US2830144A

US2830144A - Disconnecting switch

Info

Publication number: US2830144A
Application number: US449129A
Authority: US
Inventors: Thorsten A Fjellstedt
Original assignee: McGraw Edison Co
Current assignee: McGraw Edison Co
Priority date: 1954-08-11
Filing date: 1954-08-11
Publication date: 1958-04-08
Anticipated expiration: 1975-04-08

Description

April 8, 1958 T. A. FJELLSTEDT Filed Aug. 11, 1954 DISCONNECTING SWITCH 5 Sheets-Sheet l as as /oo 7 mo 97 4'7 2/\ 2/ /0 46 Q 46 ms 2a 8? INVENTOR. /05 m5 Thorsten =68 l'i'JeZ Lstedt 7 m 25 ea April 8, 1958 T. A. FJELLSTEDT I 2,830,144

DISCONNECTING SWITCH Filed Aug. 11, 1954 5 Sheets-Sheet 3 36 INVENTOR.

Thorsten o4. E/eZZstedZ BY oa *0 fitter-mgr United States Patent DISCONNECTING SWITCH Thorsten A. Fjellstedt, Ingleside, Ill., assignor to McGraw- Edison Company, a corporation of Delaware Application August 11, 1954, Serial N0. 449,129

14 Claims. 01. 200-48) This invention relates to electric switches and more particular to disconnectingswitches of the type in which the switch blade is adapted to be swung into and out of cooperating relation with stationary contacts and to be rotated about its longitudinal axis to bring oppositely disposed contact surfaces into high pressure engagement with the stationary contacts.

In the art to which the present invention relates there are several types of operating mechanisms for disconnecting switches adapted to swing the switch blade between open and closed position and also to rotate the blade to bring the ends thereof into high pressure engagement with stationary contacts. .In one type of disconnecting switch the operating mechanism does not support the blade throughout the entire movement of the rotatable insulator and a stop must be provided to limit the downward travel of the blade within the stationary contact. In opening a switch of this type, the blade would normally move downward when its rotation begins, but inasmuch as the stop prevents the blade from dropping, undue strain is placed on the blade actuating mechanism. A major portion of the force available for operating the blade is expended during initial rotation of the insulator in preventing swinging movement of the blade and only. a minor portion is available for blade rotation. That is the major portion of the power for operating the blade which should be effective in producing blade rotation is lost in strains produced by the stop. Thus the operating effort is unnecessarily high in opening the switch blade, maintenance difficulties are increased; and switch life is correspondingly reduced. In other types of switches wherein the blade is wholly supported by the actuating mechanism, the force available for operating the blade is substantially equally divided between blade rotation and, blade rise. As a consequence, the high contact pressure between blade and stationary contact is not fully relieved in this type of switch before blade rise is initiated, and unnecessarily high mechanical force, i. e., operating eifort, is required to open the switch blade. Conversely, this type of mechanism does not always allow the switch blade to enter the stationary contacts before initial contact pressure is applied.

In both types of switch maximum contact pressure is only obtained if the blade is in perfect alignment with the contact shoes, and any undertravel or overtravel of the switch blade into the stationary contacts results in contact pressure less than the maximum obtainable. The many levers and links of such prior art switches provide an operating action with high spots and stops and does not result in smooth operation. Certain prior art disconnect switches have too many contact interchange surfaces, thus raising the voltage drop across the switch and causing unnecessary heating, whereas in other prior art switches this high voltage drop is only eliminated by the use of flexible leads to connect relatively movable parts of the switch.

It is one object of the invention to provide an operat- 2,830,144 Patented Apr. 8, 1958 2 ing mechanism which furnishessmooth, positive operation for swinging and rotating a switch blade without high spots or stops in the operating action.

It is a further object of the invention to provide an operating mechanism for a disconnecting switch wherein a minimum of operating effort imparts a powerful mechanical advantage to rotate the blade prior to rise from the contacts, thus providing positive contact break under adverse conditions such as ice and corrosion.

It is a still further object of the invention to provide an operating mechanism for a disconnecting switch which does not require a stop to prevent dropping of the blade during initial blade rotation as in certain prior art switches. It will be appreciated that the. elimination of the stop decreases the operating effort and greatly increases switch life in comparison to prior art switches wherein forcing the blade against the stop during the initial movement of the rotatable insulator placed undue strain on the operating mechanism. 7

It is an object of the invention to provide a blade operating mechanism wherein substantially all of the force available for operating the blade is translated into blade rotation during the initial rotation of the insulator and is increasingly transferred to blade rise with continued crank rotation after the blade has broken free of the stationary contact jaw.

A still further object is to provide an actuating mechanism which permits the blade to fully enter the contacts before initial contact pressure is applied.

Still another object of the invention is to provide a disconnect switch wherein maximum contact pressure is obtained regardless of the amount of undertravel or overtravel of the blade into the contacts.

Still another object of the invention is to provide a disconnect switch having a minimum number of current interchange surfaces and which does not requireflexible leads, as used between relatively movable parts in prior art switches to lower the voltage drop across the switch.

Still another object is to provide a disconnect switch wherein the stationary contact jaws are preloaded prior to entrance of the blade and enable the twisting motion of the blade to establish full contact pressure with practically no movement of the contact shoes. It will be appreciated that operating effort is minimized when establishing full contact pressure with such preloaded contact shoes, thereby greatly reducing the strain on the parts and improving switch life and maintenance. 7

A still further object of the invention is to provide a disconnect switch wherein all bearings and joints are shielded by novel sealing means which prevent entrance of foreign matter such as water into the bearing race which might freeze or start corrosion. I

A further object of the invention is to provide sealing means which cause any ice accumulated over the bearing to be subjected to cantilever stress when the switch operates. It will be'appreciated that ice in this condition is weakest and that strain on the parts is thus minimized when ice breaking is necessary to permit free operation of the switch.

A further object is to provide novel bearing seals for a disconnect switch whose physical characteristics are not changed in temperature ranges fom minus de grees F. to 300 degrees F. and whose life is not aifected by sunlight, acids, or corrosive or salt atmospheres.

