US2803727A - Heavy duty hook stick pry-out and switch blade structure - Google Patents

Description

Aug. 20, 1957 F. H. TURNHAM ,8 V HEAVY DUTY HOOK STICK FRY-OUT AND. SWITCH BLADE STRUCTURE Filed Aug. 25. 195.4 a sheets-sheet 1 INVENTOR F 'rzHuaH H. TURNHAM BY mwww ATTORNEYJ' Aug. 20, 1957 F. H. TURNHAM 2,303,727

HEAVY DUTY HOOK STICK FRY-OUT AND SWITCH BLADE STRUCTURE Filed Aug. 25, 1954 3 Sheets-Sheet 2 IN VENTOR Fl TZHUGH H. TURNHAM ATTORNEYJ 2 9 F. H. TURNHAM 2,803,727

HEAVY DUTY noox sncx FRY-OUT AND SWITCH BLADE STRUCTURE Filed Aug. 25, 1954 a Sheets-Sheet z .78 INVENTOR v Fwznqeu H. TUItMHAM ATTORNEY! HEAVY DUTY HOGK STICK PRY-OUT AND SWITCH BLADE STRUCTURE Fitzhugh H. Turnham, Birmingham, Ala., assignor to USCO Power Equipment Corporation, Birmingham, Ala., a corporation of Alabama Application August 25, 1954, Serial No. 452,004

13 Claims. (Cl. 200-162) ments over the switches disclosed and claimed in the afore-' mentioned application particularly directed to providing switches for heavy duty applications but also to provide important general improvements applicable in whole or in part to lighter duty hook stick operated switches.

Inasmuch as all switches of the general type disclosed hereinafter and in application Serial No. 434,257 find their primary if not exclusive utility in high voltage lines, all are in a broad sense heavy duty switches. Therefore, for the purpose of comparison, differentiation, and example, it is pointed out that switches according to the present invention are preferred for handling currents in the order of 1200 to 2000 amperes at 7.5 through 69 kv.

It is an important object of this invention to provide a disconnect switch having a pair of transversely spaced, parallel switch blades and tip-turned contact members disposed between the blades adjacent the ends thereof and providing transversely spaced contact edges in engagement with the blades when the switch is closed with a demountable transversely disposed guide member adapted to engage the blades along an area spaced from the normal contact area and guide the blades as they descend to closed position on the contact edges.

It is a further important object of this invention to provide a hook-stick operated disconnect switch having a pair of transversely spaced parallel switch blades hinged at one end and up-turned contact members disposed be tween the blades adjacent the opposite ends thereof providing transversely spaced contact edges in engagement with the blades when the switch is closed with a curved, transversely stepped, pryout arm pivoted on the blades adjacent the other end and laterally spaced abutment surfaces adapted to be sequentially contacted by the stepped surfaces on said arm to provide a two-stage pryout means for opening the switch.

It is another object of this invention to provide the spaced blades of a disconnect switch having a pair of transversely spaced, parallel switch blades adapted to engage a contact member disposed between the blades adjacent the free end thereof and providing transversely spaced contact edges with longitudinal slots in the area of engagement with said contact edges to provide a degree of independent flexibility in the portions of the blade separated by said slots to assure optimum engagement of ired States PateI 2,803,727 Patented Au1g. 20, 1957 preceding object with novel adjustable compression means individual to the respective separated portions of said said blades throughout their Width with said contact edges.

blades on opposite sides of said slots whereby said sections may be, independently adjusted as to contact pressure.

Further objects will appear as the description is read in connection with the appended claims and attached drawings wherein:

Figure 1 isa side elevational view of one embodiment of the present invention;

Figure 2 (Sheet 2) is a View on an enlarged scale taken on line 2-2 of Figure 1;

Figure 3 is a side elevational view of the hook stick operated pryout and latch release arm of the switch shown in Figures 1 and 2;

Figure 4 is an elevational view looking at Figure 3 from the right;

Figure S is a top plan view of the hinge end contact clamp bracket of Figure 1;

Figure 6 is a side elevational view of the hinge end contact clamp bracket of Figure 5; Figure 7 is a detailed sectional view of an adjustable compression assembly for biasing the switch blades toward each otherand into engagement with the contact edges of the switch contacts;

Figure 8 is a top plan ,view ofthe combined latch supporting, pryout lug clamp bracket of Figure 1 provided for securing the free end contact element in place on its supporting insulator;

Figure 9. is a side elevational view of the bracket of Figure 8; and t Figure 10 is a fragmentary side elevational view of the free end of a blade. assembly showing a modified embodiment of the slotted blade of the invention.

