US 2885961 A
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Description (OCR text may contain errors)
May 12, y1959 F. P. HoPFr-:LD 2,885,961
' LIFTING AND sTAcKING TRUCKS Filed Nov. 20, 1952 4 Sheets-Sheet 1 'A TTORNEYS:
May 12, 1959 F. P. HOPFELD 2,885,961
' LIFTING AND sTAcKING TRUCKS Filed Nov. 20, 1952 4 Sheets-Sheet I2 Flea" ATTORNYS:
May 12, 1959 F.b P. HOPFELD LIFTING AND STACKING TRUCKS 4 Sheets-Sheet 3 Filed Nov. 20, 1952 INVENTOR:v
FRED HOPFELD ATTORNEYS:
May 12, 1959 l 9 F. P. HOPFELD 2,885,961
LIFTING AND STACKING TRUCKS Filed Nov. 2o, 1952 W7 F|G.|| W, Flam 4 Sheets-Sheet 4 INVENTR; FRED P. HoPEELo ATTORNEYS:
United States Pafsnf LIFTING AND STACKING TRUCKS Fred P. Hopfeld, Elmwood Park, lll., assignor to .Grand Specialties lCompany, p Chicago, Ill., a corporation of Illinois Application November 20, 1952, Serial No. 321,572
` 4 claims. (C1. 10s-3s) This invention relates to lifting and stacking trucks of the kind utilized to lift and to stack different kinds of relatively large and heavy objects such as boxes, crates, barrels and the like, and more particularly the invention relates to such devices that are to be manually powered and operated during lifting action as by a manually operated power unit.
Lifting and stacking trucks of the general type to which the present invention relates are well known in the materials handling field, and several such devices are illustrated in U.S. Patent 2,560,131, and also in application Serial No. 286,642, filed May 7, 1952, now abandoned. One type of lifting and stacking truck shown and described in these disclosures is a kind which embodies a so-called door level article supporting carriage arranged on the truck for selective vertical movement either during a lifting or lowering action. The operating means for this is in the form of a hydraulic motor that alfords a mechanical advantage for the lifting operation, and the present invention is concerned directly Awith such a hydraulic motor or its equivalent, in which the energy input is established through a pumping action by means of a manually operated handle. Thus, there is illustrated in the above identified disclosures an operating mechanism which includes an output element in the form of a hydraulic output piston that is adapted to exert a pulling action on a cable or chain that is connected at one end to the article transporting carriage of the lifting and stacking truck. Operation of the input element in the form of an input piston is dependent, in one form, upon manual operation by the `operator of the truck, and of course there is a mechanical advantage relation between the input and output piston. In those instances wherein it is desired to utilize the truck to lower heavy objects from an elevated position to `tioor level for instance, the lifting carriage will, of course, first be raised by the operator to the elevated position whereat the articles to be lowered are located, and during this upward vertical movement of the lifting carriage, the
weight to be lifted is only that of the platform itself.`
On the other hand, when it is desired to utilize the truck for transporting heavy articles from floor level, for instance, up to an elevated position Where such articles are to be stacked or arranged, as for instance on a shelf, the carriage must transport a relatively heavy load.
From this it will be seen that the lifting carriage during a vertical upward movement transports no load at all in some instances, whereas in other instances the carriage will be loaded to capacity. j
However, as lifting trucks embodying a manually operated power unit and lifting carriage operated thereby have heretofore Y been constructed and arranged, no accommodation has been made for the two extreme types of loading on the carriage. Thus, the distance through which the work output occurs is the same irrespective yof the amount of load on the carriage, whereas it can berecognized from the foregoing analysis that an inverse lrelation would be desirable between the distance the I '2,885,961 Patented May l2, i?v
carriage moves and the load that it carries. That is, a relation such that the carriage, when not loaded, may be moved through its greatest distance as the operator actuates the work input handle, while on the other hand the carriage will be lifted its shortest distance through each movement of the handle when loaded to capacity.
