US2781866A - Hydraulic lift - Google Patents

Description

T. B. MILAM HYDRAULIC LIFT Feb. 19, 1957 Filed Aug. 10, 1955 INVENTOR ATTORNEYS Uni Sta e Pat-em HYDRAULIC LIFT Thomas B. Milam, Leesburg, Fla.

Application August 10, 1955, Serial No. 527,567

i 3 Claims. (Cl. 187-17) This invention relates to a hydraulic lift especially designed for use in the handling of field boxes of fruit or vegetables in packing or processing-plants. The purpose of the lift is to receive field boxes of fruit at floor level, and to raise them a few feet to the level of the high ends of a chute into which the contents of the boxes are dumped by tilting them while on the lift. The hydraulic lift saves the labor of manually raising loaded field boxes from the floor to the higher level, which is generally a height of about three feet.

I One of the objects of the invention is to provide a lift of the type described, comprising a horizontal platform at floor level and filling a correspondingly shaped hole in the floor when at the lower end of its stroke, having a dependingskirt slidably coinciding with the edges of the floor which bound the hole, the skirt having a length greater than the range of movement of the lift, so that the skirt never leaves the hole, functioning as a shield or guard to prevent anyone falling through the hole or getting his feet between the floor and the descending platform, and shielding the hole so that debris on the floor will not be swept nor fall through the hole into the space beneath.

Another object of the invention is to provide a lift of the character described, the platform being centrally mounted upon the upper end of a vertical ram, and the lift being vertically guided by suitable laterally positioned slide and guide means so as to relieve the ram from any laterally acting component of force derived from the load carried by the platform, and at the same time leaving the platform entirely unobstructed on three sides so as to facilitate the placing of the field boxes upon the platform.

A further object of the invention is to provide a lift as described, having a rigid frame rigidly perpendicular to the platform, and extending downward therefrom at one side, having rollers mounted thereupon in vertically spaced relation and bearing against vertical rails which constrain the lift to move vertically, relieving the ram from lateral force components, the portion of the platform on the side remote from said frame being supported "by inclined rigid struts fixed at their lower ends to said frame, this arrangement relieving the skirt from any load bearing function, so that the construction of the lift may be cheapened to the extent that the skirt may be made light and unreinforced.

Still another object of the invention is to provide a lift for the purpose described, in which the platform is elevated by a ram operating vertically from beneath the platform at its center, and lowered by a second ram laterally disposed and operating through rigid structure,-

Figure 1 is afront elevation of a hydraulic lift embodying the principles of the invention;

Figure 2 is a side elevation of the same;

Figure 3 is a longitudinal section showing on a large scale details of construction of the lift.

I Referring now in detail to the several figures of the drawing, the numeral 1 represents the floor upon which field boxes are delivered from the field, and the numeral 2 represents the level of the high end of the chute 3 to which level the lift raises the boxes, the contents of which are then dumped into the chute while the boxes are on the lift. The vertical distance between the floor land the level 2 is, for example, about three feet. and its operating means are preferably constructed as a unit, as best illustrated in Figure 2. This figure, as well. as Figure 1, shows that a concrete foundation 4 has been! erected in the basement of the plant, and that the lift: unit is mounted upon this foundation. prises a horizontal base 5, which is fabricated from channel bars suitably welded as suggested in Figure 1. The: precise nature of the base is immaterial to the invention. A pair of spaced parallel channels 6 and 7. arise from the base 5, project through suitable notches on the floor 1, and extend to a suitable height above the floor such as: that represented by the line 2. In the embodiment, as shown, these channels have their open or flanged sides. directed inwardly, that is, facing one another. The channels are braced in vertical position by the pairs of inclined members 8 and 9, which are fixed to the base and welded to the channel members respectively at intermediate points and at points near their upper ends. The lift per se comprises the platform 10, whichas shown, is an oblong rectangle, although the shape is not particularly important. This platform is reinforced beneath by angle members 11, forming a peripheral frame, and by a transverse channel member 12, which crosses the center of the including the rigid frame and the inclined struts, which I support the platform at both sides.

