US2000080A - Switch - Google Patents

Description

P. B. HOYE May 7, 1935.

SWITCH 3 Sheets-Sheet 1 Filed June 20, 1932 May 7, 4 B HQYE SWITCH Filed June 20, 1952 3 Sheets-Sheet 2 P. B. HOYE May 7; 1935.

SWITCH Filed June 20, 1932 5 Sheets-Sheet 3 flvefifan P 667 5. 0 6

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Patented May 7, 1935 UNITED STATES SWITCH Peder B. Hoye, Maywood, 111., assignor to Electrical Engineers Equipment Melrose Park, 111., a corporation of Illinois Application June 20, 1932, Serial No.618,273

'l'l Claim s. (01. 200-48) This invention relates to disconnect switches in general, and more particularly to switches of the typeincluding a relatively long blade that cooperates with a comparatively short contact.

In its more specific aspects the present invenembodiment of my invent1on;

tion. is particularlyconcerned with the contact,

its construction and manner of mounting.

' It is one of the objects of the present invention to provide a switch having an improvedswitch contact that includes camming means for camming the contact and the blade apart as the blade moves toward its open position. The contact supporting structure is pivotally mounted so as to be drawn with the blade during the initial 1.; switch opening operation, and is provided with a cam that rolls on the edge of the blade to cam the contact supporting structure from the blade. The contact supporting structure preferably comprises a housing that serves to'protect the contactfrom rain, sleet, or snow; although it is within the province of the present invention to make the contact supporting structure inthe form 0 an open skeleton or frame.

It is a further object of the present invention to provide a contact structure that may be standardized for use on various types of disconnect switches, r

The attainment of the above and further objects of the present invention will be apparent 30 from the following specificationotaken in conjunction with the accompanying drawings forming a part thereof.

In the drawings: a

Figure 1 is a top view of a switch embodying the principles of my invention, said view showing the switch in its closed position;

Figure 2 is a view. similar to Figure 1 showing the position of the parts during the opening of the switch; 1

Figure 3 is a side elevation of the switch shown in Figure 1; r 77 Figure 4 is an enlarged side view of the housing shown in Figure l; I 45 Figure 5 shows a modified form of contact supporting structure;

Figure 6 is an end view of the structure of Figure 5; V

Figure 7 is a side view of a rocking insulator 9 type switch embodying the principles of my invention; Figure 8 is a fragmentary view of an underhung type of switch employing my improved switch contact supporting structure;

to. in any preferred manner. and support comprises a circular plate-like arm .6

W Figure 9 is a side view of a portion of another tion;' W Figure 10 is a sectional view taken along the line itiil of Figure 9;

Figure 11-is a fragmentaryvie'w: of another 5" switch embodying the principles of my invene Figure 12 is a fragmentary sectional view taken along the line |2-i2 of Figure 11; and, 1 V a Figure 13 shows a modifiedfform of switch blade. 10

Reference maynow. be had more particularly to the switch shownin Figures 1, 2 and3i The switch comprises afgrounded base I upon which is'mounted a stationary insulator 2 and arctatable insulator 3 in a manner well known in 15 the'art. A switch blade 4 is bolted or otherwise rigidly secured to the rotatable insulator and is swung thereby. from itsswitch' openp'osition to its switch closed position. The stationary insulator 2 supports a contact structure that 00- operateswith the contact making end of the bladef A strain clamp and support Sis bolted or otherwise rigidly secured to'the insulator cap at the top of the insulator 2, being secured there:

The strain clamp that is secured to the insulator. cap and from which there extends an upright portion 1 termie ating in a short upper arm 8 extending forward thereof. A line clip supporting portion 10 s is integral with the upright portion 1 and extends rearwardly fromabout the center of the upright portion. The arm I0 is adapted to receive a line wire which is'secured thereto by means of a U- shaped bolt ll thatpasses through suitable slots 'in the end of the'arm i0 and. secures theend of a line Wire IS in place. A suitable terminal i4 is secured to the line wire and is bolted to the arm La flexible braided wire l2 being interposed between the terminal lug l4'and the arm40 ill. I

The contact structure is pivotally mounted between the arms 5 and 3 and comprises a unitary cast metal housing i5 having a pair of'rearwardly extendingarms |6l6 thatare pivoted between the arms 68 of the strain clamp and support 5. A pivot bolt or pin i'i extends through alined holes in the arms'6-8 and through aligned holes in the arms Iii-46 of the contact supporting structure I5. A torsion spring I9 biases the contact supporting structure IE to its switch vclosed position.

