US2476380A - Lifting mechanism - Google Patents

Description

July 19, 1949. R. F. MANKE.

' LIFTING MECHANISM 4 Sheets-Sheet 1 Filed Sept. 17, 1943 INVEN TOR.

July 19, 1949. v I R. F. MANKE I 2,476,380

LIFTING MECHANISM Filed Sept. 17, 1943 4 Sheets-Sheet 2 INVEN TOR. JZdgzr/a/Y/ F/fc.

July 19; 1949. R. F. MANKE 5,

LIFTING MECHANISM 4 Sheets-Sheet 3 Filed Sept. 1'7, 1943 July 19, 1949. R. FQMANKE 2,476,380

LIFTING MECHANISM Filed Sept. 1'7, 1945 4 Sheets-Sheet 4 Patented July 19, 1949 l LIFTING MECHANISM RaymondiF.

Manke, Racine, Wis, assignor to.

W alkcr Manufacturing Company of Wisconsin,

Racine, Wis., a corpora tion of Wisconsin 7 Application September 17, 1943, Serial No. 502,780

4Claims. (Cl. 254-23 V The present invention relates to lifting mechanisms, and in the herein disclosed embodiments, provides improved lifting mechanisms for use in plprtable jack structures, industrial trucks and the l (e. l

The principal objects of the present invention are to provide lifting mechanisms, which may be readily and economically manufactured and assembled and which are reliable and efficient in operation; to provide such structures embodying improved arrangements of lifting elements, which can be collapsed into a relatively small space, thereby minimizing the necessary height and length of the structure; to provide such a structure wherein a substantially vertical lift may be imparted-to a load engaging element by means of a power applying member which moves in a generally horizontal path; to'provide such structures embodying a lifting arm, which carries a load engaging element and which is both swung and moved bodilyv so that the load engaging'element moves in a substantially -linear vertical path; to provide such structures including supplemental lifting elements, herein illustrated as comprising inclined planes, which function during and facilitate the initial lifting movement; to provide such structures incorporating an improved arrangement of supporting wheels, which facilitates the use of thelstructure on irregular surfaces; and to provide an improved and simplified construction and arrangement of lifting mechanisms. J f a With the above aswelljas' other and more detailed objects in view, which appearin the following description andinfithe appended claims, preferred but illustrative embodiments of the invention are shown in the accompanying drawings, throughout the several views of which corresponding reference characters are used/to designate corresponding parts and in which:

Figure 1 is a view in side elevation, with certain of the parts broken away, of a portable floor jack embodying the invention;

Fig. 2 is a plan View, with certain of the parts broken away, of the structure of Fig. 1; Fig. 3 is a view corresponding generallyto Fig. 1, but showing the structure inthe fully and partially elevated positions; Fig. 4 is a view in vertical section, taken along the 'line 4-4 of Fig.1 3; V

Fig. 5 is a fragmentary viewin vertical section, takenalong the line 5-5 of Fig. 2;

Fig. 6 is a fragmentary viewof a bodiment of the inventiqm;

further em- Figs. *7 and 8, are YlEWSg respectively, in side shields 48 and 50,

elevation withcertain of the parts broken away, and in horizontal section, of'a further embodiment of the invention; and f g Figs. 9 and 10 are,respectively, views in side elevation and in plan,'with certain of the parts broken away, of an embodiment of the invention which, corresponds generally to the embodiment of Figs. 1 through "5, with the exception that a different powerapplying mechanism is used.

It will be'appreciated standing of the preslentihvention that the improvements thereof may be embodied in lifting structures intended for widely differingus'es, and incorporating widely differing structural arrangements. Preferred applications of the invention are in connection with floor jacks, industrial trucks and the-like, and in an illustrative but not in a limiting sense, the invention is so disclosed herein. A

Referring firstto Figs. 1 through 5, the illustrated portable floor jack comprises generally a frame structure 20, which is supported by a series of four wheels 22; a lifting cap 24, which is carried at the forward end of a lifting arm 26, for movement between the retracted position shown in Figs. 1 and 2, and the fully elevated position shown in Fig. 3; and a power applying element 28, herein illustrated as a conventionalghydraulic ram and pump unit, which responds to rocking movements of a usual-handle structure, 39;."

