US2555258A - Switch - Google Patents

Description

May 29, 1951 H. H. wALLEY, JR 2,555258 SWITCH Filed ont. 25, 1947 4 sheets-sheet 1 orlazey May 29, 1951 H. H. wALLEY, JR 255.52.58

. swITcH Filed oct. 25,1947 l 4 sheets-'sheet 2 May 29, H. H. WALLEY JR SWITCH Filed Oct. 25, 1947 4 Sheets-Sheet 3 le 4a 40 May 29, 1951 H. H. WALLEY, .1R 2,555,258

SWITCH Filed Oct. 25. 1947 4 Sheets-Sheet 4 syl* 1 113910 8f- 10 1%;911.

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Patented My 29, 1951 UNITED lSTATES"-l-).1\'I`I-.NT OFFICE SWITCH Herbert H. Walley, Jr., Newton, Mass., assigner,

byy mesne assignments, to The Acro Manufacturing Co., Columbus, Ohio Application October 25, 1947, Serial No. 782,091

('Cl. 20G- 52) operatedsWitcheS.. These switches are commonly used in-vending machines or other mechanisms Which are setinoperation through a coin introduced therein.

i In. order that the switch. may operate. unfailingly, it. must be designed to be operable under 'all .conditions of humidity, heat, cold, vibration,

.and' shock.

`While a vending machine is ordinarily designed to operate with nickels, dimes, or quarters, nevertheless, a suitable switchmust also be capable of operation by. a so-called thin dime, that is, one which has .been worn to such an extent that its weight .will beapproximatelyhalf the weight of a normal dime. Accordingly, one of the ob- 'jects of the invention is .to provide a switch .mechanism operable by small weights which vary o ver. a considerable range.

"."Inthe'trade it is considered that for a switch of 'thisctypeto be fully satisfactory, it must be capable of at least amillion operations. Therefore, theswitch must not have a switch blade in'which there are highly stressed areas which fare'known'to be subject to rapid fatigue' under repeated. operation pressures at the sensitive `The switch blade should be relatively unstressed and .movable only through annular :positions well within its elastic limit.

Accordingly, another object of this invention is the ,provisionvof a switchin which the internal forcesiare small and the mechanism simple, and

in'which no `part :has been excessively stressed,

although having the desired operating characteristics. The presentinvention vfurther contemplates a switch which is small and compact so that it. may be positioned within a minimum space, and which. by `virtue of the close fitof all partsentering the cavity through the housing will substantially preclude the entrance therein of extraneous material as, for example, dust and moisture and'which will be shockproof, vibrationproof, resistant to heat and cold, and of exceptionally long life.

' The switch in the present application is shown as. an independent unit without any related mechanism, which may vary depending yupon the ytype of machine with which the switch is used.

.A ,particular feature of the invention is the arrangement whereby adequate leverage is obtained to move ,positively the switch contacts, and at thel same time there is provided means Tfor overtravelof theoperating lever to eliminate the possibility of damage to the switch contacts.

It is a further object of the invention to provide spring mechanism mountedv within the housing for providing quick return of the operating lever to normal position after the coin force has been removed therefrom. The construction is such that even though the externally applied vcoin force produces a relatively large force within f the housing as .compared with the spring forces within the housing, nevertheless, the internal spring forces will be adequate to return the switch to .normal position promptly upon the removal of the coin force.

- These and other advantages of the invention will be more apparent as the description proceeds with the aid of the accompanying drawings, Iin which Fig. l is a side elevation of the switch, showing the contacts extending' therebelow and the operating lever extending to the left.

- Fig. 2 is an end elevation of Fig. l, looking from the right.

Fig. 3 is a view looking upwardly from the bottom of Fig. 1, with the housing broken away "in part to show the means for'securing the housing parts together.

Fig. 4 is-an enlarged sectional elevation on the line #3 4 of Fig. 2, showing the switch parts in normal position.

Fig. 5 is a sectional elevation similar to Fig. 4, with the position of the contacts shifted, due to 1 coin operation.

Fig. 6 is a sectional elevation similar to Figs. 4 and 5, showing the extent of over-travel that can occur without further change in the position of the contacts.

- Fig. '7 is an enlarged vertical section on the line 'l-l of Fig. 5.

Fig. 8 is a vertical elevational view partly in section on the line 8 8 of Figs. 2 and 7.

