US2967918A

US2967918A - High speed relay

Info

Publication number: US2967918A
Application number: US731996A
Authority: US
Inventors: John H Macneill; Charles F West; Mark R Thomson
Original assignee: SOROBAN Inc
Current assignee: SOROBAN Inc
Priority date: 1958-04-30
Filing date: 1958-04-30
Publication date: 1961-01-10
Anticipated expiration: 1978-01-10

Description

Jan. 10, 1961 J. H. M NEILL ETAL 2,967,918

HIGH SPEED RELAY Filed April 50, 1958 2 Sheets-Sheet 1 i INVENTORS 45 46 5/ 49 CHARLES F WEST F/G 7 JOHN H MAC/VE/LL MARK R 77104450 W W/ ATTORNEY Jan. 10, 1961 J. H. MacNElLL ETAL 2,967,918

HIGH SPEED RELAY Filed April 30, 1958 2 Sheets-Sheet 2 INVENTORS CHARLES F WEST is; JOHN H MAC/VE/LL 3/ BY MARK P. 7/10/0150 ATTORNEY HIGH SPEED RELAY John H. Mac'Neill, Charles F. West, and Mark R. Thomson, Melbourne, Fla., assignors to Sorohan, Inc, Melbourne, Fla., a corporation Filed Apr. 30, 1958, Ser. No. 731,996

14 Claims. (Cl. 200-87) The present invention relates to multiple contact relays and more particularly to an inexpensive multiple contact relay which is capable of extremely rapid operation and which is exceptionally long-lived.

It is an object of the present invention to provide a multiple contact relay of light weight and small size which may be rapidly and economically assembled from a plu rality of pre-fabricated parts.

It is another object of the present invention to provide a multiple contact relay having a novel electromagnetic structure which insures unusually rapid operation of the relay.

It is yet another object of the present invention to pro vide a relay having a counter-balanced armature structure in which the counter-balancing members are physically disposed within the volume defined by the remainder of the relay structure.

It is still another object of the present invention to provide a multiple contact relay structure having resilient pro-stressed contact members having a backing of a soft, malleable metal so that the contact structure may be adjusted and positioned without having to develop a permanent set in the resilient members thereby to eliminate the loss of pre-stressing of the contacts after several adjustments of the relative position of the various contacts.

In accordance with the present invention the multiple contact relay includes an electromagnetic structure incorporating a C-shaped core member and a coil structure having a distinct winding disposed on each of the legs of the C. The legs of the C are tapered to provide portions of relatively large cross-section adjacent the connecting member of the C-shaped core, and portions of lesser cross-sectional area adjacent the exposed ends of the arms. An armature is disposed adjacent the exposed ends of the arms of the C-shaped core and the relatively small cross-sectional area of the core adjacent the armature provides for concentration of the flux therein so as to minimize flux leakage in the system. The relatively large cross-sectional area of the legs adjacent their intersection with the connecting member insures a magnetic path having a relatively low reluctance and therefore permits the development of a relatively high fiux concentration throughout the system.

As indicated, the winding of the electromagnetic structure is divided into two coils with each disposed about a difierent one of the legs of the C-shaped core so as to maximize the heat dissipating surface of the coils and to minimize the distance between the outermost turns of the coil and the core thereof. This latter structure minimizes leakage flux and therefore increases the eficiency of the structure. Further, the core is laminated to reduce eddy current losses. As a result of the specific structure recited, it is possible to build a relay structure having five or ten single pole, double throw contacts which may be moved from one set of contact conditions to another set of contact conditions Within two and one-half milliseconds after energization of the relay coil.

The armature of the electromagnetic structure is lee counter-balanced in order to prevent actuation by external influence (such as shock, vibration) and to permit reliable operation in the presence of shock and vibration. The armature is formed from a single stamping which may be appropriately shaped to provide a cross member, a pair of counter-weights and a pair of hinge pin receiving members; each having members on opposite sides of the cross member. The basic armature structure may be readily modified for utilization with relays employing varying numbers of contact stacks.