Other objects of the invention will appear as the following description of a practical embodiment thereof proceeds.

In the drawing which accompanies and forms a part of the following specification, and throughout the figures of which the same characters of reference denote identical parts:

platform from beneath, and to which the upper end of the hydraulic ram 13 is secured. Extending downwardly from one side edge of the platform are a pair of angle bars 14, joined at their lower ends by the transverse bar 15, and at their top by one of the angle members 11.

A rigid frame 16 is thus formed, which is rigid with the platform. Parallel transverse axles 17 are welded to said frame at upper and lower points, and carry rollers 18 which lie between the flanges of the channels 6 and -7,- i the upper pair of rollers bearing against the forward channels, and the lower pair against the rear channels, constraining the platform 10 to move in a vertical direction under the lifting effort of the ram 13. Said ram is thus relieved of any lateral force component derived from the load carried by the platform. The length of the frame 16 is somewhat greater than the distance between the surface of the floor 1 and the level line 2.

Since the frame 16 is held vertical, it is obvious that the load on the platform represented by a filled box of citrus or other fruit would create a tendency to cause the platform to tilt downwardly about a line coinciding with the apex of a dihedral angle of the angle member 11, of which the frame 16 is a part. This would be anjelement of weakness in the design of the structure and would.

throw some lateral force component upon the ram 13 as This is avoided in the present invention by the provision of the inclined struts 19 and 20, which are weldedto the angle member 11 at the side of the platform remote from the frame 16, and also welded to the transverse member 15 of the frame 16.

When the platform 10 is at the lower end of its rangeof travel, its upper surface is flush with the upper face of the floor 1, and it occupies a hole 21 cut in the floor, fitting said hole. Said platform is provided with a depending skirt 22 about three sides, that is, all sides except the one which faces the track channels 6 and 7. This The an.

The unit com-- skirt slidably coincides with the edges of the floor that bound the hole 21; the length of the skirtbeingsomewhat greater than the difference in level between the surface of the floor 1 and the line 2, so that throughout the entire range of movement ofthe lift, the skirt will still occlude the hole. The skirt thus forms ,a guardjorshield for the hole, so that it is at no time open; no one can fall intuit, nor can one get his foot between the floorand' platform. The skirt also acts as a shield to prevent fruit and'other debris from inadvertently falling or being-swept through the hole and into the space beneath. On account of the fact that the inclined struts 19, together with the frame 16, hold the platform absolutely inhorizontal position, regardless of the loadupon it, the skirt is completely relieved from any load bearing function, and can be made of-extremely light material. This contributes to the low cost at which the lift unit may be manufactured.

In the illustrated embodiment of the invention, the ram 13 is employed solely for raising the lift, a second ram 23 being devoted solely to lowering it. The ram 23 occupies a lateral position with respect to the lift, being conveniently installed back of the ram 13 and intermediate the channel members 6 and 7. The piston 24 of the ram 23 thrusts downwardly against a plate 25, which is connected to the transverse member by the divergent angle bars 26 and 27, the lower ends of which are welded to said plate and the upper ends to said transverse member directly at the foot of the struts 19 and 20.

The rams are conventionally connected into a hydraulic system, including the motor 28 and pump 29, thelatter drawing the hydraulic fluid from the reservoir 30 and supplying it to the control valve 31 by way of the conduit 32, the fluid from the rams returning to the reservoir by way of the pipe 33. A relief valve 34 is in a by-pass conduit 35 between the conduit 32 and the reservoir. The valve is connected to the respective lifting and lowering rams by means of the conduits 36 and 37. In one position of the valve, pressure is transmitted to the lifting ram. in another position, it is supplied to the lowering ram. In either position, the opposite ram is simultaneously exhausted. When the valve is turned to inoperative position with respect to both rams, the pump continues to pump fluid through the relief valve control by-pass until the motor is eventually cut off.

