US2085792A - Switch - Google Patents

Description

Jilly 937. E. CORNELL-ET AL 7 2,035,792

I SWITCH Filed June 29, 1935 3 Sheets-Sheet 'l ZZZCZS 5.6'0/V26ZZ [WC/Lola's G. Po gor (Maw/0 July 6, 1937.-

E. s CORNELL ET AL SWITCH Filed June 29, 1955 z Sheets-Sheet 2 I UUh -P L L J. w adj w flw 6 W I J a Q a .d h 5, I

Patented July 6, 1937 UNITED STATES PATENT OFFICE? SWITCH Elias S. Cornell, Evanston, and Nicholas G. PolgovpChicago, Ill., assignors to Delta-Star Elcfitric Company, Chicago, 111., a corporation of Illinois Application June 29, 1935..Serial No. 28,998

22 Claims.

This invention relates to switches, and more particularly to switches designed for high ampere capacity and employed in high tension electrical transmission lines.

In switches of this type as heretofore provided,

of which we are aware, the switches-were commonly provided with flat barspresenting a relatively large contact surface. Such switches, based upon this design, were built both with and without means for applying and releasing the pressure at the contacts. It is apparent that with such a construction, even if provided with pres sure applying means, it was necessary to provide for accurate alignment of, the contacts, blade bar and hinge, in order to eliminate, to as large extent 1 as possible, any localized points of contact.

ter if any substantial misalignment is present in switches of this type.

To overcome this disadvantage, switches have been designed with some form of restricted contact areas, and usually these switches are also provided with some type of mechanical means for applying pressure to the contact areas after movement of the switch blades into operative position. With such switches, the necessity for accurate alignment of the contacting surfaces is not as essential as in switches utilizing a fiat contacting area.

It is the object of the present invention to pro-.

vide a high ampere'capacity switch of this general type, having restricted line contact areas formed on the blade members only, which are adapted to move across the surface of the contact bars as the switch ,blade is moved into operating position, thereby providing a wiping contact that will maintain the contact surfaces clean and will reduce the electrical resistance therethrough. In this connection, the contact areas on the blades 40 may be angled with respect to the arc of movement of the blades to prevent wearing of a groove into the contact bar surfaces.

In prior art switches of the pressure contact type, considerable difficulty has been encountered I in that the pressure is entirely released at the hinge as well as at the contact so that when the blade is swung to open position, it is so loosely supported that it rattles and vibrates, which is an objectionable condition. Since in this type of switch a-mult-i-blade construction. is desirable,

vibration between the blades themselves and between the-blades and the hinge is possible.

In prior types of high amperage capacity switches with which we are familiar. it' is impracticable to provide any means for guiding the This localizing of contact areas becomes a serious mat-,

- the switch operating member and the link interconnecting the threaded studs, whereby the conblades into proper relation with the contact bars as the switch is being closed, and consequently, if there is any lost motion or play at the hinge connection, there is danger of the blade bars striking the contact bars rather than entering 5 between them.

The present invention overcomes these difliculties by providing a construction wherein the pres-'- sureat the hinge is not released entirely when the pressure at the contacts is released prior to 10 movement of the blades out of operating position. Thus, upon release of the pressure contact between the blades and the contact bars, the pressure at the hinge holds the'blades against vibra- 'tion or rattling, both when the blades are still 15 in operative position, and also after they have been moved away from the contact bars into inoperative position. Also, the line contacts at the hinge end of the blades are disposed on both sides of the hinge bolts, and the blades are thus held in alignment and no difliculty is experienced as they are moved toward and away from the contact bars. I

Another object of the present invention is to provide for applicationof pressure to both the hinge and contact by means of right and left though pressure at the contact is completely released. We accomplish this by a novel arrange- 40 ment of interconnecting linkage which produces different angular rotation of thehinge and contact studs so that when pressure at the contact is completely released there still remains suflicient pressureat the hinge to prevent rattling 45 and misalignment of the blades.

