a partial sectional view similar to FIG. 10

5 showing a switch in accordance with the invention in the same condition as illustrated in FIG. 11;

FIG. 13 is a detailed exploded illustration of a movable contact, spring and cross arm forming a part of the invention;

FIG. 14 is a perspective illustration of a resetting plunger forming a part of the invention;

FIG. 15 is a perspective illustration of the opposite side of the resetting plunger forming a part of the invention;

FIG. 16 is a perspective illustration of a pawl forming part of the thermal overload machanism incorporated in the invention;

FIG. 17 is a perspective illustration of an actuating bracket forming part of the invention;

FIG. 18 is a perspective illustration of a bracket assembly forming part of the invention; FIG. 19 is a perspective illustration of a reset bracket forming part of the invention; 7

FIG. 20 is a perspective illustration of an overload terminal forming part of the invention;

FIG. 21 is a perspective illustration of a terminal forming part of the invention;

FIG. 22 is a front view of a pair of switches in accordance with the invention including an interlocking mechanism;

FIG. 23 is a side view partially in phantom of the apparatus of FIG. 22;

FIG. 24 is an illustration of an interlocking mechanism in one operating position;

FIG. 25 is a partial illustration of the interlocking mechanism in a neutral position;

FIG. 26 is a partial illustration of the interlocking mechanism in another operative position; and

FIG. 27 is a partial illustration of a side view of the interlocking mechanism.

DETAILED DESCRIPTION The General Arrangement Referring first to FIGS. 1 through 5 of the drawing, it may be seen that a switch in accordance with the invention comprises a terminal block indicated generally by reference numeral 2. The terminal block may be formed by molding a suitable plastic material having desirable mechanical and electrical insulating properties, for instance, a phenolic plastic. As shown in the figures, the top of the terminal block is provided with an ear 4 while the bottom thereof is provided with a pair of ears 6. By passing screws or other fastening elements through the openings in the ears the terminal block may be mounted in any desired position on a suitable supporting surface such as the inside of a switch enclosure. Attached to the upper portion of the block are a plurality of conducting segments 8 into which terminals 10 are threaded. A multi-conductor supply line may have each one of its conductors connected to an individual terminal 10 which therefore provide a means for connecting the switch to a current supply line. A rocker arm 12 which may be moved to one of two positions is provided to operate the switch and is exposed through an opening in a face plate 14 held in position on the terminal block by threaded fasteners l6.

The face plate is provided with an integral boss 18 having an opening 20 for receiving and supporting a condition indicating light 22 which may be connected to the switch in such a way as to be energized when the switch is operated to the closed circuit state. Movable in a slot provided in the face plate is a locking slide 24 which may be moved laterally out of the face plate to expose an opening (not shown) to receive a locking device when it is desired to prevent unauthorized operation of the switch.

The Electrical Circuit The bottom of the terminal block is provided with a plurality of molded depressions 26, each one of which accommodates an output terminal 28 for connection to a load to be controlled. Each output terminal is in electrical contact with an overload terminal 30 (see FIG. 20) which in turn is in contact with a terminal 32 electrically connected to one end of a coiled heater element 34. The other end of the coiled heater element is connected to a terminal 36 which is displaced horizontally and vertically from the terminal 30 so as to provide mounting room for the coiled heating element 34. The purpose of the coiled heater elements will be set forth as this description proceeds.

As may be best seen in FIGS. 9 and 11, each terminal is connected to an angled conducting member 38 mounted to the terminal block 2 by means of a threaded fastener 40 and which supports a fixed contact 42 at its lower end. A movable contact assembly 44 (see FIG. 13) carries a first movable contact 46 engageable with the fixed contact 42 and extends to the rear of the terminal block where it supports a second movable contact 48. A second fixed contact 50 is supported on a second angled conducting member 52 held in position on the rear of the terminal block by means of a threaded fastener 54, and supports a terminal 56 at its upper end.

