GB2051734A

GB2051734A - Materials handling grab

Info

Publication number: GB2051734A
Application number: GB8017822A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-05-31
Filing date: 1980-05-30
Publication date: 1981-01-21
Also published as: GB2051734B

Abstract

A grab for mounting on a boom extending forwardly from an excavator, tractor, lorry or the like vehicle and for use in lifting elongated or bulky material. The grab includes upper and lower jaw members 1,3, each comprising a supporting structure 9 and a plurality of tines 7 extending from the supporting structure. The grab is pivotably mounted on the boom 5 so that a pivotal axis of each jaw member extends transversely of the boom. One of the jaw members 1 is adapted for coupling to a ram 29 associated with the boom. The other jaw member 3 is so coupled to the first member 1 that operation of the ram causes pivotal movement of the jaw members between an open position, in which the upper member extends upwardly and forwardly from the boom and is angularly spaced from the lower member, which extends downwardly and forwardly, and a closed position, in which each tine of one member extends downwardly between a pair of adjacent tines on the other member. <IMAGE>

Description

SPECIFICATION Improvements in grabs for lifting and transporting elongated materials This invention relates to grabs for use in lifting and transporting elongated materials, such as pipes and timber, or bulky materials, such as rock, boulders, stumps, undergrowth, girders and scrap metal.

There is a requirement in many industries for an implement which is suitable for lifting and transporting elongated materials, such as pipes and timber, and bulky materials, such as rocks, boulders and scrap metal. The implement is preferably one which can be mounted on a boom forwardly from a tractor, excavator or the like vehicle and which can be operated by hydraulically operable controls on the vehicle. Preferably, the implements should also be capable of lifting elongated and bulky materials without collecting unwanted dirt, smaller materials and rubbish.

According to the invention there is provided a grab for mounting on a boom extending forwardly from an excavator, tractor, lorry or the like vehicle and for use in lifting elongated or bulky material, wherein a pair of jaw members each comprise a plurality of tines which extend outwardly from one side of a supporting structure, each jaw member has a pivotal axis adjacent to a side the supporting structure remote from the outwardly extending parts of the tines, a first of the members is adapted for connection to an operating means on the vehicle, means are provided for supporting the grab on the boom so that the pivotal axis of each jaw member extends transversely of the boom, and means couple together the jaw members so that, in use, operation of the operating means moves the jaw members between an open position, wherein the first jaw member extends generally upwardly and forwardly from the boom and the second jaw member is angularly spaced from the first jaw member and extends downwardly from the boom with the outwardly extending parts of the tines thereof extending downwardly and forwardly for engagement with the material, and a closed position, wherein the first jaw member has pivoted downwardly and rearwardly from the open position, the second jaw member has pivoted so that the tines thereof have moved in a direction upwardly and forwardly relative to the boom, and the said material is gripped between the two jaw members.

Suitably, the second jaw member is pivotally connected to the first jaw member for pivotal movement relative to the first jaw member about the said pivotal axis of each member, the first jaw member is adapted for mounting on the boom for pivotal movement about a second axis which is spaced from the said pivotal axis thereof, and a restraining element is provided for pivotally connecting the second jaw member to the boom, whereby, in use, operation of the operating means causes the first jaw member to move between the open and closed positions and the pivotal connections between the second jaw member and the first jaw member and between the second jaw member and the boom cause the second jaw member to move also between the open and closed positions.

Preferably, the first jaw member is provided with a mounting element which is adapted at a first location, spaced from the said pivotal axis of the first and second members, for pivotal attachment to the boom, and is adapted at a second location, on the side of the first location remote from the said pivotal axis, for pivotal attachment to the operating means on the vehicle, and the second member is adapted, at a location spaced from the pivotal attachment of the first member to the second member, for pivotal connection via the restraining element to the boom.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure lisa side elevation, partly in section, of a grab according to the invention mounted on the nose of a dipper arm or stick, the grab being shown in a closed position (full lines) and open position (dashed lines); and Figure 2 is a rear view of the grab of Figure 1, the grab being in an open position.

The grab shown in Figures 1 and 2 is suitable for clamping securely, lifting, moving or transporting and then placing pipes, timber, scrap, girders, boulders or other bulky objects and which is suitable for mounting on a single arm excavator or a double arm loading shovel.

Referring to Figures 1 and 2, the grab is formed of two jaw members 1 and 3, respectively, each adapted for pivotal mounting at a forward end of a dipper arm 5 extending forwardly of the excavator (not shown). Each jaw member 1 and 3 includes a series of long, freestanding tines or teeth 7 and a supporting structure 9 upon which the tines are mounted.

