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Sept 17, 1946- , F. G. LOGAN . ELECTRIC 2,407,710 SWITCH Original Filed Nov. 6, 1941 )6 J 8“ +5\ 6 I 8574 3 Sheets-Sheet l Sept. 17, 1946. ‘ F. G. LOGAN 2,407,710 ELECTRIC SWITCH Original Filed Nov. 6, 1941 ‘ a - a if. 5719/ ?fjzgwgagw 30 /£ I / 3 Sheets-Sheet 2 Sept. 17, 1946. I F, G, LOGAN- 2,407,710 ELECTRIC SWITCH Original Filed Nov. 6, 1941 3 Sheets-Sheet 3 2,407,710 Patented Sept. 17, 1946 UNITED STATES PATENT OFFICE 2,407,710 ELECTRIC SWITCH Frank G. Logan, Mount Vernon, N. Y., assignor to Ward Leonard Electric Company, a corporation of New York Original application November 6, 1941, Serial No. 417,990, now Patent No. 2,378,022, dated June 12, 1945. Divided and this application March 27, 1943, Serial No. 480,767 4 Claims. (Cl. 200—144) 2 1 This invention relates to electric switches adapted for general use and for control purposes and is of the magnetically operated contacting type although certain features of this improve ment are applicable to other types of switches. Certain of the improvements disclosed herein and _ not claimed are the inventions of George M. Sta pleton and are described and claimed in his pend ing United States application Serial No. 420,327, ?led November 25, 1941, now Patent No. 2,378,162, issued June 12, 1945. This application is a division of my pending original application Serial No. 417,990, filed No vember 6, 1941, now Patent No. 2,378,022, issued 15 June 12, 1945. The general object of the improvements de scribed and claimed herein are to produce an im proved switch which is of compact form and of comparatively large current and rupturing ca pacity, and which will be durable and dependable under long continued use. A particular object is to provide an improved form of arc chambers and relationship to the contacts for effectively quenching the arc and occupying small space. This is accomplished in general by providing arc chambers which individually encircle the con tacts in comparatively close proximity thereto ple provision of arc quenching and cooling sur faces within the arc chambers; and the relation ship of the parts is such that the arc is electro magnetically forced against the walls of the chambers which are opposite the cut-away por tions which insures the effective cooling and quenching of the arcs by the arc barrier surfaces on the opposite side of the chambers from the cut-away portions. The are chambers or shields are preferably made of metal as such material can effectively withstand the heating effects of the arcs without objectionable deterioration and the high thermal conductivity of metal assists in the cooling of the arc and the heated gases. Either magnetic material, such as iron or sheet steel, may be used for the arc chambers but non magnetic material, such as brass likewise may be used. Also, the chambers may be made of other suitable material than metal which is adapted to effectively withstand the e?ects of the arcs and hot gases without objectionable deterioration of the exposed surfaces. Other objects and advantages of this invention will be understood from the following description ‘ and accompanying drawings which illustrate one embodiment of the invention. Fig. 1 is a vertical central section in a plane at right-angles to the back of the switch; Fig. 2 is a and by mounting them so as to be movable with top plan view with the connecting terminals the movable contacts of the switch. The im proved construction permits the arc chambers to 30 shown in section; Fig. 3 is a horizontal section on the line 3—3 of Fig. 1; Fig. 4 is a horizontal sec be made of light weight and of a sturdy form of tion on the line 4-—4 of Fig. 1; Fig. 5 is an en structure that will effectively cool and quench larged side view, partly in section, of one of the the arc and permit the effective carrying away of ?xed contacts; Fig. 6 is an enlarged perspective the hot gases upwardly in their natural tendency to rise. The permissible proximity of the arc 35 view of one of the arc chambers or shields; Fig. 7 is a vertical section on the line 1-1 of Fig. l; and chambers to the contacts has the advantage of ‘Fig. 8 is a horizontal section on the line 8—8 of rapidly cooling the arc and heated gases and by Fig. 7. reason of the fact that the chambers are movable The apparatus is supported by a frame or base 'with the movable contacts, there rises the advan tage of exposing fresh arc barrier surfaces to the 40 of sheet metal having a general U-shaped form.. are continuously during the opening movement The base of the U extends verticallyv and the two of the contacts. Also, during the opening move ment provision is made not only for the escape of hot gases upwardly but for providing free ac side portions extend forwardly from the base por tion. The rear portion of the frame is corrugat ed for strength, the projecting ribs Ia which cess of air to the bottom of the chambers so as 45 extend vertically along the back, being forced to permit a free and enforced movement of the forwardly from the metal sheet before it is cut hot gases upwardly and permit them to escape and bent to the desired form. At about the through the top of the arc chambers to the out middle of the back