US3088614A

US3088614A - Pallet fork

Info

Publication number: US3088614A
Application number: US51865A
Authority: US
Inventors: Sr Joe N Summers
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-08-25
Filing date: 1960-08-25
Publication date: 1963-05-07
Anticipated expiration: 1980-05-07

Description

May 7, 1963 J. N. SUMMERS, SR 4 PALLET FORK 2 Sheets-Sheet 1 Filed Aug. 25. 1960 IN VEN TOR. Joe N Summemgbf:

A TTORNEYJ;

y 7, 1963 J. N. SUMMERS, SR 3,088,614

PALLET FORK 2 Sheets-She et 2 Filed Aug. 25. 1960 INVENTOR. Jae Zlffiimzmers; 51:

ATTORNEYS United States Patent 3,088,614 PALLET FORK Joe N. Summers, Sr., R0. Box 909, Mission, Tex. Filed Aug. 25, 1960, Ser. No. 51,865 10 Claims. (Cl. 214-653) This invention relates to a novel pallet fork attachment for an industrial truck, and more specifically to a pallet fork attachment having fork members pivotally mounted and operable to grasp or clamp an article to be lifted or handled.

Most industrial trucks are equipped with a lifting device, in the form of forwardly projecting lifting forks, which are adapted to engage the under surface of a loaded pallet to lift the pallet and the load thereon for the purpose of moving the same to a different location.

It frequently becomes necessary to move large objects from the floor or ground, such as, for example, barrels, bales of material, and the like. Attachments for industrial trucks have been suggested which involve the removal of the lifting forks and the substitution of clamping members. This conversion is a troublesome and timeconsuming task.

It is an object of this invention, therefore, to provide an attachment for an industrial truck in which a pair of forwardly projecting forks can serve either as a lifting means or as a clamping means.

A further object is to provide a combined lift and clamp attachment for an industrial truck having a pair of pivoted arms or clamping fork members interconnected in a novel manner for concurrent movement.

A still further object is to provide a combined lift and clamp attachment for an industrial ,truck that is compact, involving a minimum number of parts, and which is simple in construction and reliable in operation.

The attainment of the above and other objects will be apparent from the following description when considered with the annexed drawings, in which:

FIG. 1 is a side elevation showing the pallet fork lift attachment of the present invention;

FIG. 2 is an enlarged front elevation;

FIG. 3 is an enlarged fragmentary horizontal sectional view on the line 3-3 of FIG. 2;

FIG. 4 is an enlarged top plan view taken on the line 44 of FIG. 1;

FIG. 5 is a side elevational view of FIG. 4; and

FIG. 6 is a vertical sectional view taken on the line 6-6 of FIG. 2. I

Referring to the drawings, FIG. 1 illustrates a conventional industrial truck 10 having a pair of front power wheels 12 and a pair of rear wheels 14 pivotally supported for steering by an operators steering wheel 16. The truck also includes a brake pedal 18 and a truck control lever 20, as well as a set of control levers (not shown) for the movable carriage and for other movable parts. The truck 10 carries, at its front end, a mast 22 on which is mounted a vertically movable carriage 24 (see FIG. 4), all as well known in the art.

The invention comprises a pallet fork attachment designated in its entirety by the numeral 26, in the form of a combined lifting fork and clamping mechanism.

The attachment 26 icludes a plate member 28 (FIGS. 4, 5 and 6) which is adapted for connection with the carriage 24 by a pair of spaced cap screws 30, having non-circular heads for engagement by a suitable wrench, passing through apertures in the carriage to engage aligned threaded bores in the plate member.

A support plate 32 is retained in parallel, spaced relation with the plate member 28 by a pair of spaced trunnions 34. The trunnions 34 pivotally support a pair of fork members 36 having depending, vertically extending,

3,088,614 Patented May 7, 1963 1 ice portions 38 and forwardly projecting portions 40 at the lower ends. The forwardly projecting portions 40 are parallel, at all times, and have flat upper surfaces adapted to engage the undersurface of a pallet for lifting the latter. When the depending portions 38 are brought into parallelism, as shown in full lines in FIG. 2, the upper surfaces of the portions 40 he in a common plane. The upper ends of the portions 38 include integral bearing sleeves 42 journalled on the trunnions 34 for pivotally supporting the fork members 36 and serving as spacing sleeves to retain the plate member 28 and the support plate 32 in spaced relation. Each sleeve 42 includes a first crank arm 44 and a second crank arm 46, integral with the sleeve and angularly spaced as shown in FIG. 2 for a purpose to be set forth hereinafter.

A fluid pressure actuated servomotor 48 is connected with the fork members 36 for rotation thereof about the t-runnions 34. The servomotor 48 comprises a cylinder 50 in which a piston 52 is caused'to reciprocate in one direction or the other by the admission and exhaust of fluid under pressure through a pair of

connections

62 and 64 on opposite ends of the cylinder. A piston rod 54 is attached at one of its ends to the piston 52, the rod extending through an end wall of the cylinder and being attached, at its other end, to the crank arm 44, on one of the fork members 36, by a clevis 56. One end of a rod 58 is attached to the other end Wall of cylinder 50 and the other end of said rod is attached, by a clevis 60, with the crank arm 44 on the other fork member.

