US3130283A - Multiple pole relay switch - Google Patents

Description

AprilL 21, 1964 R. w. BRENNEMAN ETAL 3,130,283

MULTIPLE POLE RELAY SWITCH l 44a 42a 41g 43g HARRY J. LEBHERZIJR.

A TTORNE Y Ap/lll 21, 1964 R. w. BRENNEMAN ETAL 3,130,283

MULTIPLE POLE RELAY SWITCH Filed Jan. '7, 1960 3 Sheets-Sheet 2 INVENTORS REXFORD W. BRENNEMAN HARRY J. LEBHERZ, JR.

ATTORNEY April 21, 1964 Filed Jan. 7, 1960 R. W. BRENNEMAN ETAL MULTIPLE POLE RELAY SWITCH 3 Sheets-Sheet 3 INVENTRS REXFORD W. BRENNEMAN HARRY J. LE'BHERZl JR.

ATTORNEY United States Patent Oiice 3,139,283 MULTIPLE POLE RELAY SWITCH Rexford W. Brenneman, ,Woodsborm and Harry J.

Lebherz, Jr., Frederick, Md., assiguors to Union- Everedy Company, Inc., Frederick, Md. yFiled Jan. 7, 196i), Ser. No. 1,070

Claims. (Cl. 20G-104) This invention relates generally to a multiple contact electromagnetic relay switch having inertially balanced moving parts of which the Larmature rotates within the solenoid coil and the switch contact actuator, connected by balanced coupling to both ends of the armature, rotates coaxially with the armature.

With increasing necessity for effective remote operation and automatic guidance of vehicular systems, the need for a compact, high performance, shock resistant relay switch has becomemost acute. For particularly in rocket vehicles, the nonfuel weight limitation is so critical that no functional redundancy can be afforded; every component is essential to proper functioning; every component must operate perfectly to avoid failure and complete loss of the vehicle. Components mounted within such a vehicle are expected to undergo severe motional disturbances. Accordingly, military performancek specifications require that components perform reliably during and afterkvery severe shock, vibration and acceleration.

It is an object of this invention to provide a relay switch of characteristicsso superior that it not only meets the requirements of such specifications, but surpasses them by a substantial margin.

A further object of the invention is to provide a relay switch which is both statically and dynamically balanced so as to be insensitive to shock, vibration and acceleration.

Another object of the invention is to provide a light weight, simplejyet rugged mechanism to withstand severe shock without contact failure and without becoming disabled.

` It is another object of the invention to provide an exceptionally rigid bobbin structure by integrally connecting magnetizable pole members and bobbin ends to a nonmagnetizable center member so as to preclude its dimensional distortions resulting from motional disturbances in operation. y

y Another 'object of the invention is to provide a coil bobbin of yrectangular cross-sectional shape so that Coil wires directly wound thereon conform to this shape and yare thus highly resistant to rotational displacement on the bobbin. y f It is'another object of the invention to obtain a fully balanced armature, centrally pivoted and arranged in the magnetic circuit so that the magnetic force is applied equally to both ends, thereby minimizing reaction on the pivot and associated friction. n

Still another object of the invention is the balancing of the switching force applied to the armature by coupling the contact actuator equallyfrom both ends of the armature. i

Another object ofthe invention is to permit the same type of power unit to actuate a variety of yswitching means yincluding a single multiple contact array disposed parallel to the armature at one end, or a double array using both ends, kor microswitch contacts acted on directly by the armature. l i

Another object kof the invention is the attainment of a compact arrangement of driving solenoid and contactsr readily packaged in a sealed container which may be lled with various desirable liquids or gases.

By way of brief description, the switch may be considered as composed of two major parts: (l) the power head which includes the bobbin, pole pieces, armature and coil winding; and (2) the switch contact assembly which maytake any of several forms. The power head contains but a single moving part, the armature, which is of generally rectilinear form. The armature is pivoted about an axle passing ythrough its center of gravityand parallel to the longer side of its rectangular cross section. f The axle is mounted in a rectangular, knon-magnetic tube of generally square cross section. The lateral clearance between the rectangular external dimensions of the armature and square internal dimensions of the tube is occupied on opposite corners of the tube by magnetic pole pieces which externally continuepthe tube Walls, and internally intrude about halfway toward .the pivot. Integral ilange material on each pole piece serves both to terminate the bobbin for coil winding and rto carry the magnetic circuit to interconnecting ferro-magnetic circuit plates. The circuit plates likewise serve a dual purposek as they also provide a suitable base upon which the switch contact assembly may be mounted. Use of a rectangular armature and matching pole pieces isk particularly advantageous in that it provides a large area for the airgap, thereby minimizing the reluctance of this critical link in the magnetic circuit and assisting the effectiveness of the power head as a whole. y

