US2149642A - Disconnecting switch - Google Patents

Description

March 7, 1939,` J. s, THMPSN 2,149,642

DISCONNECTING SWITCH Filed Jan. 31, 1958 Patented Mar. 7, 1939.

UNITED STATES PATENT oFFIcE f DISCONNECTIN G SWITCH ol' California Application January 31, 193s, semi No. 181,871

' 15 claims. (ci. zoo-4s) 'I'he present invention relates to electrical switch apparatus, and more particularly to disconnecting switches of the type used in sectionalizing and interrupting high voltage electrical transmission lines.

I'he main object of the invention is to proyvide an eiiicient circuit interrupting switch which is adapted for use in connection with single and multiphase circuits, where it is necessary to sectionalize a transmission line, or to open a branch circuit at the point of intersection with the main line, or for the protection of other electrical equipment operating in a high voltage power system.

Another object of the invention is to provide a switch of simple and novel construction which can be easily and positively operated under all conditions of use, and one which possesses all of the advantages of the more complicated switches now available for a similar purpose.

Another object of the invention is to provide a new and novel form of switch blade construction by which a high pressure contact may be obtained between the end of the switch blade and a stationary contact by a continuous operation of the switch blade operating mechanism.

Another object of the invention is to provide a circuit interrupting switch having contact pressure producing means at its end in which the contact pressure producing and operating mech-I anism are protected and enclosed Within a tubular switch blade.

Another object of the invention is to provide an operating mechanism for a switch having a pivotally mounted blade and contact pressure producing means at its end in which the movement of the switch blade and the operation of the contact pressure producing means is accomplished by the continuous movement of an operating member without loss of positive control of the switch blade.

A further object of the invention is to provide an improved blade and mounting for a circuit interrupting switch which can be moved into cooperating relation with a stationary contact terminal and then into high pressure engagement with said contact, to thus insure a good electrical engagement between the switch blade and said stationary contact when the switch is closed, all without interfering with the closing and/or opening movements of the switch blade by an operating means common to both the switch blade and said pressure producing means.

Other objects and advantages of the invention will be in part hereinafter pointed out and in part evident to those skilled in the art as the description thereof proceeds.

For a better understanding of the invention reference should be had to the following specication, taken in connection with the'accompanying drawing, wherein there is shown by way of illustration and not of limitation, a preferred embodiment thereof.

In the drawing;

Figure l is a side elevation of a complete single pole switch constructed and arranged in accordance with this invention,

Figure 2 is a fragmentary enlarged plan view of the switch operating mechanism with por-f tions broken away and in section to show details of the switch blade construction,

Figure 3 is a fragmentary side elevation with parts broken away and in section, showing the position of the parts when the switch blade is in its closed circuit position and the contact pressure producing means is operating,

Figure 4 is a view similar to Figure 3, showing the position of the parts with the switch blade in its closed circuit position and with the contact pressure producing means inoperative,

Figure 5 is a view similar to Figure 4, showing the parts in the positions assumed when the switch blade is in its fully opened position,

Figure 6 is a fragmentary plan view of the switch blade as illustrated in Figure 3,

Figure '7 is a fragmentary sectionalized plan view, showing the end of the switch blade with a preferred form of contact pressure producing means as contemplated by the present invention, and

Figure 8 is a fragmentary sectionalized view of a modied detail of the expanding means illustrated in Figure '7 of the drawing.

In the operation of disconnecting switches of the type contemplated by the present invention, particularly where the switch blades are of considerable length, it is desirable that the switch be so constructed that the movable switch blade will engage the stationary contact without requiring an excessive operating force and at the same time have a high contact pressure. In other words, it is desirable to have a high contact pressure producing means which will not interfere with the free closing and/or opening movements of the switch blade with respect to its cooperating stationary contact.

With the above and other requirements in view, the present invention contemplates a new and improved form of switch blade and an actuating mechanism therefor, which will operate to produce a high contact pressure between the switch blade and a stationary contact after the switch blade has been moved into its final closing circuit position and which will also function to relieve the high contact pressure between the switch blade and its stationary contact before the blade operating mechanism becomes operative to move the switch blade into its open circuit position.