Another novelfeature of the present invention resides in the provision of a toggle action between tact pressure can be retained after movement of v; the operating member into locking position with-, lout the necessity of providing additional locking'f means. This toggle action issuch as to prevent '5 release of the contact pressure upon ordinary vibration of the switch supporting structure.

latching mechanism is engaged to prevent furtherrelease of pressure at the contact and hinge ends of the blade bars and to provide for conjoint movement of the blades about the hinge out of operative position. u i

In the practical application of switches d this type it is essential to have a relatively high pressure between the blade bars and the hinge and contact bars when the switch is in the closed position, but when pressure is released for openvent vibration. The pressure is regulated bysprings in conjunction with the differential re- Figure 3 is a sectional elevational view of the switch shown in Figures 1 and 2, showing in detail the operatingmechanism for the switch and the position which it assumes as the switch blades are about to be separated from the contacts;

Figure 4 is a sectional view through the hinge pivot bolt assembly, taken substantially on the line 4-4 of Figure 2;

Figure 5 is a sectional view of the contact end of the switch. blade and theassociated contact bars, taken substantially on the line 5--5 of Fig-.

Figure 6 is a partial elevational view of the switch, showing the switch-blade in its full open position;

Figure 7 is a sectional view taken on the line 1-1 of Figure 2, looking in the direction indicated by the; arrows and showing in detail the contact and spring structure at the-contact end Figure 9 is an elevational view of a second modified form of switch blade; and

lease above mentioned. In switches of very high ampere capacity each spring assembly consists.

of a high pressure and a low pressure spring, so

switch is in the closed and operating position; but

when the switch is about to be opened the high pressure spring is entirely released, leaving only pressure exerted by the low pressure spring and which is more within the range of pressures required during the opening operation. On switches of lower ampere capacity it may be desirable to omit the low pressure springs.

Another advantage secured by the present invention is the equal distribution of pressure by reason of the line contacts on each side of the hinge and contact bolts, whereby, when pressure is applied at both the hinge and the contact, anyslight misalignment of the hinge and contact bars with respect to the blade bars will be rectified. Spacing bushingsbetween the blade bars intermediate their ends, also .provide for maintaining proper alignment thereof.

Another advantage of the present invention resides in the manner in which the blade bars are formed. During the forming operation the width of the bars is maintained constant, and thus the metal is caused to flow towards the ends and at the same time to flow into the raised contact portions of the bars, thus increasing the density of thecopper at these contact portions and at Figure 10 is an elevational view .of modified form .of switch blade. Referring now in detail to the switch shown in Figures 1, 2, 3, and 6, the supporting structure another for the switch comprises a channel member, indicated at II), which is provided with a pair of sup porting insulators II and I2 of any desired construction, which insulators ar'e bolted to the bolts i6. I

Considering now in detail the left-hand portion of the switch structure, the supporting cast-.

ing I3 is adapted to support a plurality of conv tact bars arranged in pairs and mounted upon the upstanding arms 18 and I9 of the casting l3.

These contact barsare indicated generally by "the reference numeral 20, and are secured in fixed position upon the arms i8 and i9 by means of a plurality of bolts 22. At their inner blade engaging ends, the contact bars. are provided with bevel portions 23 formed in their outwardly disposed face portions, which bevel portions exthe portions of the blades having minimum crosssection. This tends to maintain the currentcarrying capacity of the blade bar more uniform throughout its length, and at the same time hard-' ens theengaging portions of the blade bars so that there is less wear.

Other objects and advantages of the present invention will appear more fully from the following detailed description, which, taken in conjunction with the accompanying drawings, will disclose to those skilled in .the art the particular construction and operation of a preferred form of our invention.

Inthe drawings:

Figure 1 is a'plan view operating position;

Figure 2 is a side eievational view of the switch shown in Figure 1;

of the switch at the present invention, shown in its switch-closed or tend-a slight distance downwardly, as shown in detail in" Figure 6. 'Also, the contact bars, as

well as arms 18 and IQ of bracket l3, are provided with recessed portions or notches 24, having angularly extending defining edge Portions ings 29 which are adapted to receive suitable s'ecuring meansjor mounting bus conductors or the like in electrical connection with the contact and hinge bars.