The frame 20 is constituted by a pair of longitudinally extending, laterally spaced, similar, but oppositely presenting members All and 42, which, as best appears in Fig. 4, are of channel-shaped form throughout the ,major portions of their length. Adjacent their fronten'ds, the members 46 and 42 are formed to define hoods 4t and 66, within which the front wheels 22 are conventionally received. Adjacent their rear ends, the members 40. and 42 are provided with similar which, respectively, receive the rear wheels 22. As will be understood, the rear wheels 22 may, if desired, be carried by swivel arms. The members 40 and 42 maybe maintained in rigid unitary relation to each other in any suitable way. As shown, this is accomplished by front and rear stay bolts 52and and by the base 56 (Figl 4) of .the hereinafter described fixedplane 58. .Thebase. 55 is secured to the respective members M and, 42 by corre sponding pairs of studsiGlL, c .1

The lifting arm 25..sco1'1stituted bya. p-airof laterally spaced legs 'lflQand 312,1 which are connected together, thr dllghmlt a portionv of their length, by we ge: 'Tliel'front ends of the legs from a complete under- I 70 and 12 are pivotally connected, by a pin 78, to a cap adapter 18, to which the cap 24 is rotatably secured. The rear ends of the respective legs i8 and 12 are provided with rollers 80, one of which is shown in Fig. 2. Each roller 80 is rotatably journalled upon a pin 82, and is supported in place thereon between the enlarged head of the pin and the outerjfaceof the corresponding arm I or I2. Each'pin 82 is provided with a reduced inner end, which passes through the corresponding arm or 12, and also, through a reinforcing plate 84, carried at the inner side of 'such'arrn. As will be understood, in assembly the .pin is passed through the arm and reinforcing plate, after which the inner end of the'pi-n is radially enlarged to retain the parts in assembled relation.

The respective rollers 80ride in grooves or guideways 90 individual thereto, one of which is shown in Fig. 5, as comprising upper and lower portionswhich are integralwith and project inwardly from the w'eb ofjthe side frame member 42. The guide'or runway for the roller associated with arm 10 is similarly arranged, as will be un= derstood; As alsoappear's in'l ig. l, the front and rear ends of the'runways. 90 are closed, so that these runways may beiutilized to limit the extent of movement of the'reflar endof the lifting arm 26.

The liftingjforceisapplied to the lifting arm 26 by.meansl'oflaterallyspaced, radius or stabilizer arms I00 and;I;02'. The lower ends of arms I00 and' I02arejpivotallyconnected to the frame by means .of the prev'iously mentioned front tie rod 52, whichr nay, if desired, be provided with spacing sleeves or;other means to maintain the arms I00 and I02jinproper position lengthwise of the tie rod; Theupper endsof the arms I03 and I02 are pivotally, connectedtothe corresponding legs"10"and12' of the lifting arm 26, by means of pins I04. and I06. The pin I06 is shown in detail inFig Z and pin. I04 is similarly associated with legln anda'rmi I00.

In order to stabilize the 02.1324 and maintain its upper surface in" .a substantially horizontal position thro ughout"the travel of the lifting arm 26, a pair of similar; laterally spaced stabilizing arms' I I0 and H2, are 'pivot'ally connected at their outer ends tothe ca'p'adapted I8, as by pin IM, and are pivotally' connected at their inner ends to the corresponding radius'arms I00 and H12, by pins IIGand II'8. It will" be appreciated that the pivotal connectionsgof the'lifting arm 26 and the s'tabilizingarms I'I Band I I2 to the cap adapter I8 and totheradius'arms I00 and I02 are so located, relative to the paths-of movement of the lifting arm and-the'ra'dius as to maintain the cap 24 in a substantially horizontal position throughout its travel. a

The lifting force i's appliedto the radius arms I00 and I02 by means eithe head I20, which operatively engagesa roller I22. Roller I22 is rotatably supported upon the pin I24, which is secured to and extends between the radiusarms I00 and" I02. The head I isrigidly secured at the outer end of theram' I which, in the embodiment now' being described, constitutes the piston rod of the previously mentioned hydraulic ram and pump unit 28'. v I