For the purposeof illustration the invention is shown in the drawing as embodied in a single pole switch. It is to be understood, however, that switches made in accordance with this invention may be provided for multiphase circuits by merely mounting any number of these single pole switches side by side upon a suitable support and providing a common operating means.

As illustrated in Figure l of the drawing, the switch contemplated by this invention is adapted to be mounted upon the caps of high voltage insulator stands which are arranged in a straight line upon any suitable support. In the drawing a support I0 is shown as having two insulator stands, designated by the numerals II and I2, mounted in fixed spaced relation, and a third similar insulator stand I3 which is rotatably mounted thereupon. The insulator stand II supports a stationary contact clip I4 to which a conductor I5 leading to one side of the power circuit is attached, and at the top of the insulator stand I2 there is a switch blade support I6 upon which there is pivotally mounted a switch blade I1. The switch blade I1 is adapted to be rotated into and out of circuit making engagement with the stationary contact clip I4 by means of a connecting link I8 which extends between a switch blade operating member I9 associated with the switch blade I1 and a crank arm 20 carried at the upper end of the rotatable insulator stand I3. Extending from the switch blade support I6 and engaging the upper rotatable end of the insulator stand I3 there is a spacing strut 2| having a terminal 22 at its outer end to which a cable leading to the other side of the power line may be attached. The strut 2| provides an upper bearing for the insulator stand I3 and also operates to maintain a definite spacing between the axis of the crank 2|) and the pivotal axis of the switch blade I1, as will hereinafter appear.

For the purpose of rotating the operating crank 2li the insulator stand I3 is provided with an operating lever 23 which is adapted to be moved through the required arc to open and close the switch by any suitable operating mechanism, as is well understood in the art.

In order to provide a good current conducting path between the switch blade I1 and the terminal 22 at the outer end of the strut 2|, there is a exible jumper or shunt 24 through which the current may pass around the elements forming the pivotal mounting for the switch blade I1, and for the purpose of avoiding damage to the stationary contact I4 and the end of the switch blade I1 by arcing, such as occurs upon an opening of the switch, the stationary `contact I 4 is provided with an arcing horn 25 that cooperates with a movable arcing horn 26 extending from the end of the switch blade I1.

Reference is now made to Figure 2 of the drawing for a more detailed description of the switch blade operating mechanism. As here shown, the switch blade support I6 has an upwardly extending plate-like portion 21 through which there extends a transversely disposed shaft 28'and upon which the switch blade I1, tubular in form, is

pivotally mounted. Because of the central disposition of the plate-like member 21 with respect to the transversely extending shaft 28, the end of the tubular switch blade I1 is split centrally in a vertical plane, so as to accommodate the supporting plate-like member 21. The ends of the transversely extending shaft 28 pass through arms 29 which form a bifurcated end upon the strut 2|, and in this manner the shaft 28 is held in fixed spaced relation with the axis of the switch operating crank 20. The jumper or shunt 24 is here shown as extending between a conductor clamp 30 carried by the switch blade I1 and a lug 3| formed upon the strut 2|. Since a portion of the switch blade operating member I9 is disposed within the switch blade, this portion is also split in a vertical plane, so as to extend down over each side of the plate-like extension 21 upon the supporting member I6, and in order to provide for movement thereof with respect to the transversely extending shaft 28, this portion of the operating member I9 also has a slot 32 in each side thereof, through which the transversely extending shaft 28 extends.

