US2992751A

US2992751A - Fork extending construction

Info

Publication number: US2992751A
Application number: US757970A
Authority: US
Inventors: George F Quayle
Original assignee: Yale and Towne Manufacturing Co
Current assignee: Yale and Towne Manufacturing Co
Priority date: 1958-08-29
Filing date: 1958-08-29
Publication date: 1961-07-18
Anticipated expiration: 1978-07-18

Description

July 18, 1961 G. F. QUAYLE FORK EXTENDING CONSTRUCTION 5 Sheets-Sheet 1 Filed Aug. 29, 1958 -o sm- I; q 3

, r L l/ g\ INVENTOR. Geoyce F 004 yu- ATTOfWC) y 1961 G. F. QUAYLE 2,992,7511

FORK EXTENDING CONSTRUCTION Filed Aug. 29, 1958 5 Sheets-Sheet 3 '56 44 Ml;- QH' I M 37 i 5Q as ll i llllms HHI- 8 i {7 60 TL 56 82 1 i 6g 5 f 1 812 9 8(-, E s

. 3 7 44 Hill Hm." III 4Q INVENTOR.

,q rroglvey July 18, 1961 G. F. QUAYLE FORK EXTENDING CONSTRUCTION 5 Sheets-Sheet 3 Filed Aug. 29, 1958 lllrll's v l V. 1

INVENTOR. 6 6096: f. QUAYLE y 961 G. F. QUAYLE 2,992,751

FORK EXTENDING CONSTRUCTION Filed Aug. 29, 1958 5 Sheets-Sheet 4 Wm... ""WIHHHH INVEN 1 OR. 'Geoqvsc F Oil/7 YLe' 2,992,751 Patented July 18, 1961 2,992,751 FORK EXTENDING CONSTRUCTION George F. Quayle, Philadelphia, Pa., assiguor to The Yale and Towne Manufacturing Company, Stamford, Conn., a corporation of Connecticut Filed Aug. 29, 1958, Ser. No. 757,970 Claims. (Cl. 214-730) This invention relates to an industrial truck, and more particularly, to an industrial truck adapted to extend and retract a load relatively to the frame of the truck.

Heretofore, trucks of the class described have been developed in which a leverage system is employed to extend and retract the load, the levers themselves moving in a vertical plane and resembling spaced pairs of scissors. In this type of construction, the height of the leverage systems presents a serious problem. The levers may, for example, occupy a vertical space of as much as forty-six inches. Therefore, if a uniform load of, say, thirty inches is to be stacked, it is possible that, due to interference of the leverage system with overhead structures, an entire course of load units will not be able to be stacked atop lower courses, therefore wasting a considerable amount of warehouse storage space.

In order to overcome this serious disadvantage, it was first proposed to connect a load carrier to a back plate by a leverage system of the class described operating in a horizontal plane. Then, the levers, in extending and retracting the load, will move horizontally. It was soon realized that such an expedient is completely unsatisfactory because the ends of the levers slide toward one another when extending the load while separating when bringing the load toward the truck. Those skilled in the art will immediately appreciate the enormous vertical stresses that are applied to the levers when the load is extended and the levers are close together. In such a leverage system, instability and twisting moment produced by an off-center load is extremely serious.

I have conceived by my invention a novel construction that enables me to extend and retract a load carrier without limiting the height to which the load carrier may be elevated, while maintaining complete load stability.

:In essence, my invention resides in the utilization of a leverage system employing levers that pivot about vertical axes so that they move in horizontal planes. I am therefore able to obtain the desired amount of extension of my load carrier with a relatively low leverage system.

As a feature of my invention I utilize a separate pair of levers at each side of the load, the levers at each side being pivoted to one another, while one lever is pivoted to the load carrier and the other to the base of the truck. Those persons skilled in the art will readily appreciate that my leverage system in no way limits the amount of lift that I can achieve, so that I am able to obtain maximum vertical lift as well as horizontal thrust.

As a particular feature of my invention, I pivot to the base plate of my truck a pair of base levers, and -I utilize a pair of load levers that are pivoted to the base levers and to the load carrier, all of the pivots being substantially vertical so that the levers swing horizontally relatively to the base plate.

As another feature of my invention, I employ a ram pivotally connected through substantially vertical pivots between the base plate and one of the base levers, and a second ram pivotally connected through substantially vertical pivots between the load carrier and one of the load levers.

Another feature of the invention resides in the utilization of rods connected between the base levers and the base plate through an arm that is pivoted to the base plate and similar rods connected between the load levers and the load carrier through an arm that is pivoted to the load carrier. By this arrangement, I am able to maintain the load carrier parallel to the base plate regardless of the degree to which the carrier is extended.

