US2820664A - Multiple shell grab - Google Patents

Description

Jan; 21, 1958 F. MENDE 2,820,664

MULTIPLE SHELL GRAB Filed May 26, 1963 5 Sheets-Sheet 1 i. ZYIIIIIIIIIIIIIIIJ'IIII,

INVENTOR. Frz i'z Manda,

BY PMG Pau A TTORNEYS.

Jan. 21, 1958 F. MENDE 2,820,664

MULTIPLE SHELL GRAB Filed May 26, 1953 3 Sheets-Sheet 2 FIG: 5 FIG 6 INVENTOR. Fri i'zliefide,

.pwi PM A TTORNEYS.

Jan. 21, 1958 F. MENDE 2,820,664

MULTIPLE I SHELL GRAB Filed May 26, 1953 3 Sheets-Sheet 3 INVENTOR- Frzzz Manda,

BY PM Paul.

A TTORNEYS.

MULTIPLE SHELL GRAB Fritz Mende, Kettwig, Germany Application May 26, 1953, Serial No. 357,443

Claims priority, application Germany October 22, 1952 8 Claims. (Cl. 294-111) This invention relates to a grab, and more particularly concerns a grab of the multi-shell type which is adapted to be suspended from the boom of a crane, for example, for lifting wide varieties of objects such as ingots, stones, beams, girders and metal shavings or even bars and slabs. In grabs of this character the shells and shell operating mechanisms are subjected to very great stresses, particularly when bulky loads are to be picked up. Moreover the grab is frequently required to pick up objects of irregular form, or objects which are piles up in 'an irregular fashion; this imposes even greater stresses upon certain parts of the grab. Moreover one or more grab shells may strike a heavy or substantially immovable object as the grab is being closed, or objects may be trapped between the shells, and this subjects the shells and working parts to stresses which are sometimes sutii'cient to cause damage.

It is accordingly an object of this invention to provide a multiple shell grab of the character indicated, wherein the shell members have capacity to resist excessive stresses. Another object is to provide a grab of this character wherein the grab shells have capacity to yield to such stresses. Another object of this invention is to provide a multiple shell grab having a strong hinged connection between the shells and the mechanism which operates the shells, such connection simultaneously bracing the shells. Other objects and advantages of this invention, including the simplicity and economy of the same and the strength of the grab in proportion to its weight, will further become apparent hereinafter and in the drawings whereof:

Fig. 1 represents a view in perspective showing a multiple shell grab embodying features of this invention, some of the shells at the rear of the drawing being removed for the sake of clarity;

Fig. 2 represents a vertical sectional view of the grab shown in Fig. 1, certain parts being broken away and shown in section in order to illustrate important details;

Fig. 3 represents a plan view of the base of the grab, taken as indicated by the lines and arrows IIIIII which appear in Fig. 2;

'Fig. 4 represents a section view taken as indicated by the lines and arrows IVIV which appear in Fig. 3;

Figs. 5, 6 and 7 represent sectional views taken as indicated by the lines and arrows VV, VIVI and VII-VII which appear in Fig. 2;

Fig. 8 reprseents a view in vertical section similar to Fig. 2 showing the same grab provided with a fluid cylinder grab-actuating means;

Fig. 9 is a plan view of the grab shown in Fig. 8 as seen in the direction of lines and arrows IXIX, certain parts being shown in section; and

Figs. 10 and 11 are sectional views taken as indicated by the lines and arrows, X-X and XI-XI, which appear in Figs. 9 and 8, respectively.

Turning now to the specific embodiment of the invention selected for illustration in the drawings, the number (it) designates a grab head having a cylindrical form,

Patented Jan. 21, 1958 ice suspended from above by a rope or cable 11. Means are provided such as a hoist or the like (not shown) for raising and lowering the head 10. Suspended from another rope or cable 12, which may also be pulled up or let down by a crane hoist, independently of cable 11, is a substantially cylindrical base 13. Pivotally mounted at equally spaced points around the periphery of base 13 are a plurality of grab claws or shells 14. The shells 14 are linked to the grapple head 10 by a plurality of rigid link bars 15 the upper ends of which are pivoted to the head 10 at equally spaced points around the periphery of the head 10. The lower ends of link bars 15 are slidably pivoted to the outer edges of the grapple shells 14 at points eccentric to the pivotal connection between the shells and base 13, as will further be described.

The cable .12 is trained around a series of pulleys carried on the head 10 and on the base 13 whereby the base may be raised and lowered with respect to the head. When power is applied by means of a hoist or other apparatus to raise the cable 12, the base 13 is lifted toward the head 10, and the link bars 15 coact with the base and head to swing the shells 14 downwardly to their closed position shown in solid lines in Fig. 2. The weight of base 13 together with the weight of the members carried thereon is suflicient to open the shells 14 by gravity action alone when the cable 12 is lowered, the base 13 descending to the position shown in dotdash lines in Fig. 2.