portion, two of the ribs la side atmosphere. The free upward passage of the are further pressed forwardly forming project hot gases is facilitated further by cutting away 50 ing ribs lb, as shown in Figs. 1 and 4, for a pur pose later explained. The back portion is pro the lower parts of the arc chambers to permit free vided with openings Ic at the top and bottom, as inward passage of air upwardly through the shown in Figs. 1 and 7, for the purpose of secur chambers and these cut-away portions of the ‘ing the frame to a supporting panel. The for chambers also permit entrance of the supports for the movable contacts while maintaining am 55 wardly extending side portions Id are provided 3 2,407,710 with a number of openings to as shown in Figs. 7 and 8 for the purpose of ventilation and ac~ cessibility during assembly, and in repair or ad justment of the parts. A number of projecting portions extend from the side portions and are bent inwardly at right-angles at the front of the frame for forming supports for various parts. A pair of these projections if, shoWn in Figs. 1 4 5 is free to be raised from the frame and thus per mit the front edge of the block to be withdrawn from under the clamping extensions 2a. Thus the insulating block 5 may be readily removed and replaced, together with the parts carried by it, for inspection, cleaning or adjustment of the parts. The block or head 5 is provided on its upper and 2, forms a support for a front plate 2 which surface with ribs So, as well shown in Fig. 7, may be utilized for supporting auxiliary conti. o1 1O which extend from front to back and also an up apparatus or parts and also serves another func wardly extending rear cross-rib lib, as shown in tion to be described later. The plate is also Fig. 1. These ribs are for the purpose of secured to a pair of inwardly turned projections strengthening the block and for also separating considerable lg of the frame portion whichofextend the frame. vertically A pair along of the upper portions of the ?xed contacts which portions lie in the valleys between the ribs. The similar projections lh are positioned below the fixed contacts are in the form of downwardly projections lg, as shown in Fig. l, and serves, extending metal rods 7, the lower ends of which together with the projections lg, to support an form the contacting faces of the ?xed contacts other front plate 3 which may be utilized for sup which faces are preferably formed. of silver, or porting auxiliary control apparatus or parts. A alloys of silver, or other suitable material, for pair of similar projections it from the frame are obtaining good contact surfaces. The upper positioned below the projections lh and serve ends of the contact rods or cylinders l are of to support another plate the purpose of which reduced diameter and project upwardly through will be later explained. The extensions lg carry openings in the head 5, being secured to the head at their upper middle portions a pair of projec'~ by washers and nuts la. on the upper threaded tions i7", as shown in Figs. and 3, which are ends of the contact rods. The upper ends of the curved inwardly and outwardly and serve a pur~ contact rods are slotted so that they may be held pose later explained. They are opposite the proby a screwdriver from turning while the clamp jections lb of the rear portion of the frame. The main frame and its various extensions and pro 30 ing nuts la are turned tightly for locking the parts in ?xed position. The lower portion of each jections not only serve for supporting various fixed contact rod is encircled somewhat above its parts but also accomplish other objects, as later lower end by a ring 8 of insulating material, as described. shown in Fig. l and more particularly in Fig. 5. In describing construction of the switch This insulating ring may be secured to the rod and the relationship and operation of its parts, in any suitable manner but, as shown in Fig. 5, the upper portion will ?rst be described and the is held in place by spinning or upsetting a por description continued by reference to the other tion of the metal rod 1, as shown in Fig, 5, - parts in progressive steps downwardly. The against the upper and lower inner edges of the ?xed contacts and inter-connections thereto are insulating ring. This ring acts as a Spacer on supported by a block 5 of insulating material each ?xed contact for preventing engagement molded to the desired form. It extends horizon~ with adjoining parts and likewise as a barrier, tally across the upper portion of the switch and although permitting free escape of the gases up is supported at its sides by resting upon the side wardly around its outer rim. In the particular portions id of the frame, as shown in Fig. 7 and switch shown, there are twelve ?xed contacts 1 upon the front projection if as shown in Figs, 1 in three rows of four each. The front and rear and 2. The front tie plate 1! is provided at its contacts of each row are adapted to be connected upper part with a pair of inwardly extending to the controlled circuit, or circuits, by terminal projections 2a which extend over the front edge connections in the form of ?at strips 81) which of the insulating block 5 and