Referring now in detail to the construction of the switch member, the switch itself comprises four blade bars, indicated by the reference numeral 30, which blade bars are arranged in pairs and provided, on the opposed facing surfaces of each pair, with pairs of raised contact portions, indicated at 3|. These raised portions are'formed by holding the blade bar in fixed position, withthe upper and lower edges thereof supported against movement, and then applying suitable pressure to force the metal into the raised contact portions 3| and, at the same time, reducing slightly the cross-sectional area of that portion of the blade bars adjacent to and between the raised portions 3|. The density of the copper in the reduced cross section is increased so that the carrying capacity has a tendency to' remain constant throughout its entire length. In addition, the hardening of the contact surfaces 3| provides for eliminating. wear upo'n these contact surfaces, this wear being taken up by the engaged surfaces of the contact bars 20 and the hinge bars 25, whereby replacement of these bars upon wearing thereof may be made instead of proper position. By securing the collar 3|- for.

conjoint movement with the threaded extensions of the , studs 35 and 36, rotation -of the collar, due to movement of the lever 38, results in conjoint rotation of the studs. 6

As shown clearly in Figure 4, adjustablebushings 4| are threaded upon the inner portion of i the studs 35 and 36 and extend into engagement with the hinge clamps 42 slidably mounted on the studs. The hinge clamps 42, which are of the form shown in elevation in Figure 2, are provided with normally extending shoulder portions 43, which engage over the upper and lower edges of the blade bar 36. This provides for conjoint rotation of the clamp 42 and the blade bar 30 about the stud. High and low pressure springs, indicated at and 46, respectively, are interposed between the interior surface of the clamps 42 and the blade bars 30 at each end of the blade bars. These springs are substantially rectangular in shape, and are arcuately curved, the

outer edges thereof bearing against the outer surfaces of the blade bars 30, and are adapted to press against the blade bars, urging them inwardly, upon the tensioning of the bushings 4|. The inner blade bars 36 are positioned against the springs 45 and 46 and,within the tongue portions 43 of the clamps 42, and the studs 36 and 35 are adapted to extend through two correspondingly drilled openings in the hingebars 25 and the upstanding arms 26 and 21 of bracket I4.

. ing bearing. surfaces 3| engaging against the The outer blade bars 36 are secured in position over the outer ends of the studs 35 and 36, havouter surfaces of the hinge bars 25, and a second set of high and low pressure springs 41 and 48, respectively, engage the outer surfaces of 6 the blade bars 30 over the studs 35 and 36.

Corresponding hinge clamps 50, having: normally extending lug portions 5|, are slidably mounted on the outer ends of the'studs 35 and 36 and are positioned over the upper and lower 3v edges of the outer blade bars 30. Adjusting bushings 62 extend over the outer ends of thestudsv 35 and 36, and the entire assembly may be tensioned with respect to'the hinge .bars 25 by tightening the bushings 4| and 52.

It will be noted that the portions of the studs 35 and 36 which receive the adjusting bushings 4| and 52, respectively, are oppositely threaded, so that upon rotation of the lever 38 in one direction, the bushings 4| and 52will' be moved apart by reason of the threaded engagement with the studs 35, whereas upon rotation of the lever 38 in the opposite direction, the bushings 4| and '52 will. be threaded towards each other, thus servclamps 56 and 42, whereby the bushings may be threaded into proper position to tension the springs and the cap screws then applied to retain them in locked position with respect to the clamps 4 2 and 56, so that upon threading or unthreading of the bushings the clamps are moved conjointly therewith.

Referring now to Figure 5, which is a detailed view of the mounting of the switch blades at the contact ends thereof, the contact studs, or the studs employed at the contact ends of the blades, are indicated generally by the .reference n merals 56 and 5'|. As shown in detail in Figure '7, the central portions of the studs are reduced in cross-section, in order to accommodate the studs within the recesses 24 formed in the contact bars and supporting arms l8 and |9. The inner ends of the studs 56 and -5'! are provided with threaded extensions, which are adapted to be threaded into a collar portion 58 of an operating lever 59 having the ring portion 66 providing for engagement by any suitable switch operating device. driven through openings formed in the collar 58 and through the inner extensions of the studs 56 and 51 in order to lock the collarand studs together for conjoint movement after the studs have 41 and 48 confined within the blade clamps 65,

which blade clamps are secured in position by adjustablebushings 66 threaded onto the outer ends; of the studs56 and 61. It will be noted that the portions of the studs 56 and 51 which are engaged by the adjustable bushings 63 and 66,

respectively, are oppositely threaded, in order to ment of these bushings with respect to, the blade bars, to adjust the contact pressure thereof.