Further objects and advantages of the invention will be apparent upon consideration of the following detailed description of a preferred embodiment thereof, when taken in connection with the attached drawing wherein:

Fig. 1 is a side view of a preferred embodiment of the disconnect switch of the present invention in closed position; I

"Fig. 2 is a vertical sectional view taken on line 2-2 of 'Fig. 1 and showing the free end of the switch blade in high pressure engagement with the stationary contact; a

Fig. 3 is an enlarged end view of the switch blade illustratingthe manner in which constant contact pressure is maintained with the stationary .contact regardless of undertravel or overtravel of theblade;

Fig. 4 is an enlarged fragmentary top view of the switch illustrating the blade operating mechanism of the embodiment of Fig. 1; V

Fig. 5 is an enlarged fragmentary side elevation view of the switch illustratingthe blade operating mechanism of the embodiment of Fig. 1;

Fig. 6 is an enlarged fragmentary side view of the switch taken :on the longitudinal axis of the blade and showing the blade operatingmechanism of the embodiment ofFig. 1;

Fig. 7 is an enlarged fragmentary side view of the switch illustrating the blade operatingmechanism of the embodiment of Fig. 1 with the switch blade in open position and with the frame support partially broken away;

Fig; 8 is an enlarged fragmentary view, partly in section, taken on line 8-8 of Fig. 1 showing the blade operating mechanism in closed position;

Fig. 9 is a view similar to Fig. 8 showing the switch blade and operating mechanism in open position;

Fig. 10 is a view similar to Fig. 4 with parts removed to better illustrate the blade operating mechanism;

Fig. 11 is a set of blade motion curves plotting blade rotation and blade rise of the embodiment of Fig. 1 versus degree of crank rotation; and

Figs. 12a to 12.1 are front views of the beavertail portion of the switch blade and illustrate the rotation of the switch blade about its longitudinal axis for various positions of crank rotation shown in Fig. 11.

The overall construction and operation of the disconnect switch of the invention will. be briefly described with particular reference to Fig. 1 before the cooperating parts are discussed in detail. A rotating insulator, vertical break air switch is mounted on a horizontal channel, or base, 10 which supports spaced apart, vertical stationary insulators 11 and 12 and a rotatable insulator 14 in alignment with and disposed between the stationary insulators 11 and 12. The insulator 11, 12, and Marc of conventional construction and are illustrated as of the pin type. A bearing housing 15 extending through and secured to the base 10 encloses a main ball bearing (not shown) which supports the rotatable insulator 14 and allows it to rotate about its own axis in operating the switch. In the preferred embodiment of the invention shown in Fig. 1 the axis of rotatable insulator 14 is in a vertical plane.

The rotatable insulator 14 can be actuated either through an operating lever 17 or through a sleeve 18 at the bottom of the bearing housing 15. Mounted on the upper end of the stationary insulator 11 is the distantly disposed stationary contact jaw assembly 20 having leaf back-up springs 21 for receiving the flattened, beavertail contact portion 23 of the switch blade 24 in high pressure contact engagement therewith. The jaw contact 20 is secured to a contact adapter 25 which is rigidly aflixed to the upper end of the stationary insulator 11. The adapter 25 carries an arcing born 27 and together with a terminal clamp 28 provides a terminal connector for securing a corresponding line conductor. Attached to the free end of the switch blade 24 is an arcing loop 30 which cooperates with the arcing horn 27.

At its upper end, the stationary insulator 12 carries one end of a frame'support 32 having a terminal pad 33 which together'with a terminal clamp 34 provides a terminal connection for a corresponding line conductor 35. The inner end of the frame support32'rotatably journals the upper end of the rotatable insulator :14-and free end of the crank 44 by a ball and socket 59.

the blade operating mechanism. The frame support 32 is a casting comprising horizontally spaced inclined sides 36 terminating at their inner end in a U-shaped cradle 37 (see Figs. 8 and 9) having an approximately horizontal cross piece 39 connecting upwardly extending, horizontally spaced

trunnions

40 and 41 for pivotally mounting a U-shaped blade guide 43 about a horizontal The blade operating mechanism includes a crank 44 rotatable with and secured to the upper end of the rotatable insulator 14. The crank 44 houses a ball bearing 46 (see Fig. 6) ,the inner race of which is rigid with the cross piece 39 and the outer race of which is integral with the crank 44 to rotatably journal the upper end of the rotatable insulator 14 on the frame support 32. The free ends of the legs of the U-shaped blade guide 43 receive pintles 47 extending through the

trunnions

40 and 41 to pivotally mount the blade guide 43 on the frame support 32 about a horizontal axis and to provide a fulcrum about which the switch blade 24 swings in its connect and disconnect motions with the distantly disposed stationary contact jaw 20. The cross piece of the U-shaped blade guide 43 includes a tubular sleeve portion 49 having its axis perpendicular to a vertical plane through the horizontal axis defined by the pintles 47 and disposed below a horizontal plane through said horizontal axis. A cylindrical blade carriage 50 is co axial with and rotatably journalled within the tubular sleeve portion 49. The switch blade 24 extends through and is rigidly aflixed to the blade carriage 50 by means of a bolt 51 (see Figs. 4 and 6). A stationary jaw contact assembly '52, similar to the jaw contact assembly 20, and having backup leaf springs 53 is affixed to the frame support 32 and extends forwardly in a horizontal direction. At the end opposite the beavertail portion 23,

the switch blade 24 is provided with a contact portion 54 (see Figs. 4 and 6) for high contact pressure engagement with the contactjaw assembly 52.

A pin 55 pivotally connects a bifurcated arm 56 integral with and depending from the blade carriage 50 in the closed, or normal, position of the switch blade 24 to a bifurcated link 57 about'a pivotal axis disposed below and transversely related to the longitudinal axis of the switch blade 24. The link 57 thus maintains a radial relationship relative to the switch blade 24 and to the blade carriage 50 regardless of their rotation. The opposite end of the link 57 is universally connected to the In the normal position of the switch the pivotal and

universal connections

55 and 59 respectively of the link 57 are disposed on opposite sides of a vertical plane through the horizontal axis defined by the pintles 47 'and are also on opposite sides of the vertical axis about which the rotatable insulator 14 rotates. It will also be noted that both the pivotal and'the universal connections of the link 57 are below a horizontal plane coincident with the horizontal axis defined by the pintles 47 and below the horizontal axis coincident with the longitudinal axis of the blade 24. t

Rotation of the rotatable insulator 14 results in movement of the ball and socket 59 in an arcuate path in a horizontal plane. The resulting force at the pivotal connection of the link 57, i. e., at the pin 55, is a push" having a first component approximately axial of the pin 55 tending to rotate the switch blade 24 about its longitudinal axis and a second component vertically upward tending to swing the blade guide 43, with the switch blade 24 mounted thereon, about the horizontal axis defined by the pintles '47. During the initial rotation of the rotatable insulator 14, the first component, i. e., the component approximately axial of the pin 55, predominates and there islittle or no rise of the blade 24; After the switch blade 24 has rotated sufficiently to break the beavertail portion 23 free from the stationary contact jawltl as well as the contact portion 54 free from the stationary contact jaw 52, the second component, i. e., the vertical component tending to swing the switch blade 24, increases and the switch blade 24 continues to rotate about its longitudinal axis as it is swung in a vertical plane out of engagement with the stationary contact jaws and 52.

The path of the ball and socket'59'during the initial rotation of the rotatable insulator '14 is approximately perpendicular to the plane of swinging movement ofthe switch blade 24, i. e., the crank 44 rotates from a position beyond dead center to the plane of swinging movement of the switch blade 24 and beyond said plane in a path which varies only a few degrees from a straight line perpendicular to the plane of swinging movement of the switch blade 24. Inasmuch as the pin 55 providing the pivotal connection between link 57 and depending arm 56 is also approximately perpendicular to the plane of swinging movement of the switch blade 24 at the closed position of the switch, during the initial rotation of the rotatable insulator 14 the predominant component of I the resulting force at the pivotal connection of the link 57 with the arm 56, i. e., at the pin 55, is axial of the pin 55.