Referring to FIG. 6, each terminal 56 is connected by a conductor 58 disposed completely within a groove 60 molded within the body of the terminal block 2 and which is connected at its lower end to a terminal 62. Each terminal 62 engages in an angled conducting bar 64 (see FIG. 21) in a threaded opening 66 provided in that bar. A first angled portion 68 of that bar extends laterally through the terminal block while a second angled portion 70 extends upwardly to receive a terminal 36 in an opening 72.

As may be seen from the foregoing description, an electrical circuit may be completed from a conductor secured to a terminal 10 through an angled conducting member 38 to a first fixed contact 42, a movable contact 46, the movable contact assembly 44, a movable contact 48, a second fixed contact 50, an angled conducting member 52, a terminal 56, a conductor 58, a terminal 62, an angled conducting member 64, a terminal 36, a heating coil 34, a terminal 32, a conducting member 30, and a terminal 28 to be connected to a load.

The Movable Contact Actuator As may best be seen in FIGS. 9, 11 and 13, the movable contact assemblies 44 are supported on and caused to be moved by a cross arm 74. The cross arm comprises a platform 76 and is molded out of a plastic material having suitable mechanical and electrical insulating properties. Extending upward from the platform 76 are integrally formed rectangular compartments 78, one for each movable contact assembly. Each compartment is spaced from the other by means of a laterally extending wall 80 to minimize leakage losses between the compartments. Each compartment is provided with an upper and a lower boss 82 to support and maintain in position a coil spring 84 which presses upwardly against a movable contact assembly when mounted in its associated compartment. Each movable contact assembly is provided with a notch 86 on either side thereof for engagement with the side walls of its compartment to guide the movement of the contact assembly and to maintain it in position.

Depending downwardly from the platform 76 is a C- shaped element or hook 88 provided with a slot 90 therein which slot when the cross arm 74 is mounted in the switch opens toward the rear of the terminal block. The slot 90 of the hook is engaged by a horizontally extending bar 92 which is formed as part of an actuating bracket 94.

As may best be seen in FIG. 17, the actuating bracket 94 includes a first pair of smaller laterally extending lugs 96 and a second pair of larger laterally extending lugs 98. A first generally U-shaped portion 100 has the bar 92 formed thereon so as to extend generally upward from the. plane of the actuating bracket. A second and smaller generally U-shaped portion 102 is connected by an intermediate section 104 to the U-shaped portion 100. Formed on the intermediate portion 104 is a downwardly depending projection 106 which has a lug or nose 108 projecting rearwardly therefrom when the bracket is mounted in the terminal block. A notch 110 is formed on the bight portion of the U 102 to provide an anchor for a coil spring in a manner to be described hereinafter.

The smaller lugs 96 of the actuating bracket engage in a pair of hour glass shaped openings 112 formed in a mounting bracket 114 best shown in FIG. 18. The mounting bracket is formed in a generally U-shaped configuration including a bight portion 116 and a pair of

legs

118 and 120. The bight portion includes openings 122 whereby the mounting bracket may be secured to the terminal block by means of threaded fasteners 124 (see FIGS. 10 and 11).

The leg 118 of the mounting bracket includes an opening 126 having a generally trucated triangular configuration through which the right hand lug, as shown in FIG. 17, 98 extends. The top 127 and the bottom 128 of the opening 126 serve to limit the rocking of the actuating bracket when it is mounted in the bracket 114 by engaging the lugs 96 in the openings 112. An opening 130 adjacent the outer edge of the lug 118 is provided to accommodate a pivot pin supporting the rocker arm 12 and an actuating arm 132 (see FIG. 10). A pair of openings 134 similar in shape to the openings 112 are provided at the bottom of the

legs

118 and 120 to provide a pivoting support for a reset bracket 136.

The reset bracket is formed as a substantially flat plate having a pair of outwardly extending lugs 138 for engagement in the openings 134 to permit a rocking movement. A strengthening groove 140 extends the length of the reset bracket to provide for mechanical rigidity. Extending substantially perpendicular from the surface of the reset bracket if a first actuating arm 142 and spaced laterally therefrom extending at an angle to the surface of that bracket is a second actuating arm 144.