With continued reference to the drawings wherein like reference numerals are used throughout to indicate like parts and with particular reference first to Figure 1, numeral 20 indicates generally a hook stick switch of the present invention designed to handle currents of the order of 1200 to 200 amperes at a 7.5 through- 69 kv. rating.

7 Switch 20 conventionally embodie insulator mounting stacks 22 and 24 spaced apart on a supporting frame 26 in a well known manner and comprises in general a pair of parallel and transversely spaced blades 28 and terminal contacts 30 and 32 more fully hereinafter described. Blades 28 r are of substantially great width to assure etficient handling of the high amperage current without localized heating at the contact areas and are hinged centrally of one end on upstanding arms 34 of a clamp bracket 36. A hinge bolt 38 mounted in arms 36 pivotally supports blades 28 and is provided with spring cup washers 40 bearing against the outer faces of the blades 28 and held between the head of hinge bolt and a nut and lock nut assembly threaded on the end of bolt 38. This hinge bolt and washer assembly constitutes a compression assembly which compresses the blade ends toward each other to provide the desired contact pressure in a manner that will be clear to those skilled in the art.

As clearly shown in Figures 5 and 6 bracket 36 comprises a base portion 42 generally rectangular in configuration except for the arcuate side portions 44 curved to conform generally to the circular cap 46 of insulator stack 22 on which the bracket is mounted. Base portion 42 of bracket 36 has depending side flanges 48 conforming generally to the configuration of the sides of the base portion and terminating at 50 and 52 to form aligned chanportion 42 nearest the free end contact 3.2 has a short terminal ends 50 and 52. Consequently, approximately the inner halves of bolt holes 60 intercept the projection across portion 42 of the channel openings provided to receive base'le'g 54 of contact member-30. Suitable arcuate cutouts or notches 61 (Figure 1) provided in the side edges of base leg 54 accommodate passage ofthe bolts in holes 60 and also serve to lock the base leg 54 of contact member 30 against axial displacement, as will be clear.

Upstanding arms 34 of bracket 36, as clearly shown in Figures-5 and 6 are joined by a transversely extending'web 62 to provide a contact backing web for a purpose hereinafter pointed out. In order to provide clearance for inserting'and removing bolts in' holes 60 the lowerfportions of arms 34 are provided-with rectangular cutouts 64 and to compensate for loss in rigidity or mechanical strength due to the cutouts, the ends of arms 334 'remote' from the web62 are provided with reinforcing ribs or enlargements 66.

Web 62, as clearly seen in Figure 5, is provided witha plurality of threaded apertures 68 disposed in laterally and vertically aligned pairs adapted in use to receive contact securing screws 70, two of which appear in Figure 1. The'heads ofscrews 70 are countersunk in the exposed face of contact leg 72 and clampingly secure upstanding contact'element 72 of contact against backing web 62 thereby rigidly securing the contact element 30 and clamp bracket 36 together. As clearly seen in Figure 1, leg 54 of contact element 30 extends longitudinally between the terminal ends and 52 of clamp bracket base flanges 48 and is suitably apertured'in alignment with clamp bracket bolt opening 58 to freely receive the shaft of a securing bolt 74 threaded into the cap member 46 of conventional insulator stack 22. Cap 46 is also provided with a pair of transversely, outwardly disposed bolt holes in'alignment with bolt holes 60 of clamp bracket 36 and 61 of contact base leg 54 to receive the shank of attachment bolts 76 (one shown, 'Figure 1) adapted to secure clamp bracket 36 against relative movement with respect to cap 46 and retain ends'50 and 52 of depending flange 48 bearing against the side faces of contact base leg 54 to position the contact element 30 properly upon insulator cap 46. As previously pointed out, leg 54 of contact 30 is provided with arcuate cutouts 61 in its side edges to allow passage of bolts '76 which thus lock the leg positively against axial dislocation. As appears from Figure l, the height of depending flange 48 is less than the thickness'of leg 54 of contact element 30 so that upon tightening of bolts 74 and 76 the contact leg will be rigidly clamped between cap 46 and clamp bracket '36.

' In actual manufacture the spacing between switch blades 28 will'be of the order of 2 inches and the edges of transverselyextending contact 30 will be similarly dimensioned was to extend laterally slightly beyond the outer side. facesof upstanding arms 34' of bracket'36, which are respectively spaced apart about one and seven-eighths'inches to assure lateral protrusion of the upstanding contact element' 72 beyond arms 34 in position to be closely and tightly engaged by the switch blades 28 in use. As will be apparent from Figures 1 and 5, the upstanding arms 34 are longitudinally off-set with respect to the exposed facet of backing web 62 so that the contact element 72 of coning bosses or lugs 78, the top-surfaces of which are flattened.

to provide open switch position blade stops as will now be pointed out.