Fig. 9 is a view corresponding to Fig. 4, showing a modiiication of the invention.

'Fig 10 is a section on the line lil- Iii of Fig. 9.

Fig. l1 is a View from the reverse side of Fig. 9 breken away in part showing the manner of connecting the hair spring to the shaft.

The invention consists basically of a housing, two xed spaced contacts, an intermediate movable contact, and a lever for moving the intermediate contact from a normal position against one xed contact to a second position against the other fixed contact, all combined with means that vpermits the operating lever to continue arcuate movement after the second contact has been made without *further movement of the contacts. Referring to the relatively large scale draw- 3 ings, Figs. l, 2 and 3, the housing is shown to be comprised. of opposed cover plates 2 and 4y and a suitably cored center body portion 6. These three parts are held together by tubular rivets 8 that pass through aligned apertures in the cover plates and body.

A rotatable operating shaft I of insulating material extends laterally of the housing, and has ailixed thereto an operating lever 12. Movement of lever I2 rotates shaft I5 and in so doing, through elements that will be described hereinafter, the switching action takes place.

Referring now to the enlarged drawings, Figs. 4 to 8, it will be seen that there are two spaced terminals xed in position by being wrapped around supports IB and 2t. Surface inserts of appropriate contact material have been made at 22 and 24 for the purpose of lengthening the life of the switch.

An intermediate terminal 26 in the form of a flexible strip of beryllium copper, Phosphor bronze or other suitable material is mounted as shown. This strip has been given eXtra support by a heavy backing strip 28 along its exterior portion and along that portion secured to the housing. A two-sided Contact 30 is mounted on strip 26, which contact is adapted to make alternate contacts with xed contacts 22 and 24. Strip 25 may be referred to hereinafter as the contact lever.

Strip 26 has a normal set to the right, which, were it not for the other mechanisms, would normally hold contact 35i against contact 24, as shown in Figs. and 6.

Around that part of shaft I0 which is within the body 6 is wrapped a strip of sheet material 32 rigid enough for the purpose intended and having one end 34 embedded in slot 3,6 that extends longitudinally in shaft I0. The other end of strip 32 is slit longitudinally for a short distance to divide the end into three narrower strips, one continuing around shaft Ill as at 38, the middle part doubled back to form a, hook 4e which is adapted to receive and engage the end of the semicircular extension 42 of strip 26, and the third part extending upwardly away from shaft It as at 44 to act as a stop when it comes into enf-*agement with a protuberance 46 extending downwardly from the interior of the body. The engagement of hook 48 with extension 42 occurs preferably over the width of the hook 4e as indicated in Fig. 7 and the contact between the two may be referred to as the area of engagement.

On the outer extension of shaft IIJ is secured operating lever I2, long enough to provide the leverage required to operate the switch under the weight of a coin.

In Fig. 8 is shown the hair spring that overcomes not only the normal set of strip 26 but also the turning force caused by the mass of the unweighted lever I2. The hair spring thus holds the switch in the normal position shown in Fig. 4. The hair spring, numbered 48 in Fig. 8, has its inner end 5EI bent at an angle and positioned in slot 36, while its outer portion 52 passes between two guide posts 54 and 56, with the end coiled about the end post 5S. The spring is coiled so that it normally urges shaft I Il, as viewed in Fig. 8, clockwise. Shaft iii in Figs. 4, 5 and 6, being viewed from its opposite end, is urged counterclockwise by the hair spring. As previously mentioned, the torsional effect of the hair spring is sucient i4 and IE, having their inner ends to overcome the resistance of strip 26 and the weight of lever arm I2 to cause the switch to assume as its normal position that shown in Fig. 4. Therefore, when shaft I0 is caused to rotate clockwise by a force being applied downwardly to lever arm I2, as viewed in Figs. 4, 5 and 6, the normal set of strip 26 assists lever arm I2 in overcoming the resistance of the hair spring. That is to say, hair spring 43 is adjusted to have just enough rotative force to overcome the resistance of strip 26, which is constantly pressing through the end of semicircular portion 42 against hook 4S, and the unweighted mass of lever I2, which is continually exerting a clockwise force on shaft I0, as viewed in Figs. 4, 5 and 6.