A large 'brass block is disposed generally above and forward of the exposed ends of the legs of the core of the electromagnet and the counter-weights and hinge pin receiving members are folded at right angles to the cross member of armature and lie along the side of the brass block. The utilization of the folded armature permits the counter-balanced armature to lie substantially wholly Within the volume defined by the remaining elements of the relay structure. The armature is rotatably secured to the structure by means of a hinge pin which passes through the hinge pin receiving members of the armature and through the entire width of the brass block. The large size of the brass block permits the hinge pin to have a large cross-sectional area and by maintaining the hinge pin fixed relative to the armature while allowing it to rotate with respect to the brass block, the rotational surface area provided between the hinge pin and the brass block is quite considerable and Wear on the hinge pin is minimized.

The contact structure of the present invention constitutes one or more sets of stationary contacts and one set of movable contacts for each group of contacts. The stationary contact structures are essentially identical and constitute a pre-stressed, resilient finger, fabricated from a material such as beryllium-copper, having a backing member of a soft malleable metal such as soft iron. The purpose of the soft iron backing is to permit the contacts to be adjusted by bending the soft iron member without requiring the resilient material to take a set. In consequence, the contacts may be adjusted whenever necessary without having to apply a permanent set to the resilient material which material after a few such adjustments would otherwise lose its resiliency and thereafter could not produce the desired pressure between contacts. In an extreme case the loss of resiliency could prevent the contact fro-mbeing maintained in a position where it can be engaged by its associated movable contact. All of the stationary contacts of one group, that is, all of the stationary contacts which are engaged by the movable contact at the same time, are imbedded, adjacent one end, in a non-conductive plastic body. This construction eliminates the requirement, during assembly, of placing spacers between contacts of the same group, contacts of adjacent groups and between the contacts and bolts which are employed for securing the contacts to the assembly. The contacts are mounted on top of and secured to the brass block and extend outwardly over the electromagnet. The movable contacts are actuated by a basic frame structure that is also readily modified for use with varying numbers of contact stacks and which extends forwardly of the armature over the electromagnet. The frame structure is provided with an insulating body, such as nylon, secured to the end of the frame and disposed under the ends of the movable contact members. Energization of the relay produces rotation of the armature and movement of the nylon bushing or cylinder in a direction to cause the movable contacts to become disengaged from the first set of stationary contacts and to engage the other set of stationary contacts.

The provision of the large contact area between the hinge pin and the brass block, and the utilization of permanently pre-stressed, stationary contacts insures an extremely long life for the apparatus. One production model wascycled through 25,000,000 cycles of operation without exhibiting any noticeable wear.

The friction between the hinge pin and the brass block although insufiicient to produce appreciable wear, does have an effect upon the time required for actuation of the contacts and therefore in a further embodiment of the invention, the hinge pin constitutes a hollow cylindrical member having a wick disposed therein. The wick is maintained lubricated and the lubricant from the wick leaks through a plurality of transverse apertures in the pin and onto the bearing surface between the brass block and the hinge pin, so as to maintain the surfaces lubricated and reduce the frictional drag on the apparatus.

It is therefore yet another object of the present invention to provide a multiple contact high speed relay of relatively simple design and yet capable of rapid opera" tion and having an extremely long life.

It is yet another object of the present invention to provide a relay structure having an electromagnetic assembly in which flux leakage and coil heating is minimized and in which eddy current losses are maintained at quite a low value.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

Figure l is a vertical side elevational view of the relay of the present invention;

Figure 2 is a front elevational view of the apparatus of the present invention with the electromagnet and contact assemblies removed;

Figure 3 of the accompanying drawings is a top view of the apparatus of the invention with the contact structure removed;

Figure 4 of the present invention is a perspective view of the armature structure of the apparatus;

Figure 5 is a front view of the stamping employed to form the armature of the present invention;

Figure 6 is a longitudinal cross-sectional view of a hinge pin which may be employed with the apparatus of the present invention;

Figure 7 is a top view of a stationary contact assembly of the present invention; and

Figure 8 is a longitudinal cross-sectional view of another hinge pin which may be employed with the apparatus of the present invention.

