Patent ID: 6397501
Filing Date: 2002-06-04
Classification: E02F

Abstract:
A method for digging a trench in a hard earth formation, comprising the steps of:positioning a multiple-chain trenching head assembly in the earth formation at a desired trench depth below a ground surface, the trenching head assembly comprising a frame having a proximal end for operably connecting to a prime mover positioned on the ground surface and thereby enabling positioning of the trenching head within the trench below the ground surface, a pair of primary sprockets, the pair comprising a proximal primary sprocket rotatably mounted on the frame and a distal primary sprocket rotatably mounted on the frame at a distal end thereof, a primary chain engaged with and circulating around the pair of primary sprockets and comprising a plurality of pivotably connected links and a plurality of cutting tools substantially rigidly mounted thereon for disintegrating the earth formation, a pair of secondary sprockets, the pair comprising a proximal secondary sprocket rotatably mounted on the frame and a distal secondary sprocket rotatably mounted on the frame at the distal end thereof, and a secondary chain engaged with and circulating around the pair of secondary sprockets and comprising a plurality of pivotably connected links and a plurality of cutting tools substantially rigidly mounted thereon for disintegrating the earth formation; driving the primary chain at a primary chain linear drive speed in a forward chain direction, thereby disintegrating material at a leading edge of the trench and conveying disintegrated material upward and out of the trench; driving the secondary chain at a secondary chain linear drive speed in a reverse chain direction, thereby disintegrating material at the leading edge of the trench and depositing disintegrated material within the trench; and moving the trenching head assembly in a forward trench-digging direction.