A release or latching mechanism for the switch Suitable pins 6| and 6.2 are provide for conjoint inward and outward moveis provided, which comprises thebar member 10,

having a projecting latching portion 1| at one end thereof,'an'd a bearing portion 12 provided with an adjusting set screw 13 at the opposite 3 end thereof, the lever"!!! being provided-with an opening adapted to receives. pivot pin "which is enclosed by a'cylindrical bushing member 16 about which is coiled a spring 16 anchored atits outer ends, as indicated at Tl, in the two inner blade bars 30 and bearing at its central portion against the under side of the release-lever 10 to urge it in a counter-clockwise direction about l the pin 14, which pin is supported between thev inner set of blade bars.

In the assembly of the switch, the studs 35 and '35 are first passed through the openings in the brackets 26 and 21 and theopenlngs in the hinge bars v25. The inner blade bars 30 are then passed over the studs 35 and 38, respectively, which extend through the openings in the blade bars, andthe low and high pressure springs 45 and 45, respectively, are passedover the studs up into engagement with the adjacent surfaces] of the blade bars 30. The hinge clamps 42 are then inserted on the studs and the bushings 4| threaded onto the inner ends of the studs and into position to force the shoulders 43 of the clamps 42 over the top and bottom edges of the springs and blade bars.

The reduced inner end portions of the studs are then threaded into the collar 31. of the lever. 38 and the pin members 39 and 4|] driven through the reduced portions of the studs to lock thethe pin 74 is extended through these bushings and'through aligned openings in the two sets of blade bars to support the release or looking lever 40 and associated mechanism in position.

The contact end of the blade bars-may be assembled in a similar manner, although because of the slots 24 in the arms l8 and |9 of the con tact bracket 13 and, the slots in the contact bars 45 it is not necessary to insert the studs 55 and 51 through these openings prior to assembly of the blade bars thereon. Instead, the studs are passed through the openings in the respective pairs of blade bars, and the high and low pres- 50 sure springs are applied over thestuds'against the outside surfaces of each set of blade bars. The hinge clamps '64 and 650i each set of blade bars are then applied over the studs into engagement with the springs and the top and bot- 55 tom edges of the bars; Then the adjusting bushings 53 and 55-are threaded over the opposite ends of each stud and the adjacent ends of the studs, which are of reduced cross section, are threaded into the collar 58 of the operating lever 60 59 and pinned in position as shown in Figure 5.

The adjustable bushings are then threaded inwardly on the studs to provide the proper amount of pressure at the hinge bars and the contact struction, and the raised contact surfaces thereof v engage only the outer surfaces of the hinge and contact bars.

'5 The switch is now assembled, and the operating mechanism therefor is applied thereto by first moving the lever to about its operating position and then tensioning the bushings 52 and 4| to provide the proper pressure at the hinge end ofthe switch.

When this'has been done, the operating ring 59 and the lever 38 may be connected by the clevis member 54, which is pivoted. at 85 about the operating lever 55, and which, at its opposite end, is adapted to receive an adjusting stud 85 which threads thereinto, the adjusting stud 85 at its opposite end threading into a suitable socket 81 formed in the connecting link 88 pivoted a 59 to the extending end of the lever 38.

The opposite ends of the stud, 86 are threaded in opposite directions so'that by rotating the stud the proper adjustment may be secured between the operating lever 59 and the hinge lever 38. A suitable locking nut 90, carried by stud 86, is adapted to lock the members in position when final adjustment has been obtained.

Similarly, after the switchstructure has been assembled, the ends 11 ofthe spring 15 are engaged in suitable openings formed in the inner members of each of the blade setsfas shown more clearly in Figures 8, 9, and 10, in" which these openings are indicated by reference numeral 92. In the same figures, the openings in the blade bars which receive the pivot pin I4 are indicated by the reference numeral 93.