The switch actuating assembly is completed by the actuating arm 132 which includes a pair of upstanding legs 146, only one of which is shown in FIGS. and 12. As may best be seen in those figures, the actuating arm is formed to have a flat surface 148 extending rearwardly from the legs 146 and an angled extension 150 extending from the flat surface 148. Also extending upwardly from the flat surface 148 is an actuating cam 152 which bears against the actuating arm 144. An-

opening 154 at the free end of the angled projection 150 is engaged by the end of a coil spring 156. The other end of the coil spring 156 engages in the notch 110 of the U 102 of the actuating bracket 94 and the spring is in tension when so connected.

As assembled, the movable contact assemblies 44 are mounted in the individual compartments 78 of the cross arm 74 and are biased upwardly by the action of the coil springs 84. The actuating bracket 94 is rotatably mounted on the mounting bracket 114 by virtue of the engagement of the lugs 96 in the openings 112. The reset bracket is mounted on the mounting bracket by engagement of the lugs 138 in the openings 134. A pivot pin 158 extends through the legs 146 and a rearwardly extending generally triangular projection 160 (see FIG. 23) of the-rocker arm 12. The pivot pin also extends through the opening 130 in the leg 118 of the mounting bracket 114 and is staked or otherwise secured there so as to support the rocker arm and the actuating arm on the bracket. The coil spring 156 when mounted is in tension and therefore tends to pull the actuating arm 132 toward the U-shaped portion 102 of the actuating bracket when the switch is in the position shown in FIG. 10.

The operation of the switch is as follows. Referring first to FIGS. 9 and 10, when the switch is off rocker arm 12 is positioned with its upper end projecting outwardly of the face plate 14. As may be seen in FIG. 10, the actuating arm 150 is inclined upwardly and the spring 156 therefore asserts a counterclockwise force on the actuating arm 94 tending to maintain it with its U-shaped portion 100 in a downward position. Inasmuch as the horizontal bar 92 extending from the portion 100 engages in the slot 90 of the cross bar 74, that cross bar and the movable contacts carried thereby are held in a downward position so that there is no electrical contact between the fixed contacts 42 and 50 and the

movable contacts

46 and 48.

When the rocker arm 12 is operated by depressing its upper end inwardly causing it to rotate about the pivot pin 158, the actuating arm 132 is rotated downwardly in a counterclockwise position. When the actuating arm has rotated to approximately the solid line position shown in FIG. 12, the tension force exerted by the spring 156 acts on a line extending beneath the surface of the actuating bracket 94. The force vector therefore is one which then has a component in the clockwise direction about the outer end of the U-shaped portion 102 of the actuating bracket and therefore tends to rotate that bracket about its pivoted connection in the

legs

118 and 120 of the mounting bracket 114 so as to pull that outer end downwardly causing the actuating bracket to rotate in a clockwise direction. The clockwise rotation of the actuating bracket pushes the cross bar 74 upwardly with the horizontal bar 92 moving in the slot 90 to the position shown in FIG. 11. The upward movement of the cross bar causes the movable contact assemblies 44 to engage with their associated fixed contacts thereby completing the electrical circuit.