Referring specifically to Figures 1 through 5 of the accompanying drawings, there is provided a base member 1 of non-magnetic material which terminates at its left end, as viewed in Figure l, in an inverted U-shaped member 2 having an upper base member 3 and

leg members

4 and 6. Its right end is bent up both to afford protection to the contacts, as Well as to facilitate mounting. An electromagnet 7 is secured to the upper surface of the base plate l by means of a pair of bolts 8, only one of which is illustrated in Figure l. The bolts 3 pass upwardly through the base fl, through a spacer 5, for holding the magnet 7 above the base 1, through a base member 9 of C-shaped core 13 of the electromagnet 7 of Figures l and 3 and thread into a tapped plate on top of the core. The core 10 of the magnet further comprises a pair of tapered arms 11 and 12 which extend from the base 9 toward the forward leg 6 of the U-shaped portion 2 of the base member 1. The coil for energizing the electro-magnet 7 constitutes two

distinct windings

13 and 14 which are disposed about the legs 11 and 12 of the core 10, respectively.

A block 17 of nonmagnetic, low friction, metallic material, such as brass, is suitably secured to the'upper surface of the base member 3 of the U-shaped member 2, and is employed to support a contact structure 18 of the electromagnet relay and further to provide a low-friction, long life, pivotal support for an armature structure 19 of the relay.

The armature structure 19 and reference is now made particularly to Figures 4 and 5, constitutes a cross member 21 having a centrally arranged, downwardly depending finger 22. The cross member 21 interconnects two identical side members including upwardly and rearwardly extending

counter-weights

23 and 24 and two forwardly extending

arcuate members

26 and 27 which are disposed above the cross member 21. The

members

23 and 26 are parallel to the

members

24 and 27 and are disposed perpendicular to the cross member 21. Actually, and reference is now made to Figure 5 alone, the armature is symmetrical about a center line 28, and may be formed from a single stamping as illustrated in Figure 5. To form the completed armature, the original stamping is bent at the locations designated by the

reference numerals

29 and 31 so that those portions to the left of the section 29 and those to the right of the segment 31 are disposed at right angles to the center portion 21 subsisting between the segments 29' and 31. The

arcuate segments

26 and 27 terminate at their forward ends forwardly of the cross member 21 and are provided with

transverse apertures

32 and 33, respectively, having a common center line coincident with the rear face of the cross member 21. The

members

26 and 27 are notched as at 35 to provide a generally horizontal surface for purposes which will become apparent.

The armature 19 is mounted on the relay by means of a hinge pin 34 which extends through a suitable aperture in the brass block 17 and through the

apertures

32 and 33 in the

arcuate members

26 and 27, respectively, of the armature 19. The center of mass of the armature assembly lies on the center line of the hinge p n, thereby providing protection against effects of shock and vibration. The entire U-shaped portion 2 of the base of the mechanism is recessed along both of its external edges as at 36 and 37 in Figure 2 so that the

members

23 and 26 and 24 and 27 of the armature 19 may be received within the width of the relay as determined by the width of the base plate 1. In consequence, the armature arrangement of the present invention provides a counterweighted or counter-balanced element which is substantially completely confined within the volume of the relay as determined by the dimensions of the base plate It and the third dimension as determined by the upper surface of the contact structure 13. Further, the armature i9 is fabricated from a single stamping and therefore lends itself to rapid mass production techniques.

With the armature 19 mounted on the frame 1, by means of the hinge pin 34, the cross member 21 is disposed just to the left, as viewed in Figure l of the accompanying drawings, of the ends of the arms 11 and R2 of the electromagnetic structure '7. The downwardly depending finger 22 of the armature structure 19 is disposed in an aperture 33 in the base member 1 subsisting partially in the leg 6 of the U-shaped portion 2 and partially in the base plate 1 centrally of the transverse dimen sion of these members. The aperture 38 is defined, in part, by a forward surface 39 which in conjunction with the finger 22 limits counterclockwise rotation of the armature 19 about the hinge pin 34. Clockwise rotation of the armature 10 is limited by a screw 40 which is threaded into an aperture in the leg 6 and passes through an aperture in the leg 4 of the member 2. The screw 40 engages the rear surface of the cross member 21 to act as a stop, and is locked in position in member 2 by a nut 45.

