US2665352A - Contact-spring switch assembly - Google Patents

Description

Jan. 5, 1954 J. 1. BELLAMY ETAL CONTACT-SPRING SWITCH ASSEMBLY Original Filed April 10, 1948 3 Sheets-Sheet l FIG. I

AT TORNEY Jall- 1954 J. l. BELLAMY ETAL 2,665,352

CONTACT-SPRING SWITCH ASSEMBLY Original Filed April 10, 1948 3 Sheets-Sheet 2 INVENTORSI JOHN 1. BELLAMY RICHARD P. ARTHUR ATTORNEY 5, 1954 J. 1. BELLAMY ETAL 2,665,352

CONTACT-SPRING SWITCH ASSEMBLY Original Filed April 10, 1948 5 Sheeis-Sheet a FIG.

Fe. I 23 FIG." LA 5323 INVENTORS JOHN I. BELLAMY RICHARD P. ARTHUR ATTORNEY Patented Jan. 5, 1954 2,665,352 CONTAOT-SPRIN G SWITCH ASSEMBLY John I. Bellamy, Wheaten,

Chicago, Ill., assignors, to International Tele Corporation, a corpora Original application A Divided an 10, 1951, Serial No. 214

5 Claims.

This invention relates to a contact-spring switch assembly. The principal object is to provide an assembly of this type suitable for use in relays and other structures which make eificient use of the space they occupy on a switchboard.

This application is a division of our now abandoned application Serial Number 20,196, filed April 10, 1948.

Another object is to provide a switch assembly of the foregoing character capable of being used in relays mounted close together along a common support.

A further object is to provide a compact switch assembly which is rugged in structure and efficiently adapted for convenient operative association with cooperating parts in relay structures.

GENERAL DESCRIPTION The switch assembly is herein disclosed in its association with relay structures. The structure with which it is shown in particular utilizes a bar-like magnetic member as a common support ing means and common magnetic return member for a row of relays. As disclosed, the common bar is of L-shaped cross-section to conform to the usual construction of relays for switchboard use. Its shape provides sufiicient rigidity and strength to enable it to serve as the support member for a comparatively long row of relays.

One problem encountered in providing relay structure in the nature of the foregoing concerns assembling adjusting the contact-making structures of the several relays of a row in the comparatively limited space allotted to each in a compact arrangement. This problem is aggravated by the fact that the contact-making and by providing structure enabling the actuat-' ing portions or the relays to be readily adjusted to conform to the assembled positions of the respective pie-adjusted assemblies of contact-making parts. The contact-making assemblies are thus permitted to be handled emciently in lots of the respective types, both as, to assembly and as to adjustment.

and Richard P. Arthur, by mesne assignments, phone and Telegraph tion of Maryland pril 10, 1948, Serial No. 9this application March 08 The accompanying drawings, comprising Figs. 1 to 11, show relay structure constructed according to the invention.

Figs. 1 to 3 are respectively, top, rear, and

front views of a strip or" relays according to the first embodiment.

Fig. 4 is a sectional view taken along line 44 of Fig. 1.

Fig. 4A shows a detail of the front portion of DETAILED DESCRIPTION The invention having been described generally, a detailed description of the disclosure will now be given.

A1. General structure In the drawings, magnetic angle bar B serves as a common support, and as a common magnetic-return member, for relays mounted thereon in a row.

Referring particularly to Figs. 1 to 3, each relay includes an electromagnet C, its armature D, a switch asembly E actuatable by the electromagnet through its armature, and the portion of bar B occupied by these parts.

Angle bar B, as shown in Figs. 1, 2, and i, has a horizontal top portion supporting the switch assembliesE and their associated armatures D, and a depending vertical rear portion supporting the electromagnets C. Bar B is supported horizontally between upright mounting members A, to which it is secured, as by bolts 2. Other similar relay strips may be supported above and below the one illustrated, to form the relay apparatus of a switchboard.

