US2623756A

US2623756A - Pivoted load lifting mechanism

Info

Publication number: US2623756A
Application number: US172576A
Authority: US
Inventors: Morris R Elliott; George L Turner
Original assignee: Clark Equipment Co
Current assignee: Doosan Bobcat North America Inc
Priority date: 1950-07-07
Filing date: 1950-07-07
Publication date: 1952-12-30
Anticipated expiration: 1969-12-30

Description

Dec. 30, 1952 Filed July 7, 1950 M. R. ELLIOTT ETAL PIVOTED LOAD LIFTING MECHANISM 2 SHEETS,SHEET l mv'su'roas MORRIS R. ELLIOTT ROBERT LAPSLEY GEORGE L. TURNER J'W ATTYS.

Patented Dec. 30, 1952 PIVOTED LOAD LIFTING MECHANISM Morris R. Elliott, Robert Lapsley, and George L. Turner, Buchanan, Mich., assignors to Clark Equipment Company, Buchanan, Mich a corporation of Michigan Application July 7, 1950, Serial N 0. 172,576

Claims.

Our invention relates generally to self-propelled hand lift trucks, and, more specifically, is directed to a pivoted load lifting mechanism for hand lift trucks.

One form of hand operated lift truck, known in the art, comprises a main frame which is supported by a wheel unit. Disposed forwardly of the main frame is a loadsupporting means which is supported at its forward end by means of extensible wheel assemblies. The load supporting means is mounted, for vertical movement, on the main frame by means of vertical slides and roller members, respectively mounted to the main frame and load supporting means. Vertical movement of the load supporting means, with respect to the main frame, is effected by means of load elevating means, as, for example, one or more hydraulic piston and cylinder assemblies carried by the main frame. The hydraulic piston and cylinder assemblies are operatively connected, through suitable linkage means, to the extensible wheel assemblies for extending and retracting the latter, and thereby elevating and lowering the load supporting means which, as aforedescribed, is guided on the main frame by means of the vertical slides and roller members. This form of load elevating means has proved unsatisfactory as a load, carried by the load supporting means, is inadequately supported at the inner end of the load supporting means adjacent the guide means.

It is an object of our present invention to provide a load lifting mechanism for a hand lift truck which will elevate and lower the inner and outer ends of the load supporting means simultaneously.

We propose to accomplish this object by providing load supporting means which is pivotally mounted intermediate its ends to the the outer end of horizontal forwardly extending frame means carried by the main frame of a hand lift truck. The main frame is supported on a wheel unit, and the forward end of the load supporting means is supported on a pair of extensible wheel assemblies which are extended and retracted through suitable linkage means, preferably actuated by means of a pair of hydraulic piston and cylinder assemblies carried by the main frame. A pair of bell cranks are pivotally mounted to the main frame and at their one ends extend through openings formed in the frame means and engage the under sur face of the load supporting means adjacent the rear end thereof. The bell cranks, at their other ends, have suitable connection with the afore-- 2 described hydraulic piston and cylinder assemblies. When the piston and cylinder assemblies are suitably energized the extensible wheel assemblies are caused to be extended and the bell cranks rotated to elevate the load supporting means, while the main frame pivots about the connection between the load supporting means and the outer end of the horizontally extending frame means carried by the main frame. It will thus be realized that since the load supporting means is elevated at its innerand outer ends simultaneously, a load carried thereon is supported in a superior manner than has heretofore been possible.

It is another object of our present invention to provide a pivoted load lifting mechanism, of the character described, which is of sturdy construction and light in weight, and which is: efficient in operation and economical to manufacture.

The specific form of hand lift truck with which the load elevating mechanism of our present invention is shown embodied is described and claimed in the copending application of Boylan and Turner, Serial No. 170,828, filed June 28, 1950. It will be understood that the load elevating mechanism of our invention may be incorporated with other forms of hand lift trucks.

Now, in order to acquaint those skilled in the art with the manner of constructing and using the device of our present invention, we shall describe in connection with the accompanying drawings a preferred embodiment of our invention.

