US 3824509 A
An electromagnetically operated switching device in which movable contacts move along lines extending downwardly at an acute angle to the horizontal to engage and disengage fixed contacts. An electromagnet is mounted in the housing oriented so as to have the main axis of the magnetomotive force thereof act along a line extending downwardly at an angle from a housing wall intended to be mounted vertically and an armature is connected to the movable contact guided so as to move along the same line.
Claims available in
Description (OCR text may contain errors)
United States Patent [1 1 McGary MAGNETICALLY OPERATED ELECTRIC SWITCH DEVICE  Inventor: Robert L. McGary, Batavia, Ill.  Assignee: Furnas Electric Company, Batavia,
 Filed: May 17, 1972  Appl. No.: 254,044
 US. Cl. 335/132, 200/166 BC, 335/133  Int. Cl. H01h 50/04  Field of Search 335/202, 132, 193, 157,
335/191, 257, 262, 247, 193, 131, 133; ZOO/166 J, 166 Bl-l, 166 BC, 166 H  References Cited UNITED STATES PATENTS 2,336,871 12/1943 Lake 335/193 2,546,001 3/1951 lmmel 200/166 BC [451 July 16, 1974 2,585,824 2/1952 Noyes ZOO/166 BC 2,732,452 l/l956 Jackson et a]. 335/193 2,883,487 4/1959 Spaulding et a1. 335/157 2,924,685 2/1960 Burch 200/166 BC 3,673,525 6/1972 Collins et al 335/193 Primary Examiner'Harold Broome  I ABSTRACT An electromagnetically operated switching device in which movable contacts move along lines extending downwardly at an acute angle to the horizontal to engage and disengage fixed contacts. An electromagnet is mounted in the housing oriented so as-to have the main axis of the magnetomotive force thereof act along a line extending downwardly at an angle from a housing wall intended to be mounted vertically and an armature is connected to the movable contact guided so as to move along the same line.
21 Claims, 15 Drawing Figures PAIENTEDJUHEW 3. 24.509 SHEU 3 OF 5 PATENTEnJm 1 am;
y 3.824.509 SHEEI 5 OF 5 FIG; 12
/42 FIG, 15
MAGNETICALLY OPERATED ELECTRIC SWITCH DEVICE BACKGROUND OF THE INVENTION This invention relates generally to electrical switching devices. More specifically, it relates to electromagnetically operated switches and accessories therefor.
Electromagnetically operated switches of the type called contactors for controlling the operation of industrial machines include an electromagnet in conjunction with an armature mechanically connected to a movable contact assembly so that when the electromagnet is energized the armature will move toward it and complete a circuit from a source to a load. Numerous problems exist with respect to the contactors of the prior art. One of the more important of these is that referred to in the art as contact bounce, that is to say, the situation occurring as the movable contacts first engage the fixed contacts closing the circuit and then bounce away breaking the circuit. This occurs because the fixed and movable contacts are usually supported on resilient conductors biased toward each other to maintain good contact when they are desired to be engaged with each other. When initially engaged there is a shock or impact, due in large part to the moving mass of the armature, which causes a repeated bounce, or engagement and disengagement, until they settle down. Such bounce shortens contact life for each time it occurs there may be arcing between the contacts causing a pitting or electrical erosion of the contact material. To solve this problem various workers in the art have proposed various arrangements wherein the heavy moving armature and contacts move horizontally or perpendicular to a mounting surface. Others have proposed arrangements wherein the heavy armature moves vertically while the contacts have moved horizontally.
A complicating factor is that it is very desirable that the contacts break or move away from each other very rapidly in order to minimize arcing. Tooptimize this ability it is desirable that the contacts and armature move vertically so as to gain the help of gravity forces.
Thus, prior art designs have attempted to reconcilethesedifferent design requirements in the manners described and in sodoing haveeither not solved the problem of contact bounce or have created additional problems. For instance, an arrangement wherein both the contacts and armature move in a vertical plane require both the incoming and outgoing conductors to be attached at the top of the contactor. This is undesirable particularly when a contactor is combined with an overload relay to form a starter. The arrangement wherein the magnetic structure moves vertically and the contacts move horizontally requires a relatively expensive and complicatedmechanical linkage to translate the vertical motion of the armature to the horizontal motion of the contacts.