thereby serves .to are bent to extend under the clamping nuts la hold the front portion of the block in ?xed posi tion. The rear portion of the block 5 is held in place by a cross-pin t which extends over the rear part of the block, as shown in Fig. 1. This and locking washers on the contact posts and are provided at their outer ends with screws 8a and locking washers for receiving the conducting leads. The inner two contact posts of each row of the frame. The outer ends of the pins are 55 are connected by a metal link 9 which lies on the top of the contact head and extends under the formed with circumferential grooves which are clamping nuts 1a and washers of the two contact engaged by spring clips 6a, as shown in Fig. 2, posts. The two front contact posts of each row for preventing endwise movement of the pin. are adapted to be bridged by a movable contactor, When it is desired to remove the block 5, it is as indicated in Fig. l, and the two rear contact ‘merely necessary to remove one of the Clips 611 posts of each row are adapted to be bridged by a and then move the pin 6 endwise a short distance contactor. Thus the circuit may be traced from so as to clear the inside of a side portion of the the outer terminal 8a of one row through the frame and then by raising the free end of the pin front contact post and bridging contactor to the and after removing ‘the other clip 6a, the pin can be withdrawn from the other side of the frame. 65 second contact post and then through the link 9 to the next contact post and thence through the The slots lk permit this tilting and their ?nal rear bridging contactor to the rear contact post removal from either side of the frame as may be and rear terminal 8a. When the circuit of each desired. Of course, the pin may be removed by row is opened there are thus secured four breaks pulling it out longitudinally after removing one in the circuit in series with each other which of the pins 6a but where a number of these tends to reduce the arcing at each contact. The switches are stacked side by side closely in a row, provision of the terminals affords means for con the above described tilting method of removal necting the switch in any way desired to the out of the pin can be accomplished even though an side circuit and by locating the links 9 at the top other switch is mounted closely on each side. After removal of the pin the rear end of the block 75 of the insulating head, they are conveniently ac cessible and removable if desired for replacement pin extends through slots tic in the side portions 2,407,710 by the connection of overload controlling devices contact [50; which is securely fastened to the piece 15‘ as by riveting or otherwise. These con between the inner terminals of the different rows, tacts are preferably formed with a face of silver or by the connection of ammeters or other de or silver alloy for insuring good contact with the vices for particular purposes. ?xed contacts when engaging them. Each of The movable contact assembly is formed of two these bridging movable contact assemblies ex separable blocks of molded insulating material tends through the cut-away portions Ma of a pair which are securely clamped together for holding of shields so that the contact faces are centrally the various associated parts in place. The lower positioned within the shields and opposite a pair insulating block it extends horizontally between ?xed contacts, as shown in Fig. 1. Each bridg the side portions of the frame. The upper block 10 of ing contact is kept in proper alignment by a I l similarly extends horizontally between the side contact guide [6 in the form of a metal strip of portions of the frame and is removably secured rectangular form, as shown in Figs. 1 and 3. The to the lower block by screws l2, well shown in lower end. of each of these guiding strips is Figs. 3 and '7, which pass vertically down through knurled or roughened and is forced into an open the upper block and lower block and have a 15 ing in the insulating block In so as to be ?rmly threaded engagement at their lower ends with a retained in position by the block Ill. The strips channel shaped sheet metal strip [3 to be later are'secured in position in the block in before the described. The lower insulating block in is pro block II is fastened thereto; and the openings vided with a number of vertical openings lila formed in the insulating block I l for reception of each of which is below and opposite the previous the upper ends of these strips are of suf?cient size ly described ?xed contacts. These openings are to freely receive the upper ends of the strips in for the purpose of providing a free flow of air up assembling the parts. Each bridging piece ii of wardly to and beyond the contacts to aid in ex the movable contacts is provided with a central tinguishing the arcs and in carrying away the slot of the same form as the cross section of the hot gases. The upper block H of the movable strip and is adapted to freely move along the assembly is provided with twelve cylindrical guiding strip. A spring I‘! encircles each guid openings I la which are opposite the contact posts ing strip l6 and one end of the spring is posi ‘I and these openings