I have thus outlined rather broadly the more important features of my invention in order that the detailed description thereof that follows may be better understood, and in order that my contribution to the art may be better appreciated. There are, of course, additional features of my invention that will be describedhereinafter and which will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception on which my disclosure is based may readily be utilized as a basis for the designing of other structures for carrying out the several purposes of my invention. it is important, therefore, that the claims be regarded as including such equivalent constructions as do not depart from the spirit and scope of my invention, in order to prevent the appropriation of my invention by those skilled in the art.

A specific embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of an industrial truck utilizing my novel fork extending construction and showing the forks in dot-dash lines in an extended position and in broken lines in an extended, partially elevated position;

FIG. 2 is a plan view of the truck shown in FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 1;

FIG. 4 is a front elevation of my invention partially broken away to better illustrate certain features;

FIG. 5 is a sectional view taken along the line 5-5 of FIG. 4; J

FIG. 6 is a side view of my fork extending construction in the position shown in FIG. 5;

FIG. 7 is a fragmentary side elevation, partly in section, showing my new construction in extended position;

FIG. 8 is a sectional view taken along the line 88 :of FIG. 7; and

FIG. 9 is a sectional view taken along the line 99 of FIG. 8.

Referring to the drawings, and more particularly to FIGS. 1 and 2, it will be seen that, for the purpose of description, I have chosen to illustrate my novel truck 10 constructed with a conventional rear traction end .11. This traction end is equipped at opposed sides with a driving and steering wheel '12 and a casterwheel 14. The driving and steering wheel is controlled by ahan'd Wheel 15 accessible to an operator. The details of the traction end 11 and its wheel arrangement are not important to an understanding of my invention, it being necessary to understand only that the truck is steered and driven through its rear end.

For supporting the front end of the truck, I utilize a pair of legs 16 and 17 that extend forwardly from the opposite sides of the rear end and that are each provided with a pair of

front wheels

19 and 20*. As will be readily appreciated by those persons skilled in the :art, the disposition of the pairs of

wheels

19 and 20 in widely spaced relation to one another enable the load to be carried between the wheels, thereby contributing great stability to the truck and enabling one to handle loads in a novel way as will be realized as the description proceeds.

Between the front and rear wheels of the truck, I mount on the truck frame a pair of I beams .21 to serve as primary uprights. Secondary uprights 22 are movable vertically relatively to primary uprights 21 and are guided by rollers 24 rotatably carried on secondary .uprights 22 and extending into channels in primary uprights 21.

Upper cross members

25 and 26 are provided on primary and

secondary uprights

21 and 22, respectively.

As shown in FIGS. 2 and 3, I utilize a base or back plate 27 for supporting my extending leverage mechanism and a load carrier, as will be later described. The base plate has a pair of forwardly extending brackets 29 that support rollers 30 for vertical movement in secondary upright channels whereby the base plate 27 may move vertically relatively to the secondary uprights. A hydraulic ram 31 (FIG. 2) serves to elevate the secondary uprights relatively to the primary uprights and the base plate relatively to the secondary uprights in a manner well known in the art.

Referring now to FIGS. 3 and to 8, it will be seen that the base plate 27 has four cars 32 projecting from its corners. These ears are apertured to carry a vertical pivot shaft 34 at each side of the back plate. Each of these shafts, in turn, supports a cylindrical sleeve 35 one of which has formed integral therewith upper and lower hinge members or base levers 36, while the other sleeve has similar hinge members or base levers 37 formed integral therewith. These hinge members are slightly curved outwardly at their ends remote from the sleeves 35, as shown in FIG. 8, and these same ends are recessed to provide a pair of fingers 39 formed with holes for the reception of pivot or hinge pins 40.

The pins 40 also pass through apertured fingers 41 of hinge members or load levers 42 and 44 that are similar to hinge members or base levers 36 and 37, and that are formed integral with cylindrical sleeves 45. A front plate 46 is provided with upper and lower reinforcing

ribs

47 and 49 that are shaped at each end to form apertured lugs 50 adjacent the ends of the sleeves 45. A vertical pivot shaft 51 passes through each of the sleeves 45 and the lugs 50 at the sides of the front plate 46 to connect the

hinge members

42 and 44 to the front plate 46 for pivotal movement relatively thereto about the vertical shafts 51.

While I have chosen to illustrate the load carrier 52 as a pair of forks mounted on the front plate for movement therewith by means of upper and lower mounting

brackets

54 and 55, respectively, it will be understood that while my invention is of great utility when used with load forks, the contribution that I have made may be utilized to control the extension of other forms of load carriers as well.

