US1829656A - Lifting jack - Google Patents

Description

' LIFTING JACK Oct. 27, 1931. V A. L.. JOHNSON 1,829,656

LIETING JACK Filed Aug. 24, 1927 2 Sheets-Sheet 2 IIII Z9 Y 14 m lllulmz lvm /////////4/////%ri s Patented Oct. Y 27, 1931 umTan ,STATE/s rATENT, OFFICE ALVIN L. JOHNSON, ork WORCEsTnR, MASSACHUSETTS, AssIaNor.l Tov WALKER MANU- t FACTURING CoMrANgor RACINE, WISCONSIN, A CORPORATION or WISCONSIN LIFTING JACK A FAppiicationmed August 24, 1927.' serial No. 215,103. y

` A il his invention relates to improvements in av lifting jack adapted to handle heavyT loads, and having a low clearance when depresesd and a comparatively high lift when elevated.

double ratchet-bar vtype embodying aY pair of telescoping ratchet bars which are successively elevated or loweredby `a reciprocating pawl mechanism.y V

The principal object of theinvention is to lprovide an improved jack of the double ratchet bar type,as disclosed more in detail in the description which follows.

Another object is to provide improved ingthe inner ratchet barwith respect to the outerratchet bar, when this inner ratchet bar is extended vertically from its telescoped position yWithin theouter bar.

Another object is to provide an improved form of locking pawl adapted to sustain the ratchet bars in any of theirelevated positions without releasing the locking means' between the two bars.

Another objectA is tosprovide an improved form of driving/means for operatingthe lifting pawl, comprising worm gearing and rotary cams whereby a 'greatly increasedmechanical advantage .is obtained adapting the A,

jack for handlingfheavy loads. Y

Numerous other objects and advantages of this invention will be apparentfrom the following detailed description of one approved form of the apparatus.

n the accompanying drawings: Y Fig. 1 is a perspective view of the assembled jack with the ratchet bars in their completely lowered positions.

jack, parts being broken'away, showing the y ratchetbars .in lowered position.

Fig. 3 is a view similar to 2 showin kthe inner ratchet bar completely elevated and the `outer ratchet bar-partially elevated. Fig. 4 is a view similar to Figs. 2 and 3,

' but illustrating the jack at that stage ofthe lcweringoperation when the outer ratchet bar has been completelyV lowered and the inner bary has. just been unlocked so, that it mayy `belowered the outer bar.

tially on ythe line 5.-5 of Fig. 2.,

Fig. 6 is a vertical section taken substantially onthe line 6-.6 of F ig. 2. f The improvements relateto a jack of the The-standard l consists of a hollow casting which maybe made up of any number of partssuitably secured together for convenience in machining and/assembly.y vAs khere shown, the standard consists of a main casting 2, aback plate 3, anda cover plate 4 that may be removed to permit access to the operating mechanism. A ratchet bar 5 of rectangular cross section is guided and sup- A Y y ported for vertical movement within a Corre- ;15 means for automatically locking and un1ock.v

ard, and side ribs guided in slots 7 inthe standard support the ratchet bar against tilting into the open forward portion fof the housing. An inner ratchet bar 8 fits telescopically within the outer ratchet bar y5, the

I inner-bar having side ribs 9 guided within vertical grooves 10 in the ratchet 5. Ratchet teeth-11 having horizontal lower faces and downwardly sloping upper faces are formed along the front side of the ratchet bar 8,

vandcorresponding teeth 12 are formed in the 4*two forwardly facing side portions of the outer ratchet bar' 5.- When the two ratchet bars are telescoped, as shown in Fi 2, the

'ratchet' teeth 11 and 12will be in alignment acrossthe entire forward face ofthe .tw 'telescoped bars.

` Ina housing or pocket 13 formed in an eX- Vtension 14 on thel upper .rear face ofthe outer f ratchet-bar 5, is a pawlor dog 15 pivoted at Fig. 2 isa vertical section-'through the j 17 so that the nose 18 of the pawl will normally be forced against the rear face/19 of the yinnerl ,ratchet bar 8. When the inner ratchet bar has been elevated to approximately the position shown in Fig. 4, thedog ,15 will spring outwardly into the notch or standard (as shown in Fig. 3) the load sustainedby the inner ratchet 8 will be transon the` bars'when the ack is being elevated,

mittedr through locking dog v to' theouter ratchet bar 5 and thence through the pawls yextending tooth 23 at the upper endofpafwl v2l lis'of a width ysufficient to engage both sets of ratchet teeth 11 and 12 onv the respectivel `Vl`W'ardly,atei, -hasiaV second upwardly extendbars 8 aindv. Alsmall'notch24iscutout 0f hereinafter described. The lifting p'awl 25 shorter arms otapairotsimilar operating .levers 27 and 27".v` A transverseshai't 28,'p04