The hinge pin 34 is of such size relative to the apertures in the brass block 17 and the

apertures

32 and 33 in the armature 19 that it forms a tight friction fit with the aperture defining surfaces of the armature and rotates therewith while forming a snug fit with the brass block 17 so that the pin rotates in the brass block and provides a large low-friction, long-lived bearing surface for the pin. The hinge pin 34 is tightly fitted to the armature 19 by means of a steel ball 50, see Figure 6,

anemia which, after the armature is assembled on the block 17, is driven into an aperture 55 in at least one end of the pin 34. The entire pin is case hardened except in the region of the aperture 55 which is maintained soft so that it can expand into tight contact with the walls of the

aperture

32 or 33. In consequence of the large contact area for the hinge pin 34 and the counter-balancing of the armature 19, wear on the hinge pin 34 is minimized and the life of the apparatus is greatly extended over that obtainable with relays of more conventional design.

The specific mounting for the armature 19 not only greatly extends the useful life of the apparatus, but also is instrumental in providing a relay which is capable of exceptionally rapid actuation, since the frictional force that must be overcome is quite small. The other element of the apparatus which is responsible for its rapid actuation is the specific structure of the electromagnet 7. More particularly, the structure of the electromagnet 7 is such as to minimize flux leakage and eddy current losses and further to minimize saturation of the core structure within the range of operating flux for which it is designed. The low eddy current losses in the magnetic structure are due to the utilization of a laminated core. The minimization of flux leakage results from the utilization of a core structure having tapered legs 11 and 12 and further to the provision of a two legged member with one-half of the required number of coil windings disposed about each of the legs. The tapering of the legs provides for concentration of the flux, developed by the electromagnetic structure, at the ends of the legs 11 and 12 immediately adjacent the cross member 21 of the armature 19 and therefore provides for maximum coupling of fiux between the core structure and the armature structure. Further, the provision of two coils, one disposed about each of the legs, provides for increased coupling between the coils and the legs over that which would be obtainable with a single winding. This structure increases efiiciency due to minimization of leakage flux and also due to more efficient dissipation of heat developed in the

coil windings

13 and 14.

Proceeding now to a description of the construction of the contact section 18 of the relay, reference is made particularly to Figures 1 and 7 of the accompanying drawings. In the embodiment of the invention illustrated in the drawings, the relay is a single-pole, double-throw type having a first group of five stationary contacts 41, a second set of five stationary contacts 42 and a set of five movable contact members 43. The

contact groups

41 and 42 are substantially identical and only one of the sets, for instance, the set 41, is described herein. As previously indicated, the set of contacts 41 includes five distinct contact members 44, each including a thin strip or finger 46 of a pre-stressed hard metallic spring material, such as beryllium-copper, and a malleable metal backing member 47 of a material such as soft iron, in contact with one side thereof over a predetermined portion of its length; such as, /a of the total length. The contact members are molded in a suitable plastic 48 with the backing members 47 in intimate contact with one side of the beryllium-copper strips 46 so that each contact set is an integral unit which may be rapidly assembled to the main relay structure without having to individually assemble insulating washers, spacer strips, etc., as is the case with conventional relay structures.

The contact finger 46 extends forwardly of the backing strip 47 on the contact side of the body 48 and is slitted at its end to provide two

independent fingers

51 and 52. Each of the

fingers

51 and 52 has a short length of precious metallic wire, or

contact buttons

53 and 54, respectively, soldered, welded or brazed to the individual fingers so as to provide reliable contact surfaces for the relay. The end of the strip 46 is slitted to provide two relatively independently

movable contact members

53 and 54 so that a two point contact is insured rather than a single point contact as would be the case if the member 46 were not slitted.

