US1770956A - Positive safety lock for centrifugal extractors - Google Patents

Description

July 22, 1930. c. w. TERWILUGER 1,770,956

POSITIVE SAFETY LOCK `FOR CENTRIFUGAL EXTRACTORS Filed Dec. 27, 1927 2 Sheets-Sheet l July 22, 1930. c. w. TERWILLIGER 1,770,956

POSITIVE SAFETY LOCK FOR CENTRIFUGAL EXTRACTORS Filed Deo. 27, 1927 2 Sheets-Sheet 2 sible to unlock the .cover locking vmeans s o that before the cover canbe opened it 1sy absolutely necessary that the driving means be rendered inoperative. .However, the speed of the machine does not. materially decrease asysoon asv the power is disconnected, because its vI'nomentum-will cause it to rotate at a relatively high, speed for'som'e time there-V after; therefore, 'even when the driving vmeans .have been rendered inoperative, vitis not possibleto -unlockitlie cover until fthe machine .has slowed down. Y f

In the annexed drawings, I illustrate two embodiments offmy invention'as applied to a belt driven machine, andthereforein this case, by power control member is meant the means `for shifting the belt from-the loose to the tight pulley and vice versa; but it will be understood that with suitable modiiications, the invention can also be applied in `connectionvwith electric driven machines 4.where the powerV control member may be represented by a switch orfother suitable appliance. Y y

Referring to V-saiddrawing Fig. 1 is a topplan view of an extractor equipped with ,safety locking devices embodying my invention;

Fig. 2 is a fragmentary side elevation.

thereof; Y Y

Fig. 3 is a. fragment-ary rear elevation thereof; I v- Y Fig. 4 is-a top planview of an evtractor equipped with locking devices also embodying my invention in a different form;

Fig;`Y 5 is a fragmentary side elevation thereof; Fig. 6 is a fragmentary/'front elevation thereof, illustrating the cover locking means;

and .Y n

Fig. 711s 'la fragmentary` rear elevation thereof, illustrating-the means *associated with the cover locking means controlling th operation `of the.. shifting lever. l l

'Referring to Figs. 1,2, 3, 10 designates the extractorbody which "is, provided with a cover 11 hingedly connected thereto by hinges 12, said cover being adapted Vto vbe angularly moved upwardly and rearwardlyl about its pointlofattachment to anopen 'pos sition. '.A-'countershaft 13 is suitably lsupported at the rearof the extractor and carries al main drive pulley n 14 belt 15 is trained leading to and operating the interior mechanism of the extractor (not shown), .when thedrive pulley 14 is rotated by countershaft 13. Y

Said eountershaft carries also an idler p ulley 16 and a tight pulley 17, and a driving belt 18 may be shifted from one to the other pulley by means of a fork 19 mounted on a shifting rod 20. ySaid shifting rod may .be operated by means of a shifting lever 21 pivot'ed at 2Q onto thebody of the machine, and Yis supported and guided by brackets 23, 24. The drawings represent the machine at the timewhen the'driving belt has been shifted from the tight tothe loose pulley and the belt shifting arrangement is therefore in its inoperative position; the machine however, stillyrotating at a Yhigh'spe'ed by virtue of its own momentum, andl maintaining the cover in its locked position. The coveris provided with-an outwardlyprojecting lug with which. normally interlocks anose portion'QG of a locking lever 27 pivoted at f 28v on asuitable bracket 29 outwardly eX- tending .from-the body ofthe machine.

Said lever127 `is alsoy provided with an arm 27", the end-*0f which is disposed in the path of movement of'an axiallyinovablel push element30which formspart of a centrifugal device'30 mounted at the end of countershaft 13. Such a centrifugal rvdevice has already been described by me in detail in my other patent application above referred to, and thereforeit will besufiicient'to state, for the understandingof the present inventionV that push member 30 isforced outwardly, main Ytaining the locking-lever injits locking po# sition as shown when the countershaft rotates ata certain speed.