The supporting structure 9 in a first or upper jaw member 1 has a frame formed of four vertical members 11 and three horizontal members 13 which interconnect the vertical members. The vertical members 11 are disposed one at each side of the structure 9 and two intermediate the sides thereof, the spacing between each side vertical member 11 and the adjacent intermediate vertical member 11 being less than the spacing between the two intermediate members. Each vertical member 11 is formed of a plate having a leading edge which is generally concave about a horizontal axis. The two intermediate members 11 are longer than the side members.

A lower end of each vertical frame member 11 is welded to a lower horizontal frame member 13, which has a hollow, rectangular section. Intermediate and upper horizontal frame members 13 are each formed of three aligned plates, each of which interconnects a pair of adjacent vertical members 11.

The upper horizontal member 13 is located adjacent the upper ends of the vertical members 11 at the sides of the structure 9 so that each of the intermediate vertical members projects above the upper member 13.

Three guides 15 for tines extended forwardly from the lower horizontal frame member 13, each guide being formed of a pair of mutually spaced guide plates.

A bottom plate 17 for the first jaw member 1 is generally rectangular, as viewed from the front of the member, and is dished to conform to the shape of the leading edge of each vertical frame member 11. The bottom plate 17 is welded to the leading edge of each vertical frame member 11 and to the leading edge of each of the guide plates 15.

The present jaw member includes three tines 7, as indicated above. Each tine 7 has an upper end bolted to a pair of apertured lugs 19 on the intermediate horizontal frame member 13 and an intermediate part located in the space between a pair of guides 15, the lower horizontal member 13 and the bottom plate 17. From the guides 15, the tine 7 extends outwardly and downwardly from the supporting structure 9. The tines 7 are so shaped that the jaw member 1 is generally dish-shaped, as viewed from one side.

For mounting purposes, a mounting plate 21 is secured to each of the two intermediate vertical members 11. Each of the mounting plates 21 is located on the generally convex side of the supporting structure 9 and is formed with three apertures. A first aperture 23 in each plate 21 is aligned with a corresponding aperture 23 in the other plate 21 and these two apertures are used for pivotally connecting the two jaw members 1 and 3 together, as hereinafter described. Second apertures 25 in respective plates 21 are likewise aligned and serve for pivotally mounting the grab on the dipper arm 5 of the excavator. A third aperture 27 in each plate 21 is located on the side of the second aperture 25 remote from the first aperture 23 and is also aligned with the corresponding aperture 27 in the other plate 21.The third apertures 27 are used in pivotally connecting the first jaw member 1 to a hydraulic ram 29 on the excavator.

The second or lower jaw member 3 of the present grab has a similar construction to that of the first jaw member 1, being formed of a supporting structure 9, a bottom plate 17 and four tines 7. In the second jaw member 1, however, the spacing between each side vertical member 11 and the adjacent intermediate vertical member 11 is equal to the spacing between the two intermediate members 11 and the overall width of the second jaw member 3 is greater than the overall width of the first jaw member 1.

The mounting means on the second jaw member 3 are also different from those of the first member 1. In the case of the second jaw member 3 an aperture is formed in that part of each intermediate vertical 11 member of the supporting structure which projects above the upper horizontal frame member 13. The two apertures are aligned and, in use, receive a mounting pin 31 which pivotally attaches the second jaw member 3 to the first jaw member 1.

The second jaw member 3 is also provided with a mounting pin 33 for engagement with a manually adjustable restraining element or back stay 35 on the dipper arm 5. The mounting pin 33 extends between the intermediate vertical members 11 of the support ing structure at a vertical location immediately above the intermediate horizontal frame member 13.

In use, the jaw members 1 and 3 are pivotally connected together by means of the mounting pin 31 which extends through the aligned first apertures in the mounting plate 21 on the first member 1 and through the aligned apertures in the intermediate vertical members 11 of the second jaw member 3.

The axis of the pin 31 serves as a first pivotal axis about which the second member 3 can be pivoted relative to the member 1.

With the dipper arm 5 of the excavator substantially horizontal the jaw members 1 and 3 are then arranged below a forward end of the arm with the dished side of the bottom plate 17 on the member 3 facing forwardly of the excavator, the dished side of the bottom plate 17 on the member 1 facing rearwardly, and the tines 7 on the member 1 extending downwardly and rearwardly between the tines 7 of the member 3.

The members 1 and 3 are secured to the dipper arm 5 by means of a main mounting pin 37 which extends through the aligned second apertures 25 in the mounting plates 21 on the first jaw member 1 and through an aperture in the forward end of the arm 5. The axis of the pin 37 serves as a second pivotal axisforthe member 1. The mounting pin 33 at the rear of the second jaw member 3 is pivotally connected to the dipper arm via the back stay 35, which extends upwardly and rearwardly from the mounting pin to a location on the arm 5 rearwardly of the main mounting pin 37. Finally, a mounting pin 39 which extends through the aligned third apertures 27 in the mounting plate 21 on the first jaw member 1 is coupled to the hydraulic ram 29 of the vehicle via a pair of links 41.