Therefore, the primary object of the present invention is to permit the lifting carriage or platform of a lifting and stacking truck of the aforesaid type to be selectively set` for movement through variable distances, which depend upon the type of loading. A further object in this regard is to so arrange the parts in a lifting and stacking truck of the aforesaid type' that the distance through which the lifting platform or carriage moves may be selectively regulated for loads of varying quantities, and to permit this to be accomplished in an effectual and highly eflicient manner.
The work output in any working system or machine will, of course, never be equal to or greater than the work input. Accordingly, a mechanical advantage from a force or load output standpoint will always be accomplished at the sacrilice of distance through which the input force is required to move, and any advantage from a distance standpoint is attained only at the sacrifice of moving a load that represents a force less than that put into the machine. Accordingly, it is a further object of this invention, in view of the foregoing, to be able to move the lifting carriage its greatest distance when the force input manually supplied to the power unit is least and to be able to move the lifting carriage through its shortest distance when the :force input to the power unit is greatest.
Other and further objects of the present invention will be apparent from the following description and claims, and are illustrated in the accompanying drawings which, by way of illustration show the preferred embodiment of the present invention and the principles thereof, and what I now consider to be the best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in 'the art without departing from the present invention.
In the drawings:
Fig. 1 is a side elevational view of `a manually operated lifting and stacking truck embodying the features of the present invention;
Fig. 2 is a rear elevational view of the truck illustrated in Fig. l;
Fig. `3 is a sectional plan view on an enlarged scale and broken away in part, taken on the line 3-3 of Fig. 2; i
Fig. 4 is a sectional view on an enlarged scale of the power unit or operating system embodying features of the present invention, and being taken on the line 4--4 of Fig. 2;
Fig. 5 is a rear elevational view taken on the line 5 5 of Fig. 4;`
t Fig. 6 is a fragmentary sectional view similar to Fig. 4, showing certain operating mechanism of the power unit in a diiierent selective position for actuation;
Figs. 7 and 8 are sectional views taken on the lines 7-7 and 8-8 respectively of Fig. 4;
Figs. 9 and l0 are sectional views taken on the lines 9-9 and lil-10 respectively of Fig. 6; and] Figs. 11` to 13 inclusive are diagrammatic illustrations of certain operating principles of the present invention.
For purposes of disclosure, the invention presently disclosed is herein illustrated in the drawings as embodied in a manually powered and operated lifting and stacking` truck 20 which may be readily and easily moved about the interior of the factory, shop or warehouse wherein` lifting and stacking operations as a type of material handling operations are to be performed. The truck 20 includes a vertically extended frame structure 21 at the bottom of which is located a movable carriage 30 that is mounted on and guided by the frame 21 for vertical up and down movement. Two sets of wheels, relatively large wheels 28 and smaller caster wheels 34, are provided at the back and front, respectively, of the truck 20 to permit the latter to be readily wheeled from one location to another. The vertical frame structure 21 com prises, at the front, a pair of spaced apart and elongated angles 22 in which the forwardly facing flanges 22F thereof project in opposite directions, as illustrated in Fig. 2. The rearward section of the frame 2l. consists of a pair of hat strip-like frame members 24 which extend, at vertical sections 24V, in parallel spaced relation to the elongated angles 22 and which are then bent forwardly at 24A, as shown in Fig. 1. The forwardly bent or inclined portions 24A of the rear frame structure 24 are welded fast to the inner faces of the inside flanges of the angles 22, and the frame structures 22 and 24 are reinforced by horizontal tie braces as 23 and truss-like members 25 to constitute a rigid vertical frame.
A rear platform 2.9, Fig. 2, is secured to the respective frame members 24 and the angles 22 so as to be supported thereby as a fixed platform. As will be described below, the platform 29 supports the power unit operation mechanism that is embodied in the truck 2l? to move the carriage 3ft, and it may be pointed out trat the platform 29 also supports the axle 2.7 for the rear pair of Wheels 28. The manner in which the caster wheels 34 are mounted relative to the truck 20 will be described presently.