Attention is now directed to the fact that, as

' hereinafter appears, the relay structure is so the illustrated bell-crank form, with its fulcrum net C for attraction upon energization thereof. Effective attraction rotates the armature, whereupon rearwardly extending lifting portion 2! moves upwardly to operate the associated switch assembly E. Upon deenergizationiof the elec- V tromagnet, the armature is restored to its normal through. lihe rear end of each core c is :threade, edly received within an opening in the'rear-fiange, of bar B, rendering it longitudinalty ad'austable.

A locknut 3 is provided to retain the core in a desired longitudinal position of adjustment.

includes. a coil. and

Each coil 5 loosely encircles its core 4, and is provided with a square rear spoolhead l, and a round front spoolhead 8.

Rearwardly extending winding terminals '11, for each coil 5, are located in a row along the lower edge of rear spoolhead 1-! th'e s uare outline of which retains the coil against rotation. The upstanding base portion of any terminal lil as kept out "of iengagemen't-with bar B by an :insulating spacing collar which encirclescore 4 between the bar and rear spoclhead 1].

During-- assembly, coil 5 is slipped over :coneufl, to the position shown in Fig. 4, prior to installa tion-of theasso'c'iated armature Hand is retained in position by spring clip 9 (Fig. 3)v engaged within annular groove :19 (Fig. 4A) in:the front portion of thecore.

As shown in Fig. 4, sufficient clearance exists bet-ween spoolheads i and. 3 and the horizontal portion-of bar '13, "to prevent distortion of such bar by a crookedly mounted electromagnet bearing upwardly against the front edge thereof. Moreover, it enables the coil to be readily removed and replaced. Bar B has suficient thickness and consequent rigidity, that it does not require the support of front spoolhead-s il.

As shown in Figs. 1, 3, and l, each armature D is arranged to pivot on the upper f-rontedge of bar B, and is retained .pivotally in position by member 25.

Upon energization ofany of the electromagnets Cfithe associated-armature D turns about its axis to "bring its lower attracted portion 22 into contact with the domed end of core 4 which provides an adjustable front stop 'forthe armature. Turning "the-core in-one direction advances it toward the armature, causing the armature to engage it sooner when bein attracted. Turning the core in the opposite direction retracts it, causing the armature to travel further before it strikes it. The rotation or such 'armature'D raises its actuating portion 2 I, whereby associated control studs 40, engaged at their base by sockets 23 thereof, are :pushed upwardly to actuate associated travelinghlades of the overlying switch assembly E.

Upon deenergization of the electromagnet, the downward tension of the associated traveling bladesptassembly Etserve'to return the armature to its normal position. Asshown in Figs. 3 and4, the normal. nrhackstoppbsition of the armature is-regulated'byxthe setting of screw 28. Turning screw 25 .in'one .directionstops armature D at an earlier, point :in "its return movement. Turning the screw in the opposite direction permits a more extended return movement of the armature. Locknut 2? when tightened locksscrew 26 in a desired-position.

:As shown in *Figs. '1, 3,'and'd, each of the armatures is held in its position on 'bar'B by member 2 Member at -is provided with arms "28 preferably so disposed, as shown in Fig. i, that they make about equal angles with parts 2! and 22. The smooth working surfaces of such arms bear against the bent portion of armature D to prevent itsupwa-rd or forward displacement. As -shown in Fig. l, lateral movement of such armature is prevented by the rounded side portions of the member 24. This method of mounting the armature insures its reliable operation when mounted in any desired attitude. Similar previouslyknown armature-retaining members required expennve. milling and grinding, whereas applicants :memhenis punched and formed of sheet metal with'a smooth side thereof forming a bearing surface for the retained armature.