In order to eflect the extension and retraction of the load carrier 52 relatively to the base plate 27, I mount the cylinder of a double acting hydraulic ram 56 on a bracket 57 on the front face of the base plate by means of a vertical pivot 59. The piston rod 60 of this ram is connected to a vertical pivot 61 supported in a lug 62 integral with one of the sleeves 35, as shown in FIGS. 3 to 5 and 7 to 9. A similar ram 64 extends between the rear face of the front plate 46 to which it is connected by a bracket 65 and vertical pivot 66, and one of the sleeves 45 to which its piston rod 68 is connected by a vertical pivot 67 in a lug 69. Attention is here invited to the fact that, as shown, I prefer that the rams be connected to

sleeves

35 and 45 that are diagonally opposite one another.

Referring to FIG. 8, it will be seen that when the ram 56 is actuated to extend its piston rod, the lug 62 and consequently the sleeve 35 on the left side of the base plate 37, as viewed, will pivot in a clockwise direction about vertical shaft 34, as will the hinge members 36 connected to that sleeve. Similarly, extension of the ram 64 will effect clockwise movement of the hinge members 42 connected to the sleeve 45 at the right side of the load carrier, as viewed, about the vertical shaft 51.

In order to so interrelate the movement of the

hinge members

36 and 37, as well as the four

hinge members

42 and 44, so that they will be properly synchronized to obtain a straight line motion of the load carrier, or, in other words, to maintain the base plate 27 and the front plate 46 parallel in all positions of the load carrier, I provide a serpentine shaped reversing link or arm 70 that I connect to the front of the base plate by a pivot 71. A rod 72 is connected between one end of this link 70 and the vertical pivot 61 by

universal joints

74 and 75, respectively. A second rod 76 extends between the other end of the link 70 and a vertical pivot 77 supported by a lug 79 integral with the right hand sleeve 35, as viewed in FIG. 8, by

universal joints

80 and 81, respectively.

A reversing link 82 is mounted on the front plate by a pivot 84.

Rods

85 and 86 are connected to opposed ends of the link 82 by universal joints. The other end of rod 85 is universally jointed to the vertical pivot 67 in lug 69, and the other end of the rod 86 is universally jointed to a pivot 87 carried by a lug 89 that is integral with the left hand sleeve 45, as viewed in FIG. 8.

Because of the

rods

72, 76, 84 and 85, it will be seen that any motion imparted by

rams

56 and 64 to hinge members 36 on the left of the base plate and to the hinge members 42 on the right of the load carrier, as viewed in FIG. 8, will be duplicated in the

opposite hinge members

37 and 44. Since the

links

70 and 82 reverse the motion of

links

72 and 85, it will be apparent that clockwise movement of left hand hinge members 36 will be accompanied by equal counterclockwise movement of right hinge members 37, and that clockwise movement of the right hand hinge members 42, relatively to the front plate 46, will be accompanied by equal counterclockwise movement of left hinge members 44, relatively to the front plate, for example.

In operation, assuming the parts to be in the position shown in solid lines in FIG. 1, and in FIGS. 2 and 3, it will be understood that the load carrier may lift and transport a load in the usual manner. When it is desired to lift or deposit a load from a space that is too small for the truck to enter, the

rams

56 and 64 are extended so that hinge members 36 are swung outwardly away from base plate 27. The

linkage comprising rods

72 and 76 and link 70 transmit equal but opposite rotary movement to hinge members 37 so that they too swing outwardly, away from base plate 27. At the same time, the ram 64 causes the hinge members 42 to swing away from the front plate 47 while the

linkage comprising rods

85 and 86 and link 82 transmit equal and opposite movement to hinge members 44 so that the front plate 47, and the load carrier, are thrust outwardly of the truck 10 to the positions shown, for example, in FIGS. 7 and 8 and in dotdash of FIG. 1. It will be seen that during its movement, the load carrier front plate 47 is maintained parallel to the base plate 27. The load carrier may be elevated in any position, as shown by the broken lines of FIG. 1.

Actuation of the

rams

56 and 64 to retract the piston rods thereof operates the hinge members in the opposite manner to that just described so that the load carrier is retracted relatively to the truck until the parts again assume the position shown in solid lines in FIG. 1, and in FIGS. 2 and 3. Again, the base plate 27 and front plate 47 are maintained parallel during retraction.

From the foregoing description, it will be seen that I conceived a novel construction enabling me to extend a load carrier without limiting the height to which the load carrier may be elevated. It will also be seen that the essential characteristic of my invention resides in the utilization of a leverage system employing levers that pivot about vertical axes, so as to move horizontally, thereby permitting me to obtain the desired amount of extension, with a relatively low leverage system.