It should be mentioned that shaft I0 is carried by two closely fitting bearings and 62, the former being in side plate 2 and the latter in the body 6. The accurate close t of the bearings as shown in the drawing will have the 1usual and obvious elfect of restricting and limiting the passage therethrough of extraneous matter of all kinds. If it is found desirable to have shaft Iii extend from the opposite side of the housing, this may be readily accomplished by merely reversing shaft I8 to have the eXtension that carries lever arm I2 carried by the bearing 64 in side plate 4 instead of by bearing Sil. Without further explanation, it is believed obvious that shaft I is reversible, as the only structural feature in the shaft is the slot 36 into which the end 34 of strip 32 and end 50 of hair spring 48 may be inserted as readily with the shaft in one position or the other.

The effect of reversing the shaft in the housing so that the end to which the lever arm I 2 is connected extends from cover plate 4 rather than from cover plate 2 is to reverse the direction in which arm I2 is rotated with respect to the housing in the switch operation. That is to say, lever arm I2 is to be rotated counterclockwise, as viewed in Fig. 1. If the shaft is reversed, then the arm rotation when viewed from the arm side of the housing will be clockwise. This construction makes it possible to provide for right or left hand operation in a single unit without need of extra or alternate parts.

The feature of the over-travel construction is illustrated in Figs. 4, 5 and 6. In Fig. 4, lever arm I2 is in normal position with contacts 22 and 39 in engagement. When a descending coin engages lever I2, the latter will immediately be swung downwardly to the position indicated in Fig. 5, at which point contact 30 has engaged contact 24 under the force of the strip spring 2B. At this time the end of the semicircular extension 42 will be ready to free itself from engagement in the notch formed by hook end 4). Thus, as the weight of the coin carries lever I2 downwardly still further to a position as illustrated in Fig. 6, there will be no further movement of semlcircular portion 42 or the contacts 3@ and 24. In Fig. 6 it is noted that hook member 49 has moved away from the end of member 42 an angular amount equal to the angular movement of lever arm I2.

The dotted line position of lever I2 and hook 43 in Fig. 6 are merely included to show the possible extent of overtravel of lever arm 40 that could take place if conditions required it.

As soon as lever arm I2 has been freed of the weight of the operating coin, then hair spring 48 comes into play to rotate shaft I0 counterclockwise, as viewed in Figs. 4, 5 and 6. Hook i: w40 comes'into engagement with the end of mem- :fber 42 at the-position shown in Fig. 5, and thereafter continued rotation of' shaftl Ill4 will break theengagement betweencontacts 24 and 30 and --willfbend .strip 26 to theleft so that contacts 30 andf22 jagaincome'into engagement, as in Fig. 4.

.-As-.shaftffl -rotates counterclockwise under the .influence of -the hair spring, its movement is checked or snubbed prior to the time that fingen' 44.comes into actual engagement with stop 46. Thisfsnubbing action is-desirable for the reason `thatyif Yitfwere'not present finger 44,V` hitting `stopfl at considerable speed,.-would rebound therefrom fone.. or more times and the switch-1r would chatter.

jV The snubbingiaction is achievedby themutual action of-'hook r40 Vand the end of member 42. e Hook 40 pivots about the center of shaft I0 while the outerendl of-member 42 pivots in effect about apoint below Contact vv3i] -and very close to that -pa'rt ofthehousing that' supports strip 2 E. Hook @40f acts as a fulcrumand engages the end of "member 42 at about the position shownin Fig.

5. Thereafter, as hook 4D rotates to theleft'f' and is guided by its association with shaft I0, it l follows a downward arc or trajectory that does `:not coincide-with' the normal arc of the `end -of.member-4i),.and as a result'. the extreme end Fig. .4, and acutely bent at 45', while the re- .'mainder of member y42 is bent generally into a -smaller= circle.

The resistance ofmember 42 to assuming its 1'; new'shape causes upward pressure against thef' `under side of hook 46, which vin turnpresses -'shaft i!) with increasing force against the bearing .surfaces 60 .and 62. This increasing friction slows down the rotation of ,shaft I0 vunder the influence of theihairj spring, and brings thee .shaft..to a complete halt before finger 44 engages stopf46. However, before shaft HJ has stopped .its .counterclockwise movement, contact 30 will fbe-v-in engagement with contact .22.

.iByrthe construction thus described, it will be .apparent vthatthey load on lever arm I2 'may be 1instantly removed without danger of the switch chattering onthe rebound. TheY distorted end ;of. member 42 which has .checked counterclockr`wise-.rota-tion ofv shaft!!! assists in the initial:-

.clockwise vmovement the next time a downward '.force is Eapplied vto lever arm I2.