.A iU-shaped residual plate 23, shown in Figs. 11 andllA, is applied to armature D and then crimped in place to appear as shown in Figs. 3 and Such an applied residual plate, when employed, lies between the core and the armature. Bystrikingithecore, it holds, the'armature out of contact therewith toinsu-re that a desired amount ofythe operating: :air gap reinains "enclosed with the armature in its fully opera-ted position. This unclosed portion :cf the operating air-gap is com-. monly; referred to as the residual air gap. Its l n th, d termined by he thi lmess of plate .23.. controls a release characteristic of the relay, as is commonly known .It .is ;coritemplatecl that the relay armatures will; Joe provided in lots, disti lg lished by specifically different residual-gap lengths assigned thereto, varying from zero to about 5020 inch, for example- One lot will have no residual plate and will therefore PI OVidExHO residual gap. Theremaining :lots will have residual plates of respeciv e ses. Each, armature of a lot will carry a symbol indicative of the thickness of the residual plate 2'3 attached thereto. For example, thefirst armature to the left in Fig. .3 is marked 15" to indicate that its residual plate is fifteen thousandthsrof an inch, .to provide .a residual gap of that :length between -.a fully-operated armature andzitscored.

A2. Switchassemblics For convenience, the switch assemblies (shown at E) are illustrated as being all alike. Ordinarily, the assemblies vary from relay to relay according to the different circuit functions of the differentrelays- The assemblies may vary in the number-cf types of sets contained therein, and in the number of sets of any one type, from whichjit follows that they may Vary in overall number o-f'contact sets and in the heightioi the pileup,-as will be readily understood.

Referring-now to Figs. 5 to 8, the detached switch assembly Eshown therein may be meant shown-applied to any one of thegrelays illustrated in -'F1'-gs. l to 4. Such switch assembly includes cap plate 32 base plate 33, and parts clamped between them by screws :34, which pass through openings-inthe cap plate and intervening parts to the base plate wherein they are threadedly received. 'Two opposed columns St and 3! of contact sets-are included in the same unitary assembly E. This construction enhances rigidity and reduces the number of assembly and clamping screws required.

Referring now to Fig.4), wherein the left-hand column 31 is respectively shown in profile to include four commonly denoted types of contact sets, the *make-before-make set '(fixed blade 55 and traveling blades 55, fill), the break-make set (iixed blades 58, 553 and traveling blade 59) all the break' set (fixed blade GI and traveling blade 62) and the make set (fixed blade 64 and traveling blade 63). The right-hand column may or may not include similar sets. Fig. 4 shows the control stud 40 of column 35 which moves the traveling blades of such column 3| into and out of electrical connection with the fixed blades of their respective contact sets in response to associated armature action. A similar stud is provided, but not shown, for column 3!} which is actuated simultaneously with the stud of column 3| by the armature. Each of the contact blades of columns 30 or 3| has a terminal portion 65 for the attachment of circuit wires. The terminals are staggered, as shown in Fig. 5, for wiring convenience.

The traveling blades (51, 59, and 62) of the normally closed contacts in column 3| are downpressure against their respective fixed contact blades (55, 58, and 6!) to insure that reliable electrical connection is established therebetween. The traveling blades (56 and 63) of the normally open contacts of such column are slightly tensioned downwardly to insure that they will return to their normally open position after operation.

The fixed blades are sufficiently rigid to withstand the pressure exerted against them by their 55 is constructed in this manner to permit its associated make-before-break contact set to perform its usual functions with the actuating blade 56 thereof in an intermediate position between. blades 55 and 51, which places the control level of such contact set at the same level of control as that of the break-make sets. This is important as the two sets are actuated at the same before-break and break-make) is also the same. This is accomplished by affixing a spacing member 67 (Fig. 6) of the required thickness of the retained portion of the upper traveling blade 51 of the make-before-breal: set to raise its overall height to equal that of the b'i'eak-make set. The use of such spacing member requires the use of one additional spacing member 65 in addition to the one normally required, as will be subsequently described, in the tongue-portion of the assembly to balance the set and keep the blades parallel. Figs. 4 and 6 show spacing plate 54 which is used between the break and make contact sets to separate their traveling blades 62 and 63 to avoid spacing their actuating ledges on the control studs too close together.