Therefore, it is an object of this invention to provide a novel electrical circuit controller which eliminates or substantially reduces contact bounce in such a device.
It is another object of this invention to provide a novel electrical circuit controller which eliminates or substantially reduces the problem of contact bounce and at the same time provide terminals for the incoming and outgoing conductors which are arranged to provide for the simplest and most convenient connection to the circuit and any auxiliary devices which may be used.
A further object of this invention is to provide a novel electrical circuit controller which eliminates or substantially reduces contact bounce without the necessity of complicated and costly mechanical linkages.
In the normal useage of electrical contactors they are frequently interconnected to operate with other contactors and other switching devices such as the overload relay referred to above. In addition, they may be provided with pilot lights or other indicators intended to provide an indication of the state of a system. To this end it is desirable to provide means for permitting such interlocking and connection.
Therefore, it is a further object of the invention to provide a novel electrical contactor which includes means whereby it may be easily interconnected with other devices in an electrical contact control system.
In addition to the foregoing, the periodic inspection and maintenance of contactors is important. To this end it is desirable to provide in such a device that there be easy access to the operating parts for inspection and that the replacement of such parts be facilitated.
Accordingly, it is another object of this invention to provide a novel electrical contactor which includes components which are or can be made readily visible and can be mounted in or removed from the contactor by easy manipulation but at the same time provides reliable retaining means.
BRIEF SUMMARY OF THE INVENTION The above and other objects of the invention are achieved in one embodiment of the invention wherein the actuating armature and the movable contacts of a contactor are arranged to move along aline extending downwardly at an acute angle to horizontal, i.e., at an angle to a vertical mounting surface. As a result of such motion, the entire weight or force of the heavy magnetic structure is not supplied to the contacts so that bounce is eliminated or, at the very least, substantially reduced. Other aspects of the invention include a housing formed of component parts which are easily disassembled and to provide easy access to the operating components and those components themselves are mounted in the housing by elements permitting their easy removal and replacement.
BRIEF DESCRIPTION OF THE DRAWINGS An understanding of the structure and operation of an embodiment of the invention can be had by reference to the detailed description taken in conjunction with the accompanying drawings in which:
FIG. I is a front view of an embodiment of the invention shown in conjunction with an accessory device used therewith;
FIG. 2 is a side view of the embodiment shown in FIG. 1;
FIG. 3 is a view along the lines 3-3 of FIG. 1;
FIG. 4 is a view along the lines 44 of FIG. 1;
FIG. 5 is an exploded view of the embodiment of FIG. 1;
FIG. 6 is a sectional side view of the embodiment of FIG. 1;
FIG. 7 is a view along the lines 7-7 of FIG. 6; FIG. 8 is a view along the lines 8-8 of FIG. 7',
FIG. 9 is a front view of a contact arrangement in an embodiment of the invention taken on line 9-9 of FIG. 5; I
FIG. 9a is a view alongthe lines 9a-9a of FIG. 9;
FIG. 10 is a view along the lines l0-10 of FIG. 6;
FIG. 11 is a view along the lines 1lll of FIG. 6;
FIG. 12 is a view along the lines 1212 of FIG. 6;
FIG. 13 is a rear view similar to FIG. 12 but partially exploded; and g F 1G. 14 is a schematic diagram illustrating an electrical circuit in which a device in accordance with the invention may be connected to control a load such'as a motor.
DETAILED DESCRIPTION Referring to FIGS. 1, 2 and 5, an embodiment of the invention is illustrated generally. Thus, there is provided a housing designated generally by reference numeral 2. The housing which is formed in various parts, as will be described, is constructed by molding a plastic material having suitable mechanical strength and electrical insulating properties. Mounted in the housing 2 is the electromagnetic switch of the invention providing contacts which may be opened and closed in order to control the energization of an electrical load. The device shown is of the class of electrical switching devices known as contactors which when associated with an auxiliary device such as an overload relay, as shown generally at 4, is referred to as a starter. The particular overload relay illustrated forms no part of this invention and is shown by way of exemplification only. Its structure may be better understood by reference to the copending application of Clement P. Sitar Ser. No. 242,091 for a Bimetallic Circuit Overload Protector filed on Apr. 7, 1972 and assigned to the same assignee as is this application.