" siti'oned `substantially beneathr the shaft 22,

Y is, pivotedat'rits ends inv the"V side, walls "of r'261 thecalsing 2, and is'intermediately supported "in abossor lug 29 projecting upwardly'ffrom lthe bottom orbase portion' 30 ofthe standard "or Y' casing. The Operating levers-27 and 27 areeac'h intermediately pivoted on thisshaft 1:25 28, at the two sides of the lug 29 vand 'between 1 `thisflug andthe side walls otY the casing.. 'transverse "shaft 31, also mounted in the-side "walls, of casing 2, carries arotatable unit cnsisting :of centrally' positioned Yworm 'j wheel, 32, and a-vpairfofsimilar circula-r cams 33 a'nd 33 V"similarly positioned eccentrically I tothe .shaft 31 fat'jthe'twn sides Ofthefworm y "wheelf32-'W' Thefworm v.wheel 'and cams yare'. securedjtogether to rotate asa unit.y "A'driv- 4` 'finggworm 34 Yis 1mounted on an upwardlyinclinedfvdriv'e sha'ftv35`, pivoted at Lits lower inmerende@ metering-29, and having a bearing where it projects throughthe front wall oi'V the vhousing in a cover plate 37.. Theouter 'end38 of the shaft 35 has a squareo'r other irregular cross sectionadapting. it forengage- Y inent'by anoperatin'g crank or handle. It

vwillbfe apparentthat .r'otationof thesha't 35 fjtheupper side of the longerarms 'of levers 27 fand27, `the'rotation"ofthe cams will causeV the levers to be oscillated about their `fulcrum the central portiono` to'oth'23 for a reasonfe and for alternately moving these 'pawls into v.and outofengagement with the teeth when `Y`'the jaclri'sbeing lowered. TvVhile many diiferent forms of reversing mechanisms might fbelused andy are well kn'olwn in this art,ithe s, simple form here disclosed comprises a spring I 1:39 whichis secured4 at one end l0 to the upper end-p'ortien offlifting-.pawl 25, is bowed downsmallcam lever proj eets outwardly through raj slot 15 in the cover plate 4. lVhen thislever i 2111 is moved'tofthe'position'shown in Figs. l, 2

. and 3,- the cam Yportion 46- adj a'cent4 the 4lower end ofthe lever "will bear upon the project# ingrarm 43 ofthe spring invjsuch a manner as lagainstfthetension voie the springl 3 9. `Whenf liftingpfawl" 25` is moved downwa'rdlyjby the i :to place/"allvv portions of 'the'spring 39 under? tortionsoth'atbc'th p'awls 21 and 25 will be held yielda bly in engagement withthe ratcheiY the ratchle'tfteeth on oneiof thebars and carry the Vba,rupwardly with it? During this move- 'wment ofthev bar thefl'ocking ypawl will spring outwardly *i over-fthe y ratchet`v yteeth lopposite swingingfmovement ofthe levers n 27 andV 27, 'thispawl .will"snap'ov`er Vthe 'if A second torsio'n'spri either` direction) will, through the worm? fjgearingt and 32,cause Irotation of the cams' '133 find33f.V Sincethese cams engage against 4shaft l2,8, thereby causing 4the lifting fp`awl`25 Y `fto be reciprocated up'jand down substantially V,vantage for operating the levers L27-and 27,

Other pwer-multiplying j parallel with theftothed'faces di the'bars :55 and'S.l `'llhe'worm andcam mechanism just described constitutes a simple'andeflect-ive imea'nsfor securing valarge mechanical ad- ]teeth bythe Spline 39S! 1*.