As seen in Fig. 11 switch blade 24 drops approximately one degree during the first ten degrees of crank rotation, rises approximately one degree during the second ten degrees of crank rotation, and the blade rise after thirty degrees of crank rotation is only approximately three degrees. As seen in Figs. 11 and 12a, after the first twenty degrees of crank rotation, the switch blade 24 is still at its initial position within the stationary contact jaw 20 and has rotated substantially twenty-six degrees to break the blade 24 free from the

stationary contact jaws

20 and 52. Thus, substantially all of the force available for operating the blade 24 is translated into blade rotation before the switch blade 24 begins to rise in the stationary contact jaw 20. A maximum of the operating effort of the actuating mechanism is expended in blade rotation during the initial rotation of the rotatable insulator 14 to break the switch blade 24 free of the stationary jaw contact, to minimize contact abrasion, and to provide maximum mechanical advantage for breaking ice before the switch blade 24 begins to rise.

After the switch blade 24 is released from

stationary jaw contacts

20 and 52, the operating forces are increasingly transferred to cause blade rise at a higher rate in relation to blade rotation. This will be better understood when it is considered that with continued blade rotation the axis of the pin 55 departs more and more from the horizontal and approaches the vertical. In other words, the vertical component of the push at pin 55 resulting from rotation of insulator 14 increases with blade rotation. At the disconnect position. the switch blade 24 has swung beyond the vertical position and has rotated through more than 100 degrees. Reverse motion applies when the blade 24 enters the stationary contact jaw 20, thus providing the most effective ice breaking movement possible if the switch is iced open. On closing, as the switch blade 24 comes down, there is no silver to silver contact until the switch blade 24 is completely in the stationary contact jaw 20. Blade rotation at this point against the preloaded contact shoes of the

stationary contact jaws

20 and 52 establishes full contact pressure. Obviously, when the blade 24 has moved into the jaw contact, substantially all operating forces are translated to rotation of the blade and therefore any ice on the contacts will be cracked off by reason of the added con tact pressure and consequent movement of the contact shoes.

The link 57 includes a portion at its bifurcated end which, in the closed position of the switch, is approximately in the plane of swinging motion of the switch blade 24 and a portion 61 (see Figs. 8 and 10) angularly offset therefrom and terminating in a socket for the ball and socket joint 59. The offset permits the crank to be rotated past the plane of swinging motion of blade 24, i. e., past dead center, and thus locks the switch in closed position. The crank 44 extends radially of the vertical axis normally to the rear of the switch, i. e., toward the stationary insulator 12 and disposed to one side ofthe plane of swinging motion of the switch blade 24. The offset portion 61 of the link 57 is in alignment with the axis of the pin carrying the ball of the ball and socket joint 59 and permits the free end of the crank to be disposed to one side of the plane of swinging motion of the switch blade 24, i. e., past dead center. It will be appreciated that any force acting directly upon the switch blade 24 tending to open the switch must rotate the crank 44 to the plane of swinging motion of the blade 24, i. e., to dead center and beyond if the switch blade 24 is to be opened. Thus the switch blade 24 is effectively locked in the closed position.

The above described construction and operation will become evident from the following detailed description of the cooperating parts in reference particularly to Figs. 2 to 12 inclusive. i i

The ball bearings (not shown) enclosed in the bearing housing 15 are preferably silicone grease lubricated and sealed with silicone cord rings as described in detail hereinafter. Such silicone grease has practically flat viscosity temperature characteristics between minus 100 degrees F. and 300 degrees F. The bearing for the rotatable insulator 14 provides low friction under all types of adverse conditions such as chemical fumes, cold, heat, dust, and flyash, and the details of construction of the bearing are disclosed in my copending application Serial No. 409,694 having the same assignee as the present invention. As described therein the operating lever 17 for actuating the rotatable insulator 14 has serrations (not shown) which engage similar serrations on a face plate 78 (see Fig. l), affixed to the rotatable insulator 14 by bolts 80 to permit the operating lever 17 to be assembled on either side of the face plate 78 and to be positioned within 2 /2 degrees of the ideal location over a full range of 360 degrees.

The details of the contact jaw assembly 20 are disclosed in the copending application of Walter Kowalski and James J. Seaquist, Serial No. 388,734 having the same assignee as the present invention, to which reference is made for details of construction. As best shown in Fig. 2, two upstanding, laterally spaced contact shoes preferably of hard drawn copper have approximately right angle bends to form base portions 87 facing in opposed relation at their ends. Hexagon head machine screws 89 secure the base portions 87 rigidly to the contact adapter 25 which acts as the bottom half of the terminal connector. Both the adapter 25 and the terminal clamp 28 are provided with crossed V-grooves of different dimensions on both faces thereof. The terminal clamp 28 may be turned and reversed relative to the adapter 25 to either of four possible positions to receive and tightly clamp conductors or tubing ranging in sizes from & inch to 1%; inches diameter. This terminal arrangement eliminates one current interchange point on each end of the switch, since the conventional terminal lug is not required. It will be appreciated that the conductor can enter the terminal connector from either of three directions in the horizontal plane. Although not shown in the drawing, the clamping surfaces of each groove of the terminal clamp 28 are preferably provided with serrations to insure gripping of the conductor. The clamping surfaces of the V-grooves in the contact adapter 25 are preferably smooth and the ends are preferably rounded 'so that a stress concentration will not occur where the cable enters the clamp, thus preventing the conductor materials from crys tallizing due to vibration or oscillation of the conductor in service.

A tie-bar 94 projects through registering elongated holes (not shown) in each of the contact shoes 85. The tie-bar 94 has a spacer portion 95 integral therewith interposed 7 between the contact shoes 85 to limit the extent of-their movementtoward-each other.

The leaf :spring assemblies 21, or backup springs each comprise three heavy leaf springs of different lengths resiliently bearing against the contact shoes .85 and urging them against opposite margins 96 of the spacer portion 95. The leaf springs of each :spring assembly 21 are provided'with congruent holes (not shown) which encompass the tie-bar94. The upper end of the longest leaf 97' of each spring assembly 21 bears against a rectangular copper pad 100 silver soldered to the outer face of the shoes 85 above the margin 96 of spacer portion 95, whereas the lower end of the longest leaf 97 of each assembly 21 bears against the contact adapter 25 and embraces an anchoring .pin 102' extending laterally from the contact adapter 25. Elongated holes provided near the ends of the tie-bar 94 accommodate transverse stop pins 103 which hold the preloaded leafspring assemblies 21 against the contact shoes85. By the insertion of perforated shims 105 over the anchoring pins 102, increased loading of the leaf spring assemblies 21 against the contact shoes 85 can be accomplished.