Referring now to Figures 1 and 2, inwhich the switch is shown in closed position, it will be noted moved to or below the center line between the studs 55 and pivot 55, the switch'is locked in operative position and cannot be jarred loose by vibration of the supporting channel l0 or similar external vibrations. To open the switch, a suitable switch hook or the like is inserted in the ring 50 of the operating lever 59, and the operating lever is rotated in a clockwise direction to a position substantially as shown in Figure 3. Upon this rotation of the operating lever, the contact bolts or studs 55 and'5'l are rotated therewith, and similarly, the connecting link 84, stud 85 and link 81 provide for rotation of the hinge 'lever 35, which in turn provides for conjoint rotation of the studs 35 and. Due to the fact that the bushings 4|, and 55 are locked to the blade clamps, and that these, in turn, are in fixed. position relative to the blade bars 30, the bushings remain in a fixed position relative to the blade bars, and consequently rotation of the contact and hinge studs 35, 35, 55, and 51, causes a separation of the bushings along the. studs due to the right and left-hand threads thereof, This releases the pressureiat the hinge and contact.

It shouldbe noted, however, that the operating V lever 55 and the hinge lever 35 are so connected that the operating ring travels through an arc of approximately 120 while the hinge lever travels through an arc of only approximately 90.

This is due to the interconnection from' the pivot 55 to the pivot 55, and to the fact that during a between the contact surfaces 3| and the outer surfaces of the contact-bars 29, but providesfor retaining sufiicient pressure at the hinge to main-. tain the blades in alignment and to prevent any lost motion or play at the hinge. .The pressure at the contact is, however, not released to such an extent that the blades are entirely free from the contact bars, but just sufllcientpressure is retained to prevent arcing at the contacts in case porting bracket l3.

an attempt is made to open the switch while still under load. Further, this slight pressure be-' bars 29 is sufficient to clean the contact surfaces when the blades are opened or closed.

When the operating lever 59 has reached a position such that the desired amount of pressure release has been obtained, which can be adjusted by the bushings 4|, 59, 53, and 69, a further rotation of the operating lever 59 from the position shown in Figure 3 results in moving the end portion 12 of the release lever 19 away from bearing engagement upon the base of the clamp or sup- During the time that the switch has been in operative position, as shown in Figure 2, the end 12 of the release lever 19, providedwith the set screw 13, has been bearing against the base portion of the bracket 13 and consequently the lever 19 has been forced in a clockwise direction such that the latching portion ll thereof has been moved downwardly with respect to the stud bolts 35 and 36.

As clearly shown in Figure 3, the lever 38 is provided with a projecting portion 92, which, togetherwith a second projecting portion 93, defines a recess or notch 34 in" which the lug ll of the lever 19 is adapted to engage. This lug is disengaged during all times that the blades are in their contact engaging position, and consequently, during the initial switch opening movement of the operating lever 59, the lever 39 is free to rotate and to rotate the studs-35 and 36 therewith. However, when the lever 59 reaches a position'substantially as shown in Figure 3, any further rotation thereof provides for abutment of the projecting portion 92 against the end H of the lever 19, so that a continued pull on hook stick in eye 69 will cause the blades to .rotate towards their switch open position.

Upon such initial movement of the blades, the bearing 12 is raised and consequently the spring 16 urges the lever 19 in a counterclockwise direction to engage-the lug portion H within the notch 14, thereby preventing any further rotation, of

the lever 33. The mechanism is now latched in fixed position, and further movement of the operating lever 59 serves only to rotate the entire switch blade mechanism about the hinge studs 35 and 36 hearing within the openings in the hinge bars when theswitch is moved to the position shown in Figure 6, which is its full open position. No further rotation of the studs can be effected.

It is understood, however, that the mechanism is so adjusted that a slight rotating movement of the blades downwardly from the position shown in Figure 3 unlocks the release lever from adjacent this point.

cesses 24 which must be formed in the contact bars 29 and the supporting arms l9 and I9 'of the brackets l3.

