|Publication number||US3259369 A|
|Publication date||Jul 5, 1966|
|Filing date||Nov 12, 1964|
|Priority date||Nov 12, 1964|
|Publication number||US 3259369 A, US 3259369A, US-A-3259369, US3259369 A, US3259369A|
|Inventors||William W Gridley|
|Original Assignee||Ready Lift Mfg Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Non-Patent Citations (1), Referenced by (27), Classifications (15)|
|External Links: USPTO, USPTO Assignment, Espacenet|
y 1966 w. w. GRIDLEY LOAD LIFTING APPARATUS Filed Nov. 12, 1964 Y E m mm W m %m 5 W m w m m U n m m w B O A m United States Patent 3,259,369 LOAD LIETING APPARATUS William W. Gridley, The Ready-Lift Mfg. Co, 341 E. Leap Drive, Camariilo, Calif. Filed Nov. 12, 1964, Ser. No. 410,806 Claims. (Cl. 254-122) This invention relates generally to load lifting apparatus and more particularly to a portable hoist which may be used indoors or outdoors for elevating materials and equipment together with men to locations adjacent work ing areas.
At the present time, particularly in the residential and industrial construction trades, it is oftentimes necessary to raise heavy materials such as beams, girders, roofing materials, and the like to a considerable height above the ground level for their use in the upper portion of the structure being built. While elevators and other types of hoisting equipment are available and used in connection with multi-story building and larger industrial buildings, the need has arisen for a simple portable hoist which may be used with conventional one or two story homes and smaller business properties. In fabricating such buildings, most contractors at the present time use manual power or improvised pulley arrangements as a means of lifting materials to proper positions for fabricating roofs or forming the second story of buildings.
In my United States Patent No. 3,003,746 patented October 10, 1961, and entitled Load Lifting Apparatus there is disclosed and claimed a portable hoist or load lifting apparatus which fully conforms to the foregoing requirements. Essentially, this structure as described in the patent provides first and second frames including crossed levers interposed between the frames adapted to execute scissor-like action to expand or contract the fbames away or towards each other. The upper frame constitutes a platform and the lower frame a base support which may be provided with castors.
In the foregoing structure, there is provided an hydraulic ram means coupled between two vertices of a parallelogram portion defined by the crossed levers when the upper frame is partially extended to effect raising and lowering of one frame relative to the other. With the particular structure described in this patent, the degree of collapsing is somewhat limited as a consequence of the positioning of the hydraulic ram for actuating the structure.
With the foregoing in mind, it is accordingly a primary object of the present invention to provide a load-lifting apparatus which provides all of the various advantages of the apparatus described in my above referred to patent and in addition provides a structure capable of collapsing to a substantially fiat configuration, all to the end that a more compact structure when in a collapsed position is provided.
More particularly, it is an object of this invention to provide an improved coupling arrangement for connecting hydraulic or other expansible ram means to a crossed lever structure in a portable hoist, so designed as to reduce the travel of the ram means without changing the travel of the crossed lever structure and permit collapsing to a flat condition without interference with the crossed lever structure.
Other objects of this invention are to provide an improved load lifting apparatus which is rugged in construction, economical to manufacture and operate, and easy to move about to convenient locations both indoors and outdoors for elevating materials and equipment to various working areas.
Briefly, these and many other objects and advantages of this invention are attained by providing basic frame structures with crossed levers interposed therebetween in a manner similar to that described in my above mentioned 3,259,369 Patented July 5, 1966 United States Patent 3,003,746. However, in accordance with the instant improvement, the expansible ram means for powering the structure to raise the same between collapsed and extended positions is coupled at one end to a novel drive bar structure and at its other end, to one of the crossed levers. The drive bar structure itself is coupled to opposite sides of the central parallelogram portion defined by the crossed levers, the point of connection to the expansible ram means being displaced from a straight line drawn between the coupling points of the drive bar. By this arrangement, the travel of the ram means: is reduced and the crossed levers may collapse to a substantially flat configuration with the displaced coupling point on the drive bar extending either below or above the configuration when in flat condition. There is thus avoided interference between the expansible ram means and its coupling structure from the crossed levers proper so that substantially complete collapsing of the levers can take place.
A better understanding of the invention will now be had by referring to an illustrative embodiment thereof as shown in the accompanying drawings, in which:
FIGURE 1 is a perspective view of the load lifting apparatus of this invention illustrating the crossed lever structure in partially extended position;
FIGURE 2 is a side elevational view illustrating the apparatus in FIGURE 1 in its completely collapsed position; and,
FIGURES 3, 4, 5, 6, and 7 are schematic diagrams of the crossed lever arrangement shown in FIGURE 1 illustrating various optional locations for the expansible ram means employed to operate the structure.