It will be appreciated that high contact pressure isprovided and uniformly maintained by the leaf springs of the spring assemblies 21 held by the tie-bar 94. These leaf spring assemblies 21 preload the contact shoes 85 prior to entrance of the switch blade 24 into the stationary contacts and enable the twisting motion of the blade 24 to establish full contact pressure with practically no movement of the contact shoes 85. The stationary contact assembly is adjusted so that the contact shoes 85 are preloaded against the spacer portion 95 of the tie-bar 94 at approximately 70 percent of full pressure load and allow the beavertail portion 23 of the switch blade 20 to enter the contact shoes 85 before the blade is rotated to its .final position. Thus, operating effort is minimized when establishing full contact pressure, thereby reducing the strain on the operating mechanism "and greatly increasing switch life. The pads 100 directly behind the point of contact of the switch blade 24 with the contact shoes 85 provide means to distribute and dissipate possible heating during normal operation and supply reserve thermal capacity under short circuit conditions. Silver inserts 106 (see Fig. 3) on the blade side of the contact shoes 85 exert high contact pressure .on mating silver' inserts 107 on the curved sides of the flattened beavertail portion 23 of the blade 24 toprovide maximum conductivity at the contact points.

The terminal pad 33 on frame support 32 is similar to the contact adapter and has crossed V-grooves on the upper face thereof, and the terminal clamp 34 is identical to theclarnp 28 and has crossed V-grooves provided with serrations in both faces thereof. It will be appreciated that the terminal connector formed by pad 33 and clamp 34 permits clamping of a wide range of conductor or tubing size and further eliminates one current interchange point in a manner similar to the terminal connector on the stationary insulator 11.

The details of the rotatable bearing for the upper end of the rotatableinsulator 14 are best illustrated in Fig. 6. The crank 44 is a casting having a circular body portion provided with a cylindrical axial compartment 111 concentric with the vertical axis about which the rotatable insulator 14 rotates and a portion 112 extending upwardly at an angle of approximately 50 degrees to the horizontal. The compartment 111 accommodates the double row, radial ball bearing 46. An externally threaded retaining collar 114 engaging internal threads in the compartment 111 holdstheball bearing 46 within the compartment 111. A depending cylindrical boss 115 coaxial with the vertical axis about which the insulator 14 rotates isprovidedon the bottom surface of the cross piece 39, and athreaded hole.116 is providedthrough the boss 115. The boss 115 extends through a clearance hole 117 inthe crank 44 into the compartment 111 toinsure proper alignment of the upper endof the rotatable insulator .14 with the frame 32. The boss abuts against the inner race ,of the ball bearing 46, and aheaded crank bearing bolt 118 projecting through the ball bearing 46 and threaded within the hole 116 engages a nut .119 above the cross piece 39 to maintain the inner race of the ball bearing 46 rigid with the frame 32. Inasmuch as the crank 44 is secured to the rotatable insulator 14 and is held rigid with the outer race by collar 114, the upper end of the rotatable insulator 14 and the crank 44 are rotatably journalled on the inner end of the frame 32.

The ball bearing 46 is preferably lubricated with sillcone grease, and a silicone cord ring 120between1the collar 114 and an arcuate-in-cross section circumferential groove in the head of the crank bearing bolt 11S protects and seals the ball bearing 46 from entrance of foreign matter such as water which might freeze or initiate corrosion. The silicone cord ring 120 is a synthetic elastic ring which has uniform physical characteristics in temperature ranges from minus 100 degrees F. to 300 degrees F. and is unaffected by acids or corrosive or salt atmospheres. The advantages of such silicone cord ring seals between relatively moving parts of a disconnect switch are described in detail hereinafter.

The U-shaped blade guide 43 is pivotally mounted between the

trunnions

40 and 41 on a horizontal axis and is'adapted to swing the switch blade 24 in a vertical plane to connect and disconnect it with respect to the distantly disposed stationary contact jaw 20. Cup shaped portions 122 on the free ends of the legs 123 and 1124 respectively'of the U-shaped blade guide 43 receive the pinties 47 (see Fig. 8) extending through and engaging congruent threaded holes in the

trunnions

40 and 41 respectively to pivotally mount the blade guide 43 on the frame 32 for swinging movement about a horizontal axis thereby providing a fulcrum for the swinging movement of the switch blade 24. The U-shaped blade guide 43 is preferablya casting, and the cross piece thereof includes the tubular sleeve portion 49 having an axis which, as the blade guide 43 pivots, defines a vertical plane perpendicular to the horizontal axis defined by the pintles 47. The axis of the sleeve portion 49 substantially coincides with the longitudinal axis of the switch biade 24.

Ball bearings

128 and 129 rotatably journal the cylindrical blade carriage 50 within the sleeve portion 49 in coaxial relation therewith. Arcuate-in-cross section

circumferential grooves

132 and 133 provided in the inner periphery of the sleeve portion 49 at the front and rear ends thereof form outer races for the ball bearings 12S and 129 respectively. A radially extending collar 134 on the cylindrical blade carriage 50 intermediate its ends prevents forward axial movement of the carriage 50 within the sleeve portion 49 and retains the ball bearings 129 within their race. An arcuate-in-cross section circumferentialgroove 136 in the blade carriage 50'at the base of the'collar 134 provides an inner race for the ball bearings 129.

A radially extending collar 137 rigidly secured within a circumferential groove on the exterior surface of the cylindrical blade'ca-rriage 50 near the front end thereof prevents rearward axial movement of the carriage 50 within the sleeve portion 49 and retains the ball bearings 128 within their race. In manufacture a reduced outer diameterisprovided on the carriage 50 at the front end thereof, and after the collar 137 has been inserted over the reduced diameter portion, the front end of the carriage Sii'is spun oristaked over the collar 137 to rigidly assemble these parts. An arcuate-in-cross section .cir-

- cumferential groove 133 in the exterior periphery of the collar 137 provides an inner race forthe ball bearings 128.

The

ball bearings

128 and 129 are preferably lubri cated with silicone grease which has practically fiat viscosity temperature characteristics between minus 100 degrees F. and 300 degrees F. The exterior edges at both ends of the sleeve portion 49 are bevelled annularly at approximately 55 degrees to the axis of sleeve portion 49 forming

inclined surfaces

140 and 141, and the

surfaces

143 and 144 of the

collars

134 and 137 adjacent the

surfaces

140 and 141 respectively are also chamfered annularly at'approxirnately 55 degrees to the axis of sleeve portion 49 but at the opposite angle to which the surfaces140 and 141 are bevelled. The opposed

inclined surfaces

140 and 143 and the opposed

inclined surfaces

141 and 144 form annular V-grooves in which silicone cord rings 146 (see Figs. 4 and are inserted to seal and protect the

ball bearings

129 and 128 from the entrance of moisture or other foreign matter. The silicone cord rings 146 are synthetic elastic rings which have uniform physical characteristics over substantially the same temperature range as the silicone grease. Acids, corrosive or salt atmospheres, or sunlight has no deleterious effect on the life of the silicone material. Permanent lubrication of the ball bearings is thus provided for the life of the switch. It will be appreciated that the elastic O-rings 146 permit flushing out a bearing by grease fed under pressure internally of the bearing if it would ever be necessary to change grease in the bearing. For example, grease fed under pressure through a hole (not shown) in the sleeve portion 49 into the space between the sleeve portion 49 and the carriage 50 would flow to the

ball bearings

128 and 129 and flush the old grease past the elastic O-rings 146.