extend vertically down tioned below each of the bridging pieces 15 while ward and communicate with the openings Ida in the other end seats in an opening formed in the the lower block It], as well shown in Figs. 1 and '7. . A cylindrical arc shield or barrier i4 is positioned within each of the openings i la and each of these shields extend upwardly above the block II a short distance and the upper end of each shield insulating block l0. - The movable contact assembly, as previously described is composed of two separable blocks of molded insulation fastened together and they surrounds the insulating ring 8 ‘but is spaced support and carry the arc barriers or shields as therefrom to permit the free escape of gases up wardly between the shield and the insulating ring. The lower portion of each shield is cut fastening ‘screws 12 serves as a common means, away at Ma on one side, as particularly shown in Fig. 6 and'a space Mb is left between the edges of the upper portion of the shield. The lower portion of the shield is ?ared outwardly at 14c and, as well shown in Fig. l, the adjoining por tions of the insulating blocks Ill and I I are shaped to receive these ?ared portions of the shields so that when the two insulating blocks are clamped together by the screws l2, the shields Iii will be held in ?xed position. Provision is also made for insuring that the shields are maintained in their proper positions with reference to the movable well as the spring pressed bridging contacts. The not only for holding the insulating blocks it and H together, but by engaging the metal piece iii of U form, serve to hold all parts of the movable contact head together. The parts are shown in the open position of the sWitch and when the part i3 is moved upwardly upon the energization of the magnet, the movable contact assembly including the arc chambers or shields iii, is moved upwardly and thereby cause the bridging movable contacts to engage their re spective pairs of ?xed contacts 1. After initial engagement and upon further upward movement ' of the parts, the movable bridging contacts are forced downwardly by their engagement with the contacts. This is accomplished by forming ver ?xed contacts along the guiding strips to against tical projections Ilb on the insulating block II the pressure of the springs 11. As the bridging which project within the openings Ha, as shown contacts have a certain freedom of movement on in Fig. 3. The width of each projection llb cor - the guiding strips, they are self -adjusting so that responds with the opening Mb of each shield and the pressure of the movable contacts against the when the shield is passed into its opening in the ?xed contacts is equalized, thereby insuring insulating block, the vertical edges of the upper proper engagement and sufficient contact pres portion of the shield will engage the projection sure of each movable contact with its ?xed con l lb and thereby insure that each shield is main tact. Also, by reason of the movable contact tained in its proper position. The barriers or assembly being pivotally connected, as herein shields [4 may be formed of sheet metal and it after explained with the actuated portion of the should be noted that each of these shields is in magnet, the movable contact head is capable of dividually insulated from other portions of the movement as a whole 50 as to be self-adjusting in apparatus. Metal shields are desirable owing to their ability to resist objectionable disintegration 65 relation to the ?xed contacts in order to further insure equalization of contact pressure in all from effects of arcs; and either magnetic or non magnetic metal may be used, such as iron or brass parts. When the magnet is deenergized for opening but the shields may be made of material other the switch, the pressure of the contacts and the than metal which will retain its form and be springs I1 together with the weight of the parts, capable of withstanding the eifects of the arcs. 70 force the movable contact head downwardly with Each of the movable contacts bridges a pair of a quick opening movement. In this opening ac ?xed contacts, as shown in Fig. 1, and is in the tion the arc barriers are, of course, moved down form of a sheet metal channel piece l5, as well wardly with the movable contact head and this shown in Fig. '7 and is preferably made of cop action results inconstantly bringing fresh sure 75 per; and this channel piece carries at each end a 2,407,710 faces ofgthe. shields oppositethe arcs and thereby aid .in-coolingand. extinguishing'them. .Further more, by bringing new surfaces opposite the arcs, the arc. chambers are lesssubject .todeterloration from effects .ofthe‘arcs, as compared with ?xed arc barrierswherethe arcing effects are concen tratedon the same portions of thebarriers. .Also, the .free spaces betweenthe arc chambers and 8 opened vat'auxiliary .control contacts by ‘severe shocks on the apparatus. Referring to Fig. l, the three~legged~form ‘of the laminae E8‘ of the non-actuated portion ‘of C2 the magnetis shown as having the legs extend ing vertically downward and the three-legged laminae l9 of 'the actuated portion of themag net is shownwith :its legs extending upwardly the ?xedcontacts