In the drawings:

Figure 1 is a side elevational view of the hand truck of our present invention with portions being broken away for sake of clarity; v

Figure 2 is a plan view of the hand truck of Figure 1;

Figure 3 is a diagrammatic view of the hand truck of Figure 1, with the load supporting means in a normal position; and i Figure 4 is a diagrammatic view of the hand truck of Figure 1 with the load supporting means in an elevatedposition,

Referring: now, to Figures 1 and 2, there is shown, a hand truck, indicated generally by the reference numeral 10, having a horizontally extending main frame I l to which, at the forward edge thereof, is secured the upper edge of a vertically downwardly extending plate member l2. Secured to the vertical plate member l2 and projecting forwardly therefrom, adjacent each side thereof, are a pair of load supporting frames [3.

Each of the load supporting frames E3 is provided with a pair of horizontally spaced apart bracket members 3- suitably secured, as by welding, to the lower edge thereof. A pair of housing members 2t and are mounted on the main frame i i and are, respectively, provided for enclosing the hydraulic fluid system which controls the load elevating mechanism, to be described hereinafter, and the batteries (not shown) which supply power to the electric motor, to be described hereinafter.

Secured to the underside of the horizontal main frame H is a race member it which is supported upon a plurality of ball members El carried by a lower race member l8. cured to the underside of the race member i5 and cooperates with an annular flange extending radially from the race member is for positioning the latter relative to the race member iii. The lower race member is is secured to a rotatable horizontally extending ring member 59, to which, at each side thereof, is secured a depending plate member Ell. Rotatably mounted within the depending plate members 29, intermediate thereof, is a motor-in-Wheel construction, erally by the reference numeral 2i, which fully described in the copending application of Hawkins, Lapsley, and Turner, Serial No. 175,376, filed July 22, 1950. The motor-in-wheel construction fl comprises an electric motor casing 22 upon which is mounted, for rotation therewith, a tire 23. The horizontal rotatable ring member 19, the depending plate members 23], and the motorin=wheel construction 25, are adapted to rotate as a unit about a vertical axis and thus the mctor-in-wheel construction 2! may be utilized both for powering and steering the hand truck of our present invention.

A shaft 5! is rotatably supported within a pair of vertically extending spaced apart plate members 52 which are suitably secured to the rotatable frame it of the hand truck it. Mounted on the shaft 5| between the plate members 52 is the lower end of a tubular steering handle 54. For a more detailed description of the mounting of the steering handle 53 to the rotatable frame it reference may be had to the aforenoted copending application of Boylen and Turner. Mounted to the upper end of the steering handle 54, as shown in Figure 1, is a steering head 55 which has mounted adjacent each side thereof a pair of coaxially aligned laterally projecting hand grips 55. Mounted across the top of the steering head 55 is an inverted U-shaped hand guard 5i. Conveniently disposed about the steering head 55 are a plurality of operating buttons 58 which are adapted to be manipulated for starting and stopping the truck [9, and for operating the various hydraulic devices associated therewith. Control lines, connecting the operating buttons 58 with the various hydraulic devices and the prime mover of the truck iii, are disposed within the tubular steering handle 54.

Pivotally mounted, intermediate of their ends, by bolts 63, to the outer ends of the bracket members It, secured to the lower edge of the horizon tal frame members H), are a pair of forwardly projecting fork frames 64 which are formed with aprons around their outer edges. Interconnecting the inner ends of the fork frames 64 is a transverse vertically extending plate member 65 which has flange members 66 formed integrally along each vertical edge, which flange members are adapted to be disposed or wrapped around the vertical edges of the plate member 12 carried by the main frame l i of the hand truck i8.

A retaining ring 9 is seindicated gen- Disposed adjacent each side of the hand truck H3 is a load elevating mechanism, indicated generally by the reference numeral 62, which is adapted to cooperate with each of the fork frames 64. Since both of the load elevating mechanisms 62 are of the same construction, and operate in the same manner, it is believed that a description of one will be sufficient for purposes of the present disclosure.

Pivotally mounted to a shaft Bl, secured at its ends within the apron of the fork frame lit, adjacent the forward end thereof, is a pair of spaced bracket members 68 which, at their outer ends, are spread laterally. J ournaled in the outer ends of the bracket members 63 is a shaft 69 upon which is mounted a pair of rollers ill. When the bracket members 68 are rotated clockwise about the shaft 6'! the rollers 10 are forced downwardly, which provides a reaction point for forcing the fork frames 64 upwardly. A transverse slot H is provided in the upper surface of the fork frame 64 for receiving the upper peripheries of the roller members 70 when the fork frame 64 is in a nonelevated position. A second transverse slot 94 is provided in the upper surface of the fork frame (it for receiving the one ends of the brackets 68.