In addition to sealing the

bearings

128 and 129, the silicone O-ring 146 causes any ice accumulated over it, from the stationary sleeve portion 49 to the rotatable carriage 50, to be subjected to cantilever stress when the switch operates. Ice in this condition is weakest, and therefore ice breaking ability is assured.

The elongated switch blade 24 extends axially through the blade carriage 50 and is rigidly secured thereto by bolt 51. The switch blade 24 is of extruded hard drawn copper tubing. The front end of the tubular blade 24 is flattened to provide the beavertail portion 23 having equal radii on both sides so that its total width is constant across the contact sides. In other words, the radius of the

sides

148 and 149 of the beavertail portion 23 are equal and have the longitudinal axis of the blade 24 as a center.

High pressure point contact is accomplished in the disconnect switch of the invention by having the

curved surfaces

148 and 149 of the beavertail portion 23 at nearly right angles to the curved surfaces of the contact shoes 85. pressure remains constant and at a maximum, even though the blade 24 has overtraveled or undertraveled in rotating. The conductivity is a function of pressure applied between the points of contact, and the total pressure exerted is caused by contact shoe deflection when the blade is closing. Since the total width of the beavertail portion 23.is constant over a given blade twist, the total pressure will be constant over this same blade twist. As shown in Fig. 3, even if the blade 24 is rotated from the full line position to the dotted line position, the total pressure remains constant. This follows because the radius of the

curved surfaces

148 and 149 are equal and have the longitudinal axis of the switch blade 24 as the center. As described hereinbefore, silver inserts 107 are provided on the switch blade 24 at the

surfaces

148 and 149 where point contact with the contact shoes 85 is obtained. Back-up material (not shown) is placed directly behind the silver insert contact points 107 to give added thermal capacity.

The contact points of a switch blade, when subjected to adverse atmospheric conditions, often become coated with a surface film. Surface films of copper oxide form a very high resistance and become comparatively thick and diflicult to remove. The silver oxide or silver sulfide However, in the switch of the invention the total surface films on the contact points of the switch of the invention are very thin and can easily be removed with the wiping action of silver inserts 107 on the switch blade 24 against the silver inserts 106 on contact shoes 35.

The beavertail portion 23 of the switch blade 24 is made narrow to provide minimum travel when rotating into position between contact shoes 85. In additionthe narrow tip reduces the operating effort required to relieve the blade 24 from the stationary contact jaw 20 under adverse ice or corrosion conditions. The narrow blade tip with minimum travel when rotating into position provides sutficient wiping action but minimizes the silver to silver wear and still maintains the desired high contact pressure.

The stationary contact jaw assembly 52 engaged by the contact portion 54 at the rear end of the switch blade 24 is similar to the contact jaw assembly 20 and is mounted on a vertically extending flange 151 (see Fig. 4) integral with the frame support 32 and disposed between the rotatable insulator 14 and the stationary insulator 12. A horizontally disposed spacer bar 153 and opposed, horizontally positioned, generally 'L-shaped contact shoes 154 are rigidly afiixed to the frame support 32 by bolts 157 extending through clearance holes in the flange 151, in the spacer bar 153, and in the cross bars of the L-shaped contact shoes 154. Elongated holes (not shown) through the contact shoes 154 accommodate a tie-bar 158 with a spacer portion 159 disposed between the contact shoes 154 to limit the extent of their travel toward each other. Congruent holes (not shown) are provided through the three leaf springs of each backup spring assembly 53 to receive the tie-bar 158, and transverse pins 160 extending through holes in the ends of the tie-bar 158 hold the preloaded back-up springs 53 against the contact shoes 154.

One end of the longest leaf 161 of each backup spring assembly 53 bears against a pad, or block, of copper 162 silver soldered to the back of a contact shoe 154 behind the point of contact with the contact portion 54 of the blade 24 to distribute and dissipate heat, particularly during short circuit. The opposite end of the longest leaf 161 of each backup spring assembly 53 is perforated and embraces an anchoring projection 163 at the end of the spacer bar 153, and it is apparent that the preloading of the backup springs 53 can be varied a desired by the insertion of shims over the anchoring projection 163. The backup spring assemblies 63 preload the contact shoes 154 against the spacer portion 159 at approximately 70 percent of full load pressure and allow the contact portion 54 of the switch blade 24 to enter between the contact shoes 154 before the blade is rotated to its final position.

The switch blade 24 is deformed at its rear end to provide contact portion 54. At the diametrically opposite curved sides of contact portion 54 where point contact with shoes 154 is provided the diameter is equal to that of blade 24, but at diametrically opposite portions 164 (see Figs. 6 and 9) perpendicular thereto the blade diameter is reduced to permit the blade 24 to freely enter and rotate within stationary contact jaw 52. The reduced diameter at the rear end of the blade 24 at right angles to contact portion 54 is made less than the width of spacer 159, thus allowing the blade 24 to swing and rotate freely within jaw contact 52 after it has rotated sufiiciently to break contact portion 54 free of contact shoes 154. The radii of the curved sides of contact portion 54 are equal and have the longitudinal axis of blade 54 as a center, in the manner similar to beavertail portion 23, to provide constant contact pressure regardless of overtravel or undertravel of contact portion 54 within contact jaw assembly 52.

Although the diameter of contact portion 54 is less than the width of beavertail portion 23, the same high pressure contact is provided at the stationary contact jaw 52 as at the stationary contact jaw 20. The wider contact iportion 23;is required at the distant end of blade 24 because the torque provided to break ice is avfunction of the width of the contact portion, and a greater torque is required at the distant end of'the elongated switch blade .24, which may be several feet in length, than at .the rear .end of the blade 24 Where greater mechanical strength is provided by the shorter torque arm.

The bifurcated arm 56 integral with the blade carriage 59 extends therefrom radially of the longitudinal axis of the switch blade 24. The pin 55 extends through the spaced bifurcated portions, or cars, 165 (see Fig. 8) of the arm 56 and also through the spaced bifurcated portions 166 of the link 57 to provide a pivotal connection between arm 56 and link 57 about an axis which, in the closed position of the switch, the axis of the pin 55 is inclined at a small angle to the'horizontal (see Fig. 8) and the switch blade 24 has overtraveled within the stationary contact jaw 20 until the beavertail portion 23 is inclined at aismallangle (shown as 6 /2 degrees in Fig. 12a) to the horizontal. As described hereinbefore the contact pressure is constant regardless of overtravel of the blade 24. The overtravel of the blade 24 within the stationary contact jaw 20 results from rotation of crank 44 past dead center to lock the switch blade'24 closed. The arrangement of parts is such that most of the operating efiort during the initial rotation of insulator 14 is elfectivc in rotating the blade 24 and there is substantially no blade rise.