As the switch is moved to its full open position the "pressure at the hinged studs and 36, effected by the springs 49 and 48, is maintained, due to locking of the studs against further rotation with respect to the blade bars, and is just sufficient to prevent the blades from rattling and to hold the switch in proper position against vibration and the like. This low frictional engagement of the contact portions 3 l of the blades' about the hinge bars is maintained until the contact ends of the blade bars 39 begin to engage within the groove or notch 24 of the contact bars 29, at which time the locking engagement between the lever I9 and the lever 38 is released,

hinge bars in order to provide for proper contact between thecontact bars 29 and the blade, bars 39. It will be noted that the blade bars 39, with theircorresponding raised contact surfacesj3l,

swing about the hinge bolts 35 and 36 in such manner as to have substantially full surface con tact over the entire surface of the hinge bars This is due to the fact that these line contacts sweep over this surface while being angularly rotated. However, this same action is not effected at the contact ends of the blade bars, since these ends move only in a relatively restricted arc, during'a limited portion of l the rotation of the blade member, across the surface of the contact bars 29. If the pressure adjustment is not properly maintained, or if the switch is operated a considerable number of times, the line contacts may have a tendency to wear groovesdn the contact bars.

To overcome this tendency we have provided several modified forms of blade'bars, in which the line contacts at the contact ends of the blade bars are so /formed as to remove almost entirely any tendency of the blade bars to wear groovesdn the corresponding contact bars. For example, by

\ angling the contact surfaces 99, which correspond to the contact surfaces 3| previously described, in the manner shown in Figure 8, the contact surfaces will bear across a certain area of the contact bars and there will be little or no tendency to wear grooves in the bars, since the contacts 98 sweep across the surface of the bars in a lateral direction. The same result is'efiected by angling the contact surfaces in the opposite direction, as shown at 99 in Figure 9. If desired, the contact surfaces can be formed horizontaily of the blade bars, as shown at I99 in FigurelO, in which case they sweep across the surface of the contact bar's over an area determined by their length and the arc of rotation, thus eliminating any tendency for grooves to form in the contact bars.

It is obvious that any desired type of projecting contact surfaces may beprovided for this,

purpose, and we do not intend-to be limited to the particular form shown in connection with the by the adjustable bushings carried on the hinge and contact bolt assemblies, it is possible to protion between the operating lever and the. hinge lever, it is possible to release almost entirely the pressure at the contact end of the blades, while retaining suflicient pressure at the hinge end of the blades to prevent rattling or vibration of the blades when they are moved into their open position. Also, the latching means, which is effective upon movement of the operating member to a position to release the blades from engagement with the contact bars, provides for conjoint movement of the entire switch assembly to open position after the contact pressure has been sufficiently released. With the adjustable bushings, this contact pressure may be varied as desired, and consequently the switch operating structure is capable of a wide range of desired contact pressures.

, Certain other features which lend practicability to our switch structure are the provision of the rightand left-hand threads interconnected by the operating mechanism whereby movement of the single operating rod provides for conjoint inward or outward movement of the adjusting bushings to release or increase the bearing or contact pressure at the hinge and contact ends of the blade bars.

We do not intend to be limited to the exact details shown and described in connection with the illustrated embodiment of our invention, as we' are aware that certain modifications and changes in the design and cooperating relation of the various elements embodied in, our switch structure can be made without departing from the spirit of the present invention, and we therefore intend to be limited only as defined by the scope and spirit of the appended claims.

We claim:

1. A switch comprising hinge bars, blade members pivotally mounted in laterally spaced position on opposite sides of each of said bars, clamping means engaging the opposite faces of each set of said blade members, means interposed between said clamping means and said blade members-for preventing vibration between said'blade members and said hinge bars when said blade members are in open position, and means comprising a stud having oppositely threaded portions engaging said a clamping means to move the same toward each other to provide high pressure contact between said hinge bars and blade members when said members are in switch closed position.

2. In combination,- in a switch, a supporting structure, hinge bars and contact bars mounted in spaced relationship on said structure, a plurality of pairs of switch blade bars pivoted at one end about opposite sides of said hinge bars, and means between said pairs of bladebars for swinging said blade bars into engagement with said contact bars, said means being adapted upon continuous switch-closing motion to apply a first predetermined pressure between said hinge bars and each pair of blade bars and a second predetermined pressure between said contact bars and each pair of blade bars, and being adapted upon switchopening movement to initially release the pressure at the contact bars to a greater extent than at the hinge bars and to thereafter prevent any release of pressure at said hinge bars.

3. In combination, in a switch,hinge .bars and contact bars mounted in spaced relation, switch blade bars pivoted at one end on said hinge bars, means for swinging said blade bars into engagespaced blade bars 2,085,792 vide for any desired pressure at both the hinge ment with said contact bars, and clamping means adapted upon continuous motion of said swinging means to produce a first predetermined pressure between said hinge and blade bars, and a second predetermined pressure between saidcontact and blade bars, said clamping means being rotated through relatively different arcs by said motion of said swingingmeans.