, As stated, the conntershaftnormally drives the. vertical shaft` on which is mounted a basket orcontainer rotating within body 10, but when the driving-belt 18 is shifted to its inoperative positiomthe countershaft becomes inits turn driven by thevertic'al shaft, still rotating at a high speed.; the centrifugal device will .therefore Vbe operative' whether the countershaft is driven by its power driving means, or by the momentum of the rotating parts of the machine. Y f

The locking lever tends at all times to move vto its locking position due to the action of a spring'31attached at one end 32 to the body ofthe machine and at the other end 33 to the locking lever. Sai-,d locking lever is provided with a handle 34`by`means of which it can be moved outwardly to unlocking position against the action ofspring 31, provided such movement of the lever is not prevented by the resistance offered by push element 30 when downwardly and outwardly projecting eX- around which a tension 35, terminating inanoutwardly pro- #imagens pivoted.` at n38 onto "thei body @ofthe-machine 4and which extends eeertztin *length around point `39 underneath the front. end oi .locking lever27. Said stop lever 37 'said body to' zivis normally forced jnpivardly by efspring` 40;, and therefore Whenthe cover `islOvvered vstop lever 37 is forced clownvvardlyby lipfto-thei position shown in the drawing, against the aetion of said spring .40.

V *The end 39=ofA stops-lever 37 carri-es' tnup-r livardly projecting pinl 4l which projects" in the inward "path oi looking'lever .27. when .said

.position and' spring40 isnllevved Vto force ynpr* 37. Whren1theeerfeonditioneoc-v iverdly vlever curapinl willprojectnpwerdlyecross notch v42,1formed in lever 27,`and Wil'lltherefore effec# tively prevent-theffreturn ofsaijdl'everfm to thelocking position showninf'the'drvving, to.

ot spring 3l.

Assuming that leverQv be retainedin itsk inoperative-'position `loy pin 4l, Cover V4"llhein'g fopen, it is obvious that lif fthelcover .ijsfmeved to f its closing position', :iorcm-g down stop "le- V.ver 87T, :ns so'onms 'pin' 4I has Clear-ed lever 2.7;; sprin ;Q -31 will ypull said liever to itsl locking position-shown. 1 f f f the action-of spring 31 and eover lil fisplul'letl openystop lever 37 will` snaptothe jpositiong sition V#vvillbe,prevented.hgv pinf'l. 1 www In practice, I prefer .strong .enough to =force :not Vonly'. lever 37j` but Y; Where' the: return 4of lever 27 to:` its loekind' pfothe eoverfitself fu'pivardly, fthe AInernent lever 22T-.is -movedfeto -its"unlocking; position; so f that f as-soenas-thisisdone-lever? isfentom'aticaflly `locked in its `inoperative `position'fend ,fthe oever is slightly fopen by :the aeti'onni'rstop .fully-effective, it isneeessaryfto fnlfillother conditions, namely:

theemeans -'l. AMeans should The :provided preventing .movement oli thebeltsh `operativej-positio'n. e

2. Means shOnl'dn-lsbbe providedtworfelse previously fmentinned .should "be designed =to prevent Ithe fpossiltiflity 'odi moving lever-27fromfitsleeking'to itsun'loelting position Whenever "the belt :shifting tmfeansare' set in their'operativeiposition1 f .The 'locking devicemust otfinterferewith the free return-ofthefhelt shfitingineansfrom th-eiroperetivfe to theiriinoperetivejpsition;

VAs an addredfmeasure,y designed -to abs'ol lntel-yA prevent t e 1operationof Athe machine When-'the locking fdevices sheulcl 'beitampered with. with .melici-ousintentg1prefenfto zilso to make" "spring "".401

ifting means-to their OPGMUVG I13051131011 -Whenlever is invitsV 1n'- provide g `meal-ijs preventing movement "of l vthe belt shifting means to their f Voperzitive posi Y, tion "when the c'overj iseven but slightlynpen;

becaus-e With the @arrangement described, it

inf unlocking Wouldlie 1 possible once f lever 27 has been vs et positionie-ndz-is being'reteinedfin seid.position'fhyfpinillh While lthe cover-'rs swungfahout-its hinge'to its open positiomfto inaliciouslyor inadvertently `force 'down lever i 37,` thuspermittingthe return of locking lever 3 7 to its locking position'freeing th ebelt shiftV- in'grnieans;eventhough the'coverstillremains setuin. its "open position.