As best shown in Fig. 6 a pin 167 extending through the free end of the crank 44 is provided with a ball portion 168 for the ball and socket joint 59. The sidewall of the pin 167 is tapered intermediate the ends thereof. A conical aperture 169 in the end of the crank 44- receives the tapered portion of the pin 167, and a nut 17f) threaded on the end of the pin 167 rigidly affixes the pin 167 to the crank 44. A socket 171'in the offset portion 61, i. e., in the portion at the end of the link 57 opposite its pivotal connection with the arm 56, accommodates the ball por tion 168, and the edge at the socket 171 is staked over the ball portion 168, to provide a universal connection between crank 44 and link 57. The ball and socket joint is preferably lubricated with silicone grease and an elastic silicone O-ring '(see Fig. 5) seals the joint from entrance of foreign matter.

The switch blade 24 drops to its lowest position within the stationary contacts 20 and the crank 44 is at dead center position when the crank 44 and the ball and socket 59 are in the vertical plane of swinging movement of switch blade 24. In the closed position of the switch,

the crank 44 extends radially of the vertical axis toward 5 the rear of the switch, i. e., toward stationary insulator 12, and disposed on one side of the plane of swinging movement of blade 24. Normally the link 57 'is approximately in the plane of swinging movement of the blade 24, i. e., the reinforcing rib 172'is in this plane, and the portion 61 having the socket 171 is offset from the link 57 at approximately ten degrees to the plane of swinging movement and downward at an angle of approximately 40 degrees to the horizontal. In other words, the axis of the pin 167 carrying the ball 16% extends upwardly from the crank at an angle of approximately 40 degrees to the horizontal and at an angle of approximately degrees to the plane of swinging movement of the blade 24. This construction with the portion 61 offset from the body of the link 57 permits the crank 44 to benormally disposed past dead center, i; e., to one side of the plane of swinging movement of the blade 24. To open the switch, the insulator 14 must be rotated to move the crank 44, and with it the ball and socket 59, transversely through the plane of swinging movement of the blade 24. Thus the blade 24 is effectively locked in closed position in that inasmuch as the crank 44 is normally past dead center, no force nctingdirectly .on the blade 24 will open the switch.

The ;path of movement ofthe ball and socket 59 dur- 1'21 ing the initial rotation of the insulator 14 varies only a few degrees from a line perpendicular to the plane of swinging movement of the blade 24. As a consequence, during the initial rotation of insulator 14, the crank 44,

. in elfect, translates the link 57 laterally of the plane of swinging movement of the blade 24 with the result that the predominant component of the push at the pivotal connection of link 57 with arm 56 is approximately axial of pin 55. The axis of the pin 55 is normally inclined u at a few degrees from a perpendicular to the plane of swinging movement of the switch blade 24, and as the blade carriage 50 rotates during the initial rotation of insulator 14, the axis of pin 55 gradually approaches perpendicularity with the plane of swinging movement of the switch blade 24, becomes perpendicular to this plane, and gradually departs from perpendiculan'ty. Inasmuch as the initial rotation of insulator 14, in effect, causes lateral translation of the link 57 approximately parallel to the axis of pin 55, the initial rotation of insulator 14 results in maximum blade rotation with substantially no blade rise, and a maximum of the operating effort is expended in blade rotation. It is only when the axis of pin55 departs appreciably from the horizontal that the vertical component of the push at the pivotal connection of the link 57 becomes of sulficient magnitude to begin to pivot the blade guide 43 about the horizontal axis defined by the pintles 47.

Figs. 12:: to 12a show the position of the beavertail portion 23 within the stationary contact jaw 20 for various degrees of rotation of crank 44. In the closed position of the switch, the blade 24 has overtraveled in rotation approximately 6 /2 degrees past the horizontal and the crank is approximately 10 degrees past dead center. After the first five degrees of insulator rotation, the blade 24 has rotated to the horizontal as shown in Fig. 12b and the blade has dropped approximately /2 degree. After ten degrees of rotation of insulator 14, the crank 44 is at dead center and in the plane of swinging move.- ment of blade 24, the blade 24 has rotated 6 /2 degrees beyond the horizontal as shown in Fig. 120, and the blade has dropped approximately one degree. After 15 degrees of insulator rotation the blade has rotated 13 degrees beyond the horizontal, i. e., a total of 19 /2 degrees, as shown in Fig. 12d and the blade 24 has risen approximately /2. degree. It will thus be appreciated that the blade operating mechanism supports the switch blade 24 throughout its entire connect and disconnect motion and that no stop is required to prevent dropping of the blade. As. explained hereinbefore, in certain prior art switches the blade would normally drop during initial insulator rotation and a stop was required to prevent downward movement of the blade. In forcing the blade against the stop of such prior art switches the parts of the operating mechanism were unduly strained, an unnecessarily large operating effort was required, and switch life was considerably reduced. The operating mechanism of .the switch of the invention has high mechanical strength to support the switch blade throughout its entire connect and disconnect motions, thus obviating the need for a stop, reducing operating effort, and eliminating unnecessary strain on the parts of the blade actuating mechanism.

After ZO-degrees of insulator rotation the blade 24 has rotated 19%. degrees past the horizontal, i. e., a total of 26 degrees, as shown in Fig. 126. Thus after the first 20 degrees of insulator rotation the blade 24 is stillat its initial position within the stationary contact jaw 23 and the blade has rotated a full 26 degrees to break the blade 24 free from the contact shoes 85. t From Fig. 11 it will be noted that when the blade 24 has rotated 40 degrees the blade rise is only three degrees; that the blade 24 has rotated 21 full 48 degrees while rising only six degrees; and that at the top of the contact shoes the blade 24 has rotated 56 degrees while rising only nine degrees. Curves plotting blade rotation and blade rise for the switch of the invention in comparison to prior art switches show that the blade rise in the switch of the invention is delayed until after a much greater rotation of the blade than in any prior art switches. It will be appreciated that such high ratio of blade rotation to crank rotation, and the complementary small ratio of blade rise to crank rotation, of the switch of the invention in comparison to prior art switches provides maximum operating effort for breaking ice or possible corrosion and assures that the beavertail portion 23 is free of the contact shoes 85 before blade rise is initiated. It will further be appreciated that the blade motion is smooth and continuous without high spots or stops in the operating action.