When it is desired to interrupt the circuit, the lower end of the rocker arm 12 which is now extending forwardly to the dotted line position shown in FIG. 12 is depressed inwardly. This causes a clockwise movement 5 of the actuating arm which continues until the line of force exerted by the coil spring 156 extends above the upper surface of the actuating bracket 94. This causes a component of force acting in a counterclockwise direction to cause the actuating bracket to rotate counterclockwise moving it U-shaped portion downwardly. The downward motion of the U-shaped portion 100 of the actuating arm causes the cross arm 74 to move downwardly disengaging the movable contacts from the fixed contacts. 5 The arrangement is such that as the actuating arm 132 is rotated and the spring 156 crosses the plane of the actuating bracket 94 that bracket operates with a snap action to rapidly make or break the circuit so as to eliminate or minimize arcing between the contacts. Thermal Overload Protection Thermal overload protection for the switch is provided by means of the heater coil 34 and its associated structure which will now be described. Extending into the space encompassed by the turns of each heater coil is a thermally responsive device comprising a tubular member 161 formed of a metallic material having good heat conducting qualities. Mounted in each tubular member 161 is a shaft 162 otherwise rotatable but normally restrained against rotation by a quantity of solder or similar material adjacent the free end of the shaft. Supported on the inner end of the shaft is a detent wheel 164, the teeth of which are engaged by the outer end 166 of a spring pawl 168. As may best be seen in FIGS. 16 and 10, the spring pawl 168 is formed out of a spring material having a portion 170 extending at right angles to the main body thereof.

Referring to FIGS. 6 and 9 through 1 1, it may be seen that the terminal block 2 is provided with a plurality of recesses 172 formed therein. Slidably mounted in each recess is a thermal overload plunger 174 (see FIGS. 14 and each of which includes an upwardly extending plunger finger 176 and a body portion 180. A guide lug 182 extends from the bottom of each body portion to assist in maintaining a coil spring 184 in position. The portion of the reset plunger which extends toward the rear of the terminal block includes a recess 186 molded therein to receive the spring pawl 168. When the pawl is mounted in the reset plunger, its outer end 166 is positioned at the upper end of the recess 186 while the angled portion 170 thereof engages the bottom of the body portion. The bias of the spring pawl 168 is such as to cause the pawl tooth 166 to normally extend toward the left as shown in FIG. 15. When a reset plunger 174 and its associated coil spring 184 are assembled in their recesses 172, the pawl tooth 166 engages a tooth on the detent wheel 164. A back plate 188 held to the terminal block by the threaded fastener 124 maintains the reset plungers and their associated coil springs 184 in an assembled position as shown in FIGS. 9 and 10, that is, with the plungers in their lowermost position and held there against the force of the spring 184 by virtue of the engagement of the pawl end 166 with a detent wheel 164. In normal operation, where the shaft 162 is prevented from rotating because the solder 163 is in the solid state binding the shaft to the inside of the tube 161, the position shown in FIGS. 9 and 10 will be maintained.

By proper selection of a solder and a heater coil 34 a user may thereby determine a temperature representing a thermal condition above which is desired to protect the circuit or prevent it from operating because excessive current is being drawn. At this temperature the solder 163 will melt permitting the shaft 162 and detent wheel 164 to rotate freely. When this happens the holding force of the pawl end 166 is overcome by the force of the coil spring 184 permitting the reset plunger 174 to be pushed upwardly by the action of that spring. The upward motion of a plunger brings its tooth 176 into contact with the bottom of the reset bracket 136 causing that bracket to rotate clockwise about its pivoted connection established by the engagement of the lugs 138 in the openings 134 of the mounting bracket 114.

The clockwise rotation of the reset bracket causes its first actuating cam 142 to engage the nose 108 of the downwardly depending portion 106 on the actuating bracket 94. The force exerted by the reset plunger against the nose 108 causes the actuating bracket to rotate in a counterclockwise direction pulling down the cross bar 74 so as to disengage the movable contacts from the fixed contacts thus interrupting and protecting the circuit. At the same time the second actuating arm 144 on the reset bracket engages the cam element 152 on the actuating arm to rotate in a counterclockwise direction about its pivot pin 158 pushing the rocker arm 12 counterclockwise to the dotted line position shown in FIG. 12.