A guide support 66', in the form of an isosceles trapezoid, is secured at its base end, as by welding, to the plate member 28, the apex extending in a downward direction as seen in FIGS. 5 and 6'. The support plate 32 is generally T-shaped and includes an integral depending leg 68 forming a first guide member of a crosshead guide. The first guide member 68 and the guide support 66 are retained in spaced relation by a plurality of bolts 70 and spacing sleeves 72. A second guide member 74, attached to the guide support 66 as by welding, is disposed in alignment with and in spaced parallel relation to the first guide member 68.

A crosshead, comprising a pair of bearing plates 76 joined by a transversely extending connecting plate 78 (FIGS. 2 and 3), is mounted to slide in the guideway formed by the

guide members

68 and 74. As shown in FIG. 3, the bearing plates 76 are in sliding engagement with the edges of the

guide members

68 and 74, while the connecting plate 78 is in sliding engagement with a face of the first guide member 68. A pair of oppositely disposed lugs 80 are made integral with the bearing plates 76, as by welding. The outer ends of the lugs 80 are pivotally connected with the second crank arms 46 by a link system comprising links 83 pivotally supported by pins 86 to the outer ends of the lugs 80, and by pins 88 with the outer ends of the crank arms 46.

It will be observed, from the foregoing, that the novel pallet fork can be used as a lifting device in the manner of a conventional lifting fork when the parts are in the fluid under pressure is admitted through the connection 62 of the servomotor 48, on the left hand side of the piston 52 therein, while the fluid from the right hand side of the piston is exhausted through the connection 64, which moves the projecting portions 40 of the fork members 36 into parallel relation, as shown in FIGS. 1 and 4, and in full lines in FIG. 2. The fork members 36 are retained in this position by the fluid pressure within the cylinder, and by the crosshead, which is moved to its uppermost position, as shown in solid lines in FIG. 2. If it is desired to utilize the pallet fork as a clamping and a lifting device, the hydraulic pressure is delivered through the connection 64 and drained through the connection 62, which moves the piston 52 in the servomotor cylinder 50 toward the left, and moves the cylinder toward the right, swinging the crank arms 44 toward one another and simultaneously swinging the forwardly projecting portions 40 of the fork members 36 away from one another to the position shown in broken lines in FIG. 2. The crosshead assures a synchronous and equal movement of the fork members 36. By appropriate manipulation of the carriage 24, the clamping and lifting attachment may be brought to any desired position, and the fork members may be maneuvered into position relative to the article to be clamped and lifted. When so positioned, fluid pressure is admitted through the connection 62 and drained through the connection 64, to bring the forwardly projecting portions 40 toward one another into a position to clamp between them any desired article, such as a bale of cotton, hay, or straw, or any other article that can be clamped. By control of the pressure admitted through the connection 62, which rotates the crank arms 44 and brings the forwardly projecting portions 40 toward one another, the degree of clamping action can be controlled, while the crosshead guide assures equal and simultaneous movement of the fork members 36.

When the article has been clamped, the entire attachment can be raised by the carriage 24 in a manner known to the art and the article can be lifted and moved to any desired location where, by control of the fluid pressure through the

connections

62 and 64 of the servomotor, the fork members 36 can be separated or brought together as desired.

It is evident, from the foregoing, that the particular attachment disclosed is capable of not only functioning as a conventional lift device, but also as a clamping mechanism, without requiring any replacement of parts.

As the forwardly projecting portions 40 are always at the same elevation, because of the crosshead connection, while being swung away from or toward one another, it is evident that the forwardly projecting portions 40* can be used as a lifting fork at any position of the fork members 36. This is especially useful in lifting oversized articles, where it is desirable to provide a greater spacing than usual between the lifting forks to assure stability during a lifting, especially in case of top-heavy articles.

It is to be understood that various changes may be made in the details of the pallet fork attachment disclosed herein without departing from the principles of the invention or from the scope of the annexed claims.

I claim:

1. A combined lifting and clamping mechanism for use with an industrial truck having an upwardly extending mast including a carriage movable lengthwise thereof, comprising: a plate member adapted to be mounted on the carriage; a support attached to said plate member; and

a combined lifting and clamping means mounted on said plate member, including a pair of pivotally mounted fork members, each fork member having a depending portion and a forwardly projecting end portion; means for rotating said fork members; and additional means separate from said means for rotating said fork members, acting with said support, interconnecting said fork members and being responsive to the operation of said means for rotating said fork members for effecting concurrent movement of said fork members.

2. A combined lifting and clamping mechanism as defined in claim 1, in which said means interconnecting the fork members for concurrent movement includes a guide mounted on said support, a movable crosshead sliding in cooperative engagement with said guide, and link structure connecting said crosshead and said fork members, whereby upon operation of said means for rotating said fork members, said link structure will effect sliding movement of said crosshead upon said guide.