The switch blade 24 continues to simultaneously rise and rotate about its longitudinal axis until atthe disconnect position the switch blade 24 has swung slightly past the vertical and has rotated through a total of approximately 113 degrees. The blade actuating mechanism in the disconnect position of the blade 24 is shown in Figs. 7 and 9. In Fig. 7 the rear end of the switch blade protruding through the carriage 50 has been omitted to better illustrate the arrangement of the parts. In the disconnect position the crank 44 is approximately perpendicular to the plane of swinging movement of the blade 24, the blade carriage 50 has been rotated until the axis of pin 55 is approximately horizontal, and the link 57 is approximately vertical. Continued rotation of the insulator 14 is prevented by a stop (not shown) within the bearing housing 15. 7

Although the blade 24 is past the vertical and stays without support in disconnect position, it is not locked in open position, and a minimum of operating effort is required to initiate closing of the switch blade 24. A horizontally extending arm 173 on the frame support 32 prevents swinging of the blade 24 in a direction away from the stationary jaw contact at the beginning of the connect motion of the switch blade 24. In the disconnect position of the switch blade 24, the link 57 does not abut against the arm 173. However, it is possible to swing toward the stationary insulator 12. To prevent this the arm 173 is provided to cam the link 57, and thus the switch blade 24, in a downward direction toward the stationary contact jaw 20 at the initiation of the down ward pivoting of the blade guide 43.

It will be appreciated that a minimum of current interchange surfaces are provided in the switch of the present invention and that no flexible leads are required between relatively movable parts as were required in certain prior art switches to reduce the voltage drop across the switch. Silver to silver point contact under approximately 175. pounds pressure is provided at both ends of the switch v at the initiation of the connect motion for the blade 24 blade to provide maximum conductivity, and thus minimum'voltage drop and heating across the switch.

Certain prior art disconnect switches were mechanically weak in that the forces tending to rotate and swing the switch blade were applied at a point forward of the blade guide and not sufiicient strength was provided to prevent I axial movement of the switch blade in a forward direction.

It will be appreciated that' in the switch of the invention, wherein the collar 134 and the arm 56 are disposed to the rear of the sleeve portion 49, maximum mechanical strength is provided to prevent axial movement of switch blade 24 in a forward direction.

It is apparent that the switch can be mounted in an upright position as shown in Fig. 1, or it can be mounted in a vertical or an underhung position.

The fact that the forces applied to the blade 24 of the 14 of that plane at a point located between the vertical axis of the rotatable insulator 14 and the stationary insulator 12.

In the embodiment described herein, the longitudinal axis of blade rotation is in perpendicular and offset relation to and normally positioned below the horizontal axis about which the blade swings, the vertical axis of insulator rotation is offset laterally to one side of this horizontal axis and intersects the longitudinal axis in normal position of the blade, and the link, connecting the blade carriage and the insulator crank, is pivotally connected with the blade carriage on an axis perpendicular to and below the longitudinal axis and universally connected with the crank at a point below the longitudinal axis and disposed on a side of the vertical axis opposite that on which the link is pivotally connected with the blade carriage.

Although only a single embodiment of the invention has been illustrated and described, it will be appreciated that the invention is not necessarily limited to the particular arrangement disclosed. Since changes and modifications inthe foregoing switch construction will be obvious to those skilled in the art and different embodiments of the invention can be made without departing from the spirit and scope thereof, it is intended that all matter shown in the accompanying drawing and described hereinbefore shall be interpreted as illustrative and not in a limiting sense.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Operating mechanism for controlling an elongated 7 switch blade, said mechanism comprising a fixed support,

a guide pivotally mounted on said support for movement about a horizontal axis, a carriage rotatably mounted in said guide for rotation about an axis perpendicular to said horizontal axis offset radially therefrom and normally extending in a horizontal direction below said horizontal axis, said carriage having a bore concentric with its axis for receiving said switch blade, means on said carriage for securing said blade in fixed positionin said bore, an arm secured to said carriage and depending therefrom, a crank rotatable about a vertical axis offset in a horizontal direction relative to said horizontal axis and intersecting the axis of rotation of said carriage, and a link pivotally connected at one end with said arm on an axis disposed below and radially relative to said axis of rotation of said carriage, the other end of said link being conected to said crank by means of a universal joint, said connections of said link being on relatively opposite sides of said vertical axis.

2. Operating mechanism for controlling switch blade movement in an electrical switch, said mechanism comprising a stationary support, a blade guide pivotally mounted on said support for pivotal movement about a horizontal axis, a blade carriage rotatable in said guide about an axis perpendicular to said horizontal axis, an arm member secured to and depending from said carriage solely in a first vertical plane Wholly spaced from a second vertical plane coinciding with said horizontal axis, a crank member rotatable about a vertical axis and positioned below said carriage, said crank member in normal position extending away from said second vertical plane on a side thereof opposite that of the first vertical plane, and a link having one end pivotally connected with one of said members and the other end universally connected with the other of said members, said connections being normally disposed on opposite sides of said second vertical plane relative to each other and below said carriage.

3. In a disconnecting switch comprising relatively spaced first and second stationary insulators, a rotatable insulator disposed between said stationary insulators and more nearly adjacent the first stationary insulator than the second insulator and rotatable about a vertical axis, a frame support secured to said first stationary insulator and rotatably engaging the rotatable insulator at its upper end, a jaw contact on said second stationary insulator, a blade guide, and an elongated blade carried by said guide and rotatable about its longitudinal axis, said guide being pivoted about a horizontal axis perpendicular to said longitudinal axis to swing said blade into and out of engagement with said jaw contact; blade operating mechanism comprising, in combination, a collar secured to said blade and having in the normal closed position of said blade a member depending therefrom in a plane perpendicular to said longitudinal axis, a crank member rigidly secured to said rotatable insulator and normally extending radially of said vertical axis toward said first stationary insulator, and a link pivotally connected at one end with one of said members for pivotal movement on an axis normally disposed below and transversely related to said longitudinal axis and universally connected at its other end with the other of said members, said pivotal and universal connections of said link being normally respectively disposed on opposite sides of a first vertical plane coinciding with said horizontal axis and on opposite sides of a second vertical plane through said vertical axis and parallel to said first plane.

4. In .a disconnecting switch comprising relatively spaced first and second stationary insulators and a rotatable insulator between said stationary insulators and rotatable about a vertical axis, a frame secured to the first of said stationary insulators and having journal means rotatably engaging the rotatable insulator at its upper end, a jaw contact on the second stationary insulator, a blade guide, and an elongated blade carried by said guide and rotatable about its longitudinal axis, said guide being. pivoted on said frame about a horizontal axis above the longitudinal axis of the blade in the normal closed position of the switch blade to permit swinging of the blade into and out of engagement with said jaw contact; blade operating mechanism, comprising, in combination, an arm secured to said blade and depending therefrom in a plane pen pendicular to said longitudinal axis, a crank rigidly secured to said rotatable insulator and normally extending radially of said vertical axis toward said first insulator and approximately in a first vertical plane coinciding with said longitudinal axis, and a link pivotally connected at one end with said arm for pivotal movement on an axis normally disposed below and approximately perpendicular to said first vertical :plane and universally connected at its other end with said crank, said pivotal and universal connections of said link being normally disposed on opposite sides of a second vertical plane coinciding with said horizontal axis and perpendicular to said first vertical plane, whereby the principal component of the forces at said pivotal and universal connections due to the initial rotation of said rotatable insulator to open said blade will be in a direction to rotate said blade about its longitudinal axis.

