GB2035952A - Improvements in grabs for lifting and transporting elongated materials - Google Patents

Abstract

A grab for use in lifting elongated or bulky material comprises a pair of jaw members, each including a plurality of tines which extend outwardly from one side of a supporting structure. One jaw member is adapted for fixedly securing to a boom on an excavator, tractor or the like vehicle, A second jaw member is adapted for pivotal mounting on the boom. In use, the second jaw member is pivoted between an open position, in which the fines thereon are angularly spaced from the tines on the first jaw member, and a closed position, in which material is gripped between the jaw members. <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 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 extending forwardly form 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 smaller materials and rubbish.

According to the invention a grab for use in lifting elongated or bulky material comprises a pair of jaw members each comprising a plurality of tines which extend outwardly from one side of a supporting structure, a first of the jaw members being adapted for fixedly securing to a boom which extends forwardly from an excavator, tractor or the like vehicle so that the supporting structure extends transversely of the boom and the tines extend forwardly from the boom and downwardly towards the ground, and a second of the jaw members being adapted for mounting on the boom so that the supporting structure extends transversely of the boom and the member is pivotal about an axis which extends transversely of the boom and generally parallel with and adjacent to a side edge of each structure which is remote from the outwardly extending parts of the tines supported by that structure, and the second member being adapted, at a location spaced from the pivotal axis, for connection to an operating element on the vehicle, whereby, in use, the second jaw member is moved by the operating element between an open position, wherein the tines on the second member are angularly spaced from the tines on the first member, and a closed position, wherein the said material is gripped between the jaw members.

One embodiment of the invention is a grab 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.

The grab is formed of two jaw members, each adapted for hingedly mounting at a forward end of a dipper arm extending forwardly of the excavator.

Each jaw member includes a series of long, freestanding tines or teeth and a supporting structure upon which the tines are mounted.

The supporting structure in a first or lower jaw member has a frame formed of four vertical members and three horizontal members which interconnect the vertical members. The vertical members are disposed one at each side of the structure and two intermediate the sides thereof.

Each vertical member is formed of a plate having a leading edge which is generally concave about a horizontal axis. The two intermediate members are longer than the side members.

A lower end of each vertical frame member is welded to a lower horizontal frame member, which has a hollow, rectangular section.

Intermediate and upper horizontal frame members are each formed of three aligned plates, each of which interconnects a pair of adjacent vertical members. The upper horizontal member is located adjacent the upper ends of the vertical members at the sides of the structure so that each of the intermediate vertical members projects above the upper member.

Four guides for tines extend forwardly from the lower horizontal frame member, each guide being formed of a pair of mutually spaced guide plates.

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

The present jaw member includes four tines, as indicated above. Each tine has an upPer end bolted to a pair of apertured lugs on the intermediate horizontal frame member and an intermediate part located in the space between a pair of guide plates, the lower horizontal member and the base plate. From the guides, the tine extends outwardly and downwardly from the supporting structure.

the tines are so shaped that the jaw member is generally dish-shaped, as viewed from one side.

For mounting purposes, an aperture is formed in that part of each intermediate vertical member of the supporting structure which projects above the upper horizontal frame member. The two apertures are aligned and, in use, receive a mounting pin at a forward end of the dipper arm, as hereinafter described. The present jaw member is also provided with a mounting pin for engagement with an adjustable fixing arm on the dipper arm. The mounting pin extends between the intermediate vertical members of the supporting structure at a vertical location immediately above the intermediate horizontal frame member.

The second or upper jaw member of the present grab has a similar construction to that of the first jaw member, being formed of a supporting structure, a bottom plate and three tines. In the second jaw member, however, the spacing between each side vertical member and the adjacent intermediate vertical member is less than the spacing between the two intermediate members and the overall width of the second jaw member is less than the overall width of the first jaw member.

The mounting means on the second jaw member are also different from those of the first member. In the case of the second jaw member the mounting pin of the first member is replaced by a mounting pin which is located adjacent the upper horizontal frame member and is supported rearwarly of the vertical frame members in bearings carried by outstanding bearing plates.