The contact assembly of one form of the invention iS connected to the armature by a spider-like actuator. This actuator is pivoted about an axle mounted ona base plate which is attached to and generally parallel to one of the circuit plates; it extends the axis of rotation of the armature. Two fingers, extending perpendicular to the plane of the actuator from opposite radial extremities, mate with slots provided in opposite ends of the armature. A plurality of armsy extending generally radially from the yactuator pivot each support a driving pin extending parallel to the axis of the spider and away from the coil. These each engage a yresilient arm supporting a movable electrical contact. Fixed contacts and the base anchors for the resilient arms are supported on a base plate attached to and parallel to the circuit plates.' External electrical connection to the switch and coil winding passes through the base plate. The base plate complete with contacts, actuating spider and pivot isr assembled and adjusted i11- dependentof the power head.

Many advantages result from this arrangement. By

coupling they spider actuator to both ends of the armature, loading torqueV applied to the armature is completely balanced. The restoring force for the armature yand spider is inherent in the spring-like character of each 0f the movable contact arms and is likewise balanced with respect to the axis of the spider. Symmetry of both armaturevand actuating spider with respect to their common axis of rotation provides a condition of both static and dynamic inertial balance for theser elements. The integrated unit is extremely rugged, yet so compact that encapsulation in a 'sealed `container 'is readily accomplished.

In another embodimentthe invention provides an additional Contact header mounted on the opposite magnetic circuit plate of the coil. In still another form,

pairs of microswitch units are mounted at both ends of reference characters denote the same component through- Patented Apr. 21, 1964 amazes 3 showing the armature in relation to the pole pieces of the magnetic circuit;

FIG. 3 shows a side view of the pole pieces and magnetic circuit plates as projected on plane 3 3 of FIG. l;

FIG. 4 is a top view along section 4 4 of FIG. l, showing the actuating spider in relation to the contacts;

FIG. 5 shows an adaptation of a single power head to actuation of two contact header assemblies;

FIG. 6 shows an adaptation of the power head to actuation of eight microswitch units;

FIG. 7 is a side view of the assembly shown in FIG. 6;

FIG. 8 is an end view of the assembly shown in FIG. 6; and

FIG. 9 shows an actuating spider as in FIG. 4 but of modified proportions and an alternate means for anchoring the movable contacts.

The power head or rotary solenoid, designated generally as reference character A in FIG. 1, is basic to all species of the invention. The solenoid structure is unusual in that its coil surrounds a rotatable armature 1 which is a part of the magnetic circuit. The bobbin 2 extends the magnetic circuit to the ends of the coil unit by means of pole pieces 3a and 3b, respectively right and left hand counterparts, best shown in FIGS. 2 and 3. The pole pieces are fixed relative to each other by attachment to the coil bobbin center 4. The bobbin center section is a hollow, square sectioned, cylindrical element of a nonmagnetic material such as tubular brass. A centrally located hole permits insertion of axle pin 5 which serves as a pivot for the armature 1. The metal adjacent these holes is dimpled inward to space the armature with sufficient clearance from top and bottom walls of the bobbin tube. Opposite ends of bobbin tube 4 may be broken at right angles to provide flanges 9a and 9b to assist in attachment of the ferro- magnetic pole pieces 3a and 3b and bobbin ends 8a and 8b. Rectangular portions of opposite corners of the bobbin center 4 are removed, as shown in FIG. 2, to allow further joining of the pole pieces along junctions 6a and 6b and location of the pole faces within the core structure in proper registry with the armature, as shown in FIG. 2.

The pole piece and bobbin ends are shown as single pieces 3a and 3b although they may be fabricated of two or more parts to facilitate manufacture. The actual pole regions '7a and ilD are solid parallelopipeds in shape protruding normally from the flange portions 3a and 8b. Externally on the bobbin, the pole surfaces constitute a continuation of the generally flat surface of the bobbin center tube 4 to the flanges 9. Internally, they intrude to meet the side surface of the armature 1 when it is aligned with respect to the longitudinal axis of the bobbin, 0r in its actuated position.