The housing 2 includes abase portion 6, an intermediate portion 8 and acover portion 10. It is important to understanding the structureand operation of the invention to appreciate that a device constructed in accordance with the teachings of this application is intended to be mounted oriented as shownin FIGS. 1, 2
portion 8 by means of a pair of latches 40, one at the top on one side of the contactor and the other at the bottom on the other side of the contactor, each pivotally mounted in the intermediate portion 8 and engaging in notches 42 provided in the cover portion 10 for that purpose. v
The particular contactor illustrated is one intended for controlling at least three-phase circuits. Consequently, provided on the top of the contactor are a first set of terminals 44 constituting the incoming or input terminals to be connected to one wire of each of the wires in a three wire system. By so mounting the terminals 44 the incoming conductors may be connected at and 5. Thus, as may best be seen in FIG. 5, the base portion includes a rear wall 12 on which is formed a top mounting bracket 14 and a pair of bottom mounting brackets 16 through which screws may be passed through openings (not shown) for mounting the contactor on a vertically extending supporting surface. Extending forwardly from the rear wall 12 are a pair of spaced side walls 18. Each side wall is formed with a top surface 19 extending essentially perpendiuclarly from the rear wall 12 and a bottom surface 20 extend ing downwardly at an angle from the free ends of the side walls toward the rear wall 12.
The intermediate portion 8 isformed to have a pair of side walls 22, the rearward surfaces 24 of which are disposed at an angle matching the angle of the surfaces 20 so that when the housing is assembled the surfaces 20 and 24 will confront each other'along their entire lengths. Formed as part of the intermediate portion 8 g is an intermediate wall 26 (see FIG. 6) which spans the intermediate side walls 22 to provide a supporting surface for various switch elements as will be described. The intermediate wall 26 is disposed to lie in a plane parallel to a plane containing the surfaces 24. As may best be seen in FIG. 6, the base portion 6 in conjunction with the intermediate portion 8-form a compartthe top of the contactor. As may best be seen, in FIG. 6, each of theterminals 44 is provided at the end of the conducting element 46 mounted on the intermediate wall 26 by means of a threaded fastener 48 engaging in that wall. A second set of terminals 50 constituting the output or outgoing terminals are provided at the bottom of the housing on conducting elements 52 mounted on the intermediate wall 26 by means of threaded fasteners 54. Again, with reference to FIG. 6, it may be seen that the output terminals are mounted on the housing so that output connections may be made from the bottom of the housing. Thus, it is possible with a contactor according to the invention to bring the input conductors into the top of the contactor and provide output connections at the bottom of the contactor,
thus providing a straight line connection arrangement ing in different directions in and around the device.
By reference to FIG. 6, it may be seen that when the contactor is mounted on a supporting surface of an enclosure as intended, the terminals 44 are spaced a first distance from the rear wall 12 while the terminals 50 are mounted between the terminals 44 and that rear wall. Provided between the terminals 44 and 50 is a first set of fixed contacts 56, each individually connected to an associated first terminal 44 by means of theconducting element 46. Individually connected to the second terminals 50 by means of the conducting element 52 are the-contacts of a second set of fixed contacts 58. In order to complete an electrical circuit, when desired, a movable contact assembly including a first set of movable contacts positioned to be engageable with the first set of fixed contacts 56 are indiportion 70. The upper portion 68 comprises an elongated plastic member extending transversely across the front of the intermediate wall 26 and is provided with a plurality of openings 72. Mounted in each opening 72 is a coil spring 74 which holds its associated conducting element 66 against the bottom of the opening in the desired assembled position.
The base portion of the cross arm assembly is coextensive with the upper portion 68 and is attached thereto in assembled relationship by a pair of screws 76 passing through the upper portion 68 and threaded into the base portion 70. The base portion is formed as a substantially U-shaped member having a transversely extending portion 78 and a pair of legs 80 extending therefrom. A transverse opening 82 is provided in the intermediate wall and the base portion 70 extends therethrough into the compartment 28. Molded at the ends of the opening 82 are a pair of recesses 84 to accommodate a pair of coil springs 86, each of which bears against the bottom of its respective recess and portions 88 of the base portion 70 extending beyond the legs 80 to normally urge the cross bar assembly and the associated movable contacts outwardly of the compartment 28.