Reference is now made to Figures 3 to 6 inclusive of the drawing for a more detailed description of the switch blade operating mechanism and its mode of operation. As is clearly shown in Figure 3 of the drawing, the switch blade operating member I9 has a piston-like extension 33 which is adapted to slide within the tubular switch blade I1, and extending from this pistonlike extension there is a rod 34 that is connected at its outer end to contact pressure producing means at the end of the switch blade I1, as will be hereinafter pointed out. In addition to the piston-like extension 33, the operating member I9 also has an overhanging lever arm 35 to which the switch operating link I8 is attached. With this arrangement, when the switch blade I1 is in the position shown, it will be seen that if a pulling force is exerted upon the operating link I8, the operating member I9 will be moved to the right and thus, by virtue of the slots 32 in the operating member I9, cause the operating member I9 to slide within the tubular switch blade I1 and impart a contact pressure operating movement to the rod 34. In order to insure this sliding movement of the piston-like extension 33 within the tubular switch blade I1, the plate-like extension has a short horizontally disposed straight portion 38 which will permit an initial and also a final straight line movement of the operating member I9 when the switch blade I1 is being moved respectively out of and into circuit making engagement with the stationary contact I4. Extending downwardly from the straight portion 3B the guide 36 has an arcuate surface 39 which will operate to retain the operating member I9 against relative movement and in fixed relation with the switch blade I1 in all but the circuit closed position of the switch. At the lower end of the guide rail 36 the support I6 is provided with an adjustable stop against which the abutment 31 is adapted to engage when the switch blade I1 is in its fully opened position.

As shown in Figure 4 of the drawing, the switch blade operating member I9 has been moved to the right by the application of force through the operating link I8 to a point where the abutment 31 upon the operating member I 9 is just about to afgaan clear the horizontally disposed straight portion 38 of the guide 36, so that any further right-hand movement of the operating member I9 will cause the abutment 31 thereof to move downwardly over the arcuate portion 39 of the guide 36. This right-hand movement of the operating member I9 will thus cause a rotation thereof about the transversely extending shaft 28, and as a result the cylindrical extension 33 thereupon, together with the blade I 1,'wi1l be rotated into an open circuit position where, as illustrated in Figure 5 of the drawing, the abutment 31 upon the operating member I9 will engage the adjustable stop 48 and hold the switch blade I1 in a substantially vertical open circuit position. As shown in this latter gure of the drawing, the lever arm 35 upon the operating member I9 doubles back over the axis of the transversely extending shaft 29, and thus provides a lever arm for the operating member I9 when the switch blade I1 is in both its closed and ful1y opened positions.

As is more clearly shown in Figure 6 of the drawing, the operating member I9 is designed so as to extend over and substantially enclose the plate-like extension 21 upon the support I6 when the switch blade I1 is in its closed circuit position.

Reference is now made to Figure '1 of the drawing for a description of a preferred form of contact pressure producing means that is particularly adapted for use with a switch of the above described character. In this i'lgure of the drawing the tubular switch blade I1 is shown as split at its free end centrally along a vertical plane, as at 4I so that the portions of the switch blade at the opposite sides of this split 4I may be expanded into intimate high contact pressure making engagement with opposed contact making surfaces 42 provided upon the stationary contact I4, as is common practice. Secured over the end of the switch blade I1 there is a cap-like member 43 having an inwardly extending portion 44 that terminates at a point beyond the inner end of the split 4I in the switch blade. This cap-like member 43, together with the extension 44, is held within the switchl blade I1 by means of a transverse pin 45 that extends freely through the sides of the switch blade I1 without interfering with an expansion thereof at this point. The pin 45 is shown as having a central reduced portion 46 into which the threaded end of the arcing horn 26 extends to hold it in place. Disposed along each side of the inwardly projecting portion 44 of the cap-like member 43 there are spring bars 41, each of which carry a pad-like bushing 49 at one end which passes freely over the pin 45 and engages the inside surface of the switch blade I1 at these points. At the other end of the spring bars 41 there are similar pad-like bushings 49 that slide freely over oppositely projecting pins 58 formed upon the inner end of the projecting portion 44. 'l Intermediate the ends of the spring bars 41 the extension 44 carries a pair of oppositely disposed balls or rollers 5I between which a wedge-like plunger member 52 is adapted to be moved by the operating rod 34 which, as previously described, is connected to the cylindrical extension 33 upon the operating member I9. The plunger member 52, as here shown, is of cylindrical cross-section and has a reduced end portion 53 that engages the balls 5I without exerting any outward flexing force upon the spring bars 41, and thel remaining portion of the plunger member, designated by the numeral 54, is of such a diameter that when it is moved to the left by the operating rod 34, the balls 5I will be moved outwardly against the spring oars 41 and exert a flexing force thereupon, which will cause the padlike bushing members 48 at the outer ends thereof to expand the sides of the tubular blade I1 into high pressure contact making engagement with the contact making surfaces 42 of the stationary contact I4.