The traveling blades of the contact sets are relatively thin (approximately .0126 of an inch has been found to be satisfactory) and of a free length which is sufiicient to impart the required flexibility thereto for effective cooperation with their respective fixed contacts. Such free length of the traveling blades normally positions its contacts and the corresponding ones of the respective fixed blades at a somewhat remote point from their secured rear end portions. While such flexibility is necessary for the traveling blades, it is equally necessary that the fixed blades have sufiicient rigidity to withstand the 6 contact pressure of the traveling blades which is exerted against them.

The required rigidity of the fixed blades is progreater part of their length in the clamping pileup. Fig. 5 shows two such fixed blades 64, in clamped assembly, with only the contact bearing ends and a small adjacent portion of the blades exposed. Each of the fixed blades, in the manner of blades 64 in Fig. '7, has a semicircular cutout portion which permits the blades to be anchored at a point adjacent to the front ends and out of electrical contact with the forward clamping screw. Each of the fixed and traveling blades is provided with a dowel pin opening '58, which is used to hold the contact blades in alignment during assembly.

The fixed contact blades, as viewed from the side in Figs. 4 and 6, are generally straight and of the form of blades 64 shown in Fig. 7. An exception to the fixed blades being generally straight is the previously-mentioned fixed blade 55 which is upwardly offset at the front end.

portion) of the clamping pileup.

Fig. 9 shows the generally T-shaped form of the traveling blades which are preformed and tensioned downwardly. The traveling blades are similar with the exception of blades 56 and 51. Blade 56 is similar to the other traveling blades but is somewhat shorter. Blade 51 has a deep head portion (Figs. 5 to 8) which carries two sets of contacts, a forward set which cooperates with the contacts of the upwardly ofiset fixed blade 55 and a rear set which cooperates with the contacts of the shorter intermediate traveling blade 56.

The traveling blades are interspersed with the fixed blades in the manner shown in Figs. 5 and 6. These traveling blades are arranged in overdom of travel. A spacing member 66, having the same thickness as the traveling blades, is used, as shown in Fig. 8, in the tongue-portion of wardly to assist in returning such control studs to their normal position.

Twin contact points 53, as shown in Figs. 6 and 8, are affixed to each traveling blade adjacent eieGii -fical contact; upon the 1 en a eme w the respective fixed and travelingblades. The height of -the' contact ,jpoints carried, by the contact blades is preferablyiso related to the thickness of the'insulatorsg'-thatthe desired stroke clearance'exists between open contacts when theifixed contact blades are straight. This condition exists when the contact-point height is .004 less than half :the :thickne'ssof the insulators, or approximately .019inch.

Structural rigidity for the switch assembly-E and particularly of" the fixed blades thereof, is provided by the previously-described clamping means. This will be described more-fully atthis point, for it concerns "an important featureof the invention. As disclosed, the switch assembly is independently assembled from the remaining apparatus and includes the two columns, 30 and 3| of Fig. 5,"of contact blades arranged in sets. The upper clampin plate 32 0f the assembly, as shown in'Fig. 5,-has a square rear portion and a narrow forwardly-extending tongue-like portionwhich extends forwardly forthe greaterpart of the'assembl'y length. 'Base'plate 33 is somewhat similar in shape-and is partially shown in Fi'gsf5'to'8.

The desired 1 rigidity of the assembly (wherein two columns of contact sets are included within one structure) 1 is provided 'by clampin one end of allthe' parts;including insulators 55 which are'com'mon tothe two columns and which have the general configuration of plate '32, between thewidened end portions of plates 32 and 33, and by including the tongue portions of the insulators 45 and the greaterportion of the fixed blades within-the confines of the clamping structure. By this'arrangement, aforward anchoring point is 'provided' for the'fixed blades to keep such blades relatively rigid and level" throughout which is particularly advantageous where a common actuating means is'usedfor both columns of the-assembly.