The contact supporting-housing l5.has a. slitlike opening 28 at the front side thereof and an outwardly flared opening 2 I at an adjacent transverse side. During the switch closing operation the end of the switch blade enters the outwardly flared opening, being guided thereby, and then progresses into the slit-like opening 23. The opening terminates in a finger 36 having a curved face 3i, as indicated. A pair of contact shoes 2323 are mounted within the housing, said contact shoes being pressed towards one another by coiled springs 24 and being guided towards and away from one another by a pair of bolts 25 that extend through oversized holes in the contact shoes. I'he springs 2d are held in position by studs 24 extending into the springs from the inner sides of the outer walls of the housing. The ends of thecontact shoes are outwardly flared to guide the blade between them and are adapted to be spread apart as the blade enters between the contact shoes. For this purpose the contacting edge of the blade iswedge shaped to facilitatethe spreading of the contact shoes. The contact shoes are connected to the line clip H by theilexible braided wire-l2 that enters the housing. l5 through an opening 26 in the front of the housing.

When the switch is open the contact housing 15 is in the position shown in Figure 1. As the end of the switch approaches its closed position, it

first enters the outwardly flared opening it of the housing, and then it enters between the two conta'ct'shoes. As the blade continues moving in its closed position it finally reaches the position shown in the drawings. I

To open the switch, the insulator 3 is rotated in 'a clockwise direction as seen in Figures 1 and 2.

If there is a considerable pressure between the contact shoes and the blade, or if the blade is frozen to the contact assembly, the initial turning of the blade causes the housing to turn about its pivot l1, said housing being drawn by the blade. As the blade continues to move towards its open position-the cam surface 3| bears against the edge'of the blade 4 and rolls. thereon to force the blade and contact shoes apart. When the blade leaves the housing the spring I!) returns theh'ousing to the position shownin Figure 1, the

step limitih'g'the extent of clockwise turning of the housing. r It is to be notedfthat the blade 4 clears the contact finger 30 by a'small amount when the switch is closed. This is of importancein the present invention and is obtained by providing a stop at aco'nvenient place in the housing for preventing further movement of the blade in the housing,

duringthe closing operation, or it may be accomplished in any other desired manner. as by providing alirnit stop forlimiting the throw of the rotatable insulator 3 oroif its actuating mechani's'r'n-a As aresult of the small spacing between the blade and the cam finger 36 there is a small switch opening movement of the blade before the cam 33 engages the blade. During this movement there is a certain amount of shearing action between the blade and the contact shoes tending to. breakthe. bond. between them. Thereafter the cam finger 39 engages the blade and exerts at [5 in Figures 1, 2 and 3, differing therefrom essentially in that a portion of the top and bo tom housing partsis omitted, as indicated by'the opening 40. Insteadof providing one side of the opposite direction.

structure shown in Figure 5 with a slit corresponding to the slit 20 that entire side of the contact supporting structure is open. Likewise, the outwardly flared guiding opening 2| of Figure 4 is omitted, the blade being in this instance guided between the contact shoes by the outwardly flared lips at the ends of the contact shoes, as indicated in Figure 4. Itmay therefore be seen that the skeletonized frame consists merely of two frame portions ll-4| joined at their rear by the connecting portion 42 and at their front by the cam portion 353 to form a unitary structure. In other respects this contact supporting structure is similar to that shown in the switch previously described, being provided with the pivoting ears !6 and with the cam 30 and with bolt receiving openings 25. for receiving the bolts on which the contact shoes slide, as in the previous case.