The head 10 is a substantially cylindrical beam having upper and lower flanges 20, 21. Fixed to the beam extending vertically between flanges 20, 21 are pairs of cars 22 each pair of which is apertured and carries a transverse sleeve 23, as appears more particularly in Figs. l, 2 and 5. A pivot pin 24, of much less diameter than the aperture or the inside diameter of sleeve 23, extends longitudinally through sleeve 23. Substantial clearance is thus provided between pin 24 and sleeve 23, .permitting the longitudinal axis of the pin to rock inside the sleeve.

Each link bar 15 includes apair of channel bars 30 fixed at their upper ends to the pivot pin 24. The channel bars 39 have capacity to rock together with the pin 24, in the plane of the pin. The channel bars 30 are reinforced by upper and central transverse I- beams 31, 32 and by a lower cross beam 33 having an inclined web 34 (see particularly Figs. 1 and 2) adjacent the convex outer edge of the adjacent shell 14. Each side of the link bar 15 is reinforced by angle plates 35, 35 (see Figs. 1, 2 and 7) which have upper and lower inclined portions.

The base 13 consists of upper and lower plates 40, 41 (see particularly Figs. 1-3) which are substantially circular in form. They are centered on the perpendicular axis extending through the center of head 10. Plates 4t), 41 are welded or otherwise aflixed to a plurality of vertical web plates 42 which are arranged in pairs at equally spaced points around the peripheral edge of base 13. The lower plate 41 is notched at 43 between the web plates 42. Web plates 42 have aligned holes 44 receiving pivot shafts 45 on each of which a shell 14 is hung in a manner further to be described.

Each grab shell 14 consists of a curved metal plate 50 to the convex face of which is welded (or otherwise attached) a central perpendicular saddle plate 51. A crescent shaped side plate 52 (see also Fig. 6) is welded or otherwise afiixed to or even formed integrally with each side of saddle plate 51 and is affixed to the curved plate 50. Thus, each shell 14 has two crescent shaped side plates 52 which reinforce and rigidity the entire shell structure.

The upper end of each saddle plate 51 is apertured at 53 and the pivot'shaft -45 extends through the aperture to pivot the shell 14 to the ase 13. As appears more particularly in Fig. 4 of the drawings, the bearing 54 is rounded at the edge of aperture 53 permitting the entire shell 14 to rock laterally in.the plane ofthe pivot shaft 45. This is an important. and advantageous feature, of the invention, as will further appear. f 1

, The tips of the shells 14-are reinforced by indented plates 57 which are suitably welded to the saddle member 51. The-tips and lateral borders of theshells are'hardened as indicated M58 in Fig. 2, preferably byany hard facing operation such as applying a chrome electrode, for example. These surfaces may otherwise be processed by the use of armored plate or. speciallyhardened materials.

However for heavy duty grabs, particularly if they are intended for handling bulky loads, such as steel scrap and the like, the specific construction shown in the drawings is distinctly preferred.

Preferably the ridge portion 56 of the saddle 51 has a wall thickness of about 3 to 4 times the thickness of a single web plate such as saddle 51 thereby strengthening the oblong slot which serves as a sliding plane for the base of the link bar. I a

The grab shown in Figs. 8-11 is similar to the grab just described, and like parts bear similar numbers. However the grab shown in Figs. 8-11 is actuated by means of a pneumatic cylinder 100 which is pivotally suspended However it is preferred to harden the surface by applying a coating of weld metal from a chrome vanadium or other chrome bearing electrode.. The shells lean be provided with a plurality of bolt'holes'. for attaching supplemental scoop bowls or plates 59, one of which is shown attached in Fig. 1. With bowls 59 attached, the 'shells formfan enclosed space (an ellipsoid of rotation) when they are brought to the position shown insolidlines inFig. 2. I The grab may then be operated as a s'coo'por digging device for excavating sand or dirt or other finely divided materials, or for unloading vessels carrying ores, scrap, clay or other materials. The scoop plates'59 are readily detachable by one person in a short time. Other suitable means may be provided forattaching scoop plates 59, as will readily be apparent, It will be appreciated that other means may be provided for attaching the bowls 59 to the shells, such as groovedor flanged'means whereby the bowls may readily slide on and off of the shells but are frictionally maintained thereon.

Each shell 14. is actuated, through-a sliding pivotal connection, by the corresponding linkbar Saddle plate 51 is slotted at 55, the slot 55 being located in a ridge portion 56 disposed outwardly of and eccentric 'to' the pivot shaft 45. The slotted area is reinforced by a pair of slotted reinforcing plates 60, 60. The lower end of the link bar 15 carries a roller shaft 61 which bridges across between the lower ends of channel bars 30. A crowned roller 62 is carried by shaft 61 extending through the slot '55. By reason of the curvature of the crowned roller, the entire shell 14 has capacity to rock laterally with respect to the roller and link bar 15.

