Patent ID: 7770659
Filing Date: 2010-08-10
Classification: E21B

Abstract:
1. Rotary drive assembly for a drill rod having a drill axis, an outer tube rotatable about the drill axis, and an inner rod extending at least in sections inside the outer tube and rotatable about the drill axis, comprising a first gear unit for driving the inner rod in a rotating manner, the first gear unit including a first gear rotatable about the drill axis, one first drive unit having a first motor for operating the first gear unit for driving the inner rod in a rotating manner, a second gear unit for driving the outer tube in a rotating manner, the second gear unit being offset to the first gear unit in the longitudinal direction of the drill rod and including a second gear rotatable about the drill axis, and two second drive units each having a second motor for operating the second gear unit for driving the outer tube in a rotating manner about the drill axis, wherein the first drive unit is arranged in between the two second drive units, wherein the second drive units are spaced from the second gear unit and the second drive units are arranged adjacent to the first drive unit, with the first drive unit and the second drive units all being arranged on the first gear unit on a side thereof facing away from the second gear unit.