In Figure 8 of the drawing there is shown a modified detail of the high contact pressure producing means at the end of the tubular switch blade I1. In this embodiment of the invention, instead of providing stationary pins 58 for the pad-like bushings 49 at the inner ends of the spring bars 41, as shown in Figure 'I of the drawing, the inwardly extending portion 44 of the cap-like member 43 terminates short of the ends of spring bars 56, as at 55. The inner ends of these spring bars 56 are then threaded to carry outwardly extending studs 51 which have enlarged heads 58 that engage the inside of the tubular switch blade I1. Extending from the enlarged heads 58 there is a slotted projection 59 that passes through a hole 68 formed at this point in the blade I1. In this arrangement each of the spring bars 56 is provided with a similar threaded stud 51, so that by an adjustment of these studs 51 the effective spacing between the inner ends of the spring bars 56 may be varied to thus determine the extent, of the bowing of these spring bars 56 when the balls 5I are brought into engagement therewith by movement of the ball engaging member 52, as previously described. By thus regulating the spacing between the xed ends of the spring bars 56, it is possible to regulate the amount of the contact pressure between the stationary contact and the switch blade by an expansion of the tubular switch blade I1.

The operation of the switch blade operating mechanism and the high contact pressure producing means should be evident from the above description. However, in order that there be no misunderstanding in this respect, it may be stated that when the operating crank 20 is turned in a counter-clockwise direction, as indicated by dot and dash lines in Figure2 of the drawing, the

switch blade operating member I9 will be moved to the rightin a straight line until the abutment 31 carried thereby clears the straight portion 38 upon the guide 36. At this time the operating crank 28 will have rotated through a small portion of its arc to the point A. This movement of the operating member I9 will bring the end of the slot 32 in its cylindrical portion 33 against the transversely extending shaft 28, and as a result further movement of the operating crank 28 to L the position B, will cause the operating member I9 to pivot about the transversely extending shaft 28, and thus rotate the tubular switch blade I1 into a vertical position, as shown in Figure 5 of the drawing, at which point the abutment 31 will engage the adjustable stop 48 and stop further pivotal movement of the tubular switch blade I1.

During a reverse rotation of the operating crank 28 the operating member I9 will be held in positive operating relation with the switch blade by the arcuate surface 39 upon the guide 36, until the tubular switch blade I1 has been moved into its horizontal closed circuit position, as shown in Figure 4 of the drawing. When within the tubular switch blade I1 and move the operating rod 34 to control the contact pressure producing means at the end of the switch blade I1. This straight line movement of the switch blade operating member I9 at this point in its operation is possible as the abutment 31 here disengages the arcuate surface 39 upon the guide 36 and is free to move along the straight portion 38, as is indicated in Figure 3 of the drawing. When the contact pressure operating rod 34 is moved to the left in this manner, the enlarged` portion 54 of the wedge-like member 52 will engage the balls 5I and force them outwardly against the spring bars 41 and cause them to be flexed outwardly intermediate their ends. This flexing of the spring bars 41 will move the padlike bushings 48 and 49 at the ends thereof into engagement with the inside of the tubular switch blade I1, and as a result the outer ends. of the spring bars 41 will exert a yielding force which will expand the end of the switch blade I1 into high pressure contact making engagement with the opposed contact surfaces 42 upon the sta- -tionary 'contact I4. .At this point it should be stated that because of the disposition of the inner ends of the spring bars 41 beyond the end of the split 4I`in the switch blade I1 these ends of the spring bars 41 will have substantially no outward movement, and as a result practically all of the expanding force exerted within the tubular switch blade I1 will be applied at the end thereof through the pad-like bushings 48 which, as previously described, slide freely upon the pin 45.