Referring to Figures 1 and 5, it will be noted that the rear ends of blades 28 are cut away across one corner as indicated at 80. In consequence, blades 28, when rotated in a clockwise direction around hinge pin 38, will clear stops 78 until they reach a position approximately removed from their closed position at which time the ends 81 of blades 28 will contact the upper ends of stops 78 to limit the counterclockwise movement of the blade at the full open switch position. The ribs 66 project laterally outward a short distance only so that the ends of blades 28 extending beyond the hinge pin will clear ribs 66 of clamp bracket arms 34 during opening movement of the blades.

As will be clearly apparent from the broken line showing of blades 28 in Figure 1, the width of the blades is such that full contact is maintained between blades 28 and contact element 30 in all relative positions of the blades between closed'switch and open switch position. This being true and, as the contact portion 72 of contact 30 at all times engages the blades forwardly of hinge pin 38 and as the line terminal is directly connected to leg 54 of contact 30 through suitable bolt' holes 82 shown in Figure 1, it will be appreciated that the direct electrical path in all positions of the switch blades will be from the blades to the contact element 72 of contact30, through contact 30 to the connected line terminal and that the hinge pin 38, spring washers 40 and clamp bracket 36 at no time provide the current path between the switch blades and the line terminals at the hinge end of the blade. Consequently, arcing due to pivotal clearances and end clearances between the blades and the support arms 34 is at all times prevented and the heating up of the spring cup washers 40that would likely occur if the hinge pin carried the load current is avoided. The spring washers, therefore, can be expected to retain their resiliency indefinitely to assure adequate contact pressure between the blades 28 and contact element 72 over long periods of time without servicing.

' It will also be appreciated that the solid backing of contact element 72 provided by web 62 imparts substantial rigidity to the upstanding contact element 72 relieving the upstanding element of any stresses that result from opening and closing the switch under the high contact pressure 'maintained'by the hinge pin and washer assembly.

"Insulator stack 24 at the forward end of the switch carries a cap 84'which, like cap 46, is provided with three angularly spaced, tapped bolt holes similar to those mentioned in connection with insulator cap 46 for receiving s'imilar'secur'ing bolts 74 and 76 to fasten leg 86 of contact and terminal connector 32 betwecnthe base 88 of a combined latch supporting, pryout lug, clamp bracket 90 and cap 84 in a manner similar to that heretofore described in connection with contact element 30. As clearly seen from Figure 8, base 88, of clamp bracket 96 is generally rectangular and similar .in configuration to hinge end clamp bracket 36 and is provided with bolt holes 58 and'60 and a depending flange 38 terminating at 50, 52 as already described in connection with clamp bracket 36.

Clamp bracket 90 while generally similar to bracket 36 differs in some important respects as will now be pointed out. I

Referring for the moment to Figures 8 and 9, clamp bracket 90 is provided with a laterally spaced, upstanding backing web or flange portion 92 having flat top surfaces and flanked on either side by shorter upstanding lugs 94 of rectangular cross section having flattened top surfaces 95 providing blade engaging stops for limiting closing movement of the switch. The outer faces of backing web portions 92 define a plane, as clearly seen in Figures 2 and 9, while the inner opposed lateral faces define an upwardly open V-shaped recess 96 closed at its innermost end by a lateralweb section 97 terminating short of the upper ends of flange portions 92 in a flat top surface 98. Each of flange portions 92 in lateral alignment adjacent their upper ends and above the level of the fiat top 98 of web section 97 is provided with a tapped screw hole 99. The function of surfaces 95 and 98 and holes 99 will be hereinafter explained.

Secured to the upper ends of backing web sections 92 by a pair of machine screws 100 respectively threaded in tapped holes 99 in straddling relation to recess 96 are the upstanding contact leg 102 of contact element 32 and a separate blade guide member 104. As can best be appreciated from Figure 1, contact leg 102 and guide member 104 are provided with bolt receiving openings respectively aligned with tappedholes 99 in web 92 and screws 100 passing through these openings serve to rigidly fasten contact element 32 to bracket 90 and to mount guide member 104 in upwardly extending relation to the upper end of theexposed face of leg 102.

As best appears in Figure 2, guide contact member 104 is a plate having its upper lateral edges 106 upwardly and inwardly inclined symmetrically with respect to a plane midway between and parallel to blades 28. Inclined edges 106 extend upwardly beyond the upper edges of blades 28 in closed position and the lower regions of edges 106 extend laterally to a dimension substantially equal to the distance between the laterally spaced contact edges of contact element 32. Thus the edges 106 act as guide surfaces spreading the blades as they move toward contact element 32 so that they slide smoothly into contact with the lateral contact edges of contact leg 102..