In Figure '7 I have shown my pivoted contact structure applied to an otherwise standard type 'ofrocking insulator switch. This switch comprises a supporting base 45 on which is mounted a rocking insulator 48 that rocks about a center 4i, being actuated by a crank 58 and a connecting rod 49. A stationary insulator 50 is mounted on the base 45 and constitutes a terminal for a line wire 5i. A grasshopper linkage 52-53 connects the stationary insulator 50 with the rocking insulator M5 and supports a flexible conductor that extends the circuit from the line 5| to a contactiid that is rigidly mounted at the end of the in all respects the same as the contact supporting structure disclosed in the switch shown in Figures 1, 2 and 3-, or which may comprise a frame as shown in Figures 5 and 6. A web 62 is formed integrally with and extends between the two arms of thebifurcated support 6| at the outer ends thereof; This web not only serves to secure the 'outer ends together, but also acts to protect the contact housing pivot pin from sleet or snow. A stop 63cooperates withthe stop 35 on the contact housing to limit the extent of rotation of the housing about its pivot pin. A limit stop 64 limits-the extent of rotation of the housing in the gravity and by means of a torsion spring l9. When the switch blade 54 is moved to its open or to its closed position by the corresponding rocking of the insulator 46, the contact housing I5 is moved therewith in the same manner as was previously set forth in connection with the switch shown in Figure 1. r

Whether the spring I9 is to be arranged to bias the contact structure to'its normal closed position or to a position at an angle thereto is determined by'the question as to whether or not sleet hood protection is desired and as to which position of the hood affords a maximum protection against the entrance of sleet into the housing.

.Otherthings being equal it is desirable to arrange assists the'switch opening operation. Also, dur- The housing I5 is biased counter-clockwise to its switch open position by ing the closing operation there is a greater shearing orwiping action between the blade and the contacts, thereby producing a greater cleaning of the contacting surfaces. The switch shown in Figure 3 is adapted to be mounted with the base I extending vertically and the insulator 2 abovethe insulator 3. It is therefore desirable to bias the contact structure to its normal switch closed position to afford a greater protection against the entrance of sleet. Where such protection is of no great importance, or where the switch is mounted an insulatortpin .l! secured'thereto as inthe plate-like portion 73 that is secured to the 'bottom of the insulator pin and has a pair of arms 54 extending therefrom. Aline terminal clip 13' that is adapted to receive a terminal "at the end of a line wire is bolted or otherwise suitably secured to a web '14 that connects the lower ends of the pair of arms I4. A flexible braided conductor i5 is interposed between the clip I3 and theweb It, said braided conductor extending the circuit to the contact shoes within the housing I 5.

The contact housing I5 extends between the bifurcated arms M and is pivoted thereto by means of a pivot pin it that extends through the arms I4 and the pivot arms of the housing IS. The con tact housing may be'biased to the open position by means of a torsion spring that surroundsthe pin '!6 in the same manner as the spring IQ of the switch shown in Figures 1 to Ssurrounds the pivot pin Il of that switch. As the blade 4 swings downward to its switch open position the contact housing I5 is moved therewith in a manner such as was previously explained in connection with the switch shown in Figures 1-3. The spring, and/or gravity, retain the housing in this position. A boss TI is provided on the outside of one of the arms 14 for receiving an arcing horn if desired. i

It is to be noted that the same contact housing I5 is used in each of the three types of switches herein shown. This'permits of standardization in the manufacture of such contacts, thereby reducing the cost of manufacture and also reducing the amount of stock that must be carried on hand.

In Figure 9 I have shown afragmentary portion of a switch of the type shown in my Patent No. 1,952,436, issued March 27, 1934, differing therefrom only in that the contact and contact supporting structure are different. In so far as the structure of this switch is the same asthat of my aforesaid patent, above referred to, reference may be had to that patent for a more complete description of the details of various parts thereof that do not constitute the subject matter of this application. Briefly stated, this switch cornprisesa stationary insulator I and an axially through a limited angle.

ably longer between a pair of arms H33 and 504 of a yoke I05 that'is secured to the rotatable insulator IOI, being pivoted between said arms by a suitable pivot, thereby permitting a free rotation of the yoke crank, I58 formed therewith, which is connected,