Carried on the base portion 70 of the cross bar assembly is an armature 90 (see FIGS. 8 and 10). The armature comprises a plurality of laminations of magnetic material held together by rivets 92 passing through yokes or straps 94 and with outwardly on either side of the laminations. The armature is provided withoutwardly extending shoulders (see FIG. 7) on either side thereof to engage in slots 102 provided at the juncture of the legs 80 with the cross portion 78 of the base 70 so as to assemble the armature to the movable contact assembly. Bent portions 101 of the yoke 94 engage the sides of the legs 80 of the base 70 to position the armature when assembled.
To further aid in holding the armature in assembled position, and at the same time permit its removal when desired, a leaf spring 104 engages between the bottom of the armature and the cross portion 78 and urges the armature to the right as shown in FIG. 7. The leaf spring is bent so as to exert a force against the armature effective to cause the shoulders 100 to bear against the walls of the slots 102.
As best seen in FIG. 8, the leaf spring 104 comprises a pair of arms 106 which extend transversely of the armature and the cross bar assembly which arms are bent away from the cross bar assembly to provide the holding force described. A hole 108 in the center of the leaf spring engages a boss 110 on the bottom of the base 70 to maintain the spring in position. Also included as part of the leaf spring are a pair of arms 112 extending outwardly of the armature and provided with outwardly bent finger gripping portions 114. When it is desired to disassemble the armature from the cross bar assembly, this may be accomplished by exerting a force on the finger gripping portions 114 tending to move them toward each other, which force causes the bent arms 106 to straighten out relieving the force holding the shoulders 100 in the slots 102. When this force is sufficiently relieved, the armature may be moved laterally outward until the shoulders clear the slots.
An electromagnetic assembly comprising a U-shaped core 118 of magnetically permeable material and coil structure 120 supported in a molded encapsulating assembly 122 is mounted between the side walls 18 of the base portion 6. The molded support 122 is provided with a pair of windows 124 which receive the legs of the core 118 so that when the coil structure 120 is energized magnet flux is generated in the core. The core is formed by a plurality of laminations held together by rivets 126 and completed by a bottom yoke 128. Shoulders 130 formed on the yoke and extending outwardly therefrom engage the sides of the support 122 to properly position the core 118 in the support.
The electromagnet assembly is completed by terminals 132 molded into the support 122 to provide for connections to the coil structure 120. Provided on the free ends of the legs of the core 118 are shading coils 134 to limit stray flux from the core.
As may best be seen in FIG. 11 when the electromagnet assembly is mounted in the base portion 6 its bottom, that is, the surface opposite from that on which the terminals 132 are provided rests on a supporting ledge 136 formed on the rear 12 and projecting into the compartment 28.
The electromagnet assembly is mounted in the base 6 by inserting it between the side walls 18 and held in assembled position by a U-shaped retaining spring 138. The spring 138 is formed with a bight portion 140 having an inwardly curved center projection 142. A pair of offsets 144 are provided at each end of the bight portion and legs 146 extend therefrom. Adjacent the free end of each leg 146 are inwardly projecting offsets 148 from which finger gripping tabs 150 extend. Provided in the 'rear wall 12, adjacent the upper end thereof, is central opening 152 and end openings 154 on either side thereof.
The retaining spring 138 is mounted in the base portion 6 by inserting the legs 146 through the end openings 154 until the offsets 144 pass through those openings to snap outward and bear against the inner surface of the rear wall 12. At the same time the center projection 142 passes through the central opening 152 so that the spring is retained in the rear, wall with the legs 146 extending upwardly at an angle. To assemble the electromagnet assembly the core 118 is mounted in the support 122 and these two elements, asembled, are moved downwardly between the side walls 18. A pair of integrally formed rearwardly extending projections 156 on the support 122 first engage the legs 146 between the tabs 150 to spread them apart. The electromagnet is moved downward, with the offsets 148 sliding on the projections 156, until they snap over their upper ends. At this point the electromagnet is held in its assembled position by virtue of the spring force exerted by the legs 146. As can be seen the faces of the core 118 extend downwardly toward the armature 90 with the main axis of the magnetic field produced, when the coil 120 is energized, extending downwardly at an acute angle to the rear wall 12.
