Patent Application
20210253402
Not applicable
Not applicable
The present invention relates generally to a load lifting apparatus and, more particularly, to tongs for lifting irregularly shaped objects such as large rocks and boulders.
In the construction industry and in agriculture, it is often necessary to clear a field of large rocks and boulders. U.S. Pat. Nos. 2,561,207, 3,317,235, 9,242,840 and 7,673,918 are examples of grapples adapted for use with work vehicles such as tractors and skid steer loaders having hydraulically actuated lifting arms to which the grapple may be coupled for grasping and transporting a variety of loads.
The present invention is felt to be an improvement over the prior art, especially in the design of a rock tong arrangement with improved load engaging jaws that are able to engage irregularly shaped loads such as large rocks and small boulders and lift them without any unintended release.
The invention comprises lifting tongs especially designed to be used with a tractor or skid steer loader for grasping, lifting and transporting a variety of irregularly shaped objects such as large rocks and boulders. It comprises a conventional tong mechanism with specially designed load engagement pads shaped to engage such load items in a way that greatly inhibits loss of purchase of the load item once it has been lifted and is being transported. In accordance with the invention, the opposed pair of load engagement pads are of a rectangular configuration having a pair of parallel and spaced-apart bars affixed to and extending transversely with respect to the tong arms and where the pair of parallel and spaced-apart bars exhibit an arcuate and serrated edge as their load engaging surfaces.
The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts:
This description of the preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description of this invention. In the description, relative terms such as “lower”, “upper”, “horizontal”, “vertical”, “above”, “below”, “up”, “down”, “top” and “bottom” as well as derivatives thereof (e.g., “horizontally”, “downwardly”, “upwardly”, etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “connected”, “connecting”, “attached”, “attaching”, “join” and “joining” are used interchangeably and refer to one structure or surface being secured to another structure or surface or integrally fabricated in one piece, unless expressively described otherwise.
Referring first to
Second and third linkages 16 and 18 have first end portions 20, 22 pivotally joined by a shoulder bolt or rivet 23 to the first link member 14 such that the links can pivot with respect to one another. The second end portions 24, 26 of the linages 16 and 18 are individually pivotally joined to a pair of tong arms indicated generally by numerals 28 and 30. The tong arms each comprise first and second rectilinear segments 32, 34 that are integrally joined at a predetermined obtuse angle, A. The first, upper, segments 32 of the tong arms are pivotally coupled to one another by a bolt or pin 37 at a location offset from the first ends thereof. In
The lower end portion 38 of the second arm segments 34 are joined to load engagement pads 40, 42, preferably by bolts which allow for removal and replacement. More particularly, the load engaging pads have a generally rectangular configuration, as shown in
In order to afford a connection of the load engagement pads 40, 42 to the arm segment 34 of the tong arms, the load engagement pads include a pair of closely spaced steel bars or straps 56, 58 where the spacing between them is sufficient to create a friction fit with the flat lower end portions of the tong arm segment 34. The steel bars or straps 56,58 are welded to the rectilinear outer edges 48 proximate the midlength dimension thereof. Support struts, as at 60, are welded between the end plates 52, 54 and the straps 56, 58 to thereby reinforce a bolted connection of the load engagement pads 40, 42 with the tong arms 28, 30.
Without limitation, the tong structure may be designed so that the load engagement pads may be spaced apart about 24 inches when fully opened. At this extent of opening, the engagement pads are made to tilt at an angle of about 10 degrees with respect to the vertical such that the upper members 46 thereof are further spaced apart than are the lower members 48. This allows the load engagement pads to scoop beneath the load by a certain extent which also aids in the ability of the tongs to grasp irregular shaped loads. It has been determined through testing that by providing the arcuate serrated edges on the plates 44, 46, there is less slipping free of irregular shaped loads such as large rocks and boulders, as the tongs are used to lift and carry such loads.
This invention has been described herein in considerable detail in order to comply with the patent statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different devices and that various modifications can be accomplished without departing from the scope of the invention itself.