and aroun'dthe insulating rings 8_ provide open passages for-the. free ?ow of the 10 and, asalready explained, the engagingfacesof the legs are ground, after assembly,;in the same hot. gases upwardlyin their natural tendency of movement and out through the top of the cham bers, this free. passage of thechot gases upwardly and outwardly being assisted by the free inflowof air through the openings 10a below each of the plane so as to insure ‘uniform, good surface con~ tact. The end plates 18a of the non-actuated portion ofthe magnet core are shown inFig. .4 as‘provided at each end with angular extensions lGb which . project .rearyvardly and forwardly. These extensions respectively engage sheet . metal contacts. The are chambers also serve to-cool the hotgases as they pass freely upwardly and brackets v2i! which. are bent toladesiredishapaas out from the chambers. ‘The cut-awayportions shown, andprovidedwith side portions-Hailey of the chambers for thepurpose of permitting whichithey are securely fastened to the side por the introduction of the movable contacts and 0f the bridging elements carrying them, do not 20 tions of the main frame by the .screws'ZlJb. The projections 132) from .the end plates loosely en lessen the effectiveness of the structure in ex gage vertical Slots .230 in the cross brackets :20 tinguishing the arcs because, with reference .to so ..as.to permit considerable “freedom ‘of move each, pair of. contacts, the current passes through ment. of the.noneactuatedrportion.of the magnet a loop formed by one ?xed contact, the bridging contacts and the other ?xed contact which re 25 in all directions for the purposeof self-adjust ment, as later explained, but .is, of course,:re sults in forcing the arcs outwardly from the loop strained by the slots from assuming extreme-or always against the portions of the chambers abnormal positions. :In assembling'the core of which are not cut away. The cut-away portions tl'ie.=non-actuated.portion of ' the-magnetythe end of. the chambers serve also to facilitate the inward plates l?cz having the .projections 18b :are .per passage of air to the chambers ‘to aid in the up manently fastened to the laminae, .as by rivet ward and .outward passage of the hot .gases ing, andthe pole faces afterwards ground. This through the chambers. eliminates possible .clistortionofthe parts which The function of the inwardly pressed projec might occur if the end plates or their supporting tions 11) from the rear of the‘ main frame and of extensions were attachedai‘tcr grinding. The the projections I?‘ at the front :portion of ‘the magnet coil 2| is carried by aispool ‘Zia of-insu frame on opposite ends of the movable contact lating material and is held in.place,1as shown in head is for restraining the‘rnovement of the head Fig. .7 by a U-shaped strip 25 of ‘metaL'the .base under shocks and jars. The movable head is nor of .the U passing over the top of the laminae mally guided in its movement by parts hereinafter described ‘but the projecting portions referred to 40 l8 and the legs extending downwardly inside-the vereconditions for preventing the ‘movable head magnet'coil. The'supporting strip 23 isprovided with outwardly extending projections 23a at the being jolted to an abnormal ‘position, as one of lower ends of the legs which pass under and sup serve as restraining means under unusual or se portthe magneticoil. Tl‘hev actuated portion ‘of the .magnet. compris tation to withstand severe shocks and jars as, for 45 ing the laminae. l 9 isprovided with end platesv l9a example, when used on naval vessels. which ‘extend along. epposite‘sides of the laminae The magnet core actuating the switch to closed andiare bent. at right-angles, as shownin. Fig. 8, position is composed of two similar laminated to' pass inwardly overtheends of the‘laminaeiand parts and on account of the fact that the part corresponding to- the usual ?xed part is movable 50 again bent: outwardly:atJright-angles to formex tensions I'Sb. ‘These end extensions are spaced for-the purpose of ‘securing self-alignment and from ‘each other for :receiving the driving rods self-adjustment, it will be referred to herein as Ztwhich latter are'connected vfor actuation of the non-actuated part of the magnet and ‘the the. movable. contact‘ head. At thezfront portions other-‘part as'the-actuated part of the-magnet. Each part-is built up of laminations of general 55 of the end plates l?a is‘secured .aipair of angular pieces 25‘which are bent at right-angles sales E-form'and'the laminae‘ of each part are of the to extend toward itheside portions of the main same size-and shape which simpli?es the stock frame as shown'in Fig. 8. Innassembling the ing problem and the cost of assembly. The faces core structure ‘of theactuated-part of ‘the mag ofthe ends of the three legs ofthe E are ground, afterassembly- of the core parts, to lie in thesame 60 net, theend plates L911 and the angular pieces 25 are permanently ‘fastened together and tothe plane; and-when thelparts arein their attracted laminaeasbyriveting theparts, after which the position, there is no air gap between the engag pole faces .:of this portion of the : magnet are ing faces-of the core portions. This not only ground in a single operationin'thesame plane. simpli?es ‘the cost ofnianufacture by permitting the grinding of the engaging faces by one opera 65 This avoids possiblefdistortion. of ‘this portion tion in the same plane but the omission of any of the magnet which :otherwise might .occur if air gap results in the advantages of lower'volt the end platesor pieces ‘25 werezattachedi to the ampere input to the magnet ‘coil, uniformity of laminae after the grinding.