ng47 is anchored at 48 ratchet teeth'but the .bars will not be per# mittedto descend since the'locling pawl 21 i willi 'be held in engagement "with, one of theL on the upper 'end @flocking pawl 21, and has alower end @pressing outwardly against the pin 'on liftingpawl WV hen the spring 39 is held under tension, as shown in Figs. 1, 2-and 3, this spring 39 will overcomethe spring Il? sol -as .to continuously hold Athe liftingjpawl yieldably :in engagement with theratchet teeth. -Vhen the cam lever le is thrown tothe reversing 'position shown in'fF-ige, the tension Von spring" 39 will be sofv released that when lifting' pawl: 25 isin its"lowermost position,` the spring 47 will be effectiveto'rmove; this pawl eut ot engagementwithltheratchet teeth I an'dfhld ut,biit atthis timethe spring willho'ld the locking paw'l k2l Vin engage- Vmentwith', the ratchet teeth. "As the liftingy pawl: 25 iis 'moved upwardly, it' will be held out ofengageineiit "with thefteethuntil it nearstheupper end ot its travel, at which time the 39 V'will becomergfeffective to movethe 'pawl 25 into engagement with the ratchetiteeth and as the i'urther vupward vmovethe longer arms ofthelevers 27 and 27. Y Asui'ta'ble reversing mechanism `is 'pro' 74j-fvi'dedforheldingjboth pawlsr21 and 25 yield* i ment 01E-'thisl pawl slightly elevates ,the'bars thesloa-dffwillloe-released fromfthe locking lpawi231 and the spring'39 will now bel'under sucli'tension Y as to thrown-.this` locking-pawl Lback' out of 'f len-gag'er'nent i with the ratchet meer, As" the-'paal 25 is lowered, itfwill re- Yteeth onlthe litingbars.f-f stheliftin'g pawl is moved upwardljit willfengage one ofV inesatte j in yengagarre-nf; 'with' the' mana-teeth carrying theA loadand the loclringzjpawl 21 f'willgnot be moved back into engagement with theratchet teeth until thepawl 25-has neared l,the lowervv limit 'of its travel. At'this'point Ythe springs will become 'effective to move the "ment with the teeth. vIn this'manner, succesfsive reciprocationsiof the lifting' pawl will "result in successive downward movements ythe bars which carry the load.`

rlhemechanism whereby `*this continuous operation of the lifting and-locking p'awls'is inade effective to successively elevate or lower y the inner Yand outer ratchet bars V20 8 and 5, will now be described-` v Y f The pawl 25 is provided with along central.

" tooth 50 to engage the ratchet teeth11 of inner bar 8,'this 'tooth 50 being of insufficient width to engage the teeth'12 onbar 5 at either side'of the teeth 11. Pawl 25 also has a pair of aligned teeth 51, oneat Yeither side of tooth 50, adapted to engagethe teeth 12 on the telescoped within the outer bar 5, as in Figs.

" s 2 and 4, the engagement-of the central tooth 5O.with the teethfll Aon the inner bar will preventtlieengagement of the'shorter teeth 51 with the teeth 12 on bar 5. yHowever, `when Vthebar 8' has been elevated, as shown in Fig.

3,*the central Vtooth 50 will bepermitted to pass into the slot formerly voccupiedby the l bar 8, thus permitting the shorter teeth 51 opening at its lower end intor thespacedito come into engagement with thev teeth 12 on the outer bar 5. v Y

Positioned diagonally within the lower end portion of the inner bar 8v is a channel52,

j rectly beneath the lowermost tooth 11, and

opening atits upper end into the recess 20. ,A multi-part plunger is positioned within the plunger will be limited by the engagement "ofthe larger head? portion with the bottom AratchetV tooth 11, unless it is engaged'and` moved upwardlyl by the tooth 50 on the lift' of the larger channel' section, as shown-inl Figs. 2 and The plunger will' normally4 Vremain in this position with the reduced end portion 56 projecting'beneath the lowermost ing pawl. When 'the plunger'is pushed upplunger partv 54 willengage the dog 15 and yAssuming kthat thek :jack is completely ratchet t will expand to throw out thedog 15 as soon as the load ris released from this dog. The central'notch 24 in the locking pawl 21, as hereinabove referred to, is provided for the purpose of clearing the lower end 56 of this;l

' plunger' so that the locking'A lpawlcan engage thelo'wermost tooth on the ratchet bar 8, and corresponding teeth- 1-2 on the outer ratchet bar without operating the dogreleasing plunger. I

lowered, as shown in Fig. 2, and that cam lever 44 has been moved to the elevating position, successive reciprocations of the pawl 5.25 willcause'the central tooth 50 toV successiye'lyfengageteeth 11 of the 'inner ratchet Y' bar `8k and 'litt this bar upwardly, step by step,

the 'bar' being held in each successively elevated positionv by thespring 'pressed locking pawl 21, which` also engages with the teeth 11."` Enlarged recesses 5S above the upper-most f teeth 12 on the'outer bar 5 permits freedom of movement to the pawl 21 in `engaging and re-engaging the successive vteeth 11 on the inner bar 8. Vhen the bar 8 has reached a suiicient height, the spring-'pressing dog 15 n *will snap into the locking recess 20. Further outer ratchet-bar 5.` yVhen therinner-bar 8 is f reciprocations. of the pawl 25 will cause the outer teethV 51 toengage the teeth .12 of the outer ratchet bar 5,thus` elevating this bar' Yfromv the'standard, carrying'bodily upward with it the inner bar Sand` the load sustained thereon, the two bars being locked to operate as a untby the spring pressed dog 15. This position'of the parts isshown in Fig. 3,

although the jack is not completely elevated, as shown in that view.

