US3075663A - Clamp attachment - Google Patents

Description

Jan. 29, 1963 o. E. BIHR 3,075,663

CLAMP ATTACHMENT Filed May 27. 1960 4 Sheets-Sheet 1 FIG. I

INVENTOR.

OTTO E. BIHR ATTORNEY Jan. 29, 1963 0. E. BIHR CLAMP ATTACHMENT 4 Sheets' 2 Filed y 27. 1960 mu I fisilmil i Q\ I I I I I I LV/V/ mm 9.6 gm g INVENTOR.

O E. BIHR BY f/MWJM ATTORNEY Jan. 29, 1963 Filed May 2'7. 1960 O. E. BlHR CLAMP ATTACHMENT FlG. 5

I IIIIIIIII! 4 Sheets-Sheet 3 INVENTOR.

OTTO E. BIHR BY /wm ATTORNEY Jan. 29, 1963 o. E. BlHR 3, ,6 3

CLAMP ATTACHMENT Filed May 27. 1960 4 Sheets-Sheet 4 INVEN TOR.

OTTO E. BIHR ATTORN EY Patented Jan. 29, 1963 3,ti75,6t53 CLAMP ATTACHMENT Gtto E. Bihr, Essen-Altenessen, Germany, assignor to Ruhr Intrans Huhstapier, Gnnba a German com- P 3 Filed May 27, 196i), er. N 32,416

Ciaims priority, application Germany June 3, 1959 7 Claims. (Cl. 214655) This invention relates to an attachment for industrial trucks, and more particularly to improvements in a clamping attachment for lift trucks which is especially suited for handling stacks of building blocks, bricks, and the like wherein at least two laterally spaced fork arms are provided having facing sides equipped with clamping members for engaging and holding material to be conveyed.

Heretofore, it has been generally known to provide facing clamp members in fork arms of the type contemplated in which the clamp members are responsive to hydraulic or pneumatic fluid pressure supplied by a main pressure generating system, including a pump or compressor, whi h is connected to the engine of the lift truck.

It is an important object of the present invention to provide a generally improved clamping mechanism of the type under consideration. This is achieved in large part by connecting clamping members with a closed pressure system which may be filled with a hydraulic or pneumatic pressure-transmission medium in which pressure responsive members, such as pistons, are actuated by the mass of material to be conveyed to provide fluid pressure at the facing clamping members located in the sides of fork arms. When the material conveyed is deposited the pressure members automatically release the clamping members. The device of the present invention is, therefore, capable of engaging, conveying and de positing material without dependency upon any independ ent pressure generating means, such as a pump or air compressor. An additional resulting advantage in the use of a hydraulic pressure-transmission medium, for example, is that hydraulic lines between the fork arms, which is preferably movable vertically in a lifting mast of a lift truck, and a stationary pump are eliminated.

Thus, the attachment unit becomes a less cumbersome and neater package, and by omission of the usual movable connecting hydraulic lines the unit is less subject to malfunctioning in operation and, importantly, is insensitive to fluid losses resulting from leakage in the independent system.

If desired, the pressure transmitting system between the pressure producing pistons and the pressure responsive clamping members may be filled with a mechanical pressure transmission medium as, for example, steel balls, which is of particular advantage in applications which require that the pressure transmission medium be insensitive to large variations in temperature. The use of steel balls in the aforesaid manner as an alternative to the use of fluid, hydraulic or otherwise, makes possible the use of the attachment in areas of widely varying temperature. Also, of course, no leakage losses are encountered in the use of a mechanical pressure trans mission medium.

The fork arms are preferably equipped with pressure limiters to limit the maximum clamping pressure which can be applied to the material conveyed, thereby pro tecting same against possible damage. Also, adjustable pressure reservoirs in the system are provided so that the operating pressure of the pressure transmission mediumcan be varied as desired depending upon requirements of different operating conditions.

Another object of the invention is therefore to provide a closed circuit pressure transmission system in a clamping attachment of the type contemplated wherein means are provided to apply clamping pressure as a function of the load to be conveyed and to release such clamping pressure upon deposite of the load.

Other objects and advantages of the present invention will appear as the description proceeds.

Now, in order to acquaint those skilled in the art with the manner of constructing and using clamping means, in accordance with the principles of my present invention, I shall describe in connection with the accompanying drawings, preferred embodiments of the invention.