Mounted, adjacent its ends, to the bracket members 68 is a shaft l3 upon which is pivotally mounted the ends of a fork member 14. Rotatably mounted on the shaft 13, between the ends of the fork member M, is a roller member 15. The fork member M is suitably secured to the one end of a draw rod 15, which draw rod 16, at its other end, is secured to a T-shaped member Tl. Pivotally mounted, by a pin member 93, to the ends of the T-shaped member 11 are a pair of parallel links 18 which, at their other ends, are pivotally mounted, as by pin member 79, to the one leg of a bell crank 80. The bell crank 83 is pivotally mounted about a fixed shaft 8! carried by bracket 12 secured to the rear surface of the plate member l2. The other leg of the bell crank is pivotally mounted, as by a pin member 82, to the lower end of a piston rod it!!! of a hydraulic piston and cylinder assembly, indicated generally by the reference numeral as, which hydraulic assembly 84, at its upper closed end, is pivotally mounted, by a pin member 85, to a vertical flange member 86 secured to the lower surface of the main frame I I of the hand truck 10.

Pivotally mounted to the vertical plate member I2 is a bell crank 81 which, at its forward end, is provided with a fork member 88, between the legs of which extends a shaft upon which is rotatably mounted a roller 89. The roller 89 is adapted to extend through a slot formed in the frame member l3 so as to engage the lower surface of the fork frame 64. The other end of the bell crank 81 is pivotally mounted, by a pin 9|, to the lower end of a connecting link 83 pivotally mounted at its upper end about pin 82 to the piston rod I00.

The hydraulic piston and cylinder assemblies are connected through suitable fluid lines (not shown) to a conventional fluid pump (not shown) carried by the main frame I I.

When fluid under pressure is admitted to the upper end of the hydraulic piston and cylinder assembly 8 the piston rod lull and connecting link 83 are extended causing the bell crank so to rotate clockwise about the pin 8! and the bell crank 81 to rotate counterclockwise about the pin member 92. Counterclockwise rotation of the bell crank Bl urges the inner end of fork frame 64 upwardly. Clockwise rotation of the bell crank as causes the link members 18 to pull the draw rod 16 to the left, as viewed inFigure 1, thereby causing the bracket members 68 to be rotated clockwise about the shaft 61 which urges the outer ends of the fork frames 64 upwardly. Therefore, it will be realized that the fork frames 64 are raised adjacent their inner ends by means of the bell cranks Bl and at their outer ends by means of the bracket members 68 and the rollers l0.

When the fork frames 64 are in their nonelevated position the main frame I I and the fork frames 64 assume the position shown in Figure 3. Upon admission of fluid under pressure to the hydraulic piston and cylinder assemblies 84, the inner and outer ends of the fork frames 64 are raised simultaneously to the position shown in Figure 4, and the main frame ll, plate member l2, and frames l3 are rotated counterclockwise with respect to the fork frames 64 about the pin members 63 until they assume the position shown in Figure 4.

When fluid under pressure is bled from the hydraulic piston and cylinder assembly 84, the piston rod I00 and connecting link 83 are caused to move upwardly, thereby rotating the bell crank 80 counterclockwise about pin member 8| and the bell crank 87 clockwise about pin member 92. This movement of the bell cranks 8B and B1 lowers the fork frames 64.

It will be noted that the hydraulic piston and cylinder assemblies 84, which are utilized for actuating the elevating mechanisms of the fork frames 54, are-disposed below the main frame I I, rearwardly of the vertical transverse plate mem ber 65 which comprises part of the load supporting means of our present invention. By disposing the hydraulic piston and cylinder assemblies 84 rearwardly of the plate member 64, adjacent each side thereof, the main support Wheel 23 is permitted to be disposed closely adjacent the load supporting means, and thus the weight of a load supported on the fork frames 64 is distributed better throughout the length of the truck.

While we have shown and described what we believe to be a preferred embodiment of our invention, it will be understood that various modii'lcations and arrangements may be made therein without departing from the spirit and scope of our present invention.