All of theserequirements areprovidedfor rwayf o feXample/I yhave *illustrated `inth'e `dra-Wings. The operation o f the belt shifting meansand' of the loekinglever' arefaccnrdingly .mede interdependent, each co'ntrollingg'the other. V.To this end',`

V ,ii-io-veble bar 43, which yIneyiloe `moved*diretztly I .provide .a verti'cally byfreletively simple :arrangements which 'by andifts lower end'is pivotztllyconnee'ted 'att `to thelterallyfeirtendingferme@fofn crank .1,560

.-isipivetally mountedft lnn ai bracketing from bearing 44'.

depending These Lverrous partsere so errelnge'd that movementof Alacking'lever- 27 Et'oive rds its locking position: causes other 43", While?movement -o'lever 2"? 'to' its #unlocking position fcezus'e'sr nip vveifdnove'inen't downward movement 1 f.

becomes Iiinpessible teupvvardly shift bei' 243.v

through. zi1 'vert'ieal bearing 4'4 `ingfposition es show/vn? 'the-up' -43wju'st1cl`ers the-pth'offshiftin' if` 'shifting :rodY 20' is 'moved' to" itsoperative position by -moving'V shifting lever' 211 "to'f its position 21 shown in `dot-andedash"lines it `becomesimpossible S'tom'ove lever 27 to its 'own 'locking position because said rod` 2O is then #L trifu'gall device 30 is at the 4time inoperative,

:position'vvhen pin'4`1`n`iey snap-into'fits'retainmg position( preventing return movement oi leverj27 ;V and et thes'alrnetinegbar. 43 Will be impossible to operate the belt shifting means. If lever 37 is left undisturbed'in the position where it .retains lever 27 in itsunlocking position, the cover can be opened with the full assurance that the machine' cannot be operated; however, as stated before, it still is pos'- sible to deliberately orl inadvertently fOr/ce lever 37 downwardly while the cover is in its open position, thus releasing lever 27 and making possible for the belt shifting means to be moved to their operative position. v In order to prevent operation of the shifting means under these conditions, I provide said cover with means adapted to interlock with the lever shifting means the moment said-'cover is even but slightly open, said meanspermitting-movement of said cover to its fully opened position, but in the meantime preventing operationg'of the vbelt shifting means. 1 f

To jthis end,.the shifting rod' is provided with -a forwardly projecting vfinger 53 which is'shown attached to the-hub 54 ofi-fork 19. Said finger is formed with a segmental-portion 55, which is coaxial with pivot 56-of hinges`12, and the cover is provided with an outwardly extending plate 57 -whichxis flush with the outer end-of segmental portionV 55V of finger v53 when the cover is fully-closed and which is provided with an opening :58, registering with said segmental'portion.

' By virtue of thisarrangement, the moment c over11 iseven but slightly opened, finger 53 will interlock with opening. 58 and movement ofshifting rod 20 to its operative position will be effectively prevented. Y However, the cover 'can be moved to its fullyopen position, because as fstated, segmentalportion 55 is coaxial with its pivot 56 and as long as the cover is partly or fully open, the vbeltrshifting means will be retained in their inoperative 'position. 'f f- It is thus seen that by virtue of the arrange- Vment described, absolutelypositive means are provided', insuring safe handling of the machine at all times. It is obvious that the inventive ideak constituting vthe-,essence of :my

invention can be carried out in waysother than that described, this practicallyiinvolving only ordinarymechanical skill. :In support of this contention, in Figs. 4 to 7, I illustrate another embodiment ofmyinvention which I will now describe.

In'the same 60 designates'the body of the machine,l61 the cover hinged at 62 to said body, 63 the countershaft, 64 the main drive pulley and 65, 66, the tight 'and`loose'pulleys, respectively. The cOunterShaft. is driven by a drivingbelt 67 and is provided like in the .previouscase with av centrifugaly'device 68, the action of which is to; forceoutwardly push member 69 when said countershaft rotates at.

asufticiently high speed. 1

The cover is ,provided at its front end with yforwardly and downwardlyprojecting exten'- sion 70 formed with a laterally extending lug 71 and terminating'with an outwardly. projecting lipV 72. c y f AV latch 73 is pivotally mounted onto the body ofthe machine at 74 and is formed with an arm 75 connectedl by a tension spring 76 to body 60 at 77. VvThe action of said spring is to hold the .latch into engagement with lug 71, as'clearly shown in Fig. 6.

Y i' Directly underneath lip `72, the body of the machine vis provided with ltwo lugs 78, 79, within which slides a plunger member 'impelled against the underside of lip 72 by the Inpractice, I prefer to make the spring 81 vstr'ongenough tovforce the cover open to a certain extent when latch 7 3 releases lock 71. This can be done by means of ai lever 83 providedvwithV aV handle 84 and mounted on a shaft 85, sai-d lever being connected at 86 to the latch member by a connection 87.