‘ operation. coil inductance and a slight time delay before ac There are :two driverroids ‘24, .one in :the back tuation of the ‘switch to open position, due to and oneinithefront portion'of the'apparatus, higher residual magnetization and higher in for connecting .the. actuated :portion of the. mag duced-secondary currents in the iron core, the net with the ‘movable contacthead. 'These ‘rods last named advantage being particularlydesira areof ‘square "cross section, .as shown in Fig. .4, ble in overcoming the opening. of the switchwhen the; purposes of this'improved switch is for adap the circuit of .the magnet coil is momentarily andare pivotally connected by pins'l24a. between the extensions r Nb :of theendsplatesras :showniin 2,407,710 10 tive position of the parts is secured for insuring ' Fig. 8. The drive rods extend upwardly from these pivotal connections and are loosely guided in their movement by the two brackets Zil, as shown in Fig. 4, these brackets being bent at their middle portions to form vertical guiding a uniform and balanced engagement of the parts in proper alignment and insures a minimum noise level in later use after the magnet is energized. The usual lag loop or coil is provided within the faces of one or more poles of the magnet and channels for the rods. The upper ends of the rods are riveted, or otherwise ?rmly secured to the ends of metal strip or yoke 26 of channel in the present structure this is preferably in the form of a rectangular copper loop 28, as shown in plan view in Fig. 8 and held in place by up form, the bent side portions extending upwardly, setting portions of the edges of the'lalninae over as shown in Fig. 7. These side portions fit freely 10 the loop. As shown in Fig. 1, one of these lag within the downwardly extending side portions loops is provided on the outer pole face of the of the strip or yoke [3 which has been previ ously described as being fixed to the movable contact head by the screws E2. The two yoke nonactuated portion of the magnet, while the pieces are pivotally connected together at their magnet. This relative arrangement insures that other of the lag loops is provided on the face of the inner pole of the actuated portion of the middle portions by a pin 21, as shown in Figs. 1 and '7. Thus the actuated portion of the magnet is not only pivotally connected to the drive rods but there is also a pivotal connection between the yoke of the drive rods and the yoke of the movable contact head. This gives a ?exibility of at least one of the two engaging faces of each pole of the magnet will be a solid, smooth face and thereby avoid distortion or unevenness of the pole faces under continued/use. These lag loops are applied to and secured in place on the two portions of the magnet before the ?nal grind ing operation of the pole faces. Special additional provision is made for pre— venting undesired opening or closing of the switch movement between the parts and provides for the self-adjustment and alignment of the parts for insuring the proper seating of the pole faces ~ of the magnet and aids in the proper seating and balancing of pressure of the contacts. The axes of these pivotal connections are at right angles to the side plates of the main frame and to the bridging movable contacts for permit- j when subjected to severe vertical shocks or to vertical components of shocks. This is accom plished by the pro-vision of inertia controlled latches, the operation of which is dependent upon change of motion of the entire structure. One of the latches is for preventing the switch from closing under severe shocks and the other is for ting self-adjustment of the parts in planes per pendicular to the back portion of the main frame; and the slight looseness of the connections per mits sufficient freedom of movement for adjust ment in the direction of planes parallel to the 3 back portion of the main frame. Also, instead of providing a heavy main sup porting frame in the attempt to secure rigidity of the non-actuated part of the magnet in a fixed position, the non-actuated part of the magnet is mounted, as already described, so as to be movable with reference to the supporting frame and movable with reference to other parts of the switch for securing proper alignment and 40 preventing the switch from opening under severe shocks. One of these inertia latches is shown in the lower right-hand portion of Fig. 1. ‘It comprises a weighted body portion 29 which ex tends across the lower front portion of the main frame, as shown in Fig. 8, and is provided With a latch 29a at each end which eXtends upwardly and is provided with an inwardly projecting hooked end. These two ends of the latches are normally positioned, as shown in Fig. 1, some what above and in front of the angular pieces 25 secured to the actuated portion of the mag net core. The two latches are pivoted on a pin engagement of the parts by self-adjustment. 