The hard metallic spring material which is employed for the fingers 46 is so heat treated as to retain its resiliency indefinitely. The fingers 46 are not easily bent to assume a permanent set. By comparison, in conventional relay structures, the stationary contact members are bent in order to align them properly with the movable contact member and insure engagement between the two contacts. It has been found, however, that such members which are easily bent lose their permanent set or for various other reasons do not maintain a proper position with respect to the movable contact and therefore it is necessary occasionally to reset these fingers. After several adjustments, the pre-stressing is soon lost and then it is quite difficult to maintain a good contact or to re-establish a good contact between the movable contact and the stationary contacts. In accordance with the present invention, the stationary contact members are provided with the malleable backing fingers 47 which are used to position the contacts. The malleable material can be set and re-set indefinitely without destroying its strength and upon being set merely bends the finger 46 to the proper position without changing the pre-stress therein. Therefore, the beryllium-copper fingers 46 are not required to take a permanent set during adjustment since all adjustments of these fingers may be made by bending the soft iron or backing member 47.

The invention has been described as utilizing berylliumcopper strips with soft iron backing members. Obviously, other resilient pre-stressed materials may be employed for the contact members while other malleable and relatively strong materials may be employed for the backing members. In the

contact groups

42 and 43, the fingers 46 extend rearwardly of the supporting strips 47 so as to provide a surface to which lead wires may be connected as illustrated in Figure 1 of the drawings.

The movable contact structure 43 includes five beryllium-copper contact fingers 56, and reference is now made to Figure 1 in which only one of the contact structures is illustrated, and a backing finger 57 also of berylliumcopper. The members 56 and 57 also have a region adjacent one end of each imbedded in a unitary plastic body 58 and the fingers 56 are longer than the contact fingers 46 of the

groups

42 and 41 so that they may be contacted by the mechanism which is employed to operate the switch contacts, as will be described subsequently. The plastic bodies 4% and 58 are provided with a plurality of apertures such as the apertures 59 in the body 48, as illustrated in Figure 7, in order to receive bolts 61 which are adapted to engage threaded apertures in the brass block 17. In assembling the contact structure, one of the contact groups, such as the group 41, is placed on top of the block 17 with its apertures 59 aligned with the apertures in the block and then the

contact groups

43 and 42 are placed on top of the group 41 in the order recited. A plate 62 is placed on top of the plastic body of the group 4?. and then the threaded bolts 61 are passed through the appropriate apertures and threaded into the brass block 17. It will be appreciated that the ease with which this structure may be assembled results from the utilization of plastic bodies in which the contact members are imbedded since with such construction, no spacing members or insulation members are required for insulating the contact bars from one another, from the body to which they are secured or from the bolts 61 with which they are secured.

The switching action is produced by movement of the fingers 56 of the central contact structure which carries two

contact members

63 and 64 on each contact bar. The contact members 63 are each either a short length of, or a button of precious metal secured to the under surface of the finger 56 while the contact members 64 are each a short length or button of precious metal secured to the upper surface of the member 56. The

contact members

63 and 64 are arranged to contact the

members

53 and 54 secured to the fingers 46 of the

structures

43 and 42 and since these latter are also of precious metal, the contact life is quite long.

In order to actuate the movable contact fingers 56, there is provided a generally U-shaped frame 66 having a pair of

arms

67 and 66 and a base member 69. The

arms

67 and 68 are secured respectively to the recessed portions 35 of the

arcuate members

26, 27 of the armature 19. The base member 69 terminates in its forward end in an upwardly turned flange or plate 71 having a hollow rectangular aperture 72, as viewed in Figure 2 of the accompanying drawings. The rectangular aperture 72 defines a lower bar 73 and upper bar 74). Disposed over the upper edge of the lower bar is a generally cylindrical bushing 76 which is slotted so that it may be disposed over the upper edge of the bar '73. The cylinder 76 may be fabricated from nylon or other suitable insulating material. The spacing between the upper edge of the cylinder 76 and the contact structures is such that the arms 56 of the movable contact group 53 just clear the cylinder and engage

contact members

53 and 54 disposed on the contact fingers 46 of the stationary group 41.

