Patent ID: 7032692
Filing Date: 2006-04-25
Classification: E02F,E21B

Abstract:
1. An excavating tool for an earth drill, characterized by comprising: a tubular inner member connected to a kelly bar, a tubular second member fitted on the outer side of said inner member so as to be allowed to move up/down freely and an outer member fitted on the outer side of said second member so as to be allowed to move up/down freely; a cylindrical bucket and a grab bucket housed inside said cylindrical bucket mounted to said outer member; a first hydraulic cylinder mounted between said inner member and said second member, and second hydraulic cylinders which extend/contract by the pressure oil from said first hydraulic cylinder mounted between said second member and jaws of said grab bucket; a locking mechanism provided between said inner member and said outer member, said locking mechanism being constituted of locking elements provided at the outer circumference of said inner member and a locking element bearing plate provided at the upper portion of said outer member, said locking elements being allowed to pass through said locking element bearing plate when said inner member and said outer member achieve a specific relative rotational angle and said locking elements become locked at said locking element bearing plate to disallow relative vertical movement of said inner member and said outer member, by rotating said inner member forward when said excavating tool is in a most contracted state; and projections provided at the outer circumference of said inner member fitted at guide rails extending along the longitudinal direction at the inner circumference of said second member so as to be allowed to move up/down freely, and said inner member is allowed to rotate forward relative to said second member within a predetermined range when said excavating tool is in the most contracted state; and wherein said inner member includes said locking elements above cylindrical portions; said locking elements respectively include projecting portions projecting outward as integrated portions of disks having diameters larger than the diameters of said cylindrical portions; and said locking element bearing plate is constituted of a plate having a locking element passing portion substantially isomorphic with said locking elements and slightly larger than said locking elements.