The bobbin ends are generally square when viewed from the end of the coil (FIG. 3) and are centrally slotted at It) to permit extension of the armature through the bobbin ends. On the inner surface the bobbin ends 3 are recessed to receive the flanges 9 broken in the bobbin center 4. The outer surface contains a groove 11 generally perpendicular to the plane of rotation of the armature 1 to permit linkage connecting the armature with the switch assembly yet to be described. Corners of the bobbin ends are removed along a circumferential path as viewed from the top (FIG. 2) to permit encasement in a circularly cylindrical can 12 of minimum size. Upper and lower surfaces 13 and 14 of the bobbin ends are flat and parallel (FIG. 3) so as to be readily bridged by ferromagnetic circuit plates 15 and 16. The magnetic circuit plates may be attached by screw members such as 17 shown in FIG. 3, although other suitable means of fastening may be employed.

Before the side plates can be attached, the armature 1 must be installed in the bobbin assemblage 3 and 4 and the coil must be wound. The armature is shaped as a rectangular bar element. The rectangular cnosssection (FIG. 3) provides a desirably large airgap area against its wide side where it contacts the pole faces 7. The pivot pin 5 may be journaled in the armature and fixed in the bobbin center or vice versa. It is preferably of a ferro-magnetic material, such as hard steel, to maintain continuity of the magnetic circuit section area in this region. Slotted grooves 1Sau and 18b are provided paral lel to the long side in either end of the armature for eventual coupling of driving linkage for the switching head or heads.

Once the armature is installed, the coil winding 19 may be applied. The size of wire and number of turns may be selected to suit requirements of current or voltage sensitivity, and other factors known to those skilled in the art. Since the external section of the bobbin is square, the turns of wire will assume a correspondingly shaped prolile. The proportions indicated in the drawings provide room for adequate ampere turns in the solenoid. Suitable insulating tape and washers (not shown) be-f tween the bobbin core and ends and the coil winding are' desirable to reduce the likelihood of grounding on the metallic bobbin.

The magnetic flux induced by direct or alternating electrical current in the coil 19 may be seen to pass through the armature 1, one pole piece 7a, and the bobbin end 8a, in parallel through circuit plates 15 and 16 to the opposite bobbin end 8b, to the opposite pole piece 7b, and thence back to armature 1. The armature is urged into contact with the pole pieces by solenoid action, that is into a position minimizing the reluctance of the magnetic c1rcuit. It is rotated away from the pole pieces upon cessation of the energizing current by a constantly applied resilient restoring torque mechanically coupled to the armature end slots 1S from the switching head or heads, yet to be described. From the foregoing description 1t will be seen that the actuating torque from the solenoid action is symmetrically applied with respect to axle 5, thus minimizing lateral thrust and associated friction on this pivot.

A single switch contact header, encompassed generally by reference character B, is provided in one embodiment of the invention, illustrated in FIGS. l, 2 and 4. In the foregoing description of magnetic circuit plates 15 and 16, their function in completing the magnetic circuit was noted. Plate 15 also provides a suitable structure for attachment of the contact assembly. Four generally radial arms 2t?, 21, 22 and 23 (FIG. 2) of this plate extend to the inner peripheral limits of can 12 to provide a base for standoff legs 24, 25, 26 and 27, respectively (FIG. 3). End portions of these legs are reduced in circumferential extent so as to provide shoul* ders typied by 24S in FIG. 3 lying in a plane parallel to the plane of rotation of the armature. A base plate 2S for the contact assembly is slotted along its periphery to receive the ends of legs 24, 25, 26 and 27 soi that a rigid attachment to the power head A may be elected.

The base plate 28 is perforated to receive three lead-in terminals 29, 3f) and 31 for each of six double pole single throw switches, designated by added reference characters a through f. The six common terminals lie in an inner circle centered on the switch axis while the twelve alternate terminals lie on a circle near the periphery of the base plate 28. The switch sets are equally spaced in two groups of three, lying to either side of a plane through the longitudinal axis of the coil. At an intermediate radial position on this plane, lead-in terminals V32. and 33 are connected to the coil winding by way of leads 34 and 35.