Since contact leg 102 and guide member 104 are of substantial thickness and are mounted in face-to-face abutting contact, it will be appreciated that guide edges 106 are offset toward the hinge end of the switch blades with respect to the contact edges of contact leg 102 and, therefore, cooperate with an area of the blade faces other than the normal contact area.

The contact edges of leg 102 and of 72 as well, are silvered over the area covered by blades 28 in closed switch position to assure maximum contact efiiciency. Because of the constant contact of blades 28 with the hinge end contact 72, the silver coating on this contact is subjected only to rubbing contact with the wide smooth inner faces of the blades and therefore is not materially injured by the usual opening and closing switch movements. The silvering on the contact edges of leg 102, however, would be subjected to deleterious tearing forces, except for the fact that the guide edges 106 of guide member 104 are disposed in a plane spaced longitudinally from the contact leg and consequently as the blades are moved into closed position they are guided and spread apart by edges 106 which engage the inner faces of the blades along an arcuate path spaced from the area of said inner faces which engage the edges of the contact. Thus, burring or other deleterious action, due to the guiding and spreading of the blades into contact engagement takes place at a location where it does not adversely affect the contact efiiciency of the switch.

Offset rearwardly beyond the transverse center line of clamp plate 90 are a pair of laterally spaced upstanding integrally formed ears 107 suitably apertured at 108 in transverse alignment to receive a pivot pin 110. Pin 110 is retained against axial displacement by any suitable means such as cotter pins 112 and, as clearly seen in Figures 1 and 2, pivotally mounts a latch element 114, having a latch arm terminating in a latching finger 116. Latch element 114 also carries a right angularly disposed cam pin 118 and is spring urged to latching position by a coil spring 120 in well known manner. A limit stop arm 122, the function of which will be apparent, is also formed on latch arm 114. Leg 86 of contact element 32 like leg 54 of contact element 30 is provided with bolt receiving notches 61 while both legs 54 vided with terminal connector bolt holes 123.

As clearly seen in Figures 1 and 2, the ends of switch blades 28 remote from hinge pin 38 are connected to-' gether by a compression assembly 124 made up of a headed bolt 125 the shank 126 of which extends through suitable openings provided adjacent the free ends of blades 28, a pair of spring washers 128 supported on shank 126 in engagement with the outer faces of switch blades 28 and a lock nut assembly 130. This compression assembly is effective to draw the free ends of switch blades 28 toward each other and secure blades 28 for unitary movement while aiding in the creation of the desired high contact pressure between the blades and the edges of contact leg 102 in a manner to be hereinafter pointed out.

Shank 126 of bolt 125 also serves as a journal pin for mounting hook stick operating and latch release n'ng member 132 pivotally journalled on shank 126 by means of parallel transversely spaced segmental end walls 134 connected at their radially outer ends by an arcuate wall portion or web 136. Walls 134 are formed at their radially inner ends with hubs or bosses 137 containing aligned apertures 139 for receiving shank 126 of bolt 125.

Web 136 supports a ring element 138 transversely cen-J tered with respect to walls 134 and formed with a recess 143 into which a hook stick is inserted to operate the switch in well known manner. Each end of ring element 138 at its juncture with arcuate web 136 is provided with a reinforcing web 140 to strengthen the ring member 132 against stresses concentrated at the juncture of web 136 and ring 138 in the operation of the switch.

Each end wall 134 is provided with a respective laterally protruding compound stop lug 141, each having angularly related stop faces 142 and 144 adapted to engage, respectively, the free ends of blades 28 in closed switch position and the longitudinal edges of the blades in open switch position, as is clearly apparent in Figure 1.

Referring to Figures 1, 2 and 3, the segmental end wall 134 of ring member 132 adjacent latch element 114 is provided with a release finger 146 extending substantially radially with respect to the pivotal axis of the ring member and underlying cam pin 118 of latch element 114 when the switch is in closed position. Thus it will be seen that clockwise movement of ring member 132 first causes finger 142 to engage pin 118 to raise latch 114 in initiating the opening action of the switch as will hereinafter be explained in greater detail.