53?. At its other end the connecting rod is secured, through a universal joint IE8, to a pull rod 995 and a guiding link H5. The guiding link is pivoted about an axis 5 I I about which is also pivoted a blade I 22. The blade andthe link H9 are mechanically separate and independently movable about the axis I I I. A cam IZfiis pivoted to the opposite end of the blade through a pivot pin E2 5 said cam having an arm I22 rigid thereby means of a universal joint, to a connecting rod with and pivoted at i 23 to the opposite'end of the pull rod Hit. An arcing horn I24 is also carried by the pull rod. A cont-act making portion 525 is formed at the end of the bladegbeing, preferably, rigid with respect to the blade although I itiinay be formed rigid with the cam I28 to pivot about the pivot pin IZI, as shown in Figure 13. If desired, the Contact making portion i25 may pivoted about the pin I2! but mechanically inde endent of the cam, being biased to a given position in any preferred manner, as by means of a spring or the like.

The contact structure that cooperates with the contact making end of the blade comprises a support that is mounted upon a stationary insulator i3 5. The support includes an upwardly extending portion I32 against which the cam I26 is adapted to bear for forcing the contact making end of the blade upwardly. Thecontact support also includes an upwardly extending portion I35 which as a support for a line wire terminal i3 5, stationary arcing horn I37, and a pivot in I39 about which is pivoted a skeletonized contact supporting frame such as. is shown more particularly in Figures 5 and 6. The contact shoes 23 are mounted upon the pins 25a that ex.- tend through oversized holes in the contact shoes to permit a limited degree of rocking as Well as of sliding movement of the shoes on the pins, y as in the structures previously described. The

frame. The sleet hood comprises two similar hood members M5 and I 45 which are mounted upon the skeletonized frame by means of the frame pins 25a that support the contact shoes. For this purpose the pins are thereforeapprech than is required in the contact structures previously described. The sleet hoodmemhere are provided with openings M3 through which the pins 25a are passed, said openings being "that it employs a sleet hood over the skeletonized of a slightly larger diameter than the diameter of the pins and being provided with well rounded corners. As a'result, the two sleet hood *menn bers are permitted a limited amount of rocking movement with respect to' the skeletonized frame. The sleet hood members are normally urged into engagement wi h one another by a pair of springs I49I49. Nuts [5| are provided for hoiding the sleet hood members upon the pins and for adjusting the tension upon the spring members. The two' sleet hood members abut against one another along the line I 56-! 55, thus providing a protecting enclosure for the contact 7' shoes and for the portion of the blade contact 225' the two sleet hood members apart. switch has entered the housing and projects that may be in engagement with the contact shoes. The top of the sleet hood is downwardly and rearwardly inclined so as to provide suitable drainage for moisture. The rear of the sleet hood enclosos'the upper rearside of the contact structme, while .the front portion of the sleet hood is provided with an opening l56 through which the blade contact I25 projects when the switch is closed. The two sleet hood members are provided with upwardly and outwardly flaring guiding members 58 55 for guiding the switch blade into position. As the blade moves downward between these guiding members during the switch closing operation it is accurately alined with respect to the contact shoes and it forces After the through spacelEIl, the two sleet hood members are again closed by the springs 2:294:29 thereby again enclosing the main contacts.

To open the switch the rotatable insulator it! is rotated to turn the crank GB and thereby exert a pull on the connecting rod it! to pull the rod IE9 to the left as seen in Figure 9. This causes the cam iii) to turn about its pivot l2! and, since the cam bears against the stop i152 it exerts a powerful force tending to move the pivot pin I2i upwardly. This produces a powerful camming action that moves the blade upwardly. The frictional engagement of the contact shoes 2323 causes the contact supporting 7 structure, comprising the skeletonized frame, to swing about its pivot I39 and to bring the pry loose finger 39 of the contact supporting structure into engagement with the lower edge of the blade portion I 25. cerns the action of the contact making portion of the blade I25 with respect to the contact shoes 23, the action 'is the same as in the cases of the switches previously described. It is to be remembered that the pivot pin I39 does not pass through the two sleet hood members Hill-4M and therefore the sleet hood members move with the contact supporting structure as that structure pivots about the pin l39. It is to be noted that the upper edge of the blade I25 is wedgeshaped. As the blade continues to move in its outward direction the wedge-shaped upper edge of the contact making portion of the blade engages the tapered portions !65-I55 of the two sleet hood members and spreads them. apart, said members rocking about the pins 25a. After a predetermined amount of turning movement of 'the cam I20 about its pivot I25, a stop i220: on,

the arm I22 engages the blade and prevents further movement of the cam with respect to the blade. Thereafter continued rotation of the actuating insulator IoI causes the pull rod, the blade, and the guiding link Iii! all toswing as a truss member about the pivot axis HI to the ultimate switch open position of the switch.