In operation, the grab is suspended on cable 11 with "cable12 relaxed and the shellsopen as in Fig. 1. The

grab is lowered on top of the object or objects to be lifted. The bottom plate of base 13 rests'onthe objects. Cable :12 is then pulled tight and the grab shells are gradually closed by the combined action of base 13, which lifts the shape of the claws or shells and to the manner inwhich I they are actuated through the pivoted slotted linkage heretofore described.

The aforementioned pivot points are subjected to great for limited rockingmovement with respect to the base stresses, particularly when bulky or heavy loads are to I be picked up. When anv individual grab shell strikes an unusually heavy substantially immovable object during the closing operation, it lags behind the other shells to a limited extent by reason of the slotted pivoted structure, protecting the grab shells and even their pivoted connections to the link bars and to the base, against excessive stresses. Moreover the entire shell together with its associated link bar has capacity to rock laterallywhen an unusual resistance is encountered, or when material is mornentarily trapped between adjacent shells, thus protecting the parts and their pivoted connections. 7

It will be appreciated that other equivalent means may be utilized to accomplish the results described above. For example the pivoted connection between the grab shells and the corresponding link bars may consistof rope pulleys whichare arranged at the bottom ends of the link bars and guided on flanges on the backs of thegrab shells.

use in digging shafts for mines and the like.

from a channel iron frame 101. Attached to frame 101 is a four-way valve 102 connected to the upper and lower ends of cylinder by flexible tubing 103, 104. A piston 105 attached to piston rod 106 reciprocates in cylinder 100, the rod 106 being pivotally connected at its lower end to the base 13.. Means are provided (not shown) for compressing air and for conducting it through a flexible tube or hose 107 to the valve 102.

Referring to Figs. 8,9 and 10, the cylinder 100 has an upstanding car 110 which extends between a pair of depending ears, 111, 111 carried by the frame 101. The ears are apertured to receive a pivot pin 112. The aperture through the upstanding ear 110 has a rounded bearing surface 113, as shown in Fig. 10, which is an important feature of the invention, permitting a limited rocking movement of cylinder 100 with respect, to frame 101. The spacing between ears 111, 111 is sufiicient to permit this rocking movement. Y

As appears in Fig. 11, piston rod 106 has capacity 13, by virtue of the rocking pivot connection including spaced ears 114, 114 attachedto the base, ear 115 attached to piston rod 106, pivot pin 116, and the rounded bearing surface 117 of the opening through ear 115.

The operation of the grab shown in Figs. 8-11 will be apparent. Assuming the grab shells 14 are in their opened position (as shown in dot-dash lines in Fig. 8), the operator sets the four-way valve 102 toinject air under pressure into the bottom of cylinder 100 through tube 104. The air from above piston 105 is exhausted through tube 103 and through an exhaust pipe 120 on four-way valve 102. The piston and base 13 are. lifted, raising the grab shells to the position shown in solid lines in Fig. 8, thereby closing the grab shells. The shells are opened by setting four-way valve 102 to introduce air under pressure into cylinder 100 through tube 103, the exhaust air passing out through tube 104 and exhaust pipe 120, as will be apparent. The internal construction of four-way valve 102 is well known and conventional, and is not shown.

The pneumatic driven grab of Figs. 8-11 is advantageous for removing rock blasted from a vertical mine shaft and for other similar or special uses. The pneumatic actuating mechanism provides a positive, rapid closing action enabling the grab shells to dig into large, heavy rocks and the like. Yet the actuating mechanism has capacity to rock and to pivot with respect to the base to minimize stresses. While a pneumatic actuating mechanism is shown, other fluids may be substituted for air, such as water, glycerine, oil or the like, and a proper reservoir may be provided for re-use of hydraulic or other fluid materials.

' Accordingly it will be appreciated that the multiple shell grab in accordance with this invention is ideally suited for the movement of scrap of any sort, ore, limestones, basalt and even girders or other bulky material, for instance logs, pig iron and the like, for well-digging, and also for dredging below the surface of water. It is also, as heretofore described, capable of advantageous of substantially 100% filling each time the shells are closed, even when the grab isseverely tilted While the It is capable shells or claws shown in the drawings are cable-operated, they may readily be motor-operated if desired.

It will be appreciated that the word shell as employed herein refers to relatively narrow shells such as claws or fingers and also refers to relatively broad blades or scoops, all as disclosed herein.