After the circuit had been interrupted and the heater coil 34 permitted to cool down so that the solder can once again solidify, the shaft 162 will once again be prevented from rotating in the tube 161. Until then,

any effort to reclose the circuit by pushing on the rocker arm will be unsuccessful for the thermal overload plunger will be maintained in its upward position by the action of the spring 184. Even though it may be depressed by pushing the rocker arm 132 in a counterclockwise direction to once again close the switch and cause the reset bracket to rotate counterclockwise pushing the plunger down it will not stay down as the pawl 168 will not lock the plunger in a downward position as long as the shaft 162 is free to rotate. When the solder has cooled to the point where it once again solidifies, the shaft 162 may no longer rotate and pushing the rocker arm in the counterclockwise direction will close the switch, cause the reset plunger to be pushed downwardly by virtue of the counterclockwise rotation of the reset bracket. When pushed downwardly under these circumstances, it will be held in a downward position by virtue of the engagement of a pawl tooth 166 with a detent wheel 164 inasmuch as the shaft 162 will no longer be free to rotate.

In this manner, a single rocker arm serves to permit a closing of the circuit, an interruption of the circuit when desired, and a resetting of the circuit after it has opened due to the presence of a thermal overload as determined by the melting of the solder in any one of the tubes 161.

By particular reference to FIGS. 13 through 21 it may be seen that most of the essential elements of the switch are formed by simple relatively imexpensive fabrication methods. Thus, the cross bar and the overload plunger are formed by molding suitable plastic materials. The actuating bracket, the mounting bracket, the reset bracket and the actuating arm are all formed by stamping and bending metallic materials to the shapes indicatedand it is well known this method of metal fabrication is capable of high production rates which may be achieved at low costs. The resulting structure, however, is one which is reliable, safe and capable ofa long life.

Interlocking Of The Switches In another aspect of the invention means is provided whereby two switches may be interlocked so that when they are supplying a single load only one of the switches may be operated. For instance, interlock switches in accordance with the invention may be used to supply a reversible motor having a separate reversing winding and it is important that the forward and reverse wind ings not be excited at the same time. With interlock 5 switches in accordance with the invention the arrangement is such that if the forward winding is connected to the line, the reverse winding cannot be so connected by operating the switch controlling that winding.

With particular reference to FIGS. 22 through 27, this aspect of the invention includes a pair of switches 200 and 202, each constructed as described above. The terminal block 204 of each switch is provided with side walls 206. Intermediate the length of each side wall a cutout 208 is provided. The cutout may be provided by molding the terminal block to have a thin walled portion. As may best be seen in FIG. 7, the thin walled portion 210 so formed spans a depression 212 on each side of the terminal block, which depression normally accommodates the movement of the lugs 98 as the actuating bracket 94 is rocked about its pivotal mounting in the mounting bracket 114.

When it is desired to interlock switches in accordance with the invention, the thin walled portion 212 may be knocked out thereby opening the depressions 212 to the exterior of the terminal block so as to provide access to the lugs 98 and thereby forming the cutouts 208. The two switches may then be mounted on a common support (not shown) with a space 214 therebetween. Mounted in the space 214 on a-suitable supporting bracket 216 is a cam 218 pivoted at 220. As may be seen, the operative part of the cam is formed in a generally triangular configuration with a pair of camming faces 222 and 224 and

flat surfaces

228 and 230.

that when the switch 200 is actuated by pushing the upper end of its rocker arm 12 so that its actuating bracket is rotated counterclockwise, the lug 98 on the U-shaped portion 100 thereof is rotated so as to assume the downward position as indicated in that figure. As that lug is rotated, it projects through the cutout 208 provided by knocking out the thin walled portion 210 in the switch block of the switch 200, and by camming against the surface 222 of the cam 218 it causes that cam to move slightly clockwise as shown in the figure. When the lug 98 of the portion 100 has rotated to its forward or downwardmost position as shown in FIG. 24, its end 226 engages a flat surface 228 at the end of the cam to lock or hold the cam in the counterclockwise position illustrated in the drawing.

If an attempt is made to operate the switch 202 at this time, the lug 98 on the U-shaped portion 102 of the actuating bracket of that switch is restrained from movement by virtue of its engagement with the camming surface 224 and the inability of the cam 218 to rotate clockwise. Under these conditions, the actuating bracket 100 of the switch 202 cannot be rotated by de- With particular reference to FIG. 24, it may be seen pressing its rocker arm 12 so that that switch cannot then be effective to close a circuit when the switch 200 has been operated to close a circuit.