- Fig. 'Tf-which'is a section on .the line i-T .of .Fig` 5, illustrates the manner in which strip 26 :uh-asffbeen reduced in width in order to provide' --for maximum sensitivity under the rotative inr-.uence of vhairspring ,48- in one direction and lever larm -12 inthe other. yWhile strip `zifis Yreduced. in width, nevertheless. because of the Vmaterial ofy which it isf-made, there, is vsufficient,

resiliency to insure that contactllwvill be held tightly 4againstcontact v24 after the two 4.have come .intoengagement-there. being no forcefof the hair spring to overcome, as that has been `taken care of by lever arm i2.

In Figs. 9, and. 11 is'shown` a modified form ofthe invention which operates in sub- `---stantially the same way as that disclosed in the other figures.

.Referring to Fig. 9, itwill be noted thatfboth. ends of the shaft l!! are supported by closely fitting bearings 'i2 and i4. The uaccurate fit of the-bearings acts to limit and restrict the passage .of vextraneous matter into the housing. Square the, interior portion of the shaft. These-square sections are designed to engage the at1side80 vofthe inner end'of the hair spring 8l vshown in Fig. ll. The center part of shaft 10 comprises aV cam '824 which Vacts with respect to the movable switch member in much the same manner v as hook'40 shown in Figs. 4, 5 and 6. `Cam 82 vhas its rotation vlimited in eitherdirectionv by engagement with'thebottom surface'84of the "strip -94 carried by a reinforcing member 96 and mounted in the housing 85. The upper .end-98 of rstrip-94 is located to be engaged over offlmember :42 is flattened, as indicated at 43f30- :fitswwidth vby aw-iping actionof cam 82. The contact between the strip and cam may be :'-referred'to as the area of engagement. When shaft'i is rotated clockwise from the position shown in Fig. cam'EZ- will slide upwardly along lthe right handsurface of .member v98 with the area of engagement moving upwardly until contact-92 vhas moved to the right to'engage contact Sil. This occurs because lhairspring 8| is being overcome ,by the rotation of shaft 10, and vspring strip S4, being biasedl to the right, moves contact 92 to a position against contact 9U as cam' 32 retreats clockwise. Thereafter, 'cam 82 .may overtravel clockwise until it engages= surface 64 without causing any further movement . whatsoeverof contacts 92 and 90.

When the clockwise rotative force is'removed fromlthe controlling lever, hairspring 8| vwill cause shaft .l0 to rotate rapidly counterclockwise. In order to prevent chattering of the switch, cam 82 provides snubbing means which brings the rotation of shaft 10 to a standstill before Aorfabout -the time member 98-has come into engagement' with stop'illil. This snubbing action-is:by vir-tue of the gradually increasing frictional 'engagement between the surface of ycam-i32- -and `the corresponding surfaceof memgreater will be the frictional force therebetween. The parts are :so vdesigned that when member hits stop 10G, the cam will be in awedging position, which will`-preclude any opportunity of contact 'H8 jumping backv off contact88.

=-When linitial force is appliedy tov the'lever arm fthereafter to lcause clockwise rotation of shaft =-I'F.fl,fV there willf-be a somewhat greaterV forcewto tion shown -in Figs; 4, 5, 6 and '7.

-overcomerthan would'be the case in the construc- This difference,

ffhowever; is slight,.\and doesl not affect". normal operation.

-rAs will 'bei notedsin FigrlO, reversal' of. the r shaft may be 'accomplished by-removal of the -v twocevers andl IDI, breaking away the knock- `out'section .232," removing the hairspring from the squared end'. 18. and then vreversing the shaft `applying .the hair spring-to squared end 1 fie,

und

replacing'the covers so thatthe Ylong :end of'shaftI illv rests in..bearing *14, while the The 'construc- Ati m'of^}?ligs.` 9,`l0. and'll diifersfrom Figs; 4, 5, 6 and 7 in that in the former the shaftfis rinitialv assemblyfone covenk will be -leftwith. a

knockout section indicated at |02 in both Figs. 7 and 10.