As best seen in Figures 3 and 4, arcuate wall 136 of ring member 132 has a depending continuation or extension 148, the lower portion 150 of which is formed with sloping lateral edges 152 adapted to freely enter the wedge shaped recess 96 between backing web portions 92 of clamp bracket 90 and engage its end 153 with flat surface 98 of web 97 to provide an initial or first-stage pryout as will be explained presently. To provide itwith the necessary mechanical strength and rigidity, arcuate extension 148 is formed with a chordal web 154. The juncture of the sloping edges 152 of the lower portion 150 of extension 148 define with the remainder or upper portion of the extension a pair of laterally extending shoulders 156 adapted to contact the upper end surfaces 158 of web portions 92 on either side of recess 96 to provide a second stage pryout action as also explained in greater detail below.

Referring now to Figures 1 and 2, each blade 28, in proximity to its free end, is provided with a longitudinal slot or cutout 160 parallel to and substantially midway between the longitudinal edges of the blade and extending a considerable and approximately equal distance to each side of the area where the blade engages contact leg 102. The effect of slot 160 is to divide the switch blades into two adjacent independently flexible sections in the area of their engagement with contact leg 1102, each secand 86 are proriveted as at 184 to the respective blades.

tion. having greater'fiexibilit-y thanthe 'blades as a whole and giving-the contact area'of the-blades as a whole a great amount offiexibility with; respect to their respective longitudinal "axes; 'In the embodiment being described, slots 160 areformed in the 'blades'by slit milling them alougtheir longitudinal centerlines.

The respective opposed'flexible sections of blades 28 on each side of respective slots 160 adjacent the slot end remote from the'swin'g end of the'bl'ades 28 are independently and adjustably biased toward each other by individual compression assemblies 162. Inasmuch as compression assemblies -162'are identical only one is shown (Figure =7) and will be described-in detail. Each compression assembly-162 consistsofan adjustment stud 164, one end of which'isshown in Figure 7, extended perpendicularly through suitable holes 166 in blades 28. The opposite end ofst-ud164 from that'appearing in Figure'7 is preferably the-same as that shown.

Both'endsof stud-164 are threaded and carry a threadably adjustable cup-like member 170 serving as a spring abutment and enclosure. A coiled compression spring 172 is disposed-within each member-1'70 encircling the end of stud 164 and having one end bearing on member 170 and the'other onathe outer face of its respective blades128 through a spring seat washer- 174. A lock nut 176 locks cup-member 170 in any selected position of adjustment. A spacer sleeve'178 of a length less than the lateral dimension of contact leg 102 surrounds the shankof stud 164 between blades'28 and limits the extent to which the blades can be'forced together by springs 172 upon disengagement of-blades28 and contact leg 102. From the structure'described, it will be understood that-each cup-member 170 may be threaded to any selected position on stud 1'64. Assuming therefore, that compression assembly 124 is adjusted to obtain thedesired lateral spacing of the free ends of blades 28the individual spring cup 170 may be separatelyadjusted and locked in adjusted position to assure the desired bowing in of the flexible blade contact section to obtain the desired amount of contact pressure and assurefull contact of blades 28 with the contact area of contact leg 102 in spite of slight longitudinal contact area deformities that may be'present in contact leg 102 or the inner blade faces due to quantity production methods employed or uneven coating of the contacts.

To further insure unitary movement and assembly of blades'28, the twoblades are-anchored together by a U- shaped copper bar 180 having its opposite end flanges 182 As clearly apparent in Figure l, anchoring bar 180 is located about mid-way between the ends of the blades so that the opposite free 'ends of the blades 21 may be flexed independently under the influence of their respective compression assemblies. As also appears in Figure l the swing ends of the blades are cut off at an angle as indicated at 186 to permit free passage of stop lugs 141 during opening and closing movements of the switch.

Operation 'of theswitch takes place in the following manner.

. Inthe closed switch position, the swing ends of blades 28 are in contact with the edges of contact leg 102, the full closed position being limited and defined by engagement of thelower edges of the blades with the top surfaces of lugs 94 on clamp bracket 90. The switch is positively locked in closed position by latch finger 116 which hooks over the shank 126 of bolt 125 under the influence of spring 120. In this position of the switch, ring member 132,0ccupies the solid line position shown in Figure l with faces 142 of lugs 141. abutting the ends of the blades and finger 146 underlying cam pin 118 of latch member, 114. To open the switch, a hook stick is engagedrin recess 143 of ring 138 and ring member 132 is rotated in a,-c1ockwise direction. During initial movement of ring member. 13Z2,'.finger. 1,46 .engagespin 118 andreleases latch member 11 4. During the-same niove ment, lower portion .150 of extension 148 moves-freely into-recess 96 on the top of web 92 until, through proper proportionment of the parts,.the end oflower extension portion contacts-the top surface 98 ofweb 97 at which time the latchfinger 116 has been lifted clear of bolt shank .126. Continued pivotal movement of ring member 132sproduces 'a pryoutaction with the surface 98 of web :97 acting as a fulcrum .-for the end of extension portion 150 thusinitiating. clockwise movement of blades 28 around hinge pin 38 toward open position. The engaging surfaces of web.97 and extension portion 150 providing the first .stage pryout action slide over each otheruntil, ,at a time when the. effectiveness of this pryout force decreases because of changes in the relative. position of the parts,.shoulders 15,6. contact the upper surfaces 158 on web portions :92 thereby establishinga second stage pryout action. This two stage pryout action thus maintains an optimum opening leverage throughout the clockwise pivotal movement of ring member; 132 which, due to the proportions of the pryout extension and location of -the respective fulcrums,, continues until the contact area of the bladeswith-contact leg 102 andthe lower end of guide edges 106 of guide member 104 is reduced toan insignificant factor permitting the frictional resistance between blades 28 and contact legs .72 and 102 to be overcome smoothlyand with a minimum of applied force.