When cam lever 44 is thrown tothe position shown in Fig. 4, and the pawl 25 is reciprocated, the outer bar 5l will be lowered step by step until the position shown in Fig. 4 is reached, at which time the inner pawl tooth v will 'engage the lower tooth 11 on the inner y barB and at the same time'4 will engage the lower end 56 of the plunger and press this plunger upwardly, compressing thel spring 55. The outer bar 5 is now completely lowered-and the slight upward movement of innerbar 8 as-the pawl 25 lifts upwardly on the lowermost 'tooth 11, will release the-uy load from the dog 15, and the compressed spring will throw this dog backwardly out of ythewnotch 20, as shown in Fig. 4.5 Thefsucceedin'g downward movement of pawl 25 will lower the inner bar 8 into 'the outer bar 5, the plunger 57 holding the dogk 15 out of the recess 20 until the dog engages against the rear face 19 of the bar. Successive reciprocations ofthe pawl 25 will simply lower the inner ratchetbar 8,' the outer bar 5 now-- being inactive and serving simply as a guide y I and supporti for the inner ratchetfbar.

,n push it out ofthe locking recess20, providi 'fing the dog15 is free to move at this time.

llf not,}the spring 55' will be compressed, and

It will be noted that during the' elevating cperation,"when` the inner bar 8 has reached the engagement. et. the lifting peevvl iviththe plunger 'Will-temporarily vtend to ihold ,they

Vidog, elitof'the-vleoking reCeSsQO; Hewf. ever, .onthe-nextdownwardmovemeiit ofthe A pavvl the bar 8; will be heldin its vraised position bythe loclrngpavvl Q1 Vand assoonas the plunger 56 is released bythe vdevvnvvard,,IV ymovementof Ypawl 25,*the dog lrfi'vvillflee* f moved -iIlto the IeCeSSQO by the spring :17.

The nextupward stroke of pavvl 25 Willcause VIVthefteeth 51 to engage, certainteeth-A -12 on the oted lockingpawl and a vertically yrecipro- Heating-lifting paw-l mounted to engagethe teeth on theibars, and a 'plunger mounted 1 inone of the bars' and having a portion-pro-` jecting into `thespace y,adjacent theratchet teeth so that-it Wll'be engagedand moved lby the lifting pa-vvlto release Y .the dog, the

` "locking paWl being provided with a.,` cut- Y' avvay portion'to avoid engagement Withfthe y Vplungenl.I

i :30Y l 1 ratchet rhar guided for;verticalmovementfh f v A i the standard, a second ratchet-barguidedY for i .1112. 'A lifting] the standard, alocking; pavvl pivoted. in* .the

standard imposition 'to` engage the, ratchet teeth, ka lever-intermediatelyvpivotediin the y n y Y Y Y v y mentjWhen-the bars aretelesfcoped, a springs'tandard, a lifting p'avvlpivotallyinonnted on one one arm'of the lever infpohsitiontoengage thel ratchet-teeth, arcta-ry cam mounted Sin the standardfabo've the other arm-of the lever, andfmeans-'Yfor rotating the earn. A 3. A lifting jack comprising. a standard, .a ratchet barguided for'vertical movementin the standard, a lockingpavvl Pi-Voted in, thev standard' in position to engage the-ratchet teeth, a lever intermediately p'ivoted Vin the Y .'standard, a lifting pavvlpivotally mounted con.v onefarmk of the lever-inposition to engage Y' the ratchet teeth, a yrotagryeaife `mountedinthe standard :above vthe-other Aarm of the leVQF a' Wormwheel securedto-thecam, a rota/ry driv- 'A 'sof t 4Worm on thefshaftengaging the Wornrvvheel. 4. A liftingjack Comprising astandard,a

ratchet bar guided for verticalmovement in l i `rthestandard, a second-ratchet bar-guided for 55 ing'shaftprojecting from the standard, and a vertical movement Within th'erst har, the

ratchet teethfon thetvvo bars being in' align- .Y ment When thehars' are-,telescopech a springv4pressed .dog mounted in the'roiiterkbarfthe inner ihar` 'having a locking V'recess to receive the dog when -theinner bar is elevated to.. a..r,predeterminedpoint,a .locking pavvl piv- Yeted inithe'standard'for engaging the teeth ,ef either harto holdfthe fbars irfifelevzded,v positions, a lifting pavvlfpositioned ltoengage thejratehetteeth .and IllefillsV fQrre-V ack comprising aistandard, a