It should also be observed that the central portion of the housing 85, as shown in Fig. 10, is symmetrical, so that if desired the movable contact 92 and all associated parts may be reversed along with the cam and the hair spring. Thus, with the parts reversed, counterclockwise rotation of shaft 18, as viewed in Fig. 9, will enable contact 92 to move under the inuence of strip 84 to the left against contact 88, while clockwise movement of the shaft will bring cam 82 against member 98, which will then be to the right of shaft 10. This will move contact 92 away from contact 88 to engage contact 90.

Extension 42 of the contact lever or strip 26, as shown in Figs. 4-8, is generally circular in form, while the upper end 98 of strip or contact lever 94 is in the form of a very flat L. Nevertheless, it will be understood that the particular configuration of the extension of the contact lever may be varied without departing from the invention, so long as it is adapted to be engaged by the `particular operating means on the crank shaft. Thus, in Figs. 4 7 the hook 40 is suitable for engaging the end of extension 42 to produce a lateral movement and a downwardly compressive cam-like effect which bends the extension, as illustrated in Fig. 4. The crank shaft I8, carrying cam 82, is likewise effective to move the extending member 98 laterally and at the same time have a wiping cam-like effect to check rotation.

The extensions 42 and 98 are both in the form of leaf springs, and are subject to greater or less bending, depending upon the extent of the rotation of the crank shaft. In `general, it may be said that that portion of the contact lever in the lower section close to the lpoint of support by the housing is of more limited flexibility than the outer portion beyond the contact which is acted upon by the cam mechanism.

i It should also be pointed out that the commerical form taken by the switch of the present invention is of relatively small size, and is often referred to in the trade as a midget-type switch. However, the fact that in practice the parts will normally be small is not t limit the scope of the invention to small switches. On the contrary, the various parts may be enlarged to whatever size is deemed necessary for particular service requirements.

In the midget type form of the switch, the actual volume of air therein will be very small, as the housing has been designed to closely encompass the various working parts. Since the fit of the shaft in the bearings as shown in the drawings is close and the housing itself is otherwise sealed, it is apparent that the humiidty of the atmosphere within the housing will change slowly, if at all, as outside conditions may vary.

In the small cavity of the housing, the amount of moisture in suspension in the air therein obviously would form, if condensed, only a minute quantity of water. Additional outside more humid air would have difficulty entering the housing due to the close fit between the shaft and bearings as shown in the drawings. Thus, the limitation of condensate within the housing Vminimizes the possibility of malfunctioning of the switch.

' The foregoing description shows that I have provided a switch effective to operate under small force applied to the lever arm and on release to be free from chattering. Furthermore, the switch is reversible, so that it may meet more manufacturing requirements than would otherwise be the case. While preferred forms of the invention have been disclosed, it is not intended that the invention shall be limited thereby but only by the appended claims.

I claim:

l. In a switch of the type described, a housing comprising a central body portion and opposed cover plates, two axially aligned bearings carried by said plates, a shaft mounted for rotation in said bearings, a coiled spring for urging the rotation of said shaft in one direction, cooperating stop means for limiting rotation of said shaft by said coiled spring, a second spring applying a force substantially tangentially of said shaft in a direction opposed to that of said coiled spring, and a lever arm connected to said shaft whereby a force may be applied to said lever arm to assist in rotating said shaft in a direction opposite to that being urged by said coiled spring, and a pair of contacts within said housing adapted to be opened or closed by rotation of said shaft in one direction or the other.

2. In a switch of the type described, a housing comprising a central body portion and oppositely disp-osed cover plates, two axially aligned bearings carried by said plates, the connection be tween said body portion and cover plates being tight, a shaft of insulating material mounted for rotation in said bearings, the t between said shaft and bearings being close while allowing free rotation of said shaft, a hair spring surrounding said shaft and connected to said shaft and housing for urging rotation of said shaft in one direction, a flexible strip mounted within said body portion and curving partially around said shaft, a contact on said flexible strip, a second contact mounted on said housing at a position where it may be engaged by the said first contact, said flexible strip having a permanent bias in that part between said second contact and said housing whereby said contacts would normally be in engagement unless held apart, a cam on said shaft for engaging said flexible strip above said second contact whereby when said shaft and cam are rotated under the influence of said hair spring, the end of said flexible strip will be moved to a position against a stop on said housing and said cam will cause increased concave bending of that part of said strip above said second contact to maintain said contacts separated and incapable of engagement until said shaft and cam are rotated through a substantial angle in the opposite direction, and a lever attached to said shaft exterior of said housing to provide means whereby said shaft may be rotated in said opposite direction through a substantial angle upon the application of a small force to said lever.