The control valve 31 is operated by a workman standing on the floor 1, within reach of the hand lever 38, which is pivoted at 39 to one of the channel members 6 or 7, and connected to a link 40, which inturn is connected to the lever 41 of the valve. operated by first bringing the platform to floor level, sliding the full box onto the platform; raising the platform to the level 2, and if the contents are to be discharged, the-box is then tilted toward the chute to dump its contents onto the chute. In some instances, the box-will'be slid from the platform onto the chute, retaining its contents.

While I have in the above description disclosed what I believe to be a practical embodiment of the invention, it will be understood by those skilled in the art that the specific details of construction and arrangement of parts are by way of example and not to'be construed as necessarily restricting the scope of the invention.

What I claim is:

l. Hydraulic lift comprising a base and on said base a verticaliy extensible hydraulic lifting ram and a pair of vertically disposed spaced parallel flanges beams arranged so that the flanges of each form track means, a horizontal platform externally mounted on the upper end The lift is ordinarily of said lifting ram having one side thereof adjacent said track means; a vertically extensible lowering ram mounted adjacent said track means, a rigid framework extending downwardly from said platform and rigidly related thereto comprising a frame fixed to said platform at the side adjacent said track means, and inclined struts fixed to the opposite side of said platform extending to the lower part of said frame, means mounted at high and low points of said frame engageable with said flanges to constrain said platform to move in a vertical direction, a plate on the lower end of said ram and rigid connecting means between said plate and said framework.

2. Hydraulic lift comprising a base and on said base a vertically extensible hydraulic lifting ram and a pair of vertically disposed spaced parallel flanged beams arranged so that the flanges of each form track means, a horizontal platform centrally mounted upon the upper end of said lifting ram having one side thereof adjacent said track means, a vertically extensible lowering ram mounted adjacent said track means, a rigid framework extending downwardly from said platform and rigidly related thereto comprising a frame fixed to said platform at the side adjacent said track means, and inclined struts fixed to the opposite side of said platform extending to the lower part of said frame, means mounted at high and low points of said frame engageable with said flanges to constrain said platform to movement in a vertical direction, a plate on the lower end of said ram, rigid connecting means between said plate and framework, and a pcripheral skirt cxtending downwardly from said platform, the length of said skirt being greater than the range of reciprocatory movement of said platform.

3. Hydraulic lift comprising a base, and on said base a vertically extensible hydraulic lifting ram and a pair of vertically disposed track members, said base being adapted to he installed below floor level and said ram and track member being adapted'to extend above said floor level, a horizontal platform centrally mounted upon the upper end of said lifting ram having one side thereof adjacent said track means, said platform being adapted to rest at floor level when at the lower limit of its range of movement and to occupy and substantially fit a hole in the floor at said lower limit, a rigid framework extending downwardly from said platform and rigidly related thereto comprising a frame fixed to said platform at the side adjacent said track means, and inclined struts fixed to the opposite side of'said platform extending to the lower part of said frame, roller means mounted at high and low points of said frame engageable with said track means, the interengagement of said roller means and track members being such as to constrain said platform to movement in vertical direction, a vertically extensible lowering ram mounted adjacent said track members, rigid connecting means between said lowering ram and the lower part of said framework, and a peripheral skirt fixed to said platform extending downwardly therefrom, adapted substantially to fit the hole in said floor, the length of the skirt being greater than the length of the range of travel of said platform whereby said skirt extends at all times through said hole.

References Cited in the file of this patent UNITED STATES PATENTS 70,387 Ashcroft Nov. 5, 1867 771,108 Wallace Sept. 27. 1904 968,501 Turner Aug. 23, 1910 1,467,652 Reedy Sept. 11, 1923 1,676,449 Lederer July 10, 1928

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