As was noted above, the truck 20 includes an article supporting carriage 3@ which is arranged for vertical up and down movement relative to the frame 21 while guided by the angles 22. This carriage 3i) comprises a vertically extended rectangular main plate 31 which is located slightly forwardly of the angles 22 and arranged to slide on the forward flanges 22R As shown in Fig. 3, a forwardly extended supporting frame 32P for the articles to be transported by the carriage 3l) is welded fast to the lower margin of the plate 31 so that the plate 31 and frame 32F will move together' as one body.
A base structure or supporting base plate is afforded for the carriage 3l) in the form of a relatively large rectangular plate 33. This plate 33 is held above floor level by means including a pair of narrow forwardly extended supporting arms 33B which in turn are supported at the base of the angles 22 so that the frame 21, base plate 33 and arms 33B may be looked upon as a unitary structure. Consequently, the front caster wheels 34 are pivotally mounted on caster elements 34C located at the forward end of the base structure 33, thus permitting the truck 20 to be wheeled about as desired.
The carriage 30 is guided on the frame 21 during vertical movement by a roller structure that moves with the carriage 3f) and which engages opposite sides of the flanges ZEP of the angle members 22. Referring to Figs. 2` and 3, a pair of mounting plates 35 are secured to the back of the plate 31 slightly inwardly of the opposite sides thereof, and rollers 36 are journably mountedadjacent the tops of the respective plates 35 in position to engage the rear faces of the flanges 22R Another pair of rollers 37, spaced substantially below the rollers 36, are provided for engaging the forward faces of the flanges MF adjacent the lower edge of the plate 31. The rollers 37 are Jiournably mounted at the inside of another pair of mounting plates 38, and these latter mounting plates depend downwardly from the article supporting frame 32F of the carriage 30. It follows that the roller structure which includes the rollers 36 and 37 will move with the carriage 30 as the latter traverses the frame 21 and is effective to reduce sliding friction while assuring that 4 the carriage 30 is properly guided in its vertical movement.
The foregong simply represents one type of convenient arrangement relative to a lifting carriage and a frame structure on which the carriage is [mounted and guided for vertical movement between an elevated position and the supporting base structure which locates the carriage at its lower or floor level position. Consequently, various other equivalent arrangements may be resorted to.
Under and in accordance with the present invention, the carriage 30 is arranged for vertical up and down movement through the action of a power unit or operating mechanism S0 which in the present instance is in the form of a hydraulic motor mounted on the platform 29. The power unit 50 is arranged for manual operation and work may be supplied to the power unit to impress a mechanical advantage work output upon the carriage 30. Thus, during lifting operations with the truck 2i), the handle 80 will be alternately lowered and raised until the carriage 30 has been elevated in a corresponding step-wise manner from the main supporting structure to the desired elevated position. The work output element of the power unit Si) is in the form of a hydraulically operated piston 56 which extends vertically upward at the back of the frame 21 as shown in Fig. 1, and at its top is formed with a mount 56M, Fig. 4, upon which may belocated a sprocket assembly generally indicated at 90 in Fig. 1. A horizontall anchor element 26 is Xed to the frame structure 21 and one end of a chain 91 is fixed to the support 26 whereby the chain 91 is anchored relative to the frame 21 of the truck 20. The chain 91 constitutes a connection between the Work output element 56 and the carriage 3@ and for this purpose is extended over and about the sprocket assembly 90, and is attached at its lower end to the main plate 31 in any suitable manner, as for instance in a manner similar to that which follows from the disclosures in the aforesaid U.S. patent and application. Consequently, it will be seen that by raising the hydraulically actuated piston 56 the chain 91, in effect, will be caused to pull the carriage 30 upwardly. Since the manner in which the chain, sprocket and Work output piston are arranged relative one to another to raise and lower the carriage 30 constitutes no part of the present invention, further description in this respect is believed unnecessary, and in fact the connections are believed `to be obvious enough.