45 3%! which is supported at its ends‘ in the side por This avoids the time and expense otherwise re tions of the main frame. The weighted portion quired to machine the parts to close clearances 25! of the latch being positioned outwardly from and likewise avoids the time and care required the pin 3%, tends to maintain the latches in the in making refined adjustments after the assem position shown in Fig. 1 out of engagement with 50 bly of the parts. Furthermore in the prior rigid the angular pieces 25. An adjustable screw 3! and attempted perfectly aligned structures, the mountedon the tie-plate 4 limits the outward alignment is not permanent, especially when sub- , movement of the latches. The radius from the jected to severe shocks, owing to the distortion axis of the pin 33 to the center of gravity‘of of the parts which inevitably follows pronounced the mass 29 is shorter than the distancefrom shocks and jars. In the present form of con the axis of the pin 30 to the hooked ends of the struction the free ?oating and self-adjustment latches. It follows that any movement of the of the parts with reference to each other insures mass 29 about its pivot is ampli?ed in the move permanent and proper relationship of the parts ment of the hooked end of the latch in proportion which is not affected by distortion of the main to their relative distances from the pivot pin. support or other parts of the apparatus. More GO Under normal conditions the latches are out of over, with this improved structure the proper engagement with the angular pieces 25 and thus seating and self-alignment of the parts give con energizing of the magnet coil will permit the tinued quiet operation when energized and in switch to be closed in the manner already de fact becomes more quiet with continued use ow scribed. But if the switch is in the open position Li ing to continued improvement in the surface and the apparatus is subjected to a severe verti engagement of the parts the longer the switch is cal shock, or to the vertical component of such used. a -shock,_ the actuated portions of the switch In assembling this improved structure, the parts might move with relation to the fixed contacts are connected together as described except that and result in an undesired closing of the switch. the screws Ziib which hold the cross-brackets 2!! TO However, before this can occur, the mass 29 will to the main frame are left to loosely engage the move upwardly and by the ampli?cation of move parts until after the magnet is energized when ment referred to, the hooked ends of the latches the screws 29b are tightened up gradually in will be rapidly moved inwardly and engage the succession a little at a time until they are all angular pieces 25 before the switch can close and uniformly tight. In this manner the best rela 2,407,710 11 thereby restrain and prevent the closing of the switch. After the passing» of the shock the iner tia latch will fall to its normalposition so that the switch will be free to close upon energization of its'magnet. A similar inertia latch or stop prevents the un desired opening of the switch under severe verti cal shocks by a reverse manner of operation. A mass 32 is positioned at the lower central portion of the switch, as shown in Fig. l, and extends crosswise between the side portions of the main frame. The mass is provided near its ends with supporting plates 32a which are pivotally mount~ ed upon a; pin 33. which extends. between and is supportedby theside DOl'tlOI'lSzOf the mainframe. Between; the extensions 32a. is..a cross-bar 32b, theupper portion of. whichisnotched at 3.20. A spring,“ is connected. at oneendtotheweight 32 and at its other: end'to the. pin 30 for nor mally holding this shock preventing-means. in the position shown in Fig. 1. The mass 32' is provided with extensions 3211 as. shown in Fig. 7 which normally engage the lower edges of the side portions of the main frame for limiting the upward movement of. the restraining means to the; position shown in Fig. 1. When the switch isclosed, the. lower inside corner of the actuated portion of the core is positioned opposite and above‘ thenotch 320 of the inertia latch. When the apparatus is subjected to a severe vertical i shock, .or to a‘vertical component thereof, when the vswitch is‘closed, the opening of the switch is prevented because‘ any tendency to open the switch will cause‘ the' mass. 32 to move downward ly and due to the ampli?ed relative movement of the notch 320 by reasons of its distance from its axis from the pin 33 being greater than the dis tance from its aXis'to the‘ center of gravity of the mass 32, the notched portion 320 will move un der thelower inside corner of the actuated core 12 2\.'An electric switch comprising a?xed insu lating support, a contact carried thereby and .ex tending downwardly therefrom, a vertically mov~ able insulating support below said ?xed contact, a contact carried by said movable insulating'sup port and adapted to engage said ?rst named con tact upon the upward movement of said movabl insulating support, a vertically extending arc shield of metal surrounding and spaced from said contacts throughout the length of the shield and ?xed at its lower end to and insulated by said movable insulating support and having openings at both of its ends, said movable support having an opening opposite the lower end of said are shield for the free passage of gases therethrough and. upward through the space between. the arc shield and the contacts for extinguishing theharc upon the opening of the switch, and thedown ward movement of said insulating support and of said arc shield exposing fresh surfaces of lil'lli‘l‘l’l terior of said are shield to the effects oi the arc during-the separation of the contacts in the open ing movement. 