I believe that the construction and operation of my novel load extending construction will now be understood, and that the advantage of my invention will be fully appreciated by those persons skilled in the art.

I now claim:

1. In a truck of the class described, a base plate, a load carrier, a pair of base levers each pivoted by a fixed pivot at one end thereof to one side of said base plate on a substantially vertical pivot, laterally spaced from the fixed pivot of the other base lever a pair of load levers, each load lever being pivoted at one of its ends to one of said base levers and at its other end to one side of said load carrier on a pivot also substantially vertical and laterally spaced from the pivot of the other load lever, a ram extending between and operatively connected to said base plate and a base lever and a second ram extending between and operatively connected to said load carrier and a load lever for swinging said levers to move said load carrier between a position adjacent said base plate and a second position spaced from said base plate, and means operatively connected with said levers for providing substantially simultaneous and equal movement of the levers connected to the base plate and the levers connected to the load carrier to maintain said load carrier parallel to said base plate during movement of said load carrier toward and away from the base plate.

2. In a truck of the class described, a base plate, a load carrier, a pair of base levers each pivoted by a fixed pivot at one end thereof to said base plate on a substantially vertical pivot laterally spaced from the fixed pivot of the other base lever, a pair of load levers, each load lever being pivoted at one of its ends to one of said base levers and at its other end to said load carrier on a pivot also substantially vertical and laterally spaced from the pivot of the other load lever, and a ram extending between and operatively connected to said base plate and a base lever and a second ram extending between and operatively connected to said load carrier and a load lever to move said load carrier between positions adjacent said base plate and spaced from said base plate, and means operatively connected to said levers for maintaining said load carrier parallel to said base plate in all positions thereof.

3. In a truck of the class described, a base plate, a load carrier, a pair of base levers each pivoted at one end thereof to said base plate on a substantially vertical pivot at a point laterally spaced from the other base lever, a pair of load levers, each load lever being pivoted at one of its ends to one of said base levers and at its other end to said load carrier on a pivot also substantially vertical and laterally spaced from the pivot of the other load lever, a ram extending between and operatively connected to said base plate and a base lever and a second ram extending between and operatively connected to said load carrier and a load lever to move said load carrier between positions adjacent said base plate and spaced from said base plate, a link pivotally connected to said base plate, a pair of rods pivoted at one end to opposed ends of said link and at their other ends to opposed base levers, a second link pivotally connected to said load carrier, and a pair of rods pivoted at one end to opposed ends of said second link and at their other ends to opposed load levers whereby said load carrier is in all positions thereof maintained parallel to said base plate.

4. In a truck of the class described, a base plate, a load carrier, a pair of base levers each pivoted by a fixed pivot at one end thereof to said base plate on a substantially vertical pivot laterally spaced from the vertical pivot of the other base lever, a pair of load levers, each load lever being pivoted at one of its ends to one of said base levers and at its other end to said load carrier on a pivot also substantially vertical and laterally spaced from the pivot of the other load lever, a ram connected through substantially vertical pivots between said base plate and a base lever and a second ram connected also through substantially vertical pivots between said load carrier and a load lever to move said load carrier between positions adjacent said base plate and spaced from said base plate, a link pivotally connected to said base plate, a pair of rods pivoted at one end to opposed ends of said link and at their other ends to opposed base levers, a second link pivotally connected to said load carrier, and a pair of rods pivoted at one end to opposed ends of said second link and at their other ends to opposed load levers whereby said load carrier is in all positions thereof maintained parallel to said base plate.

5. In a truck of the class described, a base member, a load carrier, a pair of base levers each pivoted at one end thereof to said base member on a substantially vertical pivot laterally spaced from the vertical pivot of the other base lever, a pair of load levers, each load lever being pivoted at one of its ends to one of said base levers and at its other end to said load carrier on a pivot also substantially vertical and laterally spaced from the pivot of the other load lever whereby said load carrier may be extended and retracted relatively to said base member by horizontal folding movement between said base levers and said load levers, and means operatively connected with said load carrier, base member, and said levers for extending and retracting said load carrier and determining the position of said load carrier relatively to said base member during such extension and retraction of said load carrier.

References Cited in the file of this patent UNITED STATES PATENTS 518,633 Steur Apr. 24, 1894 892,413 Freeman July 7, 1908 2,471,901 Ross May 31, 1949 2,639,051 Thomas May 19, 1953 2,752,058 Gibson June 26, 1956 2,896,806 Vossenberg July 28, 1959