The hydraulic motor or power operating mechanism `50 comprises a casing 54, Fig. 4, in which is contained the working fluid, and this casing is integrally mounted on a relatively thick base 5l which houses the various passages and check valves which, through iiuid pressures, control the -ilow of the working fluid. Thus the casing 54 and base 51 constitute but a single box-like structure, and in the present instance this structure is supported on the platform 29 for pivotal movement ,from
left to right, as viewed in Fig. 2, so that the truck 20 may be maneuvered in relatively small spaces while per-k mitting the hydraulic operating mechanism to be operated from various positions. To this end, a socket 53 in the form of a short tube is welded to the upper side of the platform 29 in vertical relation thereto, and a plug 52 is secured to the underside of the base 5l so that the hydraulic unit 5t) may be removably mounted in the socket 53. This arrangement permits the whole hydraulic unit to be swiveled in the socket 53 and thus the pump handle may be operated either directly at the back of the truck 20 or olf to one or another side as desired.
The present invention is concerned directly with lregulating mechanism forthe pump handle 80 so that the 'extent of movement kof the output piston 56 may be selectively adjusted, the length of the curvilinear path traversed by the pump handle 80 being substantially equal and com stant for all practical purposes irrespective ,ofthe partie ular position at which the handle is set. `The manner `in which this regulation and adjustment is arranged will be described in detail below, but first it should be pointed out that the work action of the handle 80 is transmitted to the output piston 56 through an input piston 60 and a link connection 81 between-the pump handle 80 and the input piston 60 of the hydraulic unit. As best shown in Fig. 4, the cyclinder 55 for the output piston 56 is located at the forward end of the casing 54, and extends from the base 51 upwardly through the oil, that is the working uid, chamber to a point approximating the middle of the vertical height of the frame structure 21. It will be appreciated that the output piston 56 slides in and relative to the cylinder 55 during operation of the hydraulic unit 50, and that mechanical advantage from a load lifting or force standpoint is determined by the ratio that exists between the diameters of the pistons 56 and 60.
The input piston 60 is adapted to slide in a corresponding cylinder 61 which is located entirely within the casing 54. The lower end of the cylinder 61 communicates witha relatively short vertically extended passage 62 that isformed in the base structure 51, and this opening 62, nturn, communicates with a pair of horizontal passages 63 and 64, which interconnect, fluid-wise, the cylinders 61 and 55. The passage 64 communicates with the cylinder 55 through a vertical passage 65, and the transmittal of fluid pressure from the cylinder 61 to the cylinder 55 takes place against the action of a normally closed check valve C-l. The operating fluid contained by the casing 54 is adapted to tlowinto the passage 63 and up into the cylinder 61 through an inlet 68 located at the bottom of the casing 54, and a normally closed check valve C-2 is adjusted to be responsive to vacuums established in the cylinder 61 during upward pumping move` ment of the piston 60 so that the cylinder 61Wil1 contain ameasure of operating fluid at all times. Upon downward movement of the input piston 60, a particular fluid pressure is established in the passage 63 and the check valve C1 is opened thereby to permit this pressure to be transmitted to the output piston 56. In order to accom-` modate excessive uid pressures in the lines 63 and 64, and adjustable by-pass valve C-4 connects directly with theuid chamber in the casing 54.
. Successive transmittals of multiplied fluid pressure to` the piston 56 are effective to raise the carriage 30 in a step-wise manner to the desired position, and after the articles are either removed from or mounted on the frame 32F, the pressure acting at the bottom of the out- 'put piston 56 may be released, to permit the uid to tlow back into the reservoir in the casing 54, by means of a pressure equalizer 70, Fig. 4, which controls a relief valve (Tf-3 located in the base 51 of the hydraulic unit. The
equalizer 70 includes an outer tube 71 mounted in the` base 51 to extend up through and out the casing 54. The tube 71 is formed with spaced apart openings 71P leading from the interior of the tube 71 into the fluid reservoir.