-Each lead-in terminal is separated from base plate 28 by a cylindrical insulating bushing typified by 36a, 37a and 3st corresponding to lead-in terminals 29a, 3i]a and 31a and by 39 and 4tl= corresponding to coil energizing lead-in terminals 32 and 33. The terminal leads anchored in these bushings are of suiiicient stiffness to provide mechanical support for the contacts and switch arms. Taking set a as typical of all six (a through f) fixed its supporting pin 31a.

In assembly of the pairsr of contacts, the liixed contact arms 432"L and 44a may be Welded to their respective terminal pins so as to properly position the contacts with the needed clearance between contacts 41EL and 42a.

The spring 45a may also be attached by welding to pin 311iL but in an angular position which will bias the movable contact 46EL against Contact 42a with a positive pressure of a tixed value. i A pressure of some 3() grams per contact is permissible. The switch is then normally closed by resilient closure of contacts 46a and 42a; actuation is attended by closure of contacts 46JL and 41B.

Simultaneous actuation of the six single pole double throw switch assemblies is implemented by spider 49 (FIGS. l and 4)y which links the arcuate armature motion to the spring arms. The spider is pivoted about a stud member 50, which is anchored at the center of base plate 2S and is shouldered so as to support the spider tor planar rotation in the region above the contacts but below the ymagnetic circuit plate. kA resilient washer 50a f urges spider 49 into close contact with its seat on stud 50. kEight arms are provided on the spider, kkof which one pair, 51a and 51D, longer than the rest, extend a radial distance equal to the radius of armature 1 so that vertical extensions 52a and 52h will engage the slots 18a and 13b provided in the ends of armature 1. Angular motion of the'armature is thus directly coupled and transferred to the spider. Six shorter radial arms, such as 532e, are bent downward and terminated with beads typi'iedby 54l so as to make contact with spring arms 45a roughly midway between the fixed terminal 31a and movable contact 46a.

In operation, energization of relay coil 19 rotates armature 1 to the poles 7. In a corresponding rotation of spider 49, bead 54a pushes contact 46a from its normally'closed terminal contact 42a to normally open contact 41a. Wheny coil k19 is deenergized, the resilient force equally applied in a tangential direction to each of the six pusher beads 54a, through 54f quickly returns the armature to its open position (as shown in FIG. 2). The balance of restoring torque on the spider minimizes reaction on the stud pivot Sti, making lfor reduced friction and operational on current to o current lag or hysteresis gap. Like the armature, the radial symmetry of the spider provides inherent dynamic and static inertial balance, thus rendering this moving part insensitive to acceleration and shook. The rotational torque available from the rotary solenoid of this invention is so powerful that substantial spring contact bias can be used. The movable contacts thus obtain a high characteristic frequency, rendering them resistant to shock and vibration;

The torque available from armature `1 is so high that an additional switching header may be driven by it, thus providing a total of twelve single pole double throw switches. This embodiment, shown in FIG. 5, is essentially the lower half of the single head switch of FIG. l duplicated on the upper half. Ihe heads would be paired for opposite spider rotation; for example, the lower head for counterclockwiseactuation (as shown in FIG. 3) would require thatr the upper half be actuated by a clockwise rotation. Accordingly, the movable contact arms would be reversed and slight re-orientation of the base plate would be required. A suitable encapsulating container 55 and mounting flange may be provided for the double headed switch, as shown in FIG. 7

5. The mounting flange may be varied to suit particular design requirements without departing from the scope of the invention.

Versatility of the power head A is illustrated by still another embodiment (FIGS. 6, 7 and 8), in which microswitch elements are actuated by it. Thus, in the slotted ends 118 ofthe armature 1 rectangular plates 57?* and 57b are inserted and secured. These extend the lateral surface of the armature plate 57EL to engage actuating. buttons 59a and 6l)a or" microswitches 61a and 62al and plate 57b to corresponding elements with suflix b. Energization of the head unit drives the armature in the direction required -to actuate these switches. v removal of energization, restoring spring members 64a' and 64b. rotate the armature in the reverse direction to actuate two pairs of alternate microswitch elements 67a and 68a through contact with their respective actuating buttons '65a and 66a on one end and corresponding element with suthxb at the other end. Themicroswitches are attached to the pole pieces by means ot mounting brackets 63a and 63h. The microswitch elements shown are commercially available types and are not in themselves the subject of the present invention.