The unit 28 may be and preferably is conventionally constructed'and, consequently, does not require detailed description, It is noted, however, that this unit comprises rigidly interconnected cylinder andv pump portions I32 and I34. As shown, the pump structure embodies both speed and power elementsgvvhichgin turn, are provided with. rearwardly projecting piston portions lat 7 structure to be kept a 4 and I38, which are pivotally'couple'd to operating links I40 and I42. The operating links I40 and I42, in turn, are pivotally connected to an operating segment I50. Segment I50 is pivotally supported between the side frame members 40 and 42 by means of a pin I52. The pin I 52 also serves to pivotally support the previously, mentioned operating handle 30, which; in accordance with usual practice, is releasabli c'on'ne'ctib'l'e to the segment I50 in any of a plurality of relative rotative positions of the segment and handle, thereby enabling-adjustment of the arcuate path of travel of the handle. addition to the releasable latch: I54, which controls' the last-mentioned connec tion. the handle 30 may be and preferably is provided with a valvebontrolling element I 5%, which;

may be operatedtozpermit a return or retracting movement of the ram unit 28.

of the unit 28 with outwardly projecting trunnion's- .157, which are received; in corres'poriding sockets E59 provided'in the sid'franie "embers IEVand' 32. As thus far desc b '7 that the parts no U V occ p thepositions shown in Figs. l andf i "'ch' he lifting arms, the radius arms andtl're stab "zen armsiare' collapsed within the"confines'nf the frame-members so and 42, and in wh cn t f position substantially lev l with'itheupp-er surface of the frame. ilnden these 'condit n s, t hecol. lapsedlifting armyrad ius 'arms rid 'biiizrarms 7' i pg sition's; eightof the jack v ery'lowvalue; As thus far described, also, it will beapblie'ciated"that a rightward movement of the 'head I20? influv .i 5 out the pin 5211s a; clock h the pins I04a'nd' I00; this movement. of: the j-r'a s 'arms'ffis communicated to the liftingarm zffi nd 'cause' "'the latter to swing in a counterclockwise dire 1on1 Since the aXis of the n 1 i and I1 6 m ves; to t e wise direction. 'Ifhrouh vertical path; n H from this latter feature will beapparent; it being recognized that withconyentional cantilever-typejack structures-,the lifting movement involves either a shift in'thejposition 'ofth'e loa'd; or ashift 1 in the position of the' jack'r.

Coming" now 'to' a description ofthe supplemental lifting elements comprising-thefixed; in"- clined plane 58 and"the cooperating, inovable,

inclined plane error-ace 'by'th head rzni i ill be appreciated that w '"ft" In the present.

embodiment, the ram and pump unit partakes of;

e appreciated" inging of the arms H.30-

26' to cause leftward" -res ultant'cap.riiov-. ment is, consequentl' y a substantially" linear any'a vantages r sumes elements and the ram I30 lie substantially parallel to each other, so that a given rightward force exerted by the ram I30 against the lifting elements has only a relatively small vertical component of force. It is the purpose of the supplemental lifting elements to elevate the previously described lifting elements to such a height that the angle between the ram and the radius arms is sufficient to enable the ram unit to complete the elevating movement without the expenditure of an undue amount of force.

-lVIore particularly, the previously mentioned fixed, inclined plane 58 is provided with an inclined surface I60, which may either be formed integrally therewith or may be separately formed and thereafter fixed in place thereon. The surface I60 affords a supporting runway for a roller I62, which is supported between the bifurcated legs I64 on the head I20, by means of a pin I66.

The head I20 is provided along its forward face with an inclined surface I10, having curved or socket portion I12 at its upper end. The surface I10 is coextensive in width with the head I20 from the socket I12 down to the point a, in Fig. 1. From the point a to the point b in Fig. 1, the surface I10 is constituted by the upper surfaces of the previously mentioned legs I64.

In the normal or retracted position of the structure, the parts occupy the positions shown in Fig. 1, in which the roller I62 is seated upon the extreme lower and slightly curved end of the inclined surface I60, and in which the roller I22 is seated upon the extreme lower end of the inclined plane surface I10. The parts are normally retained in these positions, as will be understood, by a usual tension spring I80, which is connected between the head I20 and the cylinder portion of the ram and pump unit 28. A rightward move ment of the head I20, as influenced by the ram and pump unit 28, causes the roller I62 to ride upwardly along the inclined surface I60, which movement has a substantial vertical component. The rightward movement of the head I20 also causes the inclined surface I10 to move to the right relative to the pin I22, and cam the latter upwardly. The vertical movement of the pin I22 is, of course, directly transmitted to the radius arms I and I02 and, consequently, to the lifting arm 26, it being noted that the net vertical movement of the pin I22 is equal to the sum of the vertical movements of the head I20 and the vertical movement of the pin I22 relative to the head I20.