When the switch 202 is actuated to the closed position by depressing the upper half of its rocker arm 12, its actuating bracket 94 is rotated clockwise to the downward position shown in FIG. 26. The rotation of the actuating bracket, its U-shaped portion 102 and lug 98 causes'the cam 218 to be rotated slightly counterclockwise to the position shown in FIG. 26 until the end 229 of the lug engages the flat surface 230 of the cam 218 so as to prevent its clockwise rotation. Under these conditions, any attempt to operate the switch 200 will not be effective because its lug 98 on the U-shaped portion 100 of its actuated bracket 94 is prevented from moving by virtue of its engagement with the camming surface 222. Consequently, when the switches are ganged as described in cooperation with the cam 218 the arrangement is such that only one switch at a time may be operated.

The switches may be mounted in any suitable type of standard enclosure with the rocker arm projecting through the enclosure for actuation. In addition, if desired, push buttons may extend from the rocker arm so as to provide a push button type of operation if such is desired.

Modifications other than those described or suggested in the application may be made in the invention without departing from the spirit and scope thereof and it is desired by the claims appended hereto to cover all such modifications.

What is described as new and desired to be secured by Letters Patent is:

1. An electrical switch comprising at least one fixed contact, a cross bar extending beneath said fixed contact and having a slotted portion extending downwardly therefrom, a movable contact carried on said cross bar, a pivotally mounted actuating bracket having a first U-shaped portion and a second U-shaped portion, a horizontal bar extending upwardly from the first U-shaped portion and engaging in the slot in said slotted portion, whereby said cross bar and said first U- shaped portion are slideably interconnected, a pivotally mounted actuating arm having an angular extension, spring means connected between the angular extension and said second U-shaped portion of said actuating bracket and in tension when so connected so as to maintain said actuating bracket at one limit of its pivoting movement, and means for pivoting said actuating arm to cause its angular extension to move whereby the firce vector of said coil spring will pass through a plane containing said second U-shaped portion and then include a component urging said actuating bracket toward the other limit of its pivoting movement and thereby causing said cross bar to move by virtue of the interconnection between it and said first U-shaped portion.

2. The electrical switch of claim 1 wherein said cross bar includes a platform and said slotted portion extends from the bottom of said platform, and compartment holding said movable co'ntact extends above said platform.

3. The electrical switch of claim 2 wherein said movable contact is movably mounted in said compartment and a coil spring is mounted between the bottom of said compartment and the bottom of said movable contact so to urge it toward the top of said compartment.

4. The electrical switchof claim 3 wherein said actuating bracket comprises a substantially flat elongated metallic member and said first U-shaped portion extends in one direction from the longitudinal axis thereof and said second U-shaped member extends in the other direction from the longitudinal axis thereof.

5. The electrical switch of claim 4 wherein the inner legs of said first and second U-shaped portions are joined together by an intermediate section having a downwardly depending portion and said horizontal bar extends upwardly from the bight portion of said first U- shaped portion.

6. The electrical switch of claim 5 including smaller lugs extending outwa rdly of the outer legs of said first and second U-shaped portions to provide means for pivoting said actuating bracket.

7. The electrical switch of claim 6 including larger lugs extending outwardly of the outer legs of said first and second U-shaped portions.

8. The electrical switch of claim 7 including a U- shaped mounting bracket having a first small opening provided in each leg thereof to receive a smaller lug whereby said actuating bracket may be supported and pivot in said mounting bracket.

9. The electrical switch of claim 8 wherein one leg of said mounting bracket has a second large opening formed therein into which the larger lug on the outer leg of said second U-sha'ped portion extends.

10. The electrical switch of claim 9 including a substantially flat elongated reset bracket having a lug extending from each end thereof.

