Patent ID: 6263985
Filing Date: 2001-07-24
Classification: E21B

Abstract:
A drilling machine comprising:a leader (14),at least one drive carriage (16; 22) that is displaceable on said leader (14) and cooperates with a drill element (20; 26), wherein said drive carriage (16; 22) is adjustable to drill elements (20; 26) of different diameters and comprises a carriage base element (32) that is displaceable on said leader (14),and a driving unit (42) releasably secured to said carriage base element (32), said driving unit being in driving engagement with said drill (42) element (32), said driving unit (42) being selected from a set of driving units that are adapted to cooperate with said drill elements (20; 26) of different diameters such that said driving units (42) are radially compact in the vicinity of a free end portion thereof and said free and portion projects only slightly beyond an outer surface of said drill elements (20, 26).