5. An electric switch comprising a fixed contact, a switch blade rotatable about its longitudinal axis and pivotally mounted about a horizontal axis normal to said longitudinal axis for swinging movement in a vertical plane relative to said fixed contact, an arm secured to said blade and depending therefrom when said blade engages said contact, a crankmovable in a horizontal plane transversely disposed relative to said vertical plane of swinging movement of said blade, and a link pivotally connected at one end with said arm for pivotal movement on an axis normally disposed below and at an acute angle with respect to said horizontal plane and transversely related to said longitudinal axis and at its other end having a portion offset at an angle from said vertical plane and said link providing a universal joint with said crank, said crank having a dead center position when said universal joint is in said vertical plane, said universal joint being normally disposed on one side of said vertical plane and upon initial movement of said crank to open said blade said universal joint is moved transversely across said vertical plane, whereby" said blade is efiectively locked closed when said joint is on said one side and cannot be axis to provide high contact pressure engagement with a stationary contact, in combination, a rotatable insulator rotatable about a vertical axis, a fixedsupport rotatably journalling the upper end of said rotatable insulator and having spaced, upwardly extending trunnions, a U-shaped blade guide having the legs thereof pivotally mounted between said trunnions on a horizontal axis, a blade carriage extending through the cross piece of said U-shaped blade guide and being rotatably journalled therein about an axis perpendicular to said horizontal axis, an elongated switch blade extending through and rigidly affixed to said blade carriage, said blade carriage having spaced ears depending therefrom in a plane perpendicular to said longitudinal axis and disposed between said cross piece r and said horizontal axis, a crank rigidly aifixed to said rotatable insulator and movable in a horizontal plane transversely disposed relative to the plane of swinging movement of said blade, and a link pivotally connected at one end with said ears for pivotal movement on an axis disposed below and transversely related to said longitudinal axis and universally connected at its otherend with said crank, said pivotal and universal connections of said link being normally disposed on opposite sides of a vertical t plane coinciding with said horizontal axis.

'member, said exteriorperipheral surfaces of said first and second members diverging from each other and jointly defining an annular groove .therebetween exteriorly of said members, and a tensioned, elastic, silicone ring of circular cross section in said groove in compressive bearing relation to said surfaces for preventing entrance of moisture to said bearing, the cross sectional diameter of said ring being greater than the Width of said annular groove.

8. In a disconnecting switch, in combination, a jaw contact, a blade guide, and a switch blade rotatably mounted on said guide about its longitudinal axis and having a flattened beavertail portion cooperating with the jaw contact, said guide being pivoted about an axis perpendicular to said longitudinal axis to permit swinging said switch blade into and out of engagement with said jaw contact, said beavertail portion having oppositely disposed sides contacting said jaw contact, said sides being arcuate in cross section and having equal radii with the longitudinal axis of the blade as a center whereby substantially uniform contact pressure is maintained in the closed position of the switch blade regardless of rotational overtravel or undertravel of the switch blade in the jaw contact. V

9. In a disconnecting switch, in combination, a jaw contact, a blade guide, and a switch blade rotatably journalled on said blade guide about its longitudinal axis and having at one end oppositely disposed contact areas cooperating with said jaw contact, said guide being pivoted about an axis perpendicular to said longitudinal axis to permit swinging said switch blade into and out of engagement with said jaw contact, said contact areas being arcuate in cross section, the radii of curvature of said contact areas being equal and having the longitudinal axis of the switch blade as a center, the areas of said switch blade perpendicular to said oppositely disposed contact areas having, radii smaller than those of said contact areas,

10. In an operating mechanism for a disconnecting switch exposed to the atmosphere, a framesupport, a rotatable insulator rotatable about a vertical axis, a crank rigidly afiixed to the upper end of said rotatable insulator and disposed below said support, said crank having a cylindrical bore concentric with said vertical axis, a cylindrical member rigidly afiixed to and depending from said support and rotatably journaled within said bore, said crank and the surface of said frame support opposite thereto jointly defining an annular exterior groove therebetween, and an elastic, silicone ring of circular cross section with-in said groove preventing entrance of foreign material to said bore, the cross sectional diameter of said ring being greater than the width of said groove.

11. In an operating mechanism for a disconnecting switch, a blade guide having a cylindrical bore and being pivoted on an axis perpendicular to the axis of said bore, a switch blade carriage coaxial with and extending through said bore, ball bearing means rotatably journalling said carriage within said bore, said carriage having radially extending collars adjacent the ends of said bore preventing movement of said carriage in an axial direction, an annular surface on each of said collars being concentric with the axis of said bore and inclined to the axis of said bore, the surface on said guide opposite to said annular surface on said collar being inclined at the opposite angle to the axis of said bore, said inclined surfaces on said guide and said collar jointly defining an exterior, annular, V-groove therebetween, and an elastic silicone ring of circular cross section in said groove preventing entrance of foreign material to said bearing means.

12. In a disconnect switch, the combination of a fixed frame support having spaced sides, a U-shaped blade guide having the legs thereof pivotally mounted for swinging on a horizontal axis transverse to said support, a blade carriage journaled for rotation in said guide on a longitudinal axis perpendicular to said horizontal axis, said carriage being disposed in a portion of said guide intermediate said legs, a switch blade extending through said carriage and adapted to rotate and swing therewith, an arm affixed to said carriage between said horizontal axis and said guide and extending in a radial direction relative to the axis of said carriage, a rotating insulator journaled for rotation with respect to said fixed support,

18 V a crank carried on said insulator for rotation therewith in a single plane normal to said insulator axis, pivot means between the swinging end of said crank and said arm for simultaneously rotating said blade carriage and swinging it about said horizontal axis, spaced contact jaws engageable by said switch blade, one of said contact jaws being disposed within said fixed frame support for engagement by said switch blade at a point on one side of said horizontal axis opposite from the side where the other of said jaws engages said blade.

13. In an operating mechanism for a disconnect switch exposed to atmospheric conditions, a first member provided with a bearing, a second member rotatable about the axis of said bearing adjacent the first member to provide a joint to be sealed between members, at least one of said members having contiguous with said joint an annular surface radially spaced from the axis of rotation and directed away from a plane normal to the axis of rotation and thereby defining an annular ring seat groove in conjunction with a surface on the other member, and a tensioned elastic ring in said groove, said ring being in compressive bearing relation to said surfaces for preventing entry of contaminants into said bearing.

14. In an operating mechanism for a disconnect switch exposed to atmospheric conditions, first and second adjacent members providing a joint to be sealed therebetween and rotatable with respect to each other on a common axis, at least one of said members having contiguous with said joint an annular surface presented outwardly from the axis, radially therefrom and directed away from a plane normal to the axis, said surface thereby defining an annular ring seat groove in conjunction with a surface of the adjacent member, and a tensioned elastic ring in said groove, said ring having a tendency to contract into compressive bearing relation only against said surfaces for preventing contaminants from entering said joint.

References Cited in the file of this patent UNITED STATES PATENTS 2,368,462 Garrison Ian. 30, 1945 2,673,913 Heberlein Mar. 30, 1954 2,745,919 Hollander May 15, 1956