Whenjthe equalizer 70 is opened to permit the output` piston 56 to slide downward from its elevated position, the displaced working fluid in the cylinder 55 flows back into the fluid reservoir through the openings 71P. Thus, anelongated rod 72 of substantially less diameter than the` `inside diameter of tube 71 is mounted concentrically therein for free sliding movement, and this rod projects from the bottom of the tube 71 to bear against the ball valvemember of the relief valve C-3. The top of the tube 71 is threaded at 71T, Figs. 4 and 9, and a cap 73 is' threadedly mounted thereon so as to fit over the end 72E of` therod 72 which projects above the threaded end of the tube 71. Any Huid pressure established in the passage 64 is equal in all directions at any point of course,` and consequently what pressure may be thus pre'sentis also present in the vertical passage 66 that leads from the horizontal passage 64 to the normally closed 6 relief or pressure equalizer valve C3. Consequently,.the ball valve member in the valve C-3 will tend to be u ged upwardly in an opening direction when the pressure in line 64 exceeds that `in the reservoir, but this valve is normally held closed by the bottom of rod 72 which is held down by the tightened cap 73. Upon loosening the cap 73, rod 72 is accordingly unrestrained at the top and any fluid pressure in the passage 64, that is in cylinder 55, will force open the relief valve C-3, and the pressure at the bottom of the piston 56 will be dissipated as uid flows from the cylinder back into the Huid reservoir through the openings P. The output piston 56 will collapse at a speed dependent upon the extent to which the cap 73 is loosened, and the carriage 30 will drop from an elevated position back down to the base support plate 33 at a corresponding speed.
Access `may be had to the tluid reservoir contained by the casing 54 through an opening 77 at the top thereof. A closure cap 75 is afforded for the opening 77, and several 0ring seals 76 are provided at the peripheries of the opening 77 andthe opening in the top of the casing 54 through which the input piston 60 extends. 4
Under and in accordance with the present invention, the` adjusting means for `correlating the distance that the carriage 30 moves, that is, the Working distances traversed by the input and output elements of the power unit 50, to the load `that is on the carriage is arranged with respect to the work input end of the hydraulicunit 50, and` this includes, of course, the input piston 60 and the work input handle 80 which is adapted, as will be described below, to actuate piston` 60 in a regulable manner. The
a fulcrum point for the handle 80 and comprises a pair of spaced-apart arms 86 which are each bent outwardly at 86A and `extended downwardly for a substantial distance so as to embrace the outer sides of the casing 54, as best shown in Fig. 5. A pin 51P, mounted at the bottom of the base 51 of the casing 54 affords a pivotal mounting for the handle support 82, and it Will be seen from this that the handle 80 is free to pivot on the pin SGP, and in turn the support 82 for the handle 80 is free to pivot at 51P on the hydraulic motor 50.
The drive link 81 which transmits the action of the handle S0` to the input piston 60 is inthe form of a pair of link arms 87 and 88 each pivotally connected at one end to` a pin 81P on the handle 80 and at the other end to which is bifurcated at 60BF. i It can be recognized from the arrangement described f thus far that the manually operable handle 80 will be oscillated about the pin 30P as a center While moving along the arc or curvilinear path CP indicated by the Aarrow in Fig. 4. Thus, as the handle 80 is moved from an initial or normally at rest position IP to an end position DP, the handle will traverse a curvilinear path. At the same time, the supporting bifurcated arm 82 for the handle 80 will describe a similar movement but along a` `much shorter curvilinear path CP thus permitting the curvilinear motion of the handle 80 to `be translated into a linearmovement of the input piston 60. It will also be appreciated that the primary function of the support 82 is to prevent the piston 60 from binding inside its cylinder pivot point 80P of the handle 80 may be resorted to as desired.