Figs. 10 and 10A show one'of theinsulators 45 'whicl'iare common tothe twocolumns 3D'and 3|, and which are used to insulate and align the contact-blades thereof. Insulators45 insulate the parts from each other and the rest of the structure, and "additionally retain the contact blades and the "spacingmembers B6'(Fig-.8) in proper assembled'alignment. Insulators .45 have rais'e'd annular portions {46 and 'raised cylindricallportions 4 1 which are formed thereonfby .a semi periorating operation, which leaves similar depressions on 'the underneath side thereof.

"Figs. W and '8 show respectively the manner in which'the annularportions '46 of any insulator #5 are inserted in openings .69 in the retained portions of the fixed and traveling blades to hold such blades in assembled alignment. Fig. '7 shows the manner in which the raised cylindrical portions '4'! offany insulator 45 serve as flinch-stop positions for fixed blades associated therewith. 'Suchstop positions prevent'the fixed contact with each other and with the forward clamping screw 34. Fig. 8 shows the manner in which the same cylindrical portions 41, of an insulator 45 used adjacent'ly "to a traveling blade, are inserted within provided openings inv the spacing-memberste to holdsuch'members 6B in alignment. The aiorementioned depressed porti'ons-p-n the underside of insulators 45 permit a nesting of the insulators and their respective parts to; retain .=such parts in alignment clampedassembly.

blades of columns 311 and 31 from coming into -A control stud 40 is provided for cach -column 30:,and 3l, asushown-fcr column 3l-in Fig.4 forathe simultaneous actuation of the traveling blades of the :contact setscomprising such columns. Each-stud is engaged at itsbase within the associated oneyofthe pair of sockets 20in the lifting -portion'2l.of armature D and passes throughrslotsalil (Figs. 7-'to=9) in the traveling blades of the respective column and to the outside of the fixed bladesthereof. Each stud has bracket-like ledge portions which engage the traveling blades of'its respective column for their actuation-when such stud'is lifted in response to armature'action. The-upper central portion of each stud is ven'gagedjas shown in Fig. 4, in slot 42 of return spring 52 (Figs. 5 and 7) which positionsthe stud; andaided by the tension of the associatedtraveling blades returns the stud and its armatu're tonormal position upon deene'rgization of the associated electromagnet.

In the. contact-blade construction herein-dis closed (traveling and fixed blades being respectively of a thickness of .0126 and .0253 inch), and where the eliective control stud location is about 1.75 inches from the support line anda'bout ."5 of an'inch irom the contact points, it has been discovered that satisfactory contact pressure (on the order of thirty-five grams per traveling blade for the disclosedtwin-contact arrangement) is built up .by an over-travel of the stud-engaged intermediate portion of 'a'traveling blade (either upon operation of the relayor upon restoration thereof) on the order ofiOOdof aninch. 1

Observation of the "amount of over-travel (travel after the-contactpoints engage) is areliable indication of the amount-of contact pressure. This feature *avoidsfthe necessity in certain other types of contact'blade construction, of applying aten'sion gauge to the-traveling members.

In order to fulfill the objective "previously stated,-to'provide relay structure capable of being mounted in ro'ws along a common magnetic return memben'wherethe limited space allotted to each makes the assembly and adjustment of the widely varying contact sets of the various relays extremely difiicult, separate and'pre-adjusted assemblie's of'var-iou-s combinations of contact sets are provided-which are readily mounted as a'pre adjusted. unit along-such member.

It has been determinedthat the four illustrated types of contact sets (make-before-break, breakmake, break, and make) can be combined into over a thousand combinations, which will meet all normal switchboardrequirements.

It is contemplated that the desired combinations of contact 'sets forming switch assemblies willbe produced in lots in the manner previously described for the 'armatures, which will promote efiiciency inthe assem'by andiacility in the preadj'ustment thereof.

After a-desired combination of contact sets (the illustrated contact sets comprising columns 30 and 3% of-Fig's. 5 to 8for'example) are clamped in assembly, such assembly is adjusted to certain operating standards.

A3. Free-adjusting the tswitch assembly E The steps required to pie-adjust a separate switch assembly E, such as the one illustrated in Figs. 5 to 8, will now be described.