Although this invention has been described in detail with reference to one specific embodiment adapted for specific purposes, it will readily be apparent that the device has other uses, that the form of the apparatus may be considerably varied, and that equivalent structures and materials may be employed for accomplishing the same results. Such changes, including reversals of parts and the use of certain features of the invention independently of the use of other features, are within the spirit and scope of the invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A multiple shell grab comprising a head member, a base member in the form of a platform, a power cylinder pivoted to one of said members having a driven shaft pivoted to the other of said members with capacity to move said members toward and from one another, a plurality of more than two shells pivoted to said platform, means for swinging said shells about their pivots to open and close the shells in response to said relative movement of said head and base members, the pivotal connections between the cylinder, shaft, head member and base member including loose connecting means whereby the cylinder and shaft have capacity for limited rocking movement with respect to said head and base members at an angle to their pivotal movement.

2. The multiple shell grab defined in claim 1 wherein the power cylinder is pivoted to the head member and the shaft is pivoted to the base member, and wherein pneumatic couplings are connected to the cylinder to actuate the shaft.

3. The multiple shell grab defined in claim 1 wherein the pivoted connections include plate members which are apertured and linked together by a pivot shaft, and wherein one of the apertures has a rounded edge adjacent the shaft.

4. A multiple shell grab, in combination, a head member; a base member; means for moving said members toward and away from each other; a plurality of shells mounted on said base member for swinging movement relative thereto between open and closed positions; a plurality of bar members; and attaching means for pivotally attaching each bar member at one end thereof to said head member and for so attaching each bar member at the other end thereof to one of said shells at a point thereon spaced from the point at which the respective shell is swingably mounted on said base member that said other end of each bar member is pivotable about a pivot axis relative the shell to which it is attached and is slidable relative thereto between predetermined limits in a direction transverse to said pivot axis, whereby an individual shell may lag behind upon encountering strong resistance as the shells are closed.

5. A multiple shell grab, comprising, in combination, a head member; a base member; means for moving said members toward and away from each other; at least three shells mounted on said base member for swinging move ment relative thereto between open and closed positions, each shell being swingable about a respective swinging axis; a plurality of bar members corresponding in number to the number of shells; and attaching means for so attaching each bar member at one end thereof to said head member that said one end is pivotable relative to said head member about a first pivot axis substantially parallel to the swinging axis of the corresponding shell and for so attaching each bar member at the other end thereof to the corresponding shell at a point thereon spaced from the swinging axis thereof that said other end of each bar member is pivotable relative to the corresponding shell about a second pivot axis substantially parallel to said first pivot axis and is slidable relative to the respective shell between predetermined limits in a direction transverse to said second pivot axis, whereby an individual shell may lag behind the other shells upon encountering strong resistance as the shells are closed.

6. A multiple shell grab, comprising, in combination, a head member; a base member; means for moving said members toward and away from each other; a plurality of shells; mounting means for mounting said shells on said base member for such swinging movement relative thereto between open and closed positions that each of said shells has capacity for limited lateral movement at an angle to its swinging movement while said shells are being closed; a plurality of bar members; and attaching means for pivotally attaching each bar member at one end thereof to said head member and for so attaching each bar member at the other end thereof to one of said shells at a point thereon spaced from the point at which the respective shell is swingably mounted on said base member that said other end of each bar member is pivotable about a pivot axis relative the shell to which it is attached and is slidable relative thereto between predetermined limits in a direction transverse to said pivot axis; whereby an individual shell may lag behind upon encountering strong resistance as the shells are closed.

7. The combination defined in claim 6 wherein said attaching means for attaching each bar member at said other end thereof to the corresponding shell includes an elongated slot and pivot-pin arrangement.

8. A multiple shell grab, comprising, in combination, a head member; a base member; means for moving said members toward and away from each other; at least three shells; mounting means for so mounting said shells on said base member for such swinging movement relative thereto between open and closed positions that at least one of said shells has capacity for limited lateral movement at an angle to its swinging movement while said shells are being closed; a plurality of bar members corresponding in number to the number of shells; and attaching means for pivotally attaching each bar member at one end thereof to said head member and for so at taching each bar member at the other end thereof to one of said shells at a point thereon spaced from the point at which the respective shell is swingably mounted on said base member that said other end of each bar member is pivotable about a pivot axis relative the shell to which it is attached and is slidable relative thereto between predetermined limits in a direction transverse to said pivot axis, whereby said one shell may lag behind the other shells upon encountering strong resistance as the shells are closed.

References Cited in the file of this patent UNITED STATES PATENTS 247,829 Johnson Oct. 4, 1881 921,821 Frazier et al May 18, 1909 925,018 Ouchterlony June 15, 1909 1,820,118 Canulette Aug. 25, 1931 2,652,280 Billings Sept. 15, 1953 2,715,787 Williams Aug. 23, 1955 FOREIGN PATENTS 60,501 Denmark Jan. 11, 1943 302,091 Great Britain Dec. 13, 1928

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