US3482722A - Lift truck with laterally tiltable lifting unit - Google Patents

Description

1". P. SIMOVICH 3,482,722

LIFT TRUCK WITH LATERALLY TILTABLE LIFTING UNIT Dec. 9, 1969 2 Sheets-Sheet 1 Filed Jan. 19, 1968 Dec. 9, 1969 r. P. SIMOVICH 3,482,722

LIFT TRUCK WITH LATERALLY TILTABLE LIFTING UNIT Filed Jan. 19, 1968 2 Sheets-Sheet 2 mas/779E.

jw/ J- S/MOVICAG 77 64s 47922?! United States Patent 3,482,722 LIFT TRUCK WITH LATERALLY TILTABLE LIFTING UNIT Tom P. Simovich, 74 Magna Vista, Arcadia, Calif. 91006 Filed Jan. 19, 1968, Ser. No. 699,092 Int. Cl. B66f 9/16 US. Cl. 214701 3 Claims ABSTRACT OF THE DISCLOSURE A lift truck having a lifting unit which is both laterally tiltable and laterally shiftable. The lifting unit includes a supporting structure connected to the elevating means on the mast of the lift truck. Forwardly of the supporting structure is a laterally tiltable structure which is rendered laterally tiltable by means of rollers thereon in engagement with laterally spaced, arcuate tracks on the supporting structure, such arcuate tracks facing laterally outwardly relative to the forwardly-extending axis thereof. The arcuate tracks are V-shaped in cross section and the rollers have circumferential V-grooves which receive the V-shaped tracks to restrain the laterally tiltable structure against forward and rearward movement relative to the supporting structure. A laterally shiftable lifting structure is carried by the laterally tiltable structure.

BACKGROUND OF THE INVENTION Industrial lift trucks are commonly provided with lifting units having lifting structures, such as forks, which are laterally shiftable in a horizontal direction, laterally tiltable in a vertical plane and/or laterally swingable in a horizontal plane. Shifting the lifting structure laterally and swinging it laterally are maneuvers which are useful to compensate for minor misalignments of the lift truck and a load to be picked up, or a location on which a load is to be deposited. Consequently, maneuvering of the lift truck to obtain precise alignment is not necessary. Making the lifting structure laterally tiltable provides a way of compensating for any difference between the lateral slopes of the surface on which the lift truck is positioned and the surface on which a load is to be placed, or from which a load is to be removed. For example, sometimes the ground or pavement in front of a load location slopes laterally relative to the load location itself. Being able to tilt the lifting structure laterally about a generally horizontal, forwardly extending axis provides a way of compensating for such a lateral slope differential.

As further background, the invention contemplates a lifting unit, for a lift truck having a mast and having elevating means movable upwardly and downwardly along the mast, comprising: a supporting structure connectible to the elevating means of the lift truck; a tiltable structure pivotally mounted on the supporting structure for lateral tilting movement about a forwardly extending axis; actuating means interconnecting the tiltable structure and the supporting structure for tilting the tiltable structure laterally about such axis; a lifting structure mounted on the tiltable structure for lateral shifting movement of the lifting structure relative to the tiltable sructure; and another actuating means interconnecting the lifting structure and the tiltable structure for laterally shifting the lifting structure relative to the tiltable structure.

One prior lifting unit of the foregoing type with which I am familiar utilizes a simple pivot between the tiltable structure and the supporting structure, to permit lateral tilting of the tiltable structure, together with thrust rollers for offsetting the downward bending moment produced by a load on the lifting structure.

OBJECTS OF INVENTION A primary object of the invention is to provide a pivotal connection, between the laterally tiltable structure and the supporting structure, comprising: an arcuate track means on one of these structures which is symmetrical about the desired forwardly extending axis and which faces laterally outwardly away from such axis; rollers on the other of the structures in engagement with the track means to provide for lateral tilting of the tiltable structure about the forwardly extending axis; and cooperating means on the track means and the rollers for restraining the tiltable structure against forward and rearward movement relative to the supporting structure.