The movable contact assembly, including the armature, are partially guided in their path of movement by the engagement of the portions 88 of the base portion 70 in the recesses 84 in the intermediate side walls 22. Additional guide means are provided by general triangular-shaped spacer walls 158 which project outwardly from the intermediate wall 26 on either side of the cross bar assembly 64 and between the sets of movable and fixed contacts. The confronting inner ends of the spacer walls 158 extend into grooves 160 formed in the cross bar assembly to require that assembly to move in the desired path. In addition, the spacer walls function to increase the electricalv leakage path between the various sets of contacts. I
Assuming the statewherein the coil 120 is first deenergized, whenit is energized the armature willbe attracted toward the core 118. The movement of the armature will cause the cross bar assembly 64 together with the sets of movable contacts 60 and 62 to move toward and engage their associated fixed contacts 56 and 58 to complete circuits from the incoming terminals 44 to the outgoing terminals 50. As may best be seen in FIGS. and 6, the armature and movable contact assembly move upwardly along a line extending downwardly at an acute angle from the upper end of rear wall 12. By virtue of this arrangement the heavy moving weight of the armature is not transmitted in its entirety to the contacts as only a component is. When the coil is deenergized, the vertical component of the force of the armature moving downwardly under the force of gravity is available to rapidly'break the contacts to minimize arcing upon breaking.
A contactor in accordance with the invention may be provided with means for easily connecting it to the circuit it is intended to control and various auxiliary devices.
For-instance, apushbutton controller may be desired.
, This is provided by means of a casing 162 housing normally opened switches closed by a pushbutton 164 labeled start and a normally closed switch opened by pushbutton 166 labeled stop. The casing may be mounted on the front wall 32 of the cover portion by means of screws 168. Three terminals 170, 172 and 174 are provided for connections to be explained in conjunction with FIG. 13.
In order that an overload relay such as that shown by reference numeral 4 may be mechanically attached to a contactor in accordance with the invention and connected to a circuit therewith, various means are provided. Thus, as may be seen in FIG. 5, the relay 4 is provided with terminals 176 and is mounted on supporting bracket 178. A hole 180 is provided in the supporting bracket 178. Molded on the rear wall 12 of the contactor is a boss 182 to be engaged in the hole 180. Thus, when the relay 4 is to be connected to the contactor, the terminals 176 are connected to the outgoing terminals 50 and the boss 182 is engaged in the hole 180. When screws on the terminals 50 are tightened, the relay will be held in assembled relation with the contactor and an electrical circuit will be completed.
The relay, as may be seen in FIG. 1, includes heater elements 184 connected between individual terminals 176 and individual outgoing terminals 186. As is well known, the relay 4 includes means, forming no part of this invention, effective to interrupt a circuit between two output terminals 188 and 190.
To connect the pushbutton controller to the contactor the terminal 170 is connected to an incoming terminal 132 of the coil 120 while an outgoing terminal is connected to a terminal 188 of the relay 4. That is, terminal 188 in turn is connected through the normally closed contacts 192 (see FIG. 14) and terminal 190 of that relay to a terminal 194 provided at the top of the contactor and electrically connected to one of the incoming terminals 44. Another of the incoming terminals 44 is electrically connected to a terminal 196 which is connected to the terminal 174, constituting one of the terminals of switch 166 on the pushbutton controller.
The electrical connections of the pushbutton controller are completed by connecting the terminal 170 to a terminal 198 provided on the front of the contactor. A conductor 200 connects the terminal 198 to a stationary contact 202 positioned to be engaged by a movable contact 204 carried on one end of a conducting bar 206 mounted in an opening 208 in the cross bar. A coil spring 210 urges the conducting bar, its movable contact 204, and a movable contact 212 carried on its other end toward engagement with stationary contact 202 and a stationary contact 214. A conductor 216 connects stationary contact 214 to a terminal 218 at the top of the contactor which in turn is connected to the pushbutton controller terminal 172.