4. A switch blade construction comprising a pair of spaced blade bars, hinge bars for one end of said blade bars, stud means for pivotally supporting said one end of said blade bars on said hingebars, a threaded stud extending through said blade bars at the opposite end thereof, contact bars adapted to be engaged between said opposite ends of said blade bars, and interconnecting means for rotating said stud and stud means rotatable through different arcs of rotation to urge said opposite ends of said blade bars into and out of high pressure engagement with said contact bars and hinge bars, said means being interlocked during a portion of the movement thereof whereby predetermined minimum pressure is maintained on said hinge bars at all times.

5. In combination, in a switch of the class described, contact bar means, hinge bar means,

spaced blade bars extending therebetween on opposite sides thereof and having restricted line contact surfaces engaging the outer surfaces of said bar means, threaded stud means for pivotally supporting said blade bars on said hinge bar means, corresponding stud means extending through said blade bars at the contact ends thereof, pressure applying means carried by said two last named studs, and operating means interconnected between said stud means and operable to rotate the same during'initial switch opening movement, said operating means rotating said first stud means through a smaller angle than said second stud means to effect a correspondingly successive release of pressure at the hinge and contact ends of said blade bars.

6. In combination, in a switch of the class described, contact bar means, hinge bar. means, extending therebetween, threaded stud means for pivotally supporting said bladerbars on said hinge bar means, corre- I spending stud means extending through said blade bars at the contact ends thereof, pressure applying means carried by each of said stud means, operating means interconnected between said stud means and operable to rotate the same during initial switch opening movement, said operating means rotating said first stud means through a smaller angle than said second stud means, and means operable upon initial movement of said blade bars away from said contact bar means for locking said operating means for conjoint movement with said blade bars to prevent further rotation of said stud means during the remainder of said switch opening movement.

7. In a switch blade adapted for swinging movement into and out of engagement with fixed contact means, a pair of spaced blade bars, a,

threaded stud member at the hinge end of said blade bars, a second threaded stud member at the contact end of said blade bars, means carried by said stud members and adapted upon rotation thereof to be moved inwardly and outwardly for increasing and decreasing the pressure between said blade bars and said hinge supporting means and contact means, and means interconnected between said stud members and adapted upon a predetermined'rotation thereof to effect a relatively difl'erent degree of rotation position and to produce a predetermined differ-- between said studs for rotating the same during initial switch opening movement, and locking means operable upon predetermined rotation of said hinge stud for locking said stud means together. to prevent further rotation thereof and to provide for separation of said blade member and movement thereof into switch open position upon further actuation of said interconnected means.

9. A switch comprising a blade member, a

hinge element therefor, a contact bar, stud means at the hinge end and contact end of said blade member, high and low pressure spring means interposed between said stud means and the surfaces adjacent the ends ofv said blade member, clamping means carried by said stud means and engaging said spring means and adapted to urge said spring means against said blade members upon rotation of said stud means, means for rotating said stud means to apply pressure through said spring means to said blade members, said low pressure spring means being operable upon release of said pressure for holding said blade member against vibration.

10. Aswitch comprising a contact terminal, a-

hinge terminal, blade bars hinged on said latter terminaland movable into and out of engagement with said firstterminal, clamping means on said bars at the terminal ends thereof, rocker arms for actuating each of said clamping means, and interconnected actuating and release means providing for conjoint movement of said arms to swing said bladebars into and out of engagement and for relative movement of said arms when in I contact engaging position.

11. A switch comprising a contact terminal, a hinge terminal, blade means carried by said hinge terminal and movable into and out of contact with said contact terminal, clamping means for producing pressure engagement of said blade.

means with said terminals, actuating means for each of said clamping means, and means interconnecting said actuating means whereby oneof said actuating means has predetermined movement relative to the other actuating means to produce a relative difference in clamping action at said terminals.