11. The electrical switch of claim 10 wherein said mounting bracket has second smaller openings formed in each leg thereof to receive said reset bracket lugs whereby said reset bracket may pivot on said mounting bracket.

12. The electrical switch of claim 1 1 wherein said actuating arm is pivotally mounted on said one leg of said mounting bracket adjacent the outer end thereof.

13. The electrical switch of claim 12 wherein said one leg of said mounting bracket has a third opening therein adjacent the outer end thereof and, including a pivot pin mounted in said third opening, a rocker arm supported on said pivot pin and wherein said actuating arm is supported on said pivot pin.

14. The electrical switch of claim 13 including a terminal block formed from electrically insulating material and wherein said fixed contact is mounted at one end of said terminal block and said mounting bracket said actuating arm, said actuating bracket and said reset bracket are mounted below said fixed contact.

15. The electrical switch of claim 14 including a plurality of first fixed contacts mounted on the upper end of said terminal block on one side thereof, an input terminal electrically connected to each of said first fixed contacts, a plurality of movable contacts each comprising an elongated electrically conducting movable contact support having a movable contact at each end thereof, a plurality of second fixed contacts on the upper end of said terminal block on the other side thereof, and wherein a movable contact support extends between one first fixed contact and one second fixed contact.

16. The electrical switch of claim 15 including second terminals mounted on said upper end of said terminal block on said other side thereof, each individually electrically connected to one of said second fixed contacts.

17. The electrical switch of claim 16 including first terminals at the bottom of said terminal block on said other side thereof, and wherein said other side of said terminal has a plurality of grooves formed therein, and a conductor disposed in each of said grooves connecting one of said second terminals at the upper end of said terminal block to a first terminal at the bottom of said terminal block.

18. The electrical switch of claim 17 including a plurality of heater coils extending from said one side of said terminal block toward said other side of said terminal block, each individually electrically connected to one of said first terminals at the bottom of said terminal block.

19. The electrical switch of claim 18 including second terminals at the bottom of said terminal on said one side thereof, each individually connected to one of said heater coils and output terminals at the bottom of said terminal block on said one side thereof, each individually electrically connected to one of said second terminals.

20. The electrical switch of claim 19 including a hollow tube extending within the confines of each heater coil, a shaft extending within each tube, a quantity of solder normally preventing said shaft from rotating within said tube, said terminal block having a plurality of recesses formed therein at said bottom on said other side thereof, each of said shafts extending into one of said recesses, a detent wheel on each shaft portion in said recess, a reset plunger on each of said recesses, a spring pawl mounted on each plunger and having its outer end biased toward its associated detent wheel, and a coil spring in each recess mounted between the bottom of a recess and the bottom of its associated reset plunger urging it upwardly, whereby when a shaft is prevented from rotation when the solder in its tube is in a solid state the reset plunger is restrained from upward movement by virtueof the engagement of the outer end of said spring pawl with its associated detent wheel.

21. The electrical switch of claim 20 wherein said reset bracket has a first actuating arm extending substantially perpendicular from its surface toward and engaging said downwardly depending portion of said actuating bracket to cause said actuating bracket to rotate and pull said cross bar away from said fixed contacts when said reset bracket is rotated by upward movement of a reset plunger.

22. The electrical switch of claim 21 wherein said reset bracket has a second actuating arm extending an angle to the surface thereof toward said first-mentioned actuating arm whereby when said first-mentioned actuating arm is rotated said reset bracket will be rotated downwardly to force said rest plungers downwardly against the action of its coil spring. 7

23. The electrical switch of claim 22 in combination with an identical switch oriented in the same direction and spaced slightly therefrom and in further combination with a pivoted cam having a pair of oppositely inclined sloping surfaces and a flat surface. at the outer end of each sloping surface, each sloping surface and each flat surface being engageable with a larger lug on an actuating bracket of one of said switches whereby if either switch is actuated to a circuit closed position, the movement of its respective larger lug will cause said cam to pivot toward the other of said switches and said larger lug on the closed switch will engage a flat surface and thereby prevent rotation of said cam by said larger lug of the open switch thus preventing the open switch from being closed.