3. In a switch of the type described in combination, a contact lever, a support for said lever permitting angular reciprocatory movement thereof, a curved leaf spring forming an exn tension of said lever arranged at an angle to said lever, a stationary contact for engaging said lever at a point situated between said support and said curved leaf spring, said contact forming an abutment limiting the closing stroke of said lever, said lever being biased so as to cause separation of said lever from said contact if said lever is unopposed, a rotatable operating member for actuating said contact lever into engagement with said contact against said bias, said operating memberfcomprisin'g a relatively long arinadapted to be acted upon by an external force and a relatively short arm, said short arm beingadapted to transmit'tov said extension of said levenduring Vthe-closing stroke thereof an operating force atia changing" angle With respect to said contact lever, a second abutment forlimiting' the" movement of'said curved' leaf spring' and theclosing stroke of said operating member;'said stationary contact' and said second abutment being arranged to cause sequential stopping `of the' corresponding engaged parts of said contact lever-to permit overtravel of said operating member and subsequent back bouncing of said operating 'member without disengagement of said contactl lever from said stationary contact.

4. Ina midget typeswitch, the combination of a biased contact lever, fulcruinmeans for said lever permitting angular reciprocatory movement thereof, a rst Stationary contact'arranged on one-side of said lever and adapted to cooperate therewith, a second stationarycontact arranged onthe other side kof saiddeverand adapted to cooperate,v therewith, said biased Contact lever tending to move intoengageinent with said first contact," said'leveivhaving Yan'extension in the formof a curved leafspring and forming an integral`A part thereof, a forceapplying member for engaging'the said extende'dleaf spring, means for moving said member to force saidv lever into engagement with 'said second Icontact and thereafter to cause additional bending,` of said leaf spring between 'said'seccnd contact and the end of .said `leaf spring, -isaid1bending.. producing -increasing concavity of said curvedleafspring, said moving means` including a shaft forwrotating said member and located alongside of said curved i leaf spring and in algnmentwith said Contact" lever anda vsecond-biasing'means acting upon said. shaft and capable -ofvovercorning the bias of said contact lever, -and-levermeans acting upon .said-shaft for-counteracting the bias of said second biasing means-upon-'theapplication Vof a 'small force -to---said--leverA to permit said biased contact lever to move into engagement with said rst stationary Contact.

5,'In a midget type-switch, the combination of a leaf-spring contact lever; meansfor clamping one end thereof, a first stationary contact limiting the stroke of said lever in one direction, a second stationary contact limiting the stroke of said lever in the opposite direction, said lever being biased toward said first contact, a substantially curved leaf spring, one end thereof arranged in angular relation with respect to said lever and forming an integral part thereof, a cam acting on the said leaf spring, means for moving said cam to cause engagement of said lever with said second contact and to deflect said leaf spring, said moving means including a crank shaft and spring means acting upon said crank shaft and capable of overcoming the bias of said lever, and lever means associated with said crank shaft for counteracting said spring means to permit said contact lever to engage said first contact.

6. A non-chattering switch of the type described comprising a fixed immovable contact, a movable contact lever with a complementary contact thereon and biased away from said fixed contact, a flexible extension on the end of said contact lever set at an angle thereto, a rotatable shaft with a laterally extending member thereon, said member adapted when rotated in one 10 direction first to engage said extension at a constantly changing angle and as rotation continues to move said extension and contact lever until said complementary contact is moved into engagement with said fixed contact, a coil'spring of such strengtlras to not only cause the rotation of said shaft and member and the closing of said contacts as aforesaid but also to cause further rotation of said shaft and member and flexing of said extension under the pressure of said member after engagement of said contacts, whereby said contacts cannot be opened untilsaid 'shaft has been rotated somewhat in the reverse direction, and a lever of such length 'on said shaft that the application thereto of a small force in the order of the weight of a coin will be suicient to overcome said coil spring to rotate said shaft in the opposite direction to permit the bias of said contact lever to cause separation of said contacts.