While I have, for the sake of clearness and in order to disclose my invention so that the same can be readily understood, described and illustrated specific devices and arrangements, I desire to have it understood that this invention is not limited to the specic means disclosed, but may be embodied in other ways that will suggest themselves to persons skilled in the art. It is believed that this invention is new and it is desired to claim it so that all such changes as come within the scope of the appended claims are to be considered as part of this invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. In a disconnecting switch, the `combination of an insulated stationary switch blade support, a switch blade pivotally mounted at one end in a xed position upon said support, an insulated stationary contact disposed in spaced relation with said insulated support with which the end of said switch blade is adapted to cooperate, operable pressure producing means at the contact engaging end of said switch blade, an operating lever for controlling the opening and closing movements of said switch blade slidably and pivotally mounted upon said support and connected with said operable pressure producing means, said operating lever having a limited straight line slidable movement upon said in' sulated support independently of said switch blade for operating said pressure producing means when the switch blade is in its closed position, a link connected to said operating lever for imparting both the slidable and the pivotal movements thereto, and means carried by said stationary support for preventing said slidable movement of the operating lever independently of the switch blade in all but the final closed circuit position of the switch blade.

2. In a disconnecting switch, the combination of an insulated stationary support, a tubular switch blade pivotally mounted at one end upon a fixed axis carried by said support, an insulated stationary contact disposed in spaced relation with said insulated support with which the end of said switch blade is adapted to cooperate, pressure producing means at the contact engaging end of said switch blade, means at the pivoted end of said tubular switch blade connected with said contact pressure producing means and having a limited movement with respect to the xed axis upon said insulated support axially within said tubular switch blade when the switch blade is in its closed position, an operating link connected to said means for imparting said limited axial movement to said means and also a switch blade operating movement thereto, and means carried by said stationary support for preventing the axial movement of said means when the switch blade is in all but its closed position and permitting a pivotal movement thereof upon said insulated stationary support as said operating link moves to rotate said blade about its fixed pivotal axis upon said insulated stationary support.

3. In a disconnecting switch, the combination of a stationary switch blade support, a switch blade pivotally mounted at one end upon said support, a stationary contact disposed in spaced relation with said switch blade support with which the end of said switch blade is adapted to cooperate, pressure producing means at the contact engaging end of said switch blade, means pivotally mounted upon said stationary support for controlling the circuit openingand closing movements of said switch blade, said means being also movable relative to said stationary support and said switch blade when the switch blade is in its circuit closed position, and means carried bysaid stationary support for preventing relative movement of said last means with respect to the switch blade in all but the closed circuit position of said switch' blade, and a connection between the pressure producing means at the contact engaging end of said switch blade and said pivotally mounted means, whereby said contact pressure producing means will be operated upon the occurrence of relative movement between said pivotally mounted means and `said switch blade.

4. In a disconnecting switch, the combination of a stationary switch blade support, a switch blade pivotally mounted at one end upon said support, a stationary contact disposed in spaced relation with said insulated support with which the end of said switch blade is adapted to cooperate, a contact pressure producing means at the stationary contact engaging end of said switch blade, an operating lever for controlling the opening and closing movements of said switch blade mounted upon said support for both a lateral and pivotal movement and connected-with said contact pressure producing means, the lateral movement of said operating lever upon said insulated support being axial and relative to said switch blade when in its closed position and adapted to operate said contact pressure producing means, an operating crank journaled in spaced relation with said stationary switch blade support, a link connected between said operating crank and said operating lever for imparting both a lateral and pivotal movement thereto as said operating crank moves in one direction, and means carried by said stationary support in the path of said operating lever for preventing said lateral contact pressure means operating movement of the operating lever in all but the nal closed circuit position of the switch blade.

5. In a disconnecting switch of the character described, the combination of a stationary switch blade support, a switch blade pivotally mounted upon said stationary support, a switch blade operating lever slidably mounted upon said switch blade and having a limited movement axially with respect thereto, a contact pressure producing means at the end of said switch blade, a connection between said contact pressure producing means and said operating lever, and means carried by said stationary support for limiting the axial movement of said operating lever upon said switch blade in all but the closed circuit position of said switch blade.