Referring first to FIGURE 1 there is illustrated a first frame structure 10 which may be provided with castors t1. Mounted on the frame structure 10 is a crossed lever arrangement designated generally by the numeral 12. A second frame member or platform 13 is disposed at the upper end of the crossed levers. The lever arrangement is such that a portion of the levers defines a parallelogram shape with the lever ends extending downwardly and upwardly to engage the first and second frames 10 and 13 as illustrated. Thus, lower lever ends 14 are pivoted to the first frame 10 at the rear portion thereof as by pivot rod 15. The other ends of the levers 14 are pivoted at 16 to levers 17. The upper ends of levers 17 in turn are pivoted as by pivot rod 18 to the rod portion of the upper frame 13.
Similarly, another set of levers 19 have their lower extending ends terminating at the front portion of the frame iii in rollers 20 so that the ends of these levers may move horizontally away from or towards the pivot rod 1 5 for the levers 14'. The upper ends of the levers 19 are pivoted by the rod 2-1 to lever-s 22. The other ends of the levers 22 in turn similarly terminate in rollers 28 adapted to roll along the underside of the upper frame 13 so that these ends may \move horizontally away from or towards the pivot rod 18 for the levers '17.
The crossover points for the levers 14 and 19 are pivoted together by pivot rod 24 forming a lower vertex of the central parallelogram portion defined by the crossed levers, and the upper levers 17 and 22 are pivoted together at their crossover points as by pivot rod 25 at the upper vertex of the parallelogram portion.
From the arrangement described thus far it will be evident that the crossed levers are free to collapse in scissoring fashion so that the platform or upper frame 13 may engage the lower frame 10 with the collapsed lever structure lying in a substantially flat configuration.
In order to actuate the crossed levers to raise and lower the upper frame 13, the-re is provided an expansible ram means preferably hydraulically operated in the form of hydraulic ram means 26. In accordance with .the present invention, one end of the ram means 26 is coupled to a pivot bar point 27 connecting to intermediate points on drive bars 28 and 29 extending between opposite sides of the central parallelogram defined by the crossed levers. Thus the drive bar 28, by way of example, is coupled as at the points P1 and P2 substantially midway between the opposite sides of the central parallelogram defined by the levers 14 and 22. The arrangement is such that a straight line drawn between the points Pi and P2 will be parallel to the remaining opposite sides defined by the levers 19 and 17 so that collapsing or expansion of the crossed levers will not -vary the linear distance between the points P1 and P2.
It will be noted, however, that the intermediate point 27 of the drive bar 28 to which the lower portion of the hydraulic ram means 26 is coupled is displaced laterally from the straight line between the points P1 and 1 2. The purpose for this lateral spacing will become evident as the description proceeds.
As shown, the other end of the hydraulic ram means 26. connects to a pivot point 36 :which is disposed on one of the remaining sides of the central parallelogram defined by the crossed levers. This point 30 is displaced slightly from the vertex pivot rod 25 as shown. A suitable source and pump for the hydraulic fluid is carried on the base [frame as shown at 31.
Withreference now to FIGURE 2, when the upper platform is collapsed into engagement with the lower base or frame 10 the displaced point 27 to which the ram means 26 is connected can extend through .the frame 10 below the flat configuration formed by the crossed lever structure. There is thus provided room for the ram structure in a fully retracted state without inhibiting substantially complete collapsing of the crossed lever configuration.
The points between which the hydraulic rams are'coupled such as 27 and 30 are so positioned that a straight line drawn between these points will not be parallel to any of the sides of the central parallelogram define-d by the crossed levers. This non-parallelism is important since if the lines between the points 27 and .30 were parallel to the sides of the parallelogram, the distance therebetween would not change during collapsing and expansion of the crossed lever structure. By making a line drawn between these points nonparallel or out of parallelism with any of the sides, the distance between these points will vary depending upon the relative position of the platform '13 to platform 10 and therefore by applying tension or compression forces between these points, a collapsing or expansion of the crossed levers can be realized.
Referring now to FIGURES 3 to 7, there .are schematically illustrated other positions for the hydraulic ram means which are possible without departing from the scope and spirit of this invention. Thus, [for example, a drive bar 62 may extend between the other opposite sides of the parallelogram such as defined by the levers 1'9 and 17. Further, the hydraulic ram 26 may have its upper point connected to the vertex pivot that is, the vertex of the central parallelogram which is vertically spaced above its diametrically opposite vertex 24.
In 'FIGURE 4 the hydraulic ram 26 is connected between the drive bar 32 and the lower vertical vertex 24.