Claims

1. An electrical switch comprising at least one fixed contact, a cross bar extending beneath said fixed contact and having a slotted portion extending downwardly therefrom, a movable contact carried on said cross bar, a pivotally mounted actuating bracket having a first U-shaped portion and a second U-shaped portion, a horizontal bar extending upwardly from the first U-shaped portion and engaging in the slot in said slotted portion, whereby said cross bar and said first U-shaped portion are slideably interconnected, a pivotally mounted actuating arm having an angular extension, spring means connected between the angular extension and said second U-shaped portion of said actuating bracket and in tension when so connected so as to maintain said actuating bracket at one limit of its pivoting movement, and means for pivoting said actuating arm to cause its angular extension to move whereby the firce vector of said coil spring will pass through a plane containing said second U-shaped portion and then include a component urging said actuating bracket toward the other limit of its pivoting movement and thereby causing said cross bar to move by virtue of the interconnection between it and said first U-shaped portion.

2. The electrical switch of claim 1 wherein said cross bar includes a platform and said slotted portion extends from the bottom of said platform, and compartment holding said movable contact extends above said platform.

4. The electrical switch of claim 3 wherein said actuating bracket comprises a substantially flat elongated metallic member and said first U-shaped portion extends in one direction from the longitudinal axis thereof and said second U-shaped member extends in the other direction from the longitudinal axis thereof.

5. The electrical switch of claim 4 wherein the inner legs of said first and second U-shaped portions are joined together by an intermediate section having a downwardly depending portion and said horizontal bar extends upwArdly from the bight portion of said first U-shaped portion.

6. The electrical switch of claim 5 including smaller lugs extending outwardly of the outer legs of said first and second U-shaped portions to provide means for pivoting said actuating bracket.

8. The electrical switch of claim 7 including a U-shaped mounting bracket having a first small opening provided in each leg thereof to receive a smaller lug whereby said actuating bracket may be supported and pivot in said mounting bracket.

9. The electrical switch of claim 8 wherein one leg of said mounting bracket has a second large opening formed therein into which the larger lug on the outer leg of said second U-shaped portion extends.

12. The electrical switch of claim 11 wherein said actuating arm is pivotally mounted on said one leg of said mounting bracket adjacent the outer end thereof.

20. The electrical switch of claim 19 including a hollow tube extending within the confines of each heater coil, a shaft extending within each tube, a quantity of solder nOrmally preventing said shaft from rotating within said tube, said terminal block having a plurality of recesses formed therein at said bottom on said other side thereof, each of said shafts extending into one of said recesses, a detent wheel on each shaft portion in said recess, a reset plunger on each of said recesses, a spring pawl mounted on each plunger and having its outer end biased toward its associated detent wheel, and a coil spring in each recess mounted between the bottom of a recess and the bottom of its associated reset plunger urging it upwardly, whereby when a shaft is prevented from rotation when the solder in its tube is in a solid state the reset plunger is restrained from upward movement by virtue of the engagement of the outer end of said spring pawl with its associated detent wheel.

22. The electrical switch of claim 21 wherein said reset bracket has a second actuating arm extending an angle to the surface thereof toward said first-mentioned actuating arm whereby when said first-mentioned actuating arm is rotated said reset bracket will be rotated downwardly to force said rest plungers downwardly against the action of its coil spring.

23. The electrical switch of claim 22 in combination with an identical switch oriented in the same direction and spaced slightly therefrom and in further combination with a pivoted cam having a pair of oppositely inclined sloping surfaces and a flat surface at the outer end of each sloping surface, each sloping surface and each flat surface being engageable with a larger lug on an actuating bracket of one of said switches whereby if either switch is actuated to a circuit closed position, the movement of its respective larger lug will cause said cam to pivot toward the other of said switches and said larger lug on the closed switch will engage a flat surface and thereby prevent rotation of said cam by said larger lug of the open switch thus preventing the open switch from being closed.