A modified form of the invention is illustrated fragmentally in Figure 10 whereinlike refe'rence numerals are used to designate parts in common with the first de scribed form. In the embodiment of .Figure 10, slots 160 (one sho'wn).,in blades28 are .of adifferent form, having acircular enlargement 188 at each end. 'Slots 160' are 'providedby drilling holes at 1 88 and connecting them by :means of a saw cut of the desired width. The function of slots 160' is the same as corresponding slots 160, Figure 1. In all other respects this [embodiment is identical to .that of the previously described embodiment. i

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Whatis claimed and desired to be secured by United States Letters Patent is: v

1. An electrical hook stick operated disconnect switch comprising spaced insulator stacks respectively mounting upstanding terminal contacts of an electrical transmission line; a pair of laterally spaced switch blades hingedly mounted at one end on one of said insulator stacks and adapted to constantly engage the terminal contact on said one of said insulator stacks therebetween and to swing to and fro around said hinge axis to grippingly receive the terminal contact on said other insulator stack between the swing ends thereof; means connecting the swing ends of said switch blades. to assure unitary movement of said switch blades and to laterally compress said swing ends of said blades into high pressure contact withsaid terminal contact on said other insulator stack; means on said other insulator stack adjacent said terminal contact'thereon providing a first fulcrum and a second fulcrum in relative spaced relation lengthwise of said upstanding contacts and facing in a direction normal to the contact faces of said switch bladesjand a hook stick operating ring pivotally mounted on said switch blades in position to be disposed in switch closed position adjacent said fulcrums and comprising an extension portionhaving an end disposed a predetermined radial distance fromsaidring pivot axis to engage said first fultram upon initial pivotal movement ofsaid operating ring and shoulder means angularly spaced from said end and disposed a radial distance from said ring pivot axis equal to that of said end to engage said second fulcrum upon further pivotal movement of said operating ring thereby providing a two stage pryout structure adapted to provide a substantially uniform leverage advantage while overcoming the high pressure contact forces and forcing said switch blades from closed position and toward open position to an inbetween position where the frictional resistance offered by said high contact pressure is sufficiently small to permit a straight pull on said hook stick operating ring to effectively move said switch blades to full open switch position.

2. An electrical hook stick operated disconnect switch comprising spaced insulator stacks respectively mounting upstanding terminal contacts of an electrical transmission line'; a pair of laterally spaced switch blades hingedly mounted at one end on one of said insulator stacks and adapted to constantly engage the terminal contact on said one of said insulator stacks therebetween and to.

swing to and fro around said hinge axis to grippingly receive the terminal contact on said other insulator stack between the swing ends thereof; means connecting the swing ends of said switch blades to assure unitary movement of said switch blades and to laterally compress said swing ends of said blades into high pressure contact with said terminal contact on said other insulator stack; a terminal contact on said other insulator stack comprising a laterally disposed contact extending away from said insulator stack in the general direction of the path of movement of said switch blades and provided at its free end with a detachable guide member protruding beyond the end of said contact and offset from one laterally extending face of said contact and having laterally disposed, inwardly inclined end surfaces facing away from said contact end and forming guide surfaces to center said blades with respect to said contact and spread said blades into position to engage the laterally opposed faces of said contact on said other insulator stack; means on said other insulator stack adjacent said terminal contact thereon providing a first fulcrum and a second fulcrum in relative spaced relation lengthwise of and facing in a direction normal to the contact faces of said switch blades; and a hook stick operating ring pivotally mounted on said switch blades in position to be disposed in switch closed position adjacent said fulcrurns and comprising an extension portion having an end disposed a predetermined radial distance from said ring pivot axis to engage said first fulcrum upon initial pivotal movement of said operating ring and shoulder means angularly spaced from said end and disposed a radial distance from said ring pivot axis equal to that of said end to engage said second fulcrum upon further pivotal movement of said operating ring thereby providing a two stage pryout structure adapted to provide a substantially uniform leverage advantage while overcoming the high pressure contact forces and forcing said switch blades from closed position and toward open position to an inbetween position where the frictional resistance offered by said high contact pressure is sufiiciently small to permit a straight pull on said hook stick operating ring to effectively move said switch blades to full open switch position.