The first step is to visually inspect the assembly to-be adjusted to determine that all'the parts are straight and'in alignment. Any parts whicha're malformed or misaligned are manually straightened. It is contemplated that accurate preforming of the parts will make this inspection a relatively simple one.

The second step is to secure the assembly (with the control studs in position) to a special jig whose electrical or mechanical action, preferably the latter, controllably raises and lowers the control studs of the assembly in a manner which simulates actual armature action, and which permits desired fine adjustments of the contact sets comprising the two columns of such assembly.

The third step is to adjust the contact sets of the assembly to an operated engagement position which closely approximates the fully operated one. Such an engagement position is one which requires only the further travel (.006 inch over-travel) of the intermediate stud engaged portion of the traveling blades of the sets to become fully operated. The engagement position is used here, and in the normal position adjustment, to facilitate adjustment of the contact sets of the assembly without regard to contact pressure, which is regulated by the correlating armature adjustment to be described later.

The foregoing adjustment is made by operating the jig to simultaneously raise the control studs 40 of the two columns of contact sets until the make contacts of the make and break-make contact sets of the two columns initially make engagement. An inspection will be made to determine if all such contact sets are engaging simultaneously, and any such sets that appear to be engaging prematurely or late, with respect to the majority of the others, are adjusted for conformance thereto by bending the exposed front portion of the upper fixed blades 64 or 60 thereof upwardly or downwardly as required. This adjustment, being the more critical, is made first and is used as a reference point for succeeding adjustments.

The fourth step is to adjust the normal engagement position of the contact sets of the assembly. This is accomplished by lowering the control studs a predetermined amount from the reference point, where the break contacts of the break and break-make sets should initially engage. Again a visual inspection determines if all such contacts are simultaneously engaging at this point and any that are not are adjusted to do so by bending the lower fixed blades 6| or 58 thereof upwardly or downwardly as required. It should be noted that it is satisfactory if the sets engage slightly above or below that predetermined point on the downward stud travel for such point of engagement is not critical.

The fifth step is to adjust the make-beforebreak contact sets. This is readily accomplished for any such set by bending the exposed front portion of the lower fixed blade 55 upwardly or downwardly as required. Bending blade 55 upwardly, with upper traveling blade following, increases the gap between the contacts of the intermediate traveling blade 58 and the upper traveling blade 51. Bending blade 55 downwardly decreases the gap. The normal position of adjustment is where the contacts of the three blades, 55, 56, and 5'1, are in electrical connection at an intermediate point of stud travel with respect to the reference point and the point where the break contacts of the break and break-make sets initially disengage. Such intermediate position may be determined by a gauging operation with respect to the reference point.

The switch assembly E having been assembled and preadjusted to certain operating patterns, it is ready for its final assembly along a common angle bar E, which as aforesaid serves as a common magnetic return member and support for the rows of relays mounted thereon. Figs. 4 to 6 show the two mounting screws which freely pass through openings in the assembly and which are threaded into openings 36 (Fig. l) in bar B to secure the assembly thereto.

A4. Final assembly steps The final assembly of rows of relays along a common angle bar B comprises four steps which will be readily and efficiently performed by the assemblers in accordance with simple assembly sheets which may be provided.

STEP l.CORES STEP 2.COILS Each of the assembled cores is fitted with an electromagnetic coil 5 of the desired characteristics, as shown in Fig. 4. As previously described, each coil 5 is slipped over its associated core 4 from the front and is retained in position by a spring clip 9 (Fig. 3) engaged within annular groove it! (Fig. 4A) in the front portion of the core.

STEP 3.ARMAT URES Figs. 1 and 3 show the manner in which each relay location is fitted with an armature D having the desired residual characteristic. Each armature, as aforesaid, is retained in its position on bar B by an armature retainer 24 which is secured to such bar by a screw 25.