3. A combined lifting and clamping mechanism as defined in claim 1, in which said fork members are pivotally mounted on parallel, horizontal axes, and in which said means interconnecting the fork members for concurrent movement includes a guide, a movable crosshead sliding in cooperative engagement with said guide, and link structure connecting said crosshead and said fork members to assure concurrent movement of said fork members in opposite directions, whereby upon operation of said means for rotating said fork members, said link structure will effect sliding movement of said crosshead upon said guide.

4. A combined lifting and clamping mechanism as defined in claim 1, in which said means interconnecting the fork members for concurrent movement includes a depending guide connected with said plate member and support and disposed between said depending portions of said fork means, a crosshead slidably supported in said guide, and link structure connecting said crosshead and said fork members, whereby upon operation of said means for rotating said fork members, said link structure will effect sliding movement of said crosshead upon said guide.

5. A combined lifting and clamping mechanism as defined in claim 1, in which said support includes a support plate parallel with and spaced from said plate member, trunnions retaining said plate and plate member in spaced relation and pivotally mounting said fork members, and in which said means interconnecting said fork members for concurrent movement includes a guide support attached to said plate member, a pair of parallel guide members, one of said guide members being attached to said guide support and the other guide member being attached to said plate, a crosshead slidably mounted within said guide members, and link structure connecting said crosshead and said fork members, whereby upon operation of said means for rotating said fork members, said link structure will effect sliding movement of said crosshead upon said guide.

6. A combined lifting and clamping mechanism as defined in claim 1, in which the pivotal mounting for each fork member includes a lever arm, said means interconnecting said fork members for concurrent movement including a guide disposed between said plate member and said support, a crosshead slidably mounted on said guide, and in which the means for rotating the fork members includes a double acting fluid servomotor having a cylinder and a piston movable therein, and means connecting the servomotor to the lever arms for movement of the fork members, whereby upon operation of said servomotor to rotate said fork members, said means interconnecting said fork members will cause said crosshead to slide upon said guide.

7. A combined lifting and clamping mechanism as defined in claim 1, in which said means interconnecting the fork members for concurrent movement includes a guide disposed between the depending portions of said fork members, a crosshead slidably supported by said guide, a lever arm connected with the pivotal mount of each fork member, and a link structure interconnecting each lever arm and the crosshead, whereby upon operation of said means for rotating said fork members, said link structure will effect sliding movement of said crosshead upon said guide.

8. A combined lifting and clamping mechanism as de fined in claim 1, in which said means interconnecting the fork members for concurrent movement includes a verti cal guide disposed between the depending portions of said fork members, a crosshead slidably supported by said guide, a pair of lever arms connected with the pivotal mount of each fork member, a link interconnecting one lever arm of each pair and the crosshead, a double acting fluid servomotor having a relatively movable cylinder and piston, and means connecting the cylinder to one lever arm of said pair of lever arms and connecting the piston to the other lever arm of said pair of lever arms, whereby actuation of said lever arms con- 5 6 neeted with said servomotor will effect vertical translation 10. An attachment as defined in claim 9, in which each of said crosshead upon said guide. of the fork arms has a crank arm and wherein the actuat- 9. A combined lifting and clamping attachment for use ing means is disposed between and connected with said With a lift truck having a vertically movable lifting elecrank arms.

ment, comprising: a member mountable upon said lifting 5 element; a pair of horizontally extending fork arms; References Cited in the file Of this Patent rfneans pivotalljy moltllnting said fork arm; on said mgngbelrg UNITED STATES PATENTS or rotation a out orizontal axes para e wit sai or arms; actuating means connected with said fork arms to 'g s 'gi simultaneously move the same; and means including a 10 2676723 schggeder 1954 slide element independent of said actuating means inte-r- 2683546 Shemfi 1954 connecting said fork arms and limiting the same toequal movement by said actuating means.

Claims

1. A COMBINED LIFTING AND CLAMPING MECHANISM FOR USE WITH AN INDUSTRIAL TRUCK HAVING AN UPWARDLY EXTENDING MAST INCLUDING A CARRIAGE MOVABLE LENGTHWISE THEREOF, COMPRISING: A PLATE MEMBER ADAPTED TO BE MOUNTED ON THE CARRIAGE; A SUPPORT ATTACHED TO SAID PLATE MEMBER; AND A COMBINED LIFTING AND CLAMPING MEANS MOUNTED ON SAID PLATE MEMBER, INCLUDING A PAIR OF PIVOTALLY MOUNTED FORK MEMBERS, EACH FORK MEMBER HAVING A DEPENDING PORTION AND A FORWARDLY PROJECTING END PORTION; MEANS FOR ROTAING SAID FORK MEMBERS; AND ADDITIONAL MEANS SEPARATE FROM SAID MEANS FOR ROTATING SAID FORK MEMBERS, COACTING WITH SAID SUPPORT, INTERCONNECTING SAID FORK MEMBERS AND BEING RESPONSIVE TO THE OPERATION OF SAID MEANS FOR ROTATING SAID FORK MEMBERS FOR EFFECTING CONCURRENT MOVEMENT OF SAID FORK MEMBERS.