Reference may now be had more particularly to Figure 11 wherein there is shown a fragmentary portion of a modified form of contact arrangement incorporated in a switch of the type shown in Figure 9. In so far as the structure is the same as that shown in Figure 9 similar reference numerals have beenused. The cam carried integral part'of the arm I22 and, upon limited Thereafter, and in so far as con-' rotation thereof about the pivot IZI, it. abuts against the blade. The contact supporting structure is indicated in general by the reference numeral 289, being pivoted at flu and carrying the contact shoes ZEIZ-in the same manner as was previously described. The camming finger is indicated at 253. It is to be noted that when the switch blade is in its closed position the end of the blade slightly clears the camming finger 283, a step 205 being provided on the contact structure for this purpose. It is to be noted that in this construction the pivot Ila for the contact supporting structure is located between the blade pivot and the point of engagement of the blade with the contact shoes, rather than on the opposite side of the point of engagement of the two. By this arrangement a more powerful action is obtained than what is obtained in the switch shown in Figure l, or the switch as shown in Figure 9, in that there is a smaller relative movement between the contact supporting structure and the blade for a givenangular movement of the blade, and

sloping top wall. The hood portions for this switch are mounted upon the pins 25a-25a in the same manner aswas previously described in .connection with the switch of Figure 9. Most of the moisture that mayfall upon the top of the housing comprising the two hood members will drain therefrom due to the slope thereof. However, a'small amount of moisture may creep along the abutting surfaces of the two sleet hood members and thus get into th housing. If this is objectionable the two hood members may be provided with a suitable trapping portion for trapping this moisture and draining it away. The

trap or drain is indicated at 2!?) and consists merely'of a trough immediately below the top of the abutting edges of the two sleet hood members. The sideiedge of the bottom of the trough 2|!) is sloped upwardly, as may be seen at 25 l in Figure 12. As a result of this arrangement it is apparent that any moisture that may enter the trough ZIB will be guided away from the outer edge thereof and will flow in the trough along the top of the housing and down the rear side 2515 thereof. The bottom of this trough is located at the rear of the housing and is open so that the moisture may flow outward freely. The sleet hood members of the switch shown in Figure 9 may be provided with a trough similar to the trough 2M3. In the ease of the sleet hood shown in Figure 9,,the'lower rear portion must be provided with an opening to ermit the contact supporting structure to extend rearwardly therethrough to its pivot, and therefore the drain trough at the rear wall thereof terminates in an open end substantially above the bottom of the housing. In other respects the housing shown in Figure 9 is the same as that shown in Figure ll.

In Figure 13 I have illustrated an arrangement wherein the contactmaking portion of the blade is rigid with the camniing member, rather than with the blade itself. The blade is indicated at I I2 and has a forked member 5 52a secured thereto. The contacting making end of the blade is mounted within the housing.

indicatedat zsajbeing an integral part of the cam portion l20a, and being pivoted between the arms li2a'of the forked member by the pinl2l. A'flexible braided copper wire 220 extends the circuit from the switch blade H2 to the con--:

tactmaking portion l25a thereof, thereby bypassing the pivot l2l in so far as concerns the current carrying function of the-blade. The type of blade shown inFigure 13 may be embodied patent statutes I have herein shown and de-' scribed a few preferred embodiments of my'invention. It is, however, to be understood that the invention is not-limitedto the precise constructions herein shown, the same being merely illustrative of the principles of my invention.