3. An electric switch comprising a fixed insu lating support, a pair oil-contacts‘ carried thereby and extending downwardly therefrom, a movable insulating support, a pair of contacts connected by a bridge and carried ‘by the movable insulating support for engaging the ?rst named pair of con tacts respectively upon the upward movement of the movable insulating support, a pair of arc shields carried by said movable insulating sup port, each of said shields having a top opening, said shields surrounding each pair of the engag~ ing contacts respectively and spaced therefrom throughout the length of each shield for provid ing an intervening air space between the shields and the contacts for permitting the free passage of gases from the arc therethrough, each of said portion of the switchbefore the switch has had 40 shields having a side opening opposite the side time to open. This action will prevent the open opening of the other shield for receiving the ing of the switch until the full eifects of the shock bridge connection of said second pair of contacts or shocks have passed, after which the spring 34 and for permitting the free passage of air to the will move the restraining means to the normal shields and around the contacts and through said position shown in Fig; 1 where it will permit the top openings for extinguishing. the. are upon the normal opening of the switch when desired. opening of they switch, and means for actuating Although a particular embodiment of this im said movable insulating support for. closing and provement has been shown and described; var~ opening the switch and for exposing fresh sur ious modi?cations may be made therein for‘ faces of the. interior of said are shields to the ef adaptation to particular requirements without fects'of the arc during the separation of the en~ departing from thescope of the invention. gaging contacts. by the-downward movement of I claim: said movable. insulating support in opening the 1. An electric switch comprising a?xed insu switch. lating support, a contact carried thereby and ex 4.. An electric switch comprising a ?xed'insu tending downwardly therefrom, a vertically mov lating support, a pair of contacts carried thereby able insulating support ‘below said ?xed contact, and extending downwardly therefrom, a movable a contact carried by said movable insulatingsup insulating support, a pair of contacts connected port and adapted to engage said ?rst named con tact upon the upward movement of said movable 60 by a bridge and carried by the movable insulat ing support for engaging the ?rst named pair of insulating support, a vertically extending arc contacts respectively upon the upward movement shield surrounding and. spaced from said con of the movable insulating support, a pair of are tacts throughout the length of the shield and shields of metal carried by-said movable insulat~ ?xed at its lower end. to said movable insulating support and having openings at both of its ends, ing support and insulated thereby, each of said said movable support having an opening opposite shields having a top opening, said. shields. sur the lower end of saidarc shield for the free pas~ rounding each pair of the engaging contacts re sage of gasestherethrough and upward through spectively and spaced therefrom throughout the the space between the arc shield and the con length. of each shield for providing» an interven tacts for extinguishing the are upon the open- " ing. air space between. the shields and the con ing of the switch, and the downward movement of tacts. for permitting the free passage of gases said insulating. support and of said are shield ex from the arc therethrough, eachofsaid shields posingfresh surfaces of the interior of said are having a side opening opposite the side opening shield to the elfectsof the arc during the/sepae of the other shield for. receiving the bridge cone ration of the‘ contacts in the opening movement. nection of said. second pair of contacts and for 2,407,716 13 permitting the free passage of air to the shields and around the contacts and through said top openings for extinguishing the are upon the open ing of the switch, and means for actuating said movable insulating support for closing and open ing the switch and for exposing fresh surfaces of the interior of said are shields to the effects of the arc during the separation of the engag ing contacts by the downward movement of said movable insulating support in opening the switch. FRANK G. LOGAN.