STEP 4.SWITCH ASSEMBLIES Each relay location is fitted with a pre-assembled and pre-adjusted switch assembly E, which includes the contact sets adapted to meet the requirements of that particular relay. The switch assemblies are readily installed in position on bar B and are simply secured, as aforesaid, by two mounting screws 35. The switch assemblies lie fiatly upon bar B with the protruding ends of clamping screws 34 thereof being received in provided clearance openings 3! in bar B. The control studs 40, one for each column of contact sets in each relay, are now inserted into the position shown in Fig. 4. The stud is inserted from the top of the assembly within slots 41 (Figs. 5 to 8) of the traveling blades of the respective column until its base engages its respective slot 20 in armature portion 2 I. The return spring 52 is upraised to permit such insertion. After the stud is so inserted, it is moved forwardly until its ledge portions engage their respective traveling blades. whereupon the spring 52 is returned to its normal position. The normal position of the spring 52 is where the top central portion of the stud is held within slot 42 of such spring 52.

A5. Final adjustment steps After the relays are finally assembled along the common bar B, only two simple armature adjustments are ,necessar-y for ,eachrelayftotregulate its armature travel for effective. cooperation with. the pro-setting of the contact sets of its associated. switch assembly E; The firstadjustment is to set the, frontstop position of. thearmature. travel and the second is .to set the: backstop position. As aforesaid, the frontstop (operated) position is set by the longitudinal positioning ofgthe associated core 4 and thebackstop (normal); pQSition is set by the adjustment screw 26 carried by the associated retainer 2 Thefrontstop-position of the armature is adjusted to conform. to-the-operated engagement position of the-applied'pre-adjusted switch assemblyE. This is accomplished by inserting a. thickness gauge between armatureportionZQ (or residual plate 23 if used.). andwthe domed end of core 4. I (The, armature is then operated until the previously-described operated engagement position (where the make contacts of the make and. break-make sets initially. engage) of the as sembly obtainsand the core l is adjusted, in the manner previously described, toiorm a frontstop positiqn to stop the forwardtravel of the armature atthis point. The thickness gauge used is of athickness, that when removed, provides the desired amount of overtravel for the armature and the associated control studs to provide the desired contact pressure of the make contacts of the associated switch assembly E.

h a kstonpositionoi the. armatur is djusted to conform to .th e normal (unoperated) position of thev switchassernbly This, isaccomplished, Withg backstop adjustment screw p126 s ne u in he i i SQP posit n .of'th armature asrareicrence pointand, inserting a thickness .gauge between the. domed ,end of the core 4 and the armature in the manner of ;t h e previous adjustment ,Thebackstop adjustment screw is then tightened and locked in position by locknut 21-to stopthe'return travel of the armature at this point. Thethicknessgauge used thus regulates the armature travelto a desiredamount anddetermines the normal (unoperated) position or" the relay. 'Such normal position is one where the break contacts of all-the'contacts sets of the switch assembly are in engagement with sufficient nta t r sure 05 5 58 the r re a e e ir e connection. The thickn gauge usedis .oi such a thickness that it prov des suflicient overtravel (.006 inchi for -the armat re to build up the sat; isfactory contact pressure or the break contacts and also-provides for aslight, additionalarmature return travelto provide amargin ofsafetywhich s d a S t i eaimeiure backs op P9 1 tion hich 1 7 3 $12. a o rt inamoun h H l i 9 h "3 0 .1 oi rma: We e wh h e. .mits t e bre ao o the C ct QQS. FQ' W QH en a 111 131 2 position) s f ici nt t weset emek c c he o t t probate-d sengage We claim:

1. In a. contact-blade -swi h:.assembly, two op -l posed columns -of -supe rposed contact-making d s-a d s r o ur zionclampin ;t m aun tary assembly, -.said.:clamping structure including a singlezstackeof'similarsuperposed insulatg m n tion wi h. the bladeslclampedbetwoe them in-succeedinglayers, each layer including a ,separateblade preach -.colnmn th .-two. 1ade of a layer lying side-byzsidaout of contact with each other, each lamination having a relatively wide rear portion common to both columns and a relatively narrow :.forwardly a extending central tongue portion, each .column tincluding ,super.-.

clampednand extending freely alongside of:the.

tongue :portion ofethe laminations, a portion .of each fixedblade being clamped between the re' spective tongue portions of adjacent laminations substantially throughout the length .of such tongue portions.