In operation, the energization of the electromagnet attracts the cross member 21 of the armature l9 and effects counterclockwise rotation of the armature 19 about the pivot pin 34. Counterclockwise rotation of the armature 19 about the pin 34 produces upward movement of the member 66 and therefore upward movement of the cylinder 76 and of the contact arms 56 so that the contacts 63 become disengaged from the

contacts

53 and 54 of the contact group 41 and the contacts 64 engage the

contacts

53 and 54 of the contact group 42. Therefore, energization of the electromagnet 7 opens the circuit between the

contact groups

41 and 43 and closes the circuit between the

contact groups

42 and 43.

The specific structure utilized lends itself to modification by the addition of various sets of contacts. Specifically, some of the contacts may be removed or the entire structure may be reduced in size to provide less than five sets of contacts or additional sets of contact groups may be stacked on top of the

contact groups

42, 43 and 44 and the movable contacts of such a set may be actuated by a nylon cylinder fitted over the bar 74 of the member 66. Therefore, the five, single-pole, double-throw relay may be readily converted into a ten single-pole, double-throw relay, or a five single-pole, single-throw relay, etc. The illustrated frame 66 and armature 19 are basic structures which may be employed with either one or two stacks of contacts. The structures are employed in the form illustrated for two stacks of contacts but are modified when employed with a single stack. For use with single stack configuration illustrated in the accompanying drawings, the counterweights are cut back along the dashed lines 80, Figure 4, While the frame 66 is cut along the dashed lines 65, Figure 2, to remove the upper bar 74. The contact stacks may be extended and actuation may be effected by additional cross bars extending upwardly from the present flange 71. Such an upward extension of the flange 71 and addition of an additional nylon cylinder would require an increase in weight of the

counter-balance

23 and 24 which is readily effected by merely increasing their rearwardly extending length.

It is apparent from the above that the present invention provides a relay structure capable of rapid actuation and maximum life. Specifically, the rapid actuation is a function of the low frictional losses in the bearing members and the specific structure of the electromagnet 7. Further the counter-balancing of the armature prevents spurious operation of the contacts in response to vibration and shock and allows dependable operation in the presence of vibrationand shock.

A reduction of the frictional drag of the hinge pin 34 on the apparatus may be effected by fabricating the hinge pin 34 as a hollow pin having alubricant saturated wick disposed therein. The pin has a-plurality of transverse poresor apertures for permitting the lubrication to escape from the hollow Wick to the friction surfaces. Such a pin is illustrated in Figure 8 and constitutes a hollow cylindrical metallic body; 81 having a wick material 82 disposed therein. The wick material may be kept saturated with the suitable lubricant which is permitted to bleed onto the surfaces to be lubricated through a plurality of transverse apertures 83 which extend through the wall of the hollow cylinder 81. By this arrangement the friction at the hinge may be reduced as a result of the constant lubrication of the bearing surfaces. The hinge pin of Figure 8 is also-adapted to be secured to the armature 19 by a steel ball 84- that is received inone end of the pin.

The relay of the inventionis extremely compact and an important feature thereof is the fact that the counterbalancingweights 23 and 24 of the armature 19 are almost wholly maintained within the volumetric limits of the apparatus as defined by the base structures 1 and 2 and the vertical height as defined by the contact arrangement. As an indication of the overall size of the relay, it is wished to point out that the structure illustrated in Figure l is almost twice the size of the actual relay.

While we have described and illustrated one specific embodiment of our invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing fro-m the true spirit and scope of the invention as defined in the appended claims.