Referring to FIG. 14, the circuit thus provided may be seen. Thus, when switch 164 is momentarily closed the coil 120 is energized causing the armature to move toward 118 completing a circuit between associated stationary contacts 48 and 58 to energize the load, in this case a motor. At the same time a circuit is completed between stationary contacts 202 and 214 to constitute a holding around switch 164 which was closed only long enough for the contactor to operate. When it is desired to interrupt the circuit, the switch 166 is operated causing the coil to be deenergized and the contactor to drop out. In the event of thermal overload the relay 4 is operated and opens contact 190 to deenergize the coil and likewise cause the contactor to drop out.
In addition to providing for the auxiliary devices described, there is also a means for-interconnecting the contactor. Thus, the cross bar 64 is provided with extensions 220 which project through openings 222 in the intermediate side walls 22. An interconnecting means, in this case a normally opened switch 224, may be connected on a side wall 22 by means of a threaded fastener passing through a hole 226 in the switch and engaging in a nut 228 held in a recess 230. The switch includes a terminal 232 connected to a stationary contact 234 positioned to be engaged by a movable contact 236. The movable contact 236 is mounted on a leaf spring 238 electrically connected to a terminal 240. A plunger actuator 242 extends from the switch and bears againstthe cross bar extension 220 so that when the contactor is energized the movement of the cross bar causes an extension 220 to depress the plunger 242 closing the contacts 236 and 234. Any device, including another contactor, which is desired to be interlocked with a contactor in accordance with the invention may be connected to the terminals 232 and 240 to be controlled thereby.
In summary, a contactor in accordance with the invention is constructed to have its movable elements operate along lines which extend downwardly at an acute angle to a vertical supporting surface and consequently contact bounce is eliminated or substantially reduced and at the same time the weight of the armature acts to rapidly interrupt the circuit when that is desired. The arrangement further provides for easy connection in a circuit and to various auxiliary and interlocked devices.
Obviously, various changes may be made in the invention while remaining within the spirit thereof and it is intended by the claims appended hereto and forming a part of this specification to cover all such changes as fall within their scope.
I claim: 1
l. The electric switch comprising a housing having a surface intended to extend vertically when the housing is mounted on a supporting surface, a top and a bottom, a top terminal on said housing at said top,'a bottom terminal on said housing at said bottom, a fixed contact in said housing connected to said top terminal, a movable contact in said housing engageable with said fixed contact, means mounting said movable contact for movement toward and away from said fixed contact on a straight line extending downwardly at an acute angle to said surface, means connecting said movable contact to said bottom terminal, an electromagnet assembly mounted in said housing, an armature mounted in said housing adjacent said electromagnet so as to be attracted thereto along said straight line when said electromagnet is energized, and means mechanically connecting said armature to said means mounting said movable contact to cause it to move along said straight line and engage said fixed contact when said armature is attracted toward said electromagnet.
2. An electric switching device as set forth in claim 3. An electric switching device as set forth in claim 2 including a plurality of top and bottom terminals and fixed and movable contacts connected as described.
4. An electric switching device as set forth in claim 3 including a plurality of second movable contacts, each being separately electrically connected to one of said movable contacts and movable therewith, and a plurality of second fixed contacts engageable by said second movable contacts and electrically connected to said bottom terminals.
5. An electric switching device as set forth in claim 4 wherein said acute angle is about 45.
6. An electric switching device as set forth in claim 5 wherein said electromagnet assembly comprises coil means, a support for said coil means having a pair of spaced openings and a U-shaped yoke of magnetizable material having spaced legs extending through said openings and coil terminals mounted on said coil means support and connected to said coil means.
7. An electric switching device as set forth in claim 6 wherein said coil means support includes a protective coating of hardened plastic material encompassing said coil means.
8. An electric switching device as set forth in claim 7 including a spring clip mounted in said housing and having portions engaging said protective coating to retain said electromagnet assembly in said housing.
9. An electric switching device as set forth in claim 8 wherein said armature is mounted on said cross arm assembly so that said cross arm assembly and the movable contacts mounted thereon move upward along said line to engage said fixed contacts when said coil means is energized.