3. The switch of claim 1 wherein said switch blades are of approximately double width adapting said switch for efiicient transmission of high amperage electrical currents and are longitudinally slotted midway of their width only in the area of engagement with said terminal contact on said other insulator stack to assure maximum end strength of said blades and full high pressure area contact between said blades and said terminal contact in spite of longitudinal contact area deformities.

4. The switch of claim 3 wherein said means connecting the swing ends of said switch blades also mounts an adjustable compression assembly adjacent the swing ends of said blades and additional respective adjustable compression assemblies are disposed in the opposed blade portions at either side of said longitudinal slots at the side of said terminal contact opposite that at which said first mentioned adjustable compression assembly is located.

5. A switch blade assembly for a hook stick operated switch comprising a pair of parallel switch blades connected together for unitary movement; a hinge pivot at one end; lateral compression means at the other end; a hook stick operating ring pivotally supported by said compression means and having pryout lever means thereon comprising an arcuate portion coaxially related to the pivot axis of said operating ring and having a generally laterally extending shoulder between its ends and a terminal end providing a generally laterally extending end surface, said end surface and said shoulder respectively providing a first stage pryout element and a second stage pryout element providing substantially identical leverage advantages in use.

6. A contact clamp bracket for a hook stick operated switch comprising a base having a downwardly directed channel opening for receiving a portion of said contact therein and through bolt openings therethrough adapted to receive clamp bolts for securing said clamp bracket to a support with said contact portion clamped between said base and support; upstanding flange means along one edge normally related to the axis of said channel opening and comprising a centrally located web the upper end of which provides a fulcrum surface, at least one laterally offset upstanding lug formation adjacent said centrally located web the upper end of which lies at a level beyond that of said centrally located web and provides a second fulcrum surface; and a pair of upstanding lugs at the opposite ends of said one edge and of substantially less height than said centrally located web adapted to form closed switch position stops for the blades of the hook stick operated switch blades.

7. A blade guide member for a hook stick operated switch having a laterally disposed, upstanding switch contact and laterally spaced switch blades resiliently biased toward each other to effect high pressure contact with the laterally spaced edges of said contact comprising a plate like element having a mounting portion of lesser width than said contact adapted for removably attaching said blade guide member to a laterally extending face of said contact and a guide portion extending from one end of said mounting portion and having a major lateral dimension at its juncture with said mounting portion at least equal to that of said contact and laterally facing uniformly inwardly directed guide surfaces extending away from said juncture in a direction opposite to that of said mounting portion adapted to engage the inner faces of said switch blades and center the switch blades with respect to said contact and spread the blades into position to engage the lateral opposed faces of said contact.

8. A switch comprising a pair of elongated flat switch blades of substantial width and slight thickness disposed in parallel face to face spaced relation mounted adjacent end for swing movement about an axis perpendicular to the longitudinal axes of said blades; a contact member mounted to be engaged by the other ends of said blades in the closed circuit position thereof, said contact member comprising a flat contact portion disposed transversely to the longitudinal axes of said blades and having its opposite edges adapted to contact the inner faces of said blades in closed position; means defining a longitudinal slot in. each of said blades in the area opposite said contact member and terminating inwardly of said other ends of said blades to form independently flexible contact portions for each blade on each side of its respective slot thereby assuring structurally rigid and strong blade ends and localand hingedly 11 ized independent flexibility in the contact portions of each blade allowing said blades to intimately contact said contact member regardless of irregularities on said edges thereof.