An alternate structural form for the actuating spider and movable contact assembly is shown in FIG. 9. In this embodiment each radial arm 53 has been extended so as to make contact with spring arm 45 through bead 54, closer to its coatnct 46 than shown in FIG. 4. This engagement in close proximity to the concentrated mass of contact 46 provides improved vibrational characteristics of the movable contact assembly. Also modified in FIG. 9 is the means for attachment of spring arm 45 to terminal pin 31. To facilitate forming the spring arms 45, the iinal bend at the pin has been omitted and instead a clip member v69 is attached to expedite location of the spring armsy 45 with respect to the terminal pin 31 during assembly. A straight backing plate 70 replaces the angle 47 of FIG. 4 and permits spot welding of the spring arm termination to pin 31 to the backing plate 70. K

Itwill be noted in FIG. l that ther top of can 12 is fitted'into close Contact with magnetic circuit plate 16. This arrangement increases the rigidity of the encapsulated unit .as a whole. In addition when the can 12 is fabricated of ferromagnetic material, as will ordinarily be the case, the can in this region serves to augment the magnetic yflux path provided by circuit plate 16.y To permit this close contact the inner flange 71 of nipple 72 is recessed in a hole 73 which is provided in circuit plate 16. The nipple 72 will normally be pinched off and sealed after the can has been filled with a suitable liquid or gas.

What we claim is: 1. A solenoid actuated switch comprising (l) a supporting structure defining a reference axis fixed with respect thereto,

(2) a hollow cylindrical coil supported by said struc- .ture so that its longitudinal axis intersects said reference axis at right angles and its extremities are disposed symmetrically with respect thereto,

(3) a ferromagnetic armature member pivotably mounted within said coil to permit arcuate rotation about said reference axis when driven by solenoid action of said coil and protruding radially therethrough at both ends,

(4) a switch plate supportedfby said structure having a plurality of contacts ixed therein arrayed in radial symmetry about said reference axis,

(5) a corresponding plurality of movable contacts resiliently supported on elastic arms mounted on said switch plate so as to be urged into contact with said iixed contacts,

(6) a connecting spider mounted for rotation about said reference axis having extensions lying generally parallel to and symmetrically `disposed about said reference axis and external of said coil which engage protruding ends of said armature, and

Upon

(7) a plurality of radial arms extending radially from said reference axis each engaging one of said elastic arms whereby solenoid induced arcuate rotation of the spider disengages each of said movable contacts from said fixed contacts and upon coil de-energization resilience inherent in said elastic arms resets said armature.

2. A switch as in claim 1 but including a plurality of alternative contacts aflixed to said switch plate in opposing relationship to said fixed contacts whereby solenoid induced arcuate rotation of thus connected spider engages each of said movable contacts with said alternative contacts.

3. A switch as in claim 1 including a second switch plate, a second plurality of movable contacts, a second corresponding plurality of movable contacts, a second connecting spider all similar to those rst named but disposed about said reference axis on its opposite extension relative to the armature and coil.

4. A switch as in claim 3 but including a plurality of alternative contacts afhxed to each switch plate in opposing relationship to said fixed contacts whereby solenoid induced arcuate rotation of thus connected spiders engages each of said movable contacts with said alternative contacts.

5. A switch as in claim 1 in which said armature memher is of generally rectangular cross-section of longer sides disposed parallel its axis of rotation.

6. A switch as in claim 5 including a second switch plate, a second plurality of movable contacts, a second corresponding plurality of movable contacts, a second connecting spider all similar to those first named but disposed about said reference axis on its opposite extension relative to the armature and coil.

7. A solenoid actuated switch comprising (l) a supporting structure defining a reference axis fixed with respect thereto,

(2) a hollow cylindrical coil supported by said structure so that its longitudinal axis intersects `said reference axis at right angles and its extremities are disposed symmetrically with respect thereto,

(3) a ferromagnetic armature member of generally rectangular cross-section with its longer side disposed parallel to the reference axis, said armature member being pivotally mounted within the said coil to permit arcuate rotation about said reference axis when driven by solenoid action of said coil and protruding radially therethrough at both ends to define symmetrically disposed slots in its peripheral extremities parallel to its axis of rotation,

(4) a switch plate supported by said structure having a plurality of contacts fixed therein arrayed in radial symmetry about said reference axis,

(5) a corresponding plurality of movable contacts resiliently supported on elastic arms mounted on said switch plate so as to be urged into contact with said fixed contacts,

(6) a connecting spider mounted for rotation about said reference axis having axial extensions engaging protruding ends of said armature, and

(7) a plurality of radial extensions each engaging one of said elastic arms whereby solenoid induced arcuate rotation of thus connected spider disengages each of said movable contacts from said fixed contacts and open coil de-energization resilience inherent in said elastic arms resets said armature.