The action of the handle 80, then, is manifest in a linear f movement of the input piston 60 as it is caused to move 61, and therefore that an equivalent support for the,
working distance thus traversed by the piston 60 will nd its equivalent in the vertical projection of the arc CP. In order that this linear work distance of the input piston 6 1 may be shortened or lengthened to thereby produce a corresponding shortening or lengthening of the work distances traversed by the output piston 56 and the article supporting carriage to which it is connected, an adjustment is afforded for selectively locating the fulcrum SGP of the handle relative to the input piston. This relation is illustrated in Figs. 4 and 6, respectively, wherein it will be observed that the initial or at rest position for the handle 80 has been altered from an almost vertical relation in Fig. 6 to a more horizontal relation illustrated in Fig. 4. This alteration in positions for the handle 80 from an almost vertical to a more horizontal position, in effect, is simply one of relocating the handle from the top of a circle downward along the circumference toward a 90 position. The result and practical elfect of this is to lengthen the linear equivalent or projected distance of the curvilinear path or arc CP through which the handle 80 is moved during a pumping action by the operator. When considered from the position that the operator assumes during use of the truck 2), the length of the arc CP will not vary any appreciable amount between extreme initial positions of the handle 80, and for all practical purposes this arc may be assumed to be constant under all conditions, as will lbe appreciated from the description to follow.
Such adjustment in or alteration of the initial or at rest position of the handle 80 is afforded in the present instance by an adjusting link 83. As can be recognized from the drawings, the form of this link 83 together with the handle Si) constitutes a 'bell crank lever having a fulcrum at SQP at the top of the support 82. The description to follow will be based upon this analysis for purposes of simplicity.
At one end, the link 83 is pivotally connected to the pivot pin SGP for the handle 80, and at the other end is removably or dismountably mounted at one of several selective positions on the pin 60P that connects the drive link 81 andthe input piston 60. Thus, the effective length ofthe bell crank arm 83, that is, the distance between the fulcrum Stil and the pin 60P, is adjustable by providing a plurality of spaced apart yand aligned locating notches at the lower edge of the arm 83. Five such notches, N-l, N-Z, N3, N-4, and N-S are illustrated in the drawings, and it follows from this that ve different positions or effective lengths may 4be selected for the link 83. When set at the N-5 position, the pivot point or fulcru'm 80P for the handle 80 is farthest removed from the upper end of the piston 60 and the lever arm 83 is longest. The length of the lever arm 80 is unchanged, however. Under such conditions the input force on the piston 60 by the bell crank lever will be least, but the distance through which this force moves will ybe greatest. Consequently, the linear work distance that the piston V60 moves under the inlluence of the handle 89 when the latter is pressed down by the operator from the initial position IP in Fig. 4 to the end position DP is at its greatest, and the output piston 56 will traverse its greatest work distance.
By the same token, when the arm 83 is set at notch N-2, say, the fulcrum StlP is much closer to the pin 601 than when the setting is at notch N5. Assuming that the same force is applied to the en d of the handle 80 as is applied at N-5 setting and that the handle is moved through an arc that is, for all practical purposes herein, the same Ilength as the arc CP, the force applied to the piston 6i) will be lmuch greater than an N-5 setting lbut the linear work movement will be less. Consequently, a greater load can be handled by the carriage 30 but will be moved through a less distance.