In the drawings:

FIGURE 1 is a side view primarily in elevation which illustrates the clamping attachment suspended on the lifting mast of an industrial truck;

FIGURE 2 is a plan view of FIGURE 1;

FIGURE 3 is an enlarged vertical longitudinal section through a fork arm along the line 3-3 in FIGURE 2;

FIGURE 4 is an enlarged vertical longitudinal section through a fork arm along the line 44- in FIGURE 2;

FIGURE 5 is an enlarged vertical section through a pressure reservoir shown in section in FIGURE 1;

FIGURE 6 is a vertical section similar to FIGURE 3 but illustrating a modified form of the invention;

FIGURE 7 is a vertical section similar to FIGURE 4 but illustrating another portion of the modified form of the invention shown in FIGURE 6;

FIGURE 8 is a schematic representation of the form of the invention shown in FIGURES 3 and 4; and

FIGURE 9 is a schematic representation of the modified form of the invention shown in FIGURES 6 and 7.

Referring now in detail to the drawings, a lifting mast assembly 1 is supported in well-known manner upon the forward end of an industrial truck 2 and supports in turn for vertical movement therein a lift bracket 3 to which is connected a transverse support plate 4. Hydraulic hoist motor means la is associated with the lifting mast 1 and is connected by known sprocket and chain means with a transverse plate 4 for actuating same vertically in lifting mast 1 in a well-known manner.

A conveyor fork arm assembly 5 is supported from the plate 4 by a pair of vertically extending shanks 11. Assembly 5 includes a plurality of fork arms 6, five fork arms being shown, which are mounted in transversely spaced and parallel relation to each other to provide longitudinally extending openings in which material to be engaged can be located. The facing sides of the fork arms are equipped with clamping members 7 which are adapted to secure the material to be conveyed, as will be described below.

Clamping members '7 are spaced equally apart over the length of each fork arm, and are connected by common pressure conduit means 8 of a closed pressure system which may be filled, for example, with either hydraulic or pneumatic fluid or with a mechanical pressure transmission means such as steel balls. The closed pressure system is equipped with piston members 9 Which are connected to a carrier plate 10 overlying each fork arm 6 and parallel to it. Carrier plates 10 preferably extend over the entire length of the respective fork arms 6, as show in FIGURES 1 and 2.

In each of two vertical shanks 11 which are connected to the fork conveyor assembly 5 and which support the latter from transverse plate 4, there is provided a pressure reservoir (FIG. 5) comprising a spring operated plunger 12 having a sealing ring 13 associated therewith, and an adjusting nut 14 providing pre-load pressure on the plunger through a spring 15. The system, hydraulic as shown, is filled by removing nut 14 and plunger 12 and then filling the pressure system 8 with a hydraulic fluid. In frigid areas glycerin may be used as a pressure transmission medium to withstand relatively extreme degrees of cold; If'the attachment is to be equipped with a pneumatic medium it is expedient to provide in the area of hollow space 16 below the plunger 12 a connector, not shown, for receiving compressed air or the like.

As illustrated in FIGURE 3, the clamping members 7 are located in cylindrical'spaces '17' which are connected with the pressure system 8. Each of the clamp members is equipped at its outer end with a clamp jaw 18 which preferably has a serrated surface 19. An annular'packing 20 is located at the inner end of each clamp member 7. A collar 21 of each clamp member abuts one end of a return spring 22 which is, provided between the inside wall ofspace 17 and .the clamptmember' 7. Each spring 22 at its opposite end is supported by a nut 24 which is threaded into each fork arm 6 flush with the latters outer surface 23.

In FIGURE 4 is shown the relationship of one of pressure pistons 9, which is secured to carrier plate 10 as bywelding, to the system. 8. Piston 9 is, located in a cylindrical space 25 which is connected with pressure system 8, and at the upper end of piston 9 is attached the carrier plate 10. A circular packing 26 surrounds the lower end of piston 9. A compression spring 27 is located between each carrier plate and its fork arm 6 which serves as a return spring in a manner to be described. Preferably a stop member 28 islocated on each forkarm to provide a pressure limiting means for the respective piston 9,. The stops may, of course, be ad'- justable within the fork arm to provide for variations in the length of stroke of pistons 9.

Referring now especially to FIGURE 8, the operation .of the above embodiment will be described. The material to be conveyed as, for example, t-ile s,;br;icks or blocks 29, is arranged in a well-known manner so that the, fork assembly with its fork arms 6 can be driven in the direction indicated by arrow a (FIG, 1) into hollow spaces 30, which are located-between rows formed in the bottom layer of such material so that thefork arms may assume the position shown in FIGURE 2' with respect to the lowermost row-of the stack of material. The adjacent -or second layer and succeeding layers of such material 29 are stacked solidly upon the lower rows thereof without providing spaces such' as indicated at numeral'30, whereby the location of fork assembly 5 as shown. in FIGURE 2 causes carrier plates to be situated directly beneath the second layer .or the stack of bricks or other material, as shown in. FIGURE 1.