2: In a contact-blade switch assembly asset forth: in claim 1,; each travellingeblade layerincluding a third member comprising aspacer blade lying between the tongue .portions of the adja centiaminations. and having the'thicknessuofthe. travelling blades, whereby parallelism. is maintained between the clamped laminations in a structure havingtravelling blades ofa relatively simple outline.

3; In a contact-blade. switch. assembly, two opposed columns. of superposed. contact-making blades andstructure for clamping them in. a. unitaryi. assembly, said clamping structure including similar superposed. insulating laminations with thebladesclamped between them in. succeedingdayers, each layer includinga. separate blade-preach. stackup,,the two blades of alayer lying -side-by-sideout of contactwitheachother, each lamination. having a relatively wide. gen-. erally rectangular rear portion succeeded by a relatively narrow forwardly extending tongue portion,- each col-umn including..superposed :sets of. blades each including aflexible travelling blade and. a -.relati-velyl fixed blade appearing in adjacentdayers. and arranged :to vengageand disen-. gage. each; other .at their forward. end incidental to flexure of the travelling blade, each:blade.be.- ing. clamped betweenthe respective rear portions of adjacent laminations, theiorward. portion of each travelling bladeebeing unclamped andextending freely alongside of the tongueportion of the laminations,.each fixed blade being clamped between .therespective .tongue portions of adjacent. laminations substantially throughout the length of. suchetongue-portions, each lamination having-ant opening through its rear portion andan opening through its tongue portion, said clamping structure further including overlying and. underlyingelamp plates, respective clamp memberslpassing through the saidopenings .out ofengagernent. with the. blades. and engaging each clamp platetoclamp the said parts ofthe' clampingstructure. rigidly. together.

4. :In a. contact-blade switch-assembly .as --set forth: in claim 3; each lamination carrying.ana11-- rowrais'ed locatin-g member-on one s'urface'oi thetongue portionand located along-the longitudinal centre In line thereof, the raised member h con rn d la a Ser t an laye of fixed blades to maintain theadjacent edges of the itfixedblades out of contact with each other, each .layer of travelling blades including a third,inembericornprising aspacer blade lying between; the tongue portions .of the concerned d acent amin ons nd g. t e ickness. of the trave lin lade oh said cer. ade havingan openingreceiving the-said raised meme ber. .of {the concerned lamination. and havingpa further opening registering. with the said open.- ing qthroughhthe. tonguepcrtion of the laminations, whereby parallelism is maintained between the clamped laminations.

5. In a contact-blade switch assembly as set forth in claim 3, each lamination having five opening therethrough which include the two set forth in claim 3, such openings including four adjacent the respective corners of the rear portion, respective clamp members, including two of those set forth in claim 3, passing through the two rearmost openings and the foremost opening out of engagement with the blades and engaging each clamp plate to clamp the said parts of the clamping structure rigidly together, each clamp plate having openings aligned with the remaining openings through the laminations, the aligned openings adapted to receive screws for mounting the assembly on a support structure, whereby such screws aid in maintaining the parts of the clamping structure clamped firmly together when the assembly is mounted.

JOHN I. BELLAMY. RICHARD P. ARTHUR.

References Cited in the file of this patent UNITED STATES PATENTS Number 15 Number Name Date Carliss Feb. 16, 1904 Rorty Mar. 8, 1904 Grabe Aug. 6, 1918 Garvin Apr. 6, 1926 Brander Apr. 13, 1937 Vigren et a1. May 2, 1939 Wood June 21, 1949 Horlacher Mar. 14, 1950 Towner et al June 6, 1950 FOREIGN PATENTS Country Date Great Britain Apr. 1, 1949

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