8. A switch as in claim 7 in which the axial extensions of said connecting spider are engaged within said slots defined in the peripheral extremities of said armature.

9. A switch as in claim 7 including a second switch plate, a second plurality of movable contacts, a second corresponding plurality of movable contacts, a second connecting spider lall similar to those first named but disposed about said reference axis on its opposite extension relative to the armature and coil.

l0. A switch as in claim 9 in which the axial extensions of each of the two connecting spiders are engaged within said slots defined in the peripheral extremities of said armature.

References Cited in the file of this patent UNITED STATES PATENTS 2,436,354 Burke et al. Feb. 17, 1948 2,549,323 McMullen et al Apr. 17, 1951 2,606,981 Kesselring et al. Aug. 12, 1952 2,767,279 Hall Oct. 16, 1956 2,836,674 Krantz May 27, 1958 2,843,696 Sturrup July 15, 1958 2,856,483 Farmer Oct. 14, 1958 2,888,533 Koda et al May 26, 1959 2,916,584 Molyneux Dec. 8, 1959 2,946,876 Lockwood et al July 26, 1960 2,951,134 Lazich Aug. 30, 1960 2,959,648 Williams Nov. 8, 1960 2,975,252 Juptner Mar. 14, 1961 3,012,110 Price Dec. 5, 1961 3,030,469 Lazich Apr. 17, 1962

Claims (1)

1. A SOLENOID ACTUATED SWITCH COMPRISING (1) A SUPPORTING STRUCTURE DEFINING A REFERENCE AXIS FIXED WITH RESPECT THERETO, (2) A HOLLOW CYLINDRICAL COIL SUPPORTED BY SAID STRUCTURE SO THAT ITS LONGITUDINAL AXIS INTERSECTS SAID REFERENCE AXIS AT RIGHT ANGLES AND ITS EXTREMITIES ARE DISPOSED SYMMETRICALLY WITH RESPECT THERETO, (3) A FERROMAGNETIC ARMATURE MEMBER PIVOTABLY MOUNTED WITHIN SAID COIL TO PERMIT ARCUATE ROTATION ABOUT SAID REFERENCE AXIS WHEN DRIVEN BY SOLENOID ACTION OF SAID COIL AND PROTRUDING RADIALLY THERETHROUGH AT BOTH ENDS, (4) A SWITCH PLATE SUPPORTED BY SAID STRUCTURE HAVING A PLURALITY OF CONTACTS FIXED THEREIN ARRAYED IN RADIAL SYMMETRY ABOUT SAID REFERENCE AXIS, (5) A CORRESPONDING PLURALITY OF MOVABLE CONTACTS RESILIENTLY SUPPORTED ON ELASTIC ARMS MOUNTED ON SAID SWITCH PLATE SO AS TO BE URGED INTO CONTACT WITH SAID FIXED CONTACTS, (6) A CONNECTING SPIDER MOUNTED FOR ROTATION ABOUT SAID REFERENCE AXIS HAVING EXTENSIONS LYING GENERALLY PARALLEL TO AND SYMMETRICALLY DISPOSED ABOUT SAID REFERENCE AXIS AND EXTERNAL OF SAID COIL WHICH ENGAGE PROTRUDING ENDS OF SAID ARMATURE, AND (7) A PLURALITY OF RADIAL ARMS EXTENDING RADIALLY FROM SAID REFERENCE AXIS EACH ENGAGING ONE OF SAID ELASTIC ARMS WHEREBY SOLENOID INDUCED ARCUATE ROTATION OF THE SPIDER DISENGAGES EACH OF SAID MOVABLE CONTACTS FROM SAID FIXED CONTACTS AND UPON COIL DE-ENERGIZATION RESILIENCE INHERENT IN SAID ELASTIC ARMS RESETS SAID ARMATURE.

Images