As. hoist motor 1a is energized to. raise the unit in lifting mast 1 carrier plates 10 first come to bear on the undersides of the second layer of material and, because of the weight of the material, they are caused to move relative to fork arms 6 in the direction indicated by arrow b which causes pistons 9 to apply pressureto the fluid in system 8, thereby transmitting clamping pressure against piston surface 31' of collar 21 of the clamping member 7 so that the clamping members are pressed against the material in a direction indicated by arrow 0. In order to adjust the clampingpressure to the nature of the bricks or other material and to preclude damage to the clamping members or materia'l by excessive pressures, adjusting nuts 14 of the reservoir 11 may be adjusted, and pressure limiters 28 also adjusted,;if;necessary, to limit the available stroke of pistons 9.

Thus, the clamping of the material by member 7 is accomplished advantageously prior to lifting of the material by the fork assembly 5. This is in contrast to prior known structures for a similar purpose wherein pumps and the like have been providedfor the purpose of supplying pressure fluid to' clamp members which engage the bricks or other material. It will be apparent that the present invention insures that'the material is not lifted until sufficient clamping pressure is provided to insure secure gripping thereof. This avoids 'both apos- .1sible loss 0f the; load and any relative movement between the clamp member ends 18 and the load which would lead to undue wear of the clamp members and to undesirable abrasion of the bricks or other material. Of course, other forms of the clamping members 7 can be provided than that shown. For example, instead of using jaws 18 .it may be found desirable to utilize a hardened steel ball secured to clamp member 7 and usable with extremely hard bricks, for example, so that the surface thereof will not be damaged by the serration of the clamping aws.

When the material conveyed is to be deposited, pistons 9 are restored to initial position by springs 27, the fork arm 6 having been lowered so that the lowest row of bricks rests on the ground and carrier plates 10 are lowered out of contact with the second layer of bricks. The pressure of the medium in system 8 is thereby released and clamp members 7 are thereupon restored to initial position by return springs 22. Return springs 22 can be omitted in many instances inasmuch as a vacuum tends to'be developed within system 8 coincident with upward movement of pistons 9 relative to fork arms 6 in the direction indicated by arrow d, which allows clamp member 7 to return in, the direction of arrow e to the starting position thereof; Thus, the clamp jaws are actuatedaway from the bricks and the fork assembly can then be moved by the lift truck in the direction indicated by arrow 1 (FIGURE 1) out of the brick, stack.

A second embodiment of the invention is illustrated in FIGURES 6, 7 and 9, wherein an annular chamber 33 is located between each collar 21 and clamp jaw 18 in fork arm, 6 and communicates with a passage 34 which is filled with the pressure transmission medium. Passage 34 connects each annular chamber 33 with a chamber 35 formed between a piston rod 36 of a return piston 37 and the inner wall of a cylindrical space 38. Piston rod 36 is joined with carrier plate 10 as by welding. Each return piston 37 is provided with a circularpacking member 39 and is sealed with respect to fork arm 6 by packing means 40 and 41 which are located in position by a nut 42. A vent 44 to atmosphere is provided in the space beneath piston 37. The annular chamber 33 is sealed by a fiat sealing member 45 which is held in position by a nut 47 furnished with a ring packing 46.

Clamping of the bricks or other material is accomp lished in essentially the same manner as described earlier in respect of FIGURES 3, 4 and 8. The; return movement of each clamp member 7 to starting position for releasing each fork arm 6 from the stack of material after depositing same takes place in the independent upward movement of each piston 9 which is raised byspring 27, such spring action simultaneously causing upward movement of return pistons 37 which releases the pressure in conduit 34 permitting inward movement of clamping member 7. In order always to be-able to adjust'the manner of operation of the return piston 37 to the manner of operation of the fork assembly, apressure reservoir 48 is provided, schematically illustrated in FIGURE 9, which is designed in the same manner as reservoir 11.

Now, while I have shown and described only two embodiments of the present invention, it will be understood that various rearrangements and modifications may be made therein without departing from the spirittand scope of my invention.

I claim:

1. A device usable with lift trucks andthe like for-engaging, transporting and depositing material such as bricks, tile, blocks or the like, comprising a pair of fork arms supported from the truck and extending forwardly thereof in parallel spaced relation, a plurality of pairs of opposed reciprocable clamping members mounted inside the fork arms and extending outwardly thereof into the space formed therebetween, 'a common fluid pressure transmitting medium interconnecting all of'said clamping membersin each fork arm, and'a'fiuidpresusre producing means mounted inside the fork arms for generating fluid e, ovaees pressure in the pressure transmitting medium upon lifting movement of the fork arms to support a load, said fluid pressure producing means being the sole means associated with the device for generating fluid pressure in said pressure transmission medium, said generated fluid pressure transmitting through said common fluid pressure transmitting medium forces causing all of said clamping members in each fork arm to be actuated toward each other into the space between the fork arms.