Another object is to locate the arcuate track means on the supporting structure and the rollers in engagement therewith on the tiltable structure.

A further object of the invention is to provide a track means comprising two arcuate tracks spaced apart laterally of the forwardly extending axis mentioned and each engaged by two of the rollers.

An additional object is to provide a construction wherein the tracks are tapered in cross section and wherein the rollers have circumferential tapered grooves receiving the tracks therein, such rollers and tracks cooperating to restrain the tiltable structure against forward and rearward movement relative to the supporting structure, and serving to oppose the downward bending moment resulting from a load on the lifting structure carried by the tiltable structure.

Still another object is to provide a lifting unit wherein one of the tracks carries a stop which is positioned midway between the ends of such track and which is selectively engageable by the corresponding rollers so as to limit lateral tilting movement of the tiltable structure about its forwardly extending axis.

An important advantage of a lifting unit conforming to the foregoing objects of the invention is that the weight of any load carried by the lifting structure is divided between at least two of the rollers on the tiltable structure in engagement with the tracks on the supporting structure, instead of being supported entirely by a single pivot, there by avoiding concentrating the stress due to the entire load at one point.

The foregoing objects and features of the present invention, together with various other objects and features which will be evident to those skilled in the lift truck art in the light of this disclosure, may be achieved with the exemplary embodiment of the invention illustrated in the accompanying drawings and described in detail hereinafter.

DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 is a perspective vew of a lift truck equipped with a lifting unit which embodies the invention;

FIG. 2 is an enlarged, front elevational view of the lifting unit, and showing also fragments of the mast and elevating means of the lift truck;

FIG. 3 is a fragmentary view taken as indicated by the arrowed line 33 of FIG. 2, with actuating means for a laterally tiltable structure and a laterally shiftable lifting structure of the lifting unit omitted for clarity;

FIG. 4 is a fragmentary sectional view taken as indicated by the arrowed line 4-4 of FIG. 2;

FIG. 5 is an exploded perspective view illustrating the supporting, tiltable and lifting structures of the lifting unit of the invention; and

FIG. 6 is a semidiagrammatic front elevational view of the lift truck illustrating the lateral tilting movement of the tiltable structure relative to the supporting structure, the lifting structure being omitted for clarity.

3 DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION Illustrated generally in FIG. 1 of the drawings is a conventional lift truck provided with a mast 12 at its forward end. Movable upwardly and downwardly along the mast 12 is an elevating means 14 of any suitable type for raising and lowering a lifting unit of the invention.

The elevating means 14 per se forms no part of the present invention and may be of any suitable construc tion. Briefly, the particular elevating means 14 shown includes an elevating frame 22 movable upwardly and downwardly relative to the mast 12 on rollers 24. A hydraulic cylinder 26 interconnecting the elevating frame 22 and the mast 12 produces the upward and downward movement of the elevating frame. The lifting unit 20 is equipped with rollers 28 which permit the lifting unit to move upwardly and downwardly relative to the elevating frame. A chain 30 is connected at one end to the lifting unit 20 and is trained over a sprocket at the top of the elevating frame 22, the other end of the chain being anchored relative to the mast 12. Thus, as the hydraulic cylinder 26 extends the elevating frame 22 upwardly, the chain 30 moves the lifting unit 20 upwardly relative to the elevating frame. However, as previously indicated, the

lifting unit 20 of the invention may be employed with any desired type of elevating means.

