Patent ID: 7152349

Claim:
A large electric dragline of the type typically used for open cut mining operations comprising: a rotatable support mounted on a base; a boom assembly projecting outwardly from the support and rotatable therewith; a bucket suspended from a distal end of the boom assembly by adjustable hoist ropes and controllable by at least one adjustable drag rope extending from the support to the bucket; a rigging configuration providing first and second boom point sheaves located at or adjacent the distal end of the boom assembly and spaced apart one behind the other by a fixed distance such that the first sheave is located closer to the support than the second sheave; first and second hoist ropes entrained over the first and second boom point sheaves, the first hoist rope being entrained over the first sheave, extending downwardly and being operatively connected solely to a front section of the bucket, the second hoist rope being entrained over the second sheave, extending downwardly and being operatively connected to a rear section of the bucket; and a control system using a computer to control the relative movement of the first and second hoist ropes via hoisting gear arranged to alter the angle of inclination of the bucket in a vertical plane by differential movement of one hoist rope relative to the other, to maintain the bucket in a desired angle of inclination for a mode of dragline operation selected by an operator.