2. A device for handling material such as bricks, tile, blocks or the like, comprising a pair of longitudinally extending and transversely spaced parallel arm members, movable clamping means extending inwardly into the space between the arm members in opposed facing relation, a plurality of fluid pressure producing means associated with each arm member operatively connected to the clamping means, said operative connection including a common fluid conduit means conducting a fluid pressure transmitting medium between the clamping means and the plurality of pressure producing means in each arm member, said fluid pressure producing means being activated upon lifting movement of the arm members to forcefully engage a load to pressurize the medium in the common fluid conduit whereby to simultaneously actuate the opposed clamping means in opposite directious into the space between the arm members, a fluid reservoir connected to the fluid conduit means, and means in said reservoir for producing an initial pressure level in the pressure transmitting medium.

3. A device as claimed in claim 2 wherein other fluid means are associated with the clamping means and with the pressure producing means for actuating same to an initial non-clamping position upon movement of the arm members downwardly to disengage the load.

4. A clamping fork arm assembly usable with industrial trucks and the like for engaging, transporting and depositing material such as bricks, tile, blocks or the like, comprising a plurality of arm members mounted for lifting movement on the truck and extending forwardly thereof in parallel spaced relation, a plurality of opposed clamp members mounted in the sides of said arm mem bers and extending inwardly into the space formed between each pair of arm members, a closed common fluid circuit containing a pressure producing fluid and contained within the fork arm assembly interconnecting said clamp members, pressure producing means in said fluid circuit associated with each arm member and connected to the pressure producing fluid including means overlying each arm member adapted upon lifting movement thereof to contact the underside of a load to be conveyed, engagement with said load causing the pressure producing means to be actuated downwardly relative to said arm members transmitting through the fluid a force which acuates simultaneously by way of the common fluid circuit and at a common fluid pressure the clamp means into the space formed between the respective clamping arms to forcefully engage opposite sides of rows of a lowermost tier of the load located in the spaces formed between the arm members.

5. A device as claimed in claim 4 wherein manually adjustable piston means is provided for producing an initial pressure in the fluid prior to engagement of the pressure producing means with a load.

6. A device as claimed in claim 4 wherein said pres sure producing means includes piston means connected to the member overlying each arm member, and other piston means connected to the member overlying each arm member and by means of the fluid in the system to the clamping members for restoring the clamping members to initial non-clamping position upon lowering movement of the pressure producing means out of engagement with a load.

7. A device as claimed in claim 6 wherein manually adjustable piston means is also provided for producing an initial pressure in the fluid prior to engagement of the pressure producing means with a load.

References Cited in the file of this patent UNITED STATES PATENTS 2,685,976 Ulinski Aug. 10, 1954 2,983,397 Hirschboeck May 9, 1961 FDREIGN PATENTS 1,087,077 France Aug. 18, 1954 1,088,119 France Sept. 1, 1954

Claims (1)

1. A DEVICE USABLE WITH LIFT TRUCKS AND THE LIKE FOR ENGAGING, TRANSPORTING AND DEPOSITING MATERIAL SUCH AS BRICKS, TILE, BLOCKS OR THE LIKE, COMPRISING A PAIR OF FORK ARMS SUPPORTED FROM THE TRUCK AND EXTENDING FORWARDLY THEREOF IN PARALLEL SPACED RELATION, A PLURALITY OF PAIRS OF OPPOSED RECIPROCABLE CLAMPING MEMBERS MOUNTED INSIDE THE FORK ARMS AND EXTENDING OUTWARDLY THEREOF INTO THE SPACE FORMED THEREBETWEEN, A COMMON FLUID PRESSURE TRANSMITTING MEDIUM INTERCONNECTING ALL OF SAID CLAMPING MEMBERS IN EACH FORK ARM, AND A FLUID PRESSURE PRODUCING MEANS MOUNTED INSIDE THE FORK ARMS FOR GENERATING FLUID PRESSURE IN THE PRESSURE TRANSMITTING MEDIUM UPON LIFTING MOVEMENT OF THE FORK ARMS TO SUPPORT A LOAD, SAID FLUID PRESSURE PRODUCING MEANS BEING THE SOLE MEANS ASSOCIATED WITH THE DEVICE FOR GENERATING FLUID PRESSURE IN SAID PRESSURE TRANSMISSION MEDIUM, SAID GENERATED FLUID PRESSURE TRANSMITTING THROUGH SAID COMMON FLUID PRESSURE TRANSMITTING MEDIUM FORCES CAUSING ALL OF SAID CLAMPING MEMBERS IN EACH FORK ARM TO BE ACTUATED TOWARD EACH OTHER INTO THE SPACE BETWEEN THE FORK ARMS.

Images