Shaft v is rotatably mounted in a horizontal bearing 88integral with -a plate89-se`- Vcured to the side of body 60 by' means 'of screws 90. Shaft 85 is therefore madeto run from front to rear, and at its rear end, itcarfrieslan upwardly directed lever 91, the' free end ofwhich 92 abuts against push member 69. .The hub 93 on'V said lever is also formed l'with a downwardly extending arm 94, saidk armbeinginits turn connected toa downwardly directed arm 95 of ai crank'lever 96 pivoted at 97 tothe'body of the machine, by a connection 98. Said crank leveris also pro- -v'idedwith another lateral extending arm99 which is connected by a link 100 to a vertical- 'ly 4movable bar 101 slidable within a bearing 102. v

Like in thelprevious case, bar 101 can be moved in avertical direction right in the path of belt shifting rod 103, so as'to prevent the movement of said shifting rod to operative position when bar 101 occupiesits downward position shown inthe drawings, and in this case, upward movement of bar 101 `will be prevented by said Ashifting rod.

' The belt shifting rod is operated by means of a leverl04 pivotally mounted at 105, at one sidev ofthe machine and provided with an operating handle 106." Said shifting rodcarries a fork 107 engaging the driving belt in the manner previously described, and the hub portion 108 of said fork'carries a curved finger 109 concentric with pivot 62', terminating :at a point Vclose tothe upper surface of a plate 110 secured on cover 61. Like in the previous case, yplate 110 is providedwith angopening 1,11 whichregisters'with the free end of inj i gervlOQ-Whensthe shiftinggrod -isfin i'tsinojp'f Vbeltk shifting means:- isfthereby' prevented. Y The A drawings represen-t1 the; machine at `the time- `when l the. driving. belty has been. shifted ont'ethe loose pulleyand the `Inachinerstill ro tetes. at relatively highispeed :due to' its own momentum'.

Under these# conditions, .pnsh member 69- rests against-,end921of lever 91 retaining said leverin its outwardposition-and therefore tending to'ietainlatch-73m itslocking positioiildueto the actionof lever 83-vandfconnec tion 87, supplementing this; the action of spring 76; Aslong-.aspusli-member-69=rests the left `of its locking position shown in t e Ymayr entier-faul?mtothevscopeotherap;

against lever-9l With suiiieientfforee, it is impossible :te operate lever-'183 by means of hanl .20

die-84 se as to release ilo'ek 171 Vfromlateh 73.5

.As-soon lastheL speed lof the machine', andi therefore of A, countershaft 63 becomessu'ili# ci'ently'A low", l-itbeeoines f possible to". operate lever '88 so -as to'fmovelatch73 outwardly and it is then -possibleto lopen tl'ie cover; the

initial `angular movementfof said cover in theV opening direction asfstated, being preferablyeected `-by the action of" spring 81kagainst plunger member'SOL y Y 3 f Plungermemb'er SOLJWill lthenf aequirev'a position where latch 7 3 `is `held somewhatjto drawing, preventing return-of said latch [to loclringpositiong; at Ithe `Sametime -duelto connectionI 87, also lever 83 and shaft 85 will' be Vlheld'f in angular position slightly displaced in- 'a clockwise direction -froin-z Athe positionshown in thefdrawi-ng. f v Y f Wl'ieiii shaft 85 is angularly displaced in" acloelrvvise direction-in` order Ito release latcl-l 73; armJ 94 lyis' moved in vthe 'same f 'direction `causing outward displacement offlink` 98;,l

and' causing `upward movement offarm'f'99 of crank lever 96';` therefore; l'mifwllllA will vshifted to affposition lwheiemovement" of shifting, rod 103V .to 'operating plositibnL will be prevented; Y i

ne Semanasfeiovantfwiiiiigoybeee ventedv` asf an 'added'precaution;v 109 Y whichI interlocks' 'xwitlfi"plate'f1'10;"` because also;` in vthis j' case; it-l is ""cneeivable that plunger member" 8O might: inadvertently or l maliciou'slybe forced idovvnwardlyso i as? to t operateuthe belt sliiftingfinean du i760 Combined., acties pm fthe 10;V i 'fand v When operation of fthe Y Y resumed, the covenisf lowered .toE its closing,

positionrand;` slightly before ithe closing po`V sition is reached lip Z2wllmeet theupperA if to-*drivethefniaohinei ,Y i". FWilLtheI-eOe 'be' 'observed that:i inithis, `like in theprevioiisease, absolutely 'safe con;

tendr-plunger memberfpSOffandfvvillforce down said plungerrmemberzagainst'the ace 1 tionY of Aspring 8l; at the lsametime, thelovver t right hand surface of lat-ch 78,3 which fvvillbe ferced .entwarfdlyfby theeiisuing,came-action,

clesed position, latch 7 3 is freeto snapfigintor engagement@ with* lock 71-z securely/f; locking cover-i, l