As indicated by the dotted line positions in Fig. 3, just before pin I60 reaches the upper end of the inclined surface I60, the pin I22 seats in the socket I12. Further relative movement between the ram I30 and the arms I00 and I02 thus takes place about the fixed center afforded by the pin I22 and the permanent socket I12.

It will be appreciated that the lifting movement of the ram and pump unit as influenced by the rocking movements of the handle 30 transfers hydraulic fluid, such as oil, from a reservoir (not shown but contained, for example, within the ram cylinder) to the space behind the ram piston, the power and speed pumps affording a quick lift until the load is engaged and a powerful but slower lift thereafter. When it is desired. to lower the load, the control I56 may be operated to enable a retransfer of the liquid from the space behind the piston to the reservoir, at a desired regulated rate, underthe influence of the return bias afforded by the load and by the spring. I80.

It will be noticed that the very low over-all height of the above-described jack structure m= volves the use of relatively small wheels. In connection with the above, as well as other small wheeled structures, which areintended for use on irregular fioor surfaces, the arrangement of Fig. 6 is very advantageous. In this figure, a lifting cap 24 is associated with a frame structure 20, which may and preferably does duplicate the previously described frame structure 20 with the exception that the hoods, such as 46, which house the front wheels at the respectively opposite sides of the frame, .are elongated so as to accommodate a pair of front wheels 22 at each side of the frame. Both pairs of wheels are in advance of the axis of the load, and the center distance spacing between the Wheels of each pair is preferably proportioned to be somewhat in excess of the width of the normal irregularities in the associated floor I. One such irregularity is indicated at z. Accordingly, in moving the jack structure along the fioor, during the time that the foremost front wheels 22 are passing over the irregularity, the rearmost wheels 22 are still engaged with the normal floor surface and support the jack structure. By the time the rearmost' wheels 22 encounter the leading edge of the irregularity, on the other hand, the foremost wheels 22 have passed thereover and have become effective to support the jack structure. The jack is, consequently, enabled to pass over the irregularity without bumping. It will be appreciated that the double wheel arrangement may, if desired, be used in connection with the rear end of the jack, although in many cases this is not found necessary in view of the fact that the front wheels carry the major portion of the load.

Linkages embodying the arrangement described above with reference to the lifting arm 26 and the radius arms I00 and I02 may also be used to considerable advantage in instances where the initial lift afiorded by the inclined planes is not needed. An illustrative such arrangement in connection with an industrial truck structure is shown in Figs. '7 and 8. In these figures, a frame structure 200 supported by suitable pairs of front and rear wheels 202 and 204 also supports a movable platform 206. The frame 200 and platform 206 may partake of various different constructions, but are illustrated herein as being, respectively, of upwardly presenting and downwardly presenting boxlike forms.

The platform and frame are connected together by similar pairs of linkages arranged adjacent the front and rear ends of the platform, the individual linkages of each pair also being similar. More particularly, each linkage comprises a lifting arm 2I0,'which is pivotally connected to the platform at its upper end by means of a pin 2 l2, and which is provided at its lower end with a roller 2I4, which rides in a slot 2 I 6 provided in the side wall of the frame-200. Each linkage also comprises a radius arm 2 I 8, which is pivotally connected at its lower end to the frame 200 by means of a pin 220 and which is pivotally connected to the corresponding lifting arm 2 I0 by means of a pin 222. Each pin 222-is connected to the corresponding pin of the immediately opposite linkage by means ofa cross-head 22d, and two cross-heads 222 are in turn interconnected by a push rod 226, having a connection 223 to any suitable source of power. In the illustrated structure, the power applying member 228 extends to the left of the cooperating linkages and, consequently, a pulling force is required to be applied thereto in order to rock the radius arms 2I8 in a counterclockwise or lifting direction. As in the previous instance, such coun-

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