6. In a disconnecting switch of the character described, the combination of a stationary switch blade support having a iixed transversely extending shaft, a tubular switch blade pivotally mounted upon said transversely extending shaft, a piston-like member slidably mounted within the pivotally mounted end of said tubular switch blade and having an outwardly extending lever arm, a contact pressure producing means at the end of said switch blade, a connection between said high contact pressure producing means and the piston-like member disposed within said tubular switch blade, means for exerting a switch blade operating force upon said lever arm, and means carried by said stationary support and cooperating with said outwardly extending lever arm to prevent axial movement of said pistonlike member within said tubular switch blade in all but the closed circuit position of said switch blade and hold said switch blade operating lever in positive operating relation with said switch blade in all but its nal closed circuit position.

'7. In a disconnecting switch of the character described, the combination of a stationary switch blade support, a tubular switch blade pivotally mounted upon a fixed axis carried by said stationary support, a switch blade operating lever having a piston-like extension mounted within said tubular switch blade and movable axially with respect thereto, a contact pressure producing means at the outer end of said switch blade, a connecting rod between said contact pressure /producing means and the piston-like extension disposed within said tubular switch blade, means for imparting a switch blade operating movement to said operating lever, and means carried by said stationary support for holding said switch blade operating lever in positive operating relation with said switch blade in all but its final closed circuit position and permitting axial movement of said piston-like extension within said tubular switch blade in the closed circuit position of said switch blade.

8. In a disconnecting switch of the character described, the combination of a stationary switch blade support, a switch blade pivotally connected at one end to said stationary support, a, contact pressure producing means at the other end of said switch blade, a switch blade movement controlling lever slidably mounted upon said switch blade and adapted by its sliding movement to operate said contact pressure producing means, and means carried by said stationary support for holding said movement controlling lever in iixed positlon and against slidable movement upon said switch blade when the switch blade is moved out of its circuit closed position by said movement controlling lever.

9. In a disconnecting switch of the character described, the combination of a stationary switch blade support, a switch blade pivotally connected at one end to said stationary support, a switch blade movement controlling lever slidably mounted upon said switch blade, a contact pressure producing meansy at the free end of said switch blade, a connection between said operating lever effective upon a sliding movement of said operating lever with respect to the switch blade to operate said pressure producing means, 'and means carried by said stationary support for holding said movement controlling lever in a fixed position and against slidable movement upon said switch blade when the switch blade is moved out of its circuit closed position by said operating lever.

10. In a disconnecting switch of the character described, the combination of a stationary switch blade support having an upwardly extending plate-like portion disposed vertically and centrally thereupon, a transversely disposed shaft extending through said plate-like extension and projecting from each side thereof, a tubular switch blade having its end split to accommodate said plate-like extension and pivotally mounted upon said transversely extending shaft, a pistonlike member having a lever arm extending outwardly therefrom at an angle to said switch blade, said piston-like member being movable with respect to said transversely extending shaft and slidably mounted within said tubular switch blade, a contact pressure producing means at the outer end of said switch blade adapted to be operated by a sliding movement of said pistonlike'member, a crank arm for controlling the operation of said switch blade, a link connected between said crank arm and the lever arm upon said piston-like member, said crank arm being adapted upon an initial switch blade opening and a inal switch blade closing rotation thereof. to move said piston-like member Within said switch blade to operate said contact pressure producing means, and means carried by the plate-like extension upon said switch blade support for maintaining said piston-like member in positive switch blade controlling relation with said switch blade during the remaining movement of said crank arm.

11. In a disconnecting switch of the character described, the combination of a stationary switch blade support having an upwardly extending plate-like portion disposed centrally in a vertical plane thereupon, a transversely disposed shaft extending, through said plate-like extension and projecting from each side thereof, a, tubular switch blade having its end split to straddle said plate-like extension and pivotally mounted upon said transversely extending shaft, a switch blade controlling means having a lever arm extending outwardly therefrom at an angle to the switch blade, said operating member being slidably mounted upon said transversely extending shaft and extending into said tubular switch blade, 'a second support arranged in spaced relation with said switch blade support, a crank arm rotatably mounted upon said second support, a connecting link between said crank arm and the lever arm upon said switch blade controlling means, a bifurcated spacing strut secured upon said second support with its bifurcated end engaging the projecting ends of said transversely extending shaft to maintain a definite spacing between said crank arm and said transversely extending shaft, said crank arm being adapted upon an initial switch blade opening rotation thereof to move said switch blade controlling means within said switch blade, and means carried by the vertical plate-like extension upon said switch blade support for maintaining said switch blade controlling means in positive switch blade controlling relation with said switch blade during the remaining switch blade opening movement of said crank arm.