10. An electric switching device as set forth in claim 9 including spring means mounted between a portion of said housing and cross arm assembly to urge said cross arm assembly downwardly along said line against the force of said electromagnet.
11. An electric switching device as set forth in claim 10 wherein said housing surface is constituted by a surface of the rear wall of said housing and including brackets formed on said rear wall for mounting said housing and supporting surface.
12. An electric switching device as set forth in claim 11 including a boss formed on said rear wall for engagement by a switch supporting plate.
13. An electric switching device as set forth in claim 10 including lugs formed at the ends of said cross arm assembly extending beyond the side walls of said housmg.
14. An electric switching device as set forth in claim 13 including a switch mounted on a side wall of said housing, said switch including a switch actuator extending toward a lug on said cross arm assembly and engageable therewith when said cross arm assembly moves to operate the switch.
15. An electric switching device comprising a housing having: a base portion having a rear wall intended to extend vertically when mounted on a supporting surface, and base side wall portions extending from said rear wall; an intermediate portion having side walls, each intermediate side wall aligned with a corresponding rear wall side wall portion, and an intermediate wall extending from one intermediate side wall to the other intermediate side wall and disposed at an acute angle to the rear wall; a cover portion having side walls aligned with corresponding intermediate side walls and a front wall portion extending from one cover portion side. wall to the other, an electromagnet assembly mounted in said portion oriented to exert a magnetomotive force along a line extending downwardly from said rear wall at an acute angle; and a movable contact assembly including an armature and movable contacts mounted on said intermediate portion for movement along said line.
16. An electric switching device as set forth in claim 15 wherein: each said base side wall has an upper surface extending substantially perpendicularly from said rear wall andfront surface extending from the free end of each base wall at an acute angle toward the rear wall; each intermediate side wall has a rear surface extending at an acute angle matching that of the front surfaces of said rear side walls and a front surface parallel to said rear surface and said intermediate wall extends from the front surface ofone intermediate side wall to the front surface of the other intermediate side wall so as to form a compartment with said rear wall.
17. An electric switching device as set forth in claim 16 wherein: said intermediate wall has a transversely extending opening formed therein; and said cross bar assembly extends transversely of said intermediate wall and has a base portion extending through said transverse opening into said compartment.
18. An electric switching device as set forth in claim 17 including a spring retaining element engaging said cross arm base portion and said armature to retain said armature on said base portion.
19. An electric switching device as set forth in claim 18 including a first set of terminals mounted on said intermediate portion and spaced a first distance from said rear wall, a second set of terminals mounted on said intermediate portion and spaced a second and shorter distance from said rear wall, a first set of fixed contacts mounted on said intermediate portion between said first set of terminals and said second set of terminals and electrically connected to said first set of terminals, a second set of fixed contacts mounted on said interme- 19 including latch means mounted on said intermediate portion and engaging said cover portion to retain said cover portion on said intermediate portion.
21. An electric switching device as set forth in claim 20 including a normally opened switch and a normally closed switch mounted on said housing and means for connecting said normally opened and said normally closed switches in series with said electromagnet.
I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,824,509 Dated July, 16, 1974 Inventor(s) Robert-L. McGary It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
C'olumn 5, line 29, after "94" and 96- has been omitted and "with outwardly" has been inserted in error.
Signed and sealed this 3rd day of December 1974.
McCOY n. GIBSON JR. c. I'IARSHALL' DANN Attesting Officer Comissioner of Patents FORM PO-105O (10-69) v v usco -pc 60376-P69 v I v t .5. GOViRNHENT PRINTING OFFICE: ".5 0-35.!1,
UNITED STATES PATENT OFF ICE CERTIFICATE OF CORRECTION Patent No. 3,824,509 Dated July. 16, 1974 Inventor(s) Robert L. McGary It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown-below:
Column 5, line 29, after "94" and 96-- has been omitted and "with outwardly" has been inserted in error Signed and sealed this 3rd day of December 1974.
MCCOY M. GIBSON JR. c. l-iARSHALLDANN Attesting Officer Connnissioner of Patents FORM (10-69) I 1 USCOMM-DC 60378-P69 I U.5. GOVERNMENT PRINTlNG OFHCEZ I," D-36"!34,