Considering the lifting unit 20 generally, it includes a supporting structure 34 connectible to the elevating means 14 of the lift truck 10 and provided with an arcuate track means 36 which is symmetrical about an axis 38, FIG. 6, extending forwardly from the lift truck and which faces laterally or radially outwardly away from such axis. Forwardly of the supporting structure 34 is a structure 40 which is tiltable laterally, i.e., which is tiltable in a generally vertical plane, about the forwardly extending axis 38. More particularly, the laterally tiltable structure 40 is provided with rollers 42, preferably four in number, which engage the track means 36 to permit the structure 40 to tilt laterally relative to the supporting structure 34. As will be described hereinafter, the track means 36 and the rollers 42 have cooperating means for restraining the tiltable structure 40 against forward and rearward movement relative to the supporting structure 34 and for resisting the downward bending moment produced by a load on the lifting unit 20. An actuating means 44 interconnects the tiltable structure 40 and the supporting structure 34 and serves to tilt the structure 40 laterally about the forwardly extending axis 38. Forwardly of and carried by the tiltable structure 40 is a laterally shiftable lifting structure 46, the latter being shifted laterally, along a generally horizontal path, by an actuating means 48 interconnecting the tiltable and lifting structures.

Considering the foregoing basic components of the lifting unit 20 in more detail, the supporting structure 34 comprises simply a heavy plate which is oriented generally vertically and which is provided on its rear side with rearwardly extending flanges 52 carrying the rollers 28. The plate is provided with laterally horizontally spaced arcuate edges respectively forming arcuate tracks 54 which constitute the arcuate track means 36. The arcuate tracks 54 face laterally outwardly from the forwardly extending axis 38, and are tapered in cross section, as best shown in FIG. 4.

The tiltable structure 40 is shown as comprising a rec tangular frame on which the four rollers 42 are mounted in laterally spaced pairs, the rollers of the respective pairs engaging the respective tracks 54. As shown in FIG. 4, each roller 42 is provided with a circumferential tapered groove 56 complementary to the corresponding track 54. Thus, the flanges on the rollers 42 and the arcuate tracks 54 cooperate to resist forward and rearward movement of the tiltable structure 40 relative to the supporting structure 34, and to resist the downward bending moment created by a load on the lifting structure 46.

With the foregoing construction, the structure 40 can tilt laterally relative to the supporting structure 34 about the forwardly extending axis 38, as clearly shown in FIG. 6 of the drawings. Tilting of the structure 40 is limited by a stop 58 mounted on the plate 50 of the supporting structure 34 midway between the ends of one of the arcuate tracks 54. The laterally outer end of the stop 58 projects into the paths of the corresponding rollers 42 and is selectively engageable by such rollers to limit tilting of the structure 40 in both the clockwise and counterclockwise directions. The rollers 42 may be provided with suitable thrust bearings, not shown, resisting the axial loads imposed thereon.

The actuating means 44 for tilting the structure 40 comprises simply a hydraulic cylinder 60 pivotally connected at its ends to brackets 62 and 64 respectively mounted on the plate 50 of the supporting structure 34 and on the tiltable structure 40.

As will be apparent, the foregoing construction provides a. very simple way of making the structure 46 tiltable relative to the supporting structure 34, only simple parts being required which can be manufactured relatively inexpensively. Further, it will be noted that the weight transferred from the tiltable structure 40 to the supporting structure 34 is divided bet-ween two of the rollers 42, instead of being concentrated on a single pivot, and that the downward bending moment due to the load is divided among all four of the rollers 42, thereby further avoiding stress concentrations.

Turning now to the lifting structure 46, it is shown as including a rectangular frame having adjacent the top thereof a transversely extending shaft 72 to which L-shaped tines 74 are pivotally connected. The tines 74 have forwardly extending portions 76 which are capable of supporting a load, such as a palletized load, and the downward bending moment resulting from the load is resisted by engagement of upright portions 78 of the tines with the front side of the frame 70. Also, the tines 74 may be shifted laterally along the shaft 72 to vary the spacing therebetween to accommodate a particular load.

The lifting structure 46 is connected to the tiltable structure 40 by means of transverse shafts 80 carried by the tiltable structure 40 and rearwardly extending blocks 82 carried by the lifting structure frame 70 and slidable on the respective shafts 80. The downward bending moment produced by a load on the forwardly extending portions 76 of the tines 74 is resisted by horizontal rollers 84 on the tiltable structure 40 in engagement with the rear surface of a transverse member 86 of the frame 70.