9. An electrical disconnect switch comprising a pair of insulator stacks rigidly supported in spaced relation to each other; a cap structure individual to each insulator stack; a terminal connector disposed in contactwith the top surface of each cap structure and providing an upstanding transversely disposed contact portion; a clamp bracket associated with each insulator cap and terminal connector for fastening said terminal connectors to said insulator caps; a pair of switch blades hinged in transversely spaced relation to one of said insulator caps for swinging movement toward and away from the upstanding contact portion on the other insulator stack to make and break a connection therewith and in constant lateral engagement with the contact portion of the terminal connector of said one insulator cap; a hook stick operating ring pivotally mounted on said blades for moving said switch blades to open and closed switch positions and means for guiding said blades into contacting engagement with said first named contact portion, said guiding means comprising a guide member removably secured to the upper end of said first-mentioned upstanding contact portion, said guide member being of a planar configuration extending transversely to said blades and having symmetrical, upwardly, inwardly inclined edges the lower portions of which extend laterally to points substantially in the plane of the lateral edges of the said associated contact portion thus providing guide surfaces located adjacent but longitudinally spaced from said contact portion to engage the inner faces of said blades along an arcuate path spaced from the area of said inner blade faces making electrical contact with the lateral edges of said associated contact portion.

10. A disconnect switch comprising a pair of spaced, rigidly mounted insulator stacks; a terminal connector supported by each of said stacks; an upstanding contact member supported by each of said stacks electrically connected to the respective terminal connectors and providing oppositely facing, laterally spaced contact surfaces;

a pair of switch blades hinged in'transversely spaced relation on one of said insulator stacks for swinging movement toward and away from the upstanding contact on the other insulating stack to make and break connection therewith; a pryout member on said other insulator stack in adjacent relation to the contact member thereon and having first and second abutment surfaces spaced lengthwise of said u .anding contact member and adapted to provide a pair of sequentially engageable fulcrums; and a hook stick operating ring assembly pivotally mounted adjacent the free ends of said switch blades and having angularly spaced, equi-radially outwardly disposed pryout surfaces thereon adapted sequentially to engage said fulcrums to pry said blades out of contact with said upstanding contact as said operating ring is pivotally operated, said fulcrurns and pryout surfaces because of their construction and relative arrangements assuring substantially uniform pryout leverage throughout the pivotal operating range of said hook stick operated ring assembly.

11. A disconnect switch comprising a pair of spaced, rigidly mounted insulator stacks; a terminal connector supported by each of said stacks; an upstanding contact member supported by each of said stacks electrically connected to the respective terminal connectors and providing oppositely facing, laterally spaced contact surfaces; a

pair of switch blades hinged in transversely spaced relation on one of said insulator stacks for swinging movement toward and away from the upstanding contact on the other insulating'stack to make and break connection therewith; a pryout member comprising upstanding substantially planar portions substantially perpendicular to the planes of said switch blades and having an upwardly diverging recess therein, a connecting web spanning a portion of said recess and terminating at a level below the ends of said planar portions to provide a pryout fulcrum; a pair of flat coplanar abutment surfaces on the upper ends of said upstanding planar portions jointly providing a second pryout fulcrum; a hook stick operated ring assembly mounted adjacent the free ends of said switch blades for pivotal movement about an axis parallel to and spaced from the planar portion of said pryout member and having a curved aim adapted upon pivotal movement of said hook stick operated ring in switch opening direction to enter said recess and engage the fulcrum provided by said web and initiate pryout of said switch blades from said contact member, said hook stick operated ring assembly having secondary pryout surfaces disposed laterally on each side of said curved arm and adapted to contact said second pryout fulcrum after a predetermined pivotal movement of said ring assembly in switch opening direction, said pryout fulcrums, curved arm and secondary pryout surfaces being relatively so dimensioned and disposed as to provide substantially uniform pryout leverage throughout the pivotal operating range of said hook stick operated ring assembly.

12. In combination with a hook-stick operated disconnect switch having a pair of parallel switch blades pivotally mounted at one end and swingable into and out of contact with a contact member at the other end, a

switch opening and pryout assembly comprising: an operating lever mounted between said blades adjacent the free ends thereof for pivotal movement about an axis substantially parallel to the pivotal axis of said blades; 2. pryout arm on operating lever curved about the pivotal axis of said lever; a pryout member fixed with respect to said contact member having a planar portion extending transversely with respect to said blades and received between said blades in closed switch position; a recess in said pryout member adapted to receive said arm upon initial pivotal movement of said lever toward switch opening position and provide a first stage pryout fulcrum for said lever; and complementary abutment surfaces on said pryout member and operating lever adapted to engage upon continued pivotal movement of said lever toward switch opening position to provide a second stage pryout fulcrum for said operating lever superseding said first stage pryout fulcrum.

13. The combination of claim 12 including a guide member for said blades mounted on said pryout member and having laterally spaced upwardly converging edges adapted to contact the respective inner surfaces of said blades in an area displaced from that engaging said contact member in closed position and guide said inner.

surfaces of said blades into engagement with said contact member.

References Cited in the file of this patent UNITED STATES PATENTS Hoye Aug. 18, 1931 FOREIGN PATENTS Switzerland Dec. 16, 1941

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