What I consider new and desire to secure by Letters Patent is: V

l. A pivotally mounted. contact housing com prising a substantially box-like structure having a slit opening on one side merging at one-end with an outwardly flared openingat an adjacent side for receiving a switch blade, a stop member extending outwardly of the housing adjacent the opposite end of the slit and having a curved camming surface, a pair of mounting ears projecting from the housing from adjacent the side opposite the side having the slit opening,

a pivotal mounting for the housing including a pivot pin extending through the mounting ears, spring means biasing the housing about its pivot to a predetermined normal position, stop means for, limiting the extent of turning of the housing about its pivot to a fractional part of a half revolution, and contact means mounted within the housing and adapted to receive a blade.

2. A contact housing comprising a substantially box-like structure having an opening at one side for receiving connecting leads and having a blade receiving slit opening on the same side merging at one end with an outwardly flared opening at an adjacent side, said first mentioned opening and said blade receiving slit opening being separated by a member formed integrally with the housingfand extending outwardly thereof and having a curved camming surface facing the blade receiving opening, and'contact means 3. A contact supporting structure comprising a unitary-frame having integral parallel spaced .rearwardly extending ears adapted to receive a pivot pin for'pivotally mounting the structure, a pair of contact shoes carried by the contact structure and spring pressed towardsone another, said contact shoes being outwardly flared at their outer end for guiding a blade'between them, said structure being adapted to be drawn about its pivot by the outward swinging of a blade from between the contact shoes, abutment means comprising an integral-part of the supporting structure, said abutment meanscomprising a curved camming, surface extendingoutwardly of said frame along said blade and normally spaced therefrom, said means being adapted to bear against the switch blade only after initial opening movement and pry the supporting structure and the switch blade apart as the switch blade is moved outward of the contact shoes, means for limiting the extent of pivotal motion'of the supporting structure in one direction, and means forlimiting the extent of pivotal motion of the supporting structure in the opposite direction.

pivoted contact structure engageable thereby, said contact structure including contact making 4. A switch' comprising a switch bladeand a means having frictional engagementwith the blade whereby, upon movement of the blade out- I ward of the contact making'means'the contact structure is turned about its, pivot, cam means on the contact structure initially moved into camming engagement with the blade as theblade moves outward of the contact making means, and means for returning the contact structure to its switch closed position after the blade moves out of engagement therewith.

5; In a switch, the combination of a relatively f short contact member a relatively'long' switch arm swingable into and out of engagement there? with, pivots for said contactmember and said switch arm providing for large angular movement of said arm upon a relatively small angular movement of said switch arm, said' contact member being'freely'swingable and'swung toward the open position by the opening movement of said arm, cam means'movable' with the contact mem her for forcing the contact member and the switch arm out of engagement during: switch opening operation, and spring means for biasing the contact member to the switch closed position.

6. A contact supporting structure comprising a frame having means for pivotally mountingthe same, contact means carried by the structure and adapted to receive a blade, stop means for limiting the extent of engagement of thecontact means by a blade, said structure being adapted to be drawn about its pivot as a blade is moved therefrom, and pry loose cam means comprising an integral part of the structure and out of engagement with a blade that is in engagement. with the contact, said cam being brought into camming engagement with the blade as the contact structure is drawn about its pivot by the switch'opening movement of the blade, to pry the contact structure and blade apart.

7. A contact supporting structure comprising a frame having means for pivotally mounting the sameabcut a stationary pivot, contact means carried by the structure and adapted to receive cooperating contact making means, stop meansfor limiting the extent of engagement of the contact means with the contact making means, saidstructure being adapted to be swung about itspivot by the frictional engagement between the two contacting means upon the initiation of the separating movement of the two contacting" means, cam means carried by said structure and movable into independent engagement with the contact makingmeans after a predetermined separating motion of the two contacting means for prying the'two contacting means apart, and

spring means for biasing the contact means about its pivot to a predetermined position.