12. A switch comprising a contact. terminal, a

hinge terminal, blade means carried by said hinge terminal and movable into and out of contact with said contact terminal, clamping means for producing pressure engagement 0! said blade means with saidterminals, actuating means for each of said clamping means, means interconnecting said actuating means whereby oneof said actuating means has predetermined movement relative to the other actuating means to provide a relative difference in clamping action. at said terminals, and means operableupon predetermined movement of said other actuating means during switch-opening movement 01' said interconnecting means to prevent ,iurthcr movement of eitherof said actuating means for effecting swinging movement of said blade means out of engagement with said contact terminal.

13. A high tension switch including a pair of spaced terminals, switch blade means in said one terminal and movableinto and out of engagcment with theother terminal, meansengaging said blade means for moving the same into substantially equalized contact pressure with each of said terminals, said means being releasable upon switch-opening movement and prior to arcuate movement of said blade means todecrease the pressure at one terminal to a greater extent than at the other terminal.

14. In combination, a contact terminal, a hinge terminal, blade means pivotally supported on said hinge terminal and movable into and out of engagement with said contact terminal, clamping means at the hinge and contact ends of said blade means, and interconnected means operable to produce a successivemovement of said clamping means during predetermined movement for producing a greater clamping pressure at the con-tact end of said blade means than at the hinge end thereof when said blade means is in contactengaging position.

15. In combination, a contact terminal, a hinge terminal, blade means pivotally supported on said hinge terminal and movable into engagement with said contact terminal, clamping means at the hinge and contact ends of {said blade means, rocker arms foractuating each of said clamping means, and means interconnected between said arms for producing an increased clamping pressure at one of said arms.

16. In combination, a contact terminal, a hinge 'blade means, rocker arms; for actuating each of .said clamping means, and means for. actuating said arms including means for rotating one of said arms through a greater arc than the other of saidarms.

17. In combination, a contact terminal, a hinge terminal, blade means pivotally supported on said hinge terminal and movable into and out of engagement with said contact terminal, clamping means at the hinge andcontact ends of said blade means, rocker arms for actuating each of said clamping means, and means interconnecting said. arms for conjoint movement in switch opening direction only after said arms have been succes-- sively rotated through arcs to effect a corresponding'seque'ntial release of the associated clamping means. f

18. In combination, U-shaped contact and hinge brackets, contact and hinge bars carried thereby, a plurality of pairs of blade bars on opposite sides ofsaid hinge bars, studs pivoting sald'pairs of blade bars on said hinge bars, said studs having oppositely threaded ends, clamp means threadedon' said studs and held against movement with respect to said blade bars, a rocker arm non-rotatably secured over the adiacent ends of said studs for rotating said studs to move said. blade bars into and out of pressure engagement with said hinge. bars, corresponding -reaching interconnecting means between said 'a predetermined angle produces a different an-I gular movement of said other arm, and releasable means engaged-after predetermined movement of one of said arms locking said arms for conjoint movement to effect separation of said blade bars from said contact bars.

19..A switch comprising'a hinge bar, a switch blade bar pivotally mounted at one end on said hinge bar, a contact bar adapted to be engaged by the opposite end of said blade bar, clamping means at opposite ends of said blade bar .and' rotatable through different arcs of rotation to effect different clamping pressures at the opposite ends of said blade bars, and interconnecting means between said clamping means and operable upon initial switch opening movement to release the clamping pressure between said blade bar and contact bar and to reduce the clamping pressure between said blade bar and hinge bar and thereafter interlocking said clamping means to prevent further decrease of pressure between locking said arms against further pressure-releasing movement as said blade is moved into switch open position.

21. Operating means for a switch blade of the type having one end hinged for pivotal movement of said bladeinto and out of switch closed position, means'for maintaininga predetermined minimum clamping pressure at the hinge end of said blade throughout swinging movement of said blade and a substantiallyreduced pressure at the contact end of saidblade and means for increasing the pressure at said hinge end a predeter- .mined amount as said blade moves into switch closed position including, interconnected means for producing a corresponding predetermined pressure at the contact end of said blade after said blade has moved into switch closed position.

22, Operating means for a switch blade of the type having one end hinged for pivotal movement of said blade into and out of switch closed position, means for maintaining a predetermined minimum clamping pressure at the hinge end of said blade throughout swinging movement of said blade and a substantially reduced pressure ELIAS S. CORNELL. NICHOLAS ,G. POLGOV.

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