12. In a disconnecting switch of the character described, a tubular switch blade having its end split along a plane parallel with its path of movement, a parir of spaced bars disposed within and extending parallel with the plane of the split in said switch blade, the ends of said spring bars near the pivoted end of said switch blade being disposed beyond the split in the end of said switch blade and the outer ends of said bars being free to spread and exert an expanding force within the switch blade to spread the split end thereof, a supporting guide disposed Within the split end of said switch blade, a paid of oppositely disposed balls carried by said supporting guide and engaging said spring bars between the ends thereof, and a ball engaging member movable between said balls and having an enlarged portion adapted to move each of said balls outwardly against a cooperating spring bar to exert an expanding force at the split end of said switch bladef 13. In a disconnecting switch of the character described, the combination of a stationary contact having rigid opposed contact forming surfaces between which a switch blade is adapted to engage, a switch blade pivotally mounted to cooperate with said stationary contact and having spaced outwardly movable end portions adapted to engage the opposed surfaces of said stationary contact, a pair of spaced spring bars disposed between the movable end portions of the switch blade and extending parallel therewith, the ends of said spring bars near the pivoted end of said switch blade being held against a spreading movement and the outer ends of said spring bars being free to spread and exert an expanding force between the movable end portions of said switch blade to move said portions outwardly into engagement with said opposed contact surfaces, a supporting guide having opposed elements adapted to move outwardly against a point intermediate the ends of said spring bars, and a wedge-like member disposed between said elements adapted to slide axially of the switch blade and move said elements outwardly to exert a flexing force upon said spring bars, whereby the outer ends of said spring bars will cause the movable end portions of said switch blade to spread into high pressure contact making engagement with the opposed surfaces of said stationary contact.

14. In a disconnecting switch of the character described, the combination of a stationary contact having rigid opposed contact forming surfaces between which a switch blade is adapted to engage, a tubular switch blade pivotally mounted to cooperate with said stationary contact and having its contact engaging end split along its central axis in a plane parallel with the opposed surfaces of said stationary contact, a. pair of spaced spring bars disposed within the split end portion of the switch blade and extending parallel with the plane of the split in said switch blade, the ends of said spring bars near the pivoted end of said switch blade extending beyond the split in the end thereof and the outer ends of said spring bars being free to spread and exert an expanding force within the split end of the switch blade, a ball supporting guide having oppositely disposed balls adapted to move outwardly against a point intermediate the ends of said spring bars, and a ball engaging member slidably disposed between said balls and having an enlarged portion adapted to move said balls outwardly to exert a flexing force upon said spring bars, whereby the outer ends of Vsaid spring bars will cause the split end of said switch blade to expand into high pressure contact making engagement with the opposed surfaces of said stationary contact.

15. In a disconnecting switch of the character described, a tubular switch blade having its end split along n plane parallel with its path of movement, a pair of spaced spring bars disposed within and extending parallel with the plane of the split in said switch blade, the ends of said spring bars near the pivoted end of said switch blade being disposed beyond the split in the end of said switch blade and the outer ends of said bars being free to spread and exert an expanding force within the switch blade to spread the split end thereof, a supporting guide disposed within the split end of said switch blade, a pair of oppositely disposed elements carried by said supporting guide and engaging said spring bars between the ends thereof, an element engaging member movable between said elements and having an enlarged portion adapted to move each of said elements outwardly against a cooperating spring bar to exert an expanding force at the split end of said switch blade, and means at the inner ends of said spring bars for adjusting the eiective spacing therebetween, whereby the amount of contact pressure produced by said spring bars may be determined JOSEPH S. THOMPSON.

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