.ciproatig this.pawl,vertieally2 mid e; pli-111g- .errmonntedin the 4innerbar andhaving one y,end :projecting intoV the pavvl-engaging space beneath oney toothy .ofthe vhar and the other Vendiadapted to be Aprejected into the:

from. t Y Y A *Y i5; A lifting jack comprisinga standard, a

@ratchet bar-guided for yvertical movementflll fthe Standard, a secend ratchet bar guided for;v

.vertical movementV WithinV the lrstfbar, the pratchet teeth onthe twobars being in align.. ment when the bars are telescoped,a spring-Y pressedv dog I'hounted inthe'outer-leanA the innerl bar having. a locking recess to receive thedog Whenthe inner bar is elevated to a Y Av`rdog-receiving recess ,to Vrelease .the dog theref predetermined point, a lloclzingpa-vvl pivoted in:thestvandardl forl engaging thefteethjof' t either bar to hold the harsain ,elevatedl posivtions, a lifting paivll positioned toengage the.;

ratchet teethl and means Vfor[reciprocating v thispaivl vertically, and aplunger mountedY in theinner r'liar and `having one `end proje'cting into thepaWl-engagingspace beneath one tooth ofthe jbar and theether end ,adapted to be projected-into the dog-,receiving recess tofrelease therdog therefrom, the plungfer comprising two plungerfheadsand an vinterposed-,compression springt- 'v i i v6. Alftingjaclgcompri ng astandard@ ratchet bar. guided for vertical movement in vertical vmovement Within thev first har, the

et,l

ratchetteeth on the two-hars beingin alignpressed dogmountedintlie outer bar, the?l innerhar having a lockingrecess to Vreceive the dog when-the innerybarqiselevated to la Y predetermined point, aflocking pavvl pivoted n thefstandard .for engaging the teeth of either. bar-to hold the harsy in elevated positions, aflifting pavvl positioned toengage the -ratchet kteethand means lfor reciprocating this pawl vertically, 'and a plnngermounted 1n vtheinner har vand having oneend project- ,ing-into the paWl-engaging,spacebeneatli one l:tooth of ,bar and the other endk adapted itc Yheprojected into ktherdog-receiving recess yto-relea.se the deg therefrom, .the` 'locking pavvl-havmg ,a cut-away portion to .clear the a plungerwhenf-in AengagementWithithe adj acentratchetatooth.

spring-pressed dog moiinted in the outer har, the inner bei having aloeking recesst'o' receivejthe dog when therinnerb'ar is elevated to af predetermined point, a locking paWl pivotedin theistandard for engagingthe teeth of l either bar to j hold the bars inf'elevated posi- /tOIXSi a lifting Pa-Wl OStOIledt engagethei ratchet teeth and means lfor reciprocating this pavvlvertieally, this pawl having a long tooth to engage the teeth of the inner bar and a shorter tooth to engage the teeth of the outerA bar after the inner bar has been elevated, and a plunger mounted inthe inner bar and projecting at'its lower end into the space beneath the loWermost ratchet tooth on the barythe upper end of the plunger. being adapted to be projected into the dog-receivingv recess torelease the dog therefrom.

8. A lifting jack comprising a standard, a ratchet bar guided for vertical movement in the standard7 a second ratchet bar guided for 'vertical movement Within the first bar, the

ratchet teeth on the two bars being in alignment when the bars are telescoped, a springpressed dog mounted in the outer bar, the inner bar having a locking recess to recelve the dog when the .inner'bar is elevated to a v predetermined point,va locking pavvl pivoted in the standard .for engaging the teeth of either bar to hold the barsin elevated positions, a lifting pavvl positioned to engage the ratchet teeth and means for reciprocating this paWl vertically, this pawl having a long tooth to engage the teeth of the inner bar and a shorter tooth to engagethe teeth of the outer bar after the inner bar has been elevated, and a plunger mounted in the inner bar and projecting at its lower; end into the space loeneathl the lovvermost ratchet tooth on they har,` the upper end ofthe plunger f being adapted to beprojected into the dog-receiving recess to releasethe dog therefrom, the plunger comprising two plunger heads and an interposed compression sprlng.

ALVIN L. JOHNSON.v`

esY

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