7. In a midget type switch, the combination of a first stationary contact, a second stationary contact, a leaf spring contact means adapted to cooperate with said contacts, a support` for said leaf spring contact means permitting angular reciprocatory movement thereof,v said leaf spring contact means comprising a first portion substantially straight and a second portion extending in curved formation from said rst portion, said rst portion being adapted to engage selectively either of said stationary contacts and being biased to engage said first stationary contact, means for overcoming the bias of said first portion toward said first stationary contact and for actuating said first portion into engagement with said second contact, said means comprising a rotatable shaft arranged on the concave side of said second portion and in alignment with said first portion, a force applying member 'on said shaft for engaging said second portion remote from said support, and spring means sufficiently strong to rotate said shaft and member to" overcome the bias of said first portion and to bring said leaf.- spring Contact means into engagement with said second contact and then to increase the ccncavity of said curved second portion whereby said shaft must lbe rotated somewhat inthe reverse direction before said leaf spring contact means and said second contact can be separated, and lever means associa-ted with said shaft for counteracting said spring means and causing rotation of said shaft and member by the application of a small force to said lever to remove the force of said member from said second portion and to permit the bias of said first portion to cause engagement thereof with said first stationary contact.

8. in a midget type switch the combination of a leaf spring contact lever, means for clamping one end thereof, a first stationary contact limiting the stroke of said lever in one direction, a second stationary contact limiting the stroke of said lever in the opposite direction, said lever being biased toward said rst contact, a substantially curved leaf spring, one end thereof arranged in angular relation with respect to said lever and forming an intergral part thereof, a shaft having a lateral extension for engaging said leaf spring when said shaft is rotated, means for rotating said shaft to cause said extension to engage and deflect-said leaf spring thereby to cause said lever to engage said second contact and thereafter to cause additional bending of said leaf spring upon further rotation of said shaft, said means for rotating said shaft including spring means acting upon said shaft and capable of overcoming the bias of said lever, and a lever associated with said shaft providing means for applying rotative force to said shaft in the opposite direction to counteract said spring means to permit said contact lever to engage said first contact.

9. In an electric switch, in combination, a stationary contact, a movable contact cooperating therewith, a leaf spring carrying said movable contact and acting as means tending to cause separation of said movable contact from said stationary contact, said leaf spring having a sub-- stantially straight portion and a curved portion, a xed support for said straight portion permitting angular reciprocatory movement of the said straight portion, a movable member for engaging said curved portion, guiding means for said movable member to cause movement thereof along a trajectory such that the area of engagement of said movable member with said curved portion progressively decreases in distance from said stationary Contact and from said Xed support for causing engagement of said movable contact with said stationary contact and for stressing the curved portion of said leaf spring when the area of engagement of said movable member with said curved portion is moved further along said trajectory, and operating means for moving the said area of engagement of said movable member along said trajectory.

10. In an electric switch, the combination of a stationary contact, a movable contact adapted to cooperate therewith, means tending to cause separation of said movable Contact from said stationary contact, said means comprising a leaf spring carrying said movable contact and having a curved portion, a fixed support for said leaf spring permitting angular reciprocatory movement of that portion carrying said movable contact, a movable member for engaging said curved portion, a rotatable shaft for supporting said movable member in spaced relation to the geometrical axis of said shaft, said movable member being arranged to move in a plane at right angles to the geometrical axis of said shaft, and operating means for rotating said shaft and movable member to cause engagement of said movable Contact with said stationary contact, the said curved portion of said leaf spring being sufficiently flexible to permit limited continued rotation of said shaft upon engagement of said stationary contact by said movable contact which continued rotation is accomplished by additional bending of said curved portion to increase the concavity thereof.

11. In a switch of the type described, the combination of a stationary contact, a switch lever cooperating therewith,-a xed support for said switch lever permitting angular reciprocatory movement thereof, resilient means on said switch lever remote from said Xed support, a movable member for applying a force to said resilient means, a rotatable shaft supporting said movable member in spaced relation to the geometrical axis of said shaft, said switch lever having a bias tending to cause separation of said switch lever from said stationary contact, spring means for rotating said shaft and said movable member to cause said switch lever to engage said stationary contact, said movable member being adapted to be moved by further rotation of said shaft after engagement of said switch lever and said stationary contact from a position wherein the stress of said resilient means and the bias thereof in a direction inwardly radially of said shaft are relatively small toward a position wherein the stress of said resilient means and the bias thereof in a direction inwardly radially of said shaft are relatively large.

HERBERT H. WALLEY, J R.

REFERENCES CITED The following references are of record in the nie of this patent:

UNITED STATES PATENTS Shaw Mar. 23,

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