Only vvlienithis taires laceg'itwi'll -loee'oine possi-ble' tojoperate n the ilbelty shifting' means .because bar-101 Will reach;V its lower position` clearingpshiftingprod l03xonly` whenelatch 73freachesits locking,- position-z; V:andV fat, ,the Vsametimefingery 109' iwillu'be :entirelyfclear of plate lll), so-that` powerx can' be"appliedY diie'rent fromf thosefsho'vvnf; il# accordingly reserve :myself theyri'ghtfffto' apply my` ini vention in all those WaysandV manners Whichpended' claims? 'f I clfairn: 'Y ,-1. f lIn a maehinef'of )the class;t describedgthe coinbinatioiiwithfa body,` afic'oveit therefor, rotatable elements` mounted :on said;v body,

Itis obvio-.us therefore' i that;any#inventiveV idea; may, be carried into `pra'eiride inf-Ways infl their inoperative' ,Y

pol-Wer`V driving.i meansv therefor, "and imeans i v controlling fsaid drii'fifng means,- ofxinanuallly releasfalole;V mean'sf5adaptedf, to; automatically ingmeansin their]inoperativepbsition# and means-associated Witlisaid fc'oVFei forcingsaid retainingsmeansfout of'engagementWiilrsaidl lockingmeans,-releas1ngthe'same,:when said l Y cover is movedtolitsclo'sed-ffposition,"said 4' t Y Y ,115

retaining means' automaticallyHT resnming theiri i retainingposition when:said` 4locking means .aremovzed 4to: their:` inoperative posi its f @mesdames 11m-mnei ensenada Power dnrieefnee thereon-eed i means i controlling said driving; means,` of 'manually releasablemeans .adapted'lto automatically locklsaidfcover .in its'. ,elosedv n-Ipo s'itifonl Avvlien said'gcover reachessaid position, sprin actuatedj-Ameans normally retaining,said, cel--V ingfm'eans'-infth irginopgeraeve'pesi/asa,

"iso

said retaining means out of engagementlvvith said locking..means, releasinosame, When xvid cover isinoved to its cljosed position, said retaining means 'automatically resuming ,their retaining position, forcing said cover out ofits closed position, When said locking means are movedto their inoperative position. v p

3. ;In a machine of the class described, the combination with a body, a cover therefor, rotatable'elements mounted on said body, power driving'means for automatically locking sai-d cover in closed position, means for retainingv tatable elements mounted on said body, power driving meansvtherefor, `and means controlling saidy driving means,`of means for automatically locking said cover in closed position, means operativelyassociated With said locking means preventing movement of said controlling meansto their'operative position, when said locking 'means are in their inoperative position, and means releasable by said cover, When said cover is moved toits closed position,` normally retaining`v sai-d locking means in their inoperative position.- f f 5. In a machine ofthe lclass described, the combination With a body, a cover therefor, rotatable'elements mounted on said body, power drivingmeans therefor, yand means controlling saiddriving means, of manually releasable means adaptedto automatically lock said cover in its closed position when said cover reaches said position, spring actuated means normally retaining said locking means in their inoperative-"position, means associated with said' cover forciiigsaid retaining means out of engagement with said'locking means, releasingthe saine, when said cover is moved to its closed position, said retaining means automatically resuming their retaining position Whenl'said l'ocliingmeans' are moved totlieir inoperative position, vand said: cover` isV disi placedV froinits closed position, and means associated with 'said`cover, preventing the movefment'of saidicontrollingmeans to their operfrom its I fully closed position.