The blocks 82 are laterally slidable on the shafts 80, and the rollers 84 are in rolling engagement with the frame member 86, to permit lateral shifting of the lifting structure 46 relative to the tiltable structure 40. The actuating means 48 for producing such lateral shifting comprises simply a hydraulic cylinder 90 pivotally connected at one end to a bracket 92 on the tiltable structure 40 and at its other end to a bracket 94 on the liftingstructure frame 70.

It will be understood that the various hydraulic cylinders hereinbefore described are powered by hydraulic fluid supplied by a suitable pump, not shown, on the lift truck 10.

Although an exemplary embodiment of the invention has been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiment without departing from the spirit of the invention.

I claim as my invention:

1. In a lifting unit for a lift truck having a mast and having elevating means movable upwardly and downwardly along the mast, the combination of:

(a) a supporting plate having front and rear sides and having laterally spaced, upright, tapered arcuate edges symmetrical about a fore-and-aft tilt axis;

(b) means on said rear side of said supporting plate 5 for mounting it on the elevating means of the lift truck;

(0) a laterally extending, tiltable, rectangular frame on said front side of said supporting plate;

(d) four rollers mounted on said tiltable frame equal distances from said tilt axis in a rectangular pattern and rotatable about axes parallel to said tilt axis;

(e) there being two of said rollers adjacent each end of said tiltable frame in vertically spaced relation;

(f) said rollers having tapered circumferential grooves complementary to said tapered arcuate edges;

(g) the two rollers adjacent one end of said tiltable frame engaging one of said tapered arcuate edges and the two rollers adjacent the other end of said tiltable frame engaging the other of said tapered arcuate edges, whereby said tiltable frame may pivot about said tilt axis as said rollers roll along said tapered arcuate edges, and whereby said rollers and said tapered arcuate edges cooperate to prevent downward and forward tipping of said tiltable frame relative to said supporting plate;

(h) actuating means interconnecting said supporting plate and said tiltable frame for pivoting said tiltable frame about said tilt axis; and

(i) lifting means carried by said tiltable frame.

2. A lifting unit as defined in claim 1 wherein said lifting means includes:

(a) a laterally extending, rectangular lifting frame on the front side of said tiltable frame;

(b) transverse shaft means on said tiltable frame adjacent the upper edge thereof;

(c) bearing means on said lifting frame and slidable laterally along said shaft means to permit lateral shifting of said lifting frame;

(d) thrust rollers carried by said tiltable frame adjacent the lower edge thereof and rotatable about upright axes and engageable by the lower portion of said lifting frame to prevent downward and forward tipping of said lifting frame; and

(e) actuating means interconnecting said lifting and tiltable frames for shifting said lifting frame laterally relative to said tiltable frame.

3. A lifting unit according to claim 2 including:

(a) transverse rod means on said lifting frame adjacent the upper edge thereof; and

(b) L-shaped tines having upright portions the upper ends of which are pivotable on and slidable laterally along said rod means, which bear intermediate their ends against the front side of said lifting frame adjacent the lower edge thereof, and which terminate at their lower ends in forwardly extending portions.

References Cited UNITED STATES PATENTS 1,878,994 9/1932 Abbe.

2,287,469 6/ 1942 Cochran.

2,468,326 4/1949 Gleason.

2,522,128 9/ 1950 Lehmann.

2,752,055 6/ 1956 Hoppert 2l4-652 2,940,068 6/1960 Stiefel.

3,002,639 10/1961 Cavanagh 214-701 X 3,143,233 8/1964 Evans et al. 214-652 3,148,793 9/1964 Walter 214-715 X 3,289,873 12/1966 Hansen 2l4730 GERALD M. FORLENZA, Primary Examiner RAYMOND B. JOHNSON, Assistant Examiner US. Cl. X.R. 214 -730

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