As described so far, the jaw members 1 and 3 are in the closed position. To move them to the open position the hydraulic ram 29 is operated to pivot the mounting plate 21, and hence the first jaw member 1, about the main mounting pin 37. The jaw member 1 pivots in a direction such that the tines 7 thereof are disposed upwardly and forwardly of the dipper arm 5, in the open position of the member. At the same time pin 31 at the pivotal connection between the first and second jaw members 1 and 3, respectively is caused to move downwardly and forwardly relative to the dipper arm 5, causing the second jaw member 3 to pivot about the pin 33 at its pivotal connection to the back stay 35. Pivotal movement of the second jaw member 3 is such that the tines 7 of that member move in a direction downwardly and rearwardly from the closed to the open position.

With the jaw members 1 and 3 in the open position, the dipper arm 5 on the excavator is moved forwardly so that the projecting parts of the tines 7 on the second jaw member 3 are engaged below elongated or bulky material to be lifted, smaller material passing between the tines The hydraulic ram 29 is then operated to pivot the first jaw member 1 downwardly and forwardly and then downwardly and rearwardly towards the closed position of the member. At the same time, the second jaw member 3 is pivoted about its connection to the back stay 35 and also returns to its closed position. The second jaw member 3 engages from the rear the material to be lifted, and the material is therefore gripped between the two jaw members 1 and 3.

With the material gripped by the two jaw members 1 and 3, the dipper arm 5 is raised and the material is transported as required. It is then unloaded by lowering the dipper arm 5 and operating the hydraulic ram 29 to move the first and second jaw members towards the open position described above.

twill be appreciated that the bottom plates 17 on the jaw members 1 and 3 described above serve to prevent material falling through the supporting structtlre 9 of the grab, particularly in a case where the grab is used for handling mixed scrap metal. The bottom plates 17 can be dispensed with, however, if only elongated material is being handled.

In a second embodiment of the invention there is no mounting plate 21 on the upperjaw member 1.

The pin 31 is then located at the forward end of the dipper arm 5, in the position occupied by the main mounting pin 37 in the embodiment described above. Instead of a restraining element 35, the lower jaw member 3 is coupled directly via links to the ram 29 and to the arm 5. Operation of the ram causes pivotal movement of both jaw members.

Claims

1. A grab for mounting on a boom extending forwardly from an excavator, tractor, lorry or the like vehicle and for use in lifting elongated or bulky material, wherein a pair of jaw members each comprise a plurality of tines which extend outwardly from one side of a supporting structure, each jaw member has a pivotal axis adjacent to a side the supporting structure remote from the outwardly extending parts of the tines, a first of the members is adapted for connection to an operating means on the vehicle, means are provided for supporting the grab on the boom so that the pivotal axis of each jaw member extends transversely of the boom, and means couple together the jaw members so that, in use, operation of the operating means moves the jaw members between an open position, wherein the first jaw member extends generally upwardly and forwardly from the boom and the second jaw member is angularly spaced from the first jaw member and extends downwardly from the boom with the outwardly extending parts of the tines thereof extending downwardly and forwardly for engagement with the material, and a closed position, wherein the first jaw member has pivoted downwardly and rearwardly from the open position, the second jaw member has pivoted so that the tines thereof have moved in a direction upwardly and forwardly relative to the boom, and the said material is gripped between the two jaw members.

2. A grab as claimed in claim 1, wherein the second jaw member is pivotally connected to the first jaw member for pivotal movement relative to the first jaw member about the said pivotal axis of each member, the first jaw member is adapted for mounting on the boom for pivotal movement about a second axis which is spaced from the said pivotal axis thereof, and a restraining element is provided for pivotally connecting the second jaw member to the boom, whereby, in use, operation of the operating means causes the first jaw member to move between the open and closed positions and the pivotal connections between the second jaw member and the first jaw member and between the second jaw member and the boom cause the second jaw member to move also between the open and closed positions.

3. A grab as claimed in claim 2, wherein the first jaw member is provided with a mounting element which is adapted at a first location spaced from the said pivotal axis of the first and second members, for pivotal attachment to the boom, and is adapted at a second location, on the side of the first location remote from the said pivotal axis, for pivotal attachment to the operating means on the vehicle, and the second member is adapted, at a location spaced from the pivotal attachment of the first member to the second member, for pivotal connection via the restraining element to the boom.

4. A grab for mounting on a boom extending forwardly from an excavator, tractor, lorry or the like vehicle and for use in lifting elongated or bulky material, the grab being constructed, arranged and adapted to operate substantially as herein before descriped with reference to the accompanying drawings.