ative position, "Whenf saidfcover isi displaced combinationivithia'bo'da lcover therefor, rotatableelements mounted on-said body, power driving" means therefor, and means controlling said driving means, of ns'ianuall'y releascover in its closed position When said cover reaches said'position, spring actuated means norina-llyrretaining said locking'means in their inoperative position, means associated With saidvcoverforcing said retaining means out of engagement with said locking means, releasing the saine, vWhen said cover is mov-ed to its closed position, said retaining means automatically resuming their retaining position when said locking means are moved to Atheir inoperativeposition, and s'aidcover is displaced from itsclosed position, means operatively ass ociated With said locking means preventing movement-ofsaid controlling means to their operative V position when said locking means are-in their ,inoperative position, and additionalvmeans, associated with said cover, preventing V-the movement of said controlling means to their operative yposition When said coveris displaced fromV its fully closed position, independently of lsaid operatively associated means. i, s Y v Y v n 1 7.V In amach'ine ofthe class described, the combination With a body, a cover therefor, rotatable elements mounted on said body, power driving means therefor, and means controlling said driving means, of means for automatically locking said cover in closed position, means operatively associated With said lockingvmeans preventing movement of said controlling means to their operative position, when said locking meansare in their inoperative position, ineansreleasable by said cover, When said `cover Vis moved to itsfclosed position, normally retaining said locking means in I their inoperative position, means operatively associated with said locking means preventing movement of saidl controlling means to their operative position -When said locking means are in their inoperative position, and additional meansA associated `with said cover, preventing; the movementy of said controlling means toftheir operative lposition When said cover is displacedfroin its fully closed positionindependently of saidoperatively assosV l.,

ciate-d means ,Y

K 8. Infa machine of the class described, the combination ivvith abody, a cover therefor, rotatable :elements mounted on rsaid, body, power driving means :,tlierefor, and means controlling gsaid driving means, of means for automaticallylocking said coverin closed position,1means operativelyassociated with said locl'iingmeans preventing movement of said controlling means to ytheir operative position, When saidvlolcling means are in their inoperativeposition, 'and preventing return of said locking'means to 'thei-r, inoperative position s V'when said 'controlling'm'eans are in their op- 6."`In1a machine of the' `classdescribed,'the y power driving means therefor,

. L said controlling means to their operative position, when said lockingine'ans are in their inoperative position, and preventing retiirnV of said locking means to their inoperative position when said controlling means arein their operativeposition, means releasable by said cover, when said cover is moved to its closed position,'normally retaining said locking means in their inoperative position, and

means to their operative position" when said locking means are in their inoperative position, additionalv means associated with said cover, preventing the movement of said controlling means to; their Y operative position ywhen said cover is displaced from its fully closedposition, independently of said opera-iV tively associated means, and means operative ly associated with said. rotatable elements,

preventing movement of said locking meansV from their operative to their inoperative posi,-

certain speed.

CHARLES TERWILLIGER. Y- N means operativelyassociated with said ro-fV tatable elements, preventing movement of said lockingmeans from. their operative -totheir inoperative position, when said rotatable lelements rotate at a certain speed. r

Y l0. In a-machine oftheclassdescribed,theV i combination with -a bod rotatable elements mounted on said body, power driving means therefor, and means controlling said drivingmeans, of manually releasable' means adapted vto automatically `lock said cover in its closed-position whensaid cover reaches said position, spring actuated A means normally retaining said locking means in their inoperative position, means associated with said cover forcing said retaining means out of engagement with said locking means, releasing the same, when said cover ismoved .to its closedposition, said retaining means automatically resuming their retaining position when said lockingmeans are moved to their inoperative position,vand said cover is displaced from its elosedposition, and means operatively associated with said rotatable elementspreventing movement ofsaid lock'- ing means from their operative to their inop# erative position, wh-en said rotatable Y elements rotate at a certain speed. y

, a cover therefor,

tion, when said rotatable elements rotate ata l1. In a machine of the class described, the p combination with a body, acover therefor,

rotatable elements mounted Von said body, n power driving means therefor,`pand .means controlling said drivingmeans, of manually releasable means adapted to Yautomatically,

lock said cover in its closed position when saidV cover reaches said positiomspring actuated means normally retaining said locking means -V in their inoperative position, means associated withV said cover forcing saidretaining means out of engagement with said locking means,

,releasing the same, when said cover is moved to its closed position,said-,retaining means automatically resuming their retaining posi;` tion when said locking means aremovedto their inoperative position, and saidfcover is- Ldisplaced'froin its closed position',means operatively associated with saidlocling means if preventing movement of said Vcontrolling iso

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