8. A contact supporting structure eomprising" a frame having means for pivotally mounting the same about a stationary pivot, contact means carried by the structure and adapted to receive cooperating contact making meansr stop means forflimiting the extent f-engagement of the contact means with the contact making means, said structure being adapted to be swung about its pivot by the frictional engagement between the twocontacting means upon the initiation of I the separating movementjof the :two contacting-i means, cam means carried'by said structureand movable into independent "engagement with the contact making means after a;predetermined separating motion of the two contacting means for prying the two contacting means apart, and a sleet hood carried by said contact supporting structure and having a rocking motion with respectthereto. I v

9. A switch comprising a contact structure mounted for swinging movement, a switch; blade swingable'into and out of engagement therewith, cam means carried by the switch blade for initiating the switch openingmovement of the blade, said: str 1cture beingswung by the blade upon the initial switch opening movement of the blade, and cam meanscarried by the contact structure andengaging the blade to pry the contact structure and blade apart.

,10. A switchcomprising a stationary insulator, a contact pivotally mounted thereon, a switch blade 'swingable into and out of engagement with 1 the contact, a pull rod extending substantially the full length of the blade, a cam member pivoted on the blade and having pivotal connection with the pull rod whereby the pull rod actuates the cam member to impart an initial powerful switch: opening movement to the blade, abutment means between the cam and the blade whereby upon continued movement of the pull rod the blade is moved therewith as a unit, said contact being drawn about its pivot by the frictional engagement with the blade, and cam means carried by the contact and independently engaging said blade after predetermined rotation of said contact about its pivot for prying the contact and the blade apart.

11. A switch having a relatively short pivoted contact member and a relatively long pivoted switch arm movable into and out of engagement therewith, the point of engagement of the contact and the arm being adjacent the contact pivot and remote from the arm pivot, characterized in that the contact pivot is located between the blade pivot and the point of engagement of the blade with the contact, whereby the direction of rotation of the contact is the same as that of the blade during the initial switch opening movement, and cam means carried by the contact for forcing the blade out of the contact after a predetermined rotative movement thereof, said cam means engaging said blade only during switch opening movement thereof.

12. A switch including a relatively short pivoted contact member and a relatively longpivoted switch arm movable into and out of engage ment therewith, a relatively short prying cam pivoted on the switch arm adjacent the contact making end thereof, a pull rod pivoted to the cam for swinging it about its pivot on the switch arm in one direction to initiate the switch opening movement, said contact member being drawn about its pivotin anopposite direction by the switch arm, a second cam carried by said contact member forforcing it from the switch arm during the switch opening movement, abutment means between the prying cam and the. switch arm for limiting the relative movement between the two and swinging the switch arm about its own pivot to its fullopen position upon continued pull of, the pull rod, and a guiding link pivoted pull rodindependently of the switch arm.

thereof, a slit along an adjacent side connnunicatadjacent the pivoted end of the blade and con-4 nected to the pullrod for guiding the end of the on the side opposite said slit, spring-pressedcom tact members'carried within said frame and flared outwardly toward said opening, said frame having integral guide means upon which said contact members are mounted, and a cam member projecting outwardly of said frame from the side having the slit formed therein and having a camming surface curved outwardly away from said slit.

15. A switch of the class described including a contact structure comprising a unitary frame having an outwardly flared opening at one side thereof, a slit along an adjacent side communicating with said flared opening, a pair of integral projecting pivot lugs extending from said frame on the side opposite said slit, spring-pressed contact members carried within said frame and fiared'outwardly toward said opening, said frame having integral guide means upon which said contact members are mounted, means extending through said frame for securing said contact members in position therein, and a pair of opposed sleet hood members enclosing said frame and having spring-pressed rocking movement about said securing means.

164A switch comprising a pair of insulator stacks, one of said stacks being rotatable, a switch blade carried by said rotatable stack, a contact cap mounted on the other of said stacks, a pivot pin carried by said cap, a contact supporting frame having integral spaced ears supporting said frame for rotation about said pivot, springpressed contact members carried within said frame, meanson said pivot for biasing said frame into a predetermined position, stop means on said frame for limiting movement of said blade between said contact members, a curved camtact supporting frame pivoted on said other stack, contact means within said frame adapted to be engaged by said blade, stop means for limiting switch closing position of said blade, and cam'means carried by said contact frame and normally disposed. out of contact with said blade, said cam means independently engaging said bladev only during switch opening movement thereofifor prying said blade out of engagement between said contact members.

manna B. HoYE.

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