In Figs. ll to 13, this feature of adjustability is illustrated diagrammatically for three different settings of the adjustable link 83. In Figs. 11 and 11A, the link 83,
which constitutes the shorter arm of the bell crank lever, is set at notch N-S so that it assumes its greatest effective length. The N-5 setting also establishes a relatively large angle A-S which represents the inclination of the link 81 from vertical. in moving the handle 84B through its normal working arc, the input piston 60 will travel a working distance D-S. i
By setting the link 83 at the N- position, Figs. l2 and 12A, the angle A- becomes less than the angle A-S and consequently the force transmittal to the input piston 60 has a greater vertical component than in the case `ot" the angle A-S. However, the shorter arm, 83, of the bell crank lever is shortened and consequently the input piston is moved through a shorter working distance, D-3, in comparison to the working distance D-S. f
A third condition is illustrated in Figs. 13 and 13A in which the bell crank is set at its shortest setting in the notch N-l, and the corresponding working distance D-l is the shortest, of the ve possible distances. However, the angle A-l is quite small, approaching 0, and consequently the vertical or effective force on the input piston 60 is largest. ln this manner, different settings may be selected for the bell crank lever in accordance with the type of loading on the lifting carriage 30. When the lever arm 83 of the bell crank lever is shortened, the lifting carriage is adapted for maximum loading, and as the lever arm 82 is lengthened the load lifting eliiciency of the carriage 3d is decreased but the distance through which the carriage 30 moves for each stroke of the handle 30 is increased.
It will be seen from the foregoing that the present in-` vention afords a highly eicient and adaptable type of manually operated lifting device and one in which the principle may be applied in different, but equivalent, manners from the one form shown and described.
l. In a manually operable hydraulic pump in which work is supplied to an input piston adapted to movein` a cylinder through a linear working distance, and wherein there is a vertically disposed cylinder for the piston secured to a base: a manually operable handle for supplying work to said input piston and being mounted on a shiftable fulcrurn adjacent thereto for oscillating movements along a substantially constant curvilinear path from an initial location, a link pivotally connected to and between said handle and the input piston to impart the force of the handle to the input piston upon movement of the handle, an adjustable arm extended from the ful- Crum to said input piston to enable said fulcrum to be shifted to a plurality of selected positions toward and away from said input piston to thereby alter the initialk location of said handle on said curvilinear path between a more vertical and more horizontal position and to alter the angle at which the force o-f the handle is exerted on said input piston by said link.
2. In a manually operable pump in which work is supplied to an input piston adapted to move in a cylinder through a linear working distance, and wherein there is a vertically disposed cylinder for the piston secured to a base: a vertically disposed handle support pivotally mounted to said base adjacent said cylinder, a manually operable handle for supplying work to said piston and being fulcrumed on said handle support for oscillating movements along a substantially constant curvilinear path from an initial location, a force transmitting link pivotally connected to and between said handle and the piston to impart the force of the handle to said piston upon movement of said handle, and an adjustable arm extended from said handle support to said piston to enable said fulcrum to be located at a plurality of selected positions toward and away from said piston to thereby alter the and to alter the angle at which the force of the handle*- is applied to said piston by said link.
3. An arrangement according to claim 2 wherein said arm has a plurality of spaced notches in an edge thereof and wherein there is a pin on the piston ttable selectively in said notches.
4. In a manually operable iluid pump in which work is supplied to a vertically disposed input piston arranged in a cylinder to move through a vertical linear working distance: a manually operable handle disposed above the cylinder for supplying work to said input piston and being fulcrumed on a pivotal support shiftable toward and away from said input piston7 said handle being in lthe form of a bell crank lever having one arm fulcrumed as aforesaid and extended outwardly and upwardly from the point of fulcl'uming to enable a manual force to be applied thereto to move said one arm from `an initial location downwardly along a curvilinear path, the other arm of said bell crank being shorter than the rst-named arm and having the lower end thereof pivotally connected to said input piston, the upper end of said other arm being pivotally connected to said one arm at an intermediate point and defining an acute enclosed angle with the portion of said one arm which lies between the fulcruming point and the point of attachment between said arms, and means for moving said pivotal support toward and away from a selected position relative said piston and for maintaining said pivotal support in such a selected position to thereby selectively determine said acute angle and the initial location of said one arm on its curvilinear path.
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