We claim:

1. In an industrial truck, the combination of a wheel unit, a main frame mounted on said wheel unit, load supporting means pivotally mounted to said main frame about a single axis extending transversely thereof, extensible ground engaging means for supporting the forward end of said load supporting means, a lever pivotally mounted to said main frame with one end engaging the underside of said lead supporting means, actuating means for extending said extensible ground engaging means, and said actuating means having connection with said lever whereby when said actuating means is energized said ground engaging means is extended and said end of said lever engaging said load supporting means is urged upwardly thereby elevating said load supporting means while said main frame is pivoted with respect to the latter.

2. In an industrial truck, the combination of a main frame including a forwardly extending portion, a wheel unit for supporting said main frame, load supporting means pivotally mounted adjacent the outer end of said forwardly extending portion about a single axis extending transversely thereof, extensible ground engaging means for supporting the forward end of said load supporting means, a lever pivotally mounted to said main frame with one end engaging the underside of said load supporting means, actuating means for extending said extensible ground engaging means, and said actuating means having connection with said lever whereby when said actuating means is energized said ground engaging means is extended and said end of said lever engaging said load supporting means is urged upwardly thereby elevating said load supporting means while said main frame is pivoted with respect to the latter.

3. In an industrial truck, the combination of a main frame including a forwardly extending portion, a wheel unit for supporting said main frame, load supporting means pivotally mounted intermediate its ends adjacent the outer end of said forwardly extending portion about an axis extending transversely thereof, ground engaging means for supporting the forward end of said load supporting means, and means between said main frame and said load supporting means for pivoting the former with respect to the latter whereby said load supporting means is elevated.

4. In an industrial truck, the combination of a main frame including a pair of forwardly extending frame members, a pair of forwardly extending fork frames pivotally mounted intermediate their ends adjacent the outer ends of the adjacent frame members about an axis extending transversely thereof, ground engaging means for supporting the forward ends of said fork frames, and means between said frame and at least one of said fork frames for pivoting the former with respect to the latter whereby said load supporting means is elevated.

5. In an industrial truck, the combination of a main frame including a pair of forwardly horizontally extending frame members, a wheel unit for supporting said main frame, a pair of forwardly extending fork frames pivotally mounted intermediate their ends to the outer ends of the adjacent frame members about an axis extending transversely thereof, extensible ground engaging means mounted adjacent the forward ends of each of said fork frames, and means between said main frame and said ground engaging means for extending and retracting the latter whereby said main frame is pivoted with respect to said fork frames and said fork frames are thereby elevated.

6. The combination of claim 5 wherein said ground engaging means comprises wheel units pivotally mounted about transverse axes to said fork frames.

'7. The combination of claim 6 wherein said ground engaging means are extended by means of rectilinearly movable draw rods actuated by means of hydraulic piston and cylinder assemblies.

8. The combination of claim 5 including slots formed in said horizontal frame members, a pair of levers pivotally mounted to said main frame having ends extending through said slots into engagement with the lower surfaces of said :fork frames, and means for rotating said levers whereby said fork frames are elevated and lowered.

9. The combination of claim 5 wherein said ground engaging means comprises wheel assemblies pivotally mounted about transverse axes to the outer ends of said fork frames, a pair of draw rods having connection adjacent their one ends to said wheel assemblies, actuating means for efiecting rectilinear movement of said draw rods, slots formed in said horizontal frame members, a

pair of levers having connection adjacent their one ends to said actuating means and at their other ends extending through said slots in said horizontal frame members for engagement with the lower surfaces of said fork frames, whereby when said actuating means are energized said Wheel assemblies are extended and said ends of said levers engaging said fork frames are urged upwardly thereby elevating said fork frames While said main frame is pivoted with respect to the latter.

10. In an industrial truck, the combination of a main frame including a pair of horizontal for- Wardly extending frame members, a Wheel unit for supporting said main frame, a pair of fork frames pivotally mounted intermediate their ends to the outer ends of the adjacent frame members, auxiliary wheel units pivctally mounted adjacent the outer ends of said fork frames, load elevating means associated with at least one of said fork frames comprising, a draw rod connected adjacent its one end to one of said auxiliary Wheel units, a pair of first levers having connection adjacent their one ends with the other end of said draw rod, a slot formed in the surface of the REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,358,957 Barrett Sept. 26, 1944 2,520,857 Schreclr Aug. 29, 1950