What we claim is:

1. An electromagnetic relay comprising an electromagnet including at least one pole having a pole face, a large body of low-friction, non-magnetic bearing material disposed adjacent said pole face, an armature having a cross member disposed adjacent to and spaced from said pole face, said armature further comprising a pair of members disposed generally perpendicular to said cross member and each lying on a different side of said body, each of said members including a counterweight and a curved member, and a hinge pin disposed in aligned apertures in said curved members and said body, said hinge pin being secured to said curved members and rotatable in said body, and the center of mss of said armature lying approximately on a center line of said aligned aperture.

2. The combinationaccording to claim 1, further com prising at least one stationary contact member and one movable contact member, a frame member secured to said armature and movable therewith, said frame member being disposed in contact with oneside of said movable contact member.

3. The combination according to claim 2, wherein said stationary contact member comprises a flat prestressed, resilient finger and a relatively soft, malleable finger in contact with said resilient finger over a large area of one side thereof.

4. The combination according to claim 3, further comprising a pluralityof stationary contact members and a plurality of movable contact members, said stationary contact members having a region adjacent one end of each imbedded in a single insulating plastic body.

5. The combination according to claim l, wherein said electro-magnet comprises a C-shaped laminated core having tapered generally parallel pole pieces defining the legs of said C- shaped core, said pole pieces having a smaller cross-sectional area adjacent their pole faces than adjacent their ends remote from said pole faces, and a distinct coildisposed about each of said pole pieces.

6. The combination according to claim 1, wherein said body is disposed above the plane of said electro-magnc-t and said cross member, and further including a plurality of contact members disposed above and secured to said body, said contacts extending outwardly over said electin-magnet.

7. The combination according to claim 6, further comprising a frame member secured to said curved members and extending outward over said electro-magnet, said frame member having a cross piece disposed under and in contact with predetermined ones of said contact members.

8. The combination according to claim 1, wherein said body is disposed above and generally forward of said electromagnet and above said cross member, a plurality of stationary contacts having a region adjacent one end of each imbedded in a non-conductive moldable body, a plurality of movable contacts having a region adjacent one end of each imbedded in a non-conductive moldable body, said moldable bodies being stacked one above the other on top of said body of low-friction, non-magnetic bearing material and secured thereto, said contacts extending outwardly over said electromagnet with each contact of one plurality of contacts aligned above a distinct contact of another plurality of contacts, a U-shaped frame member having legs and a base member, said legs having their free ends secured to said curved members of said armature and extending outwardly over said electromagnet, said base member of said U-shaped frame member being adapted to actuate all of said movable contacts.

9. The combination according to claim 7, wherein each of said stationary contacts comprises a finger of prestressed resilient material and a finger of soft malleable material, said fingers being in intimate contact over a predetermined portion of their lengths and both having one end imbedded in said moldable material.

10. The combination according to claim 9, wherein said pie-stressed resilient material is beryllium-copper.

11. The combination according to claim 9, wherein said malleable material is soft iron.

12. A stationary contact arrangement comprising a plurality of elongated, pre-stressed, resilient members, a plurality of elongated soft malleable members, said elongated members each having a region adjacent corresponding ends imbedded in an insulating, moldable material with each of said malleable members in intimate contact with one side of a different one of said resilient members substantially along the entire length of the shorter of the members.

13. The combination according to claim 12, wherein said resilient members are fabricated from berylliumcopper and said malleable members are fabricated from soft iron.

14. The combination according to claim 1 wherein said hinge pin further comprises a hollow cylinder having one or more holes in the cylinder wall, and a porous material contained within said hollow cylinder capable of becoming saturated with a lubricant.

References Cited in the file of this patent UNITED STATES PATENTS 789,814 McGrath May 16, 1905 977,114 Manson Nov. 29, 1910 1,503,090 Carichoff July 29, 1924 1,639,901 Sampson Aug. 23, 1927 1,785,702 Osborne Dec. 16, 1930 2,069,171 Merkel Jan. 26, 1937 2,134,448 Knos Oct. 25, 1938 2,290,725 Bartels et a1 July 21, 1942 2,428,218 Herbst Sept. 30, 1947