In FIGURE 5 there is illustrated both the drive bar 28 and the additional drive bar 32 forming a crossed configuration with a connected portion of the hydraulic ram 26 being coupled to the crossover points of the drive bars.
In FIGURE 6 the arrangement is the same as in FIG- URE 5 except that the other end of the hydraulic ram 26 connects to the lower vertex of the central parallelogram rather than the upper vertex.
Finally, in FIGURE 7 there is shown the hydraulic ram means 26 connected between the drive bar 28 and a point 33 displaced slightly from the lower vertex point in the same manner that the pivot bar in FIGURE 1 is displaced from the upper vertex pivot bar 25.
In all of the embodiments, it is to be noted that there is a displacement of the intermediate point on the drive bar to which the hydraulic means is connected, this displacement enabling substantially complete collapsing of the crossed lever structure while accommodating the hydraulic ram means.
As a consequence of the foregoing, it is possible to provide a portable lift apparatus having all of the advantages and features of my referred to United States patcut with the added feature of being capable of more complete collapsing to provide a more compact unit when in collapsed position.
In addition, by positioning the ram means between the drive bar and one of the crossed levers making up the central parallelogram configuration, the travel length of the ram means is reduced without changing the travel distance of the upper platform frame 13.
The entire structure is also simplified and considerably easier to operate than prior devices as a consequence of the hydraulic ram side by side configuration with the expanding piston rods moving in opposite directions as shown in FIGURE 1. This arrangement minimizes the space occupied by the ram means. Moreover, the cylinders are connected together hydraulically and are fed by a single hydraulic line from the pump and source 31. Thus, only one pressure is required to expand the structure for a given load and this pressure is constant. When the pressure is relieved, the structure collapses by gravity. Accordingly, one valve is necessary to apply and release and no skill is required to operate the mechanism.
Various modifications that fall clearly within the scope and spirit of this invention will occur to those skilled in the art. The load lifting apparatus is, therefore, not to be thought of as limited to the few embodiments set forth merely for illustrative purposes.
What is claimed is:
1. A load lifting apparatus comprising: first and second frames; upper and lower crossed lever means pivotally interposed between said frames, the inner ends of said lever means being pivotally interconnected to define a central parallelogram portion when said frames are in a partially extended condition with the extending outer ends of said lever means coupled to said first and second frames, respectively; drive bar means coupled to opposite sides of said parallelogram; and expansible ram means coupled to an intermediate point on said drive bar means displaced laterally from a straight line drawn between the ends of said drive bar means and to a point on one of said crossed lever means defining a remaining side of said parallelogram so that said crossed lever means may collapse in scissoring fashion to a substantially flat configuration with the displaced intermediate point extending laterally from the plane of said fiat configuration.
2. A load lifting apparatus comprising: a first frame; a second frame; upper and lower lever means pivotally interposed between said first frame and said second frame, the inner ends of said lever means being pivotally interconnected to define a central parallogram portion when said frames are in a partially extended condition with the extending outer ends of said lever means coupled to said first and second frames respectively; a drive bar means having its ends coupled to opposite sides of said portions of said crossed lever means defining said central parallelogram, a line drawn between the points of coupling of the ends of said drive bar to said opposite sides being parallel to the remaining sides of said parallelogram; and expansible ram means coupled to an intermediate point on said drive bar means and a point on one of said crossed lever means defining a remaining side of said parallelogram, such that the longitudinal axis of expansion and contraction of said ram means is out of parallelism with any of the sides of said parallelogram.
3. An apparatus according to claim 2, in which said intermediate point is spaced laterally from said line drawn between the points of coupling of the ends of said drive bar means whereby collapsing of said first and second frames together can take place until said parallogram is substantially flat.
4. An apparatus according to claim 2, in which said point on one of said crossed lever means defining a remaining side of said parallelogram coincides with a vertex of said parallelogram in a position in vertical alignment with the diagonally opposite vertex of said parallelogram.
5. An apparatus according to claim 2, including an additional drive bar means having its ends coupled between the other opposite remaining sides of said parallelogram, a straight line drawn between the points of coupling of said additional drive bar means being parallel to said first mentioned opposite sides of said parallelogram, said intermediate point on said first mentioned drive bar means being pivoted to said additional drive bar means at its crossover point with said first mentioned drive bar means.
No references cited.
WILLIAM FELDMAN, Primary Examiner.
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|U.S. Classification||254/122, 187/269, 187/900, 182/141, 187/243|
|Cooperative Classification||B66F7/065, B66F7/0625, B66F7/0666, Y10S187/90, B66F7/08|
|European Classification||B66F7/06X, B66F7/06M, B66F7/06X2, B66F7/08|