In use, the two jaw members described above are mounted at the forward end of the excavator dipper arm by means of a main mounting pin which extends through aligned apertures in the arm and the aligned apertures in the upwardly projecting parts of the intermediate vertical frame members.

With the dipper arm substantially horizontal, the first jaw member is arranged with the dished side of its bottom plate facing forwardly of the excavator, the vertical frame members inclined to arm at approximately 650, and the outwardly projecting parts of the tines extending downwardly and forwardly from the supporting structure to the ground. The first jaw member is locked into this position relative to the dipper arm by connecting the mounting pin at the rear of the supporting structure to the fixing arm on the dipper arm. As indicated above, the fixing arm is adjustable in length so that the inclination of the first jaw member to the dipper arm can be manually adjusted forwards or backwards as required.

The second jaw member is initially arranged in its closed position, wherein the member is disposed forwardly of the first jaw member with the dished side of its bottom plate facing rearwardly of the excavator and adjacent the dished side of the first member. The tines of the second jaw member are then projecting downwardly and rearwardly of the excavator, between the tines of the first member.

The mounting pin on the second jaw member is then coupled to a hydraulic ram on the dipper arm via a link and a bell-crank lever, the ram being coupled to the bight of the lever and the ends of the lever being pivotally connected to the mounting pin and to a location on the dipper arm rearwardly of the main mounting pin.

In using the present grab to lift pipes, timber, rocks, boulders or scrap metal the hydraulic ram on the excavator is operated so that its operating member is withdrawn and the second jaw member is pivoted from the closed position, described above, to an open position. During an initial part of the pivotal movement the projecting parts of the tines move forwardly and upwardly relative to the dipper arm. Movement may be continued until these projecting parts are vertically above the supporting structure in the second member and the dished side of the bottom plate in that member is facing forwardly of the dipper arm.

The dipper arm on the excavator is now moved forwardly so that the projecting parts of the tines on the first jaw member are engaged below elongated or bulky material to be lifted, smaller material passing between the tines. The hydraulic ram is then operated to pivot the second jaw member downwardly and forwardly and then downwardly and rearwardly towards the closed position of the member. In so moving, the second jaw member engages from the rear the material to be lifted, and the material is therefore gripped between the two jaw members.

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

It will be appreciated that the bottom plates on the jaw members described above serve to prevent material falling through the frame of the grab, particularly in a case where the grab is used for handling mixed scrap metal. The bottom plates can be dispensed with, however, if only elongated material is being handled.

The grab described above is shown in the accompanying drawings, in which: Figure 1 is-a side elevation of the grab mounted on a dipper arm and in its closed position; Figure 2 is a vertical section of the grab in its open position; and Figure 3 is a rear view of the grab in its open position.

Claims (3)

1. A grab for use in lifting elongated or bulky material comprises a pair of jaw members each comprising a plurality of tines which extend outwardly from one side of a supporting structure, a first of the jaw members being adapted for fixedly securing to a boom which extends forwardly from an excavator, tractor or the like vehicle so that the supporting structure extends transversely of the boom and the tines extend forwardly from the boom and downwardly towards the ground, and a second of the jaw members being adapted for mounting on the boom so that the supporting structure extends transversely of the boom and the member is pivotal about an axis which extends transversely of the boom and generally parallel with and adjacent to a side edge of each structure which is remote from the outwardly extending parts of the tines supported by that structure, and the second member being adapted, at a location spaced from the pivotal axis, for connection to an operating element on the vehicle, whereby, in use, the second jaw member is moved by the operating element between an open position, wherein the tines on the second member are angularly spaced from the tines on the first member, and a closed position, wherein the said material is gripped between the jaw members.

2. An excavator tractor or the like vehicle having a boom extending forwardly therefrom and a grab as claimed in claim 1 mounted on the boom.

3. A grab for use in lifting elongated or bulky material, the grab being constructed arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.