Dragline bucket rigging and control apparatus

Abstract

A large electric dragline having a housing ( 35 ) and boom ( 37 ) is provided with spaced apart in-line sheaves ( 34 ) and ( 36 ) at boom point to separate hoist ropes ( 31 ) and ( 32 ) which are led to the front and rear of bucket ( 30 ) respectively. Differential hoist rope control allows accurate and continuous adjustment of the bucket carry angle during all modes of operation. Also described is a computer control system giving continuous accurate control of carry angle by differential hoist rope operation, with manual selection of mode operation.

1 - 19 . (canceled) 
     
     
         20 . A rigging configuration for a dragline having a rotatable support mounted on a base, a boom assembly projecting outwardly from the support and rotatable therewith, and a bucket suspended from the boom assembly by adjustable hoist ropes and controllable by adjustable drag ropes extending from the support to the bucket,
 the rigging configuration providing at least two boom point sheaves located at or adjacent the distal end of the boom assembly and spaced apart from each other by a fixed distance such that the first said sheave is located closer to the support than the second said sheave,   two hoist ropes entrained over the boom point sheaves, one to each, the first said hoist rope being entrained over the first sheave, extending downwardly and being operatively connected to a front section of the bucket, the second said hoist rope being entrained over the second sheave, extending downwardly and being operatively connected to a rear section of the bucket,   and at least one drag rope extending from the support and being operatively connected to a front section of the bucket.   
     
     
         21 . A rigging configuration for a dragline as claimed in  claim 20 , wherein the first and second sheaves are spaced apart by a fixed distance of a similar order to the spacing of the operative connections of the first and second hoist ropes to the bucket. 
     
     
         22 . A rigging configuration for a dragline as claimed in  claim 20 , wherein the first and second sheaves each have a medial plane extending from the mid point of the sheave perpendicular to the axis of rotation of that sheave, and wherein the medial planes of the first and second sheaves lie substantially in a common vertical plane. 
     
     
         23 . A dragline having a rigging configuration as claimed in  claim 20  and further incorporating differential control for hoist rope payout and retrieval, arranged such that the length of one said hoist rope may be adjusted relative to the other to control the angle of inclination of the bucket in a vertical plane. 
     
     
         24 . A dragline as claimed in  claim 23  wherein one said hoist rope is wound on to a first drum located on the base, and the other said rope is wound on to a second drum located on the base, the first and second drums being independently rotatable to achieve said differential control 
     
     
         25 . A dragline as claimed in  claim 24  wherein said first and second drums are mounted adjacent one another on a common axis with their inner ends adjacent to one another, each being driven by a motor located respectively on the outer ends of the drums. 
     
     
         26 . A rigging configuration for a dragline as claimed in  claim 20  wherein the first hoist rope is connected directly to a front section of the bucket, and the second hoist rope is connected directly to a rear section of the bucket, without the use of intervening rigging such as spreader bars or trunnions. 
     
     
         27 . A rigging configuration for a dragline as claimed in  claim 26  wherein the first hoist rope is connected to the mid point of an arch extending across the mouth of the bucket 
     
     
         28 . A rigging configuration for a dragline as claimed in  claim 26  wherein the second hoist rope is connected to a top rail extending across a rear wall of the bucket. 
     
     
         29 . A rigging configuration for a dragline as claimed in  claim 26  wherein the second hoist rope is connected to a rear wall of the bucket at a point between a top rail of the rear wall and a base of the bucket, said point being located significantly below the top rail. 
     
     
         30 . A control system for a dragline of the type having a rotatable support mounted on a base, a boom assembly projecting outwardly from the support and rotatable therewith, and a bucket suspended from the boom assembly by adjustable hoist ropes and controllable by adjustable drag ropes extending from the support to the bucket, therebeing at least two adjustable hoist ropes of which the first is operatively connected to a front section of the bucket and the second is operatively connected to a rear section of the bucket, each hoist rope being actuated by 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,
 the control system using a computer to control the relative movement of the first and second hoist ropes via the hoisting gear, to maintain the bucket in a desired angle of inclination for a mode of dragline operation selected by an operator.   
     
     
         31 . A control system for a dragline as claimed in  claim 30  wherein, in one or more of the selected modes of operation, the computer controls the desired angle of operation continuously throughout that mode. 
     
     
         32 . A control system for a dragline as claimed in  claim 31  wherein said one or more selected modes of operation are selected from the group comprising digging, carrying, and cleaning modes. 
     
     
         33 . A control system for a dragline as claimed in  claim 30  wherein the computer is used to limit the rates of dynamic transition that the hoisting gear may apply. 
     
     
         34 . A control system for a dragline as claimed in  claim 33  wherein the dynamic transition occurs during a change in the mode of operation. 
     
     
         35 . A control system for a dragline as claimed in  claim 30  when arranged to allow the operator to control movement of the bucket relative to the boom assembly and housing. 
     
     
         36 . A control system for a dragline as claimed in  claim 35  wherein the control system is arranged to allow the operator to control movement of the bucket relative to the boom assembly and housing only within preset safe operating parameters. 
     
     
         37 . A control system for a dragline as claimed in  claim 30  wherein the modes of dragline operation selected by the operator can include any one or more of chopping, digging, disengaging, carrying, dumping and cleaning modes. 
     
     
         38 . A control system for a dragline as claimed in  claim 30  wherein the dragline includes at least two boom point sheaves located at or near the distal end of the boom assembly, spaced apart from each other by a fixed distance such that the first said sheave, the first said hoist rope being entrained over the first sheave and the second said hoist rope being entrained over the second sheave. 
     
     
         39 . A rigging configuration for a dragline having a rotatable support mounted on a base, a boom assembly projecting outwardly from the support and rotatable therewith, and a bucket suspended from the boom assembly by adjustable hoist ropes and controllable by adjustable drag ropes extending from the support to the bucket,
 the rigging configuration providing at least two boom point sheaves located at or adjacent the distal end of the boom assembly and spaced apart from each other by a distance such that the first said sheave is located closer to the support than the second said sheave,   two hoist ropes entrained over the boom point sheaves, one to each, the first said hoist rope being entrained over the first sheave, operatively connected to a front section of the bucket, the second said hoist rope being entrained over the second sheave, operatively connected to a rear section of the bucket,   and at least one drag rope extending from the support and being operatively connected to a front section of the bucket,   a differential control for hoist rope payout and retrieval, arranged such that the length of one said hoist rope may be adjusted relative to the other to control the angle of inclination of the bucket in a vertical plane,   wherein one said hoist rope is wound on to a first drum located on the base, and the other said rope is wound on to a second drum located on the base, the first and second drums being independently rotatable, and   wherein said first and second drums are mounted adjacent one another with their inner ends substantially adjacent to one another, each being driven by a motor located respectively on the outer ends of the drums.   
     
     
         40 . A control system for a dragline as claimed in  claim 30 , further incorporating a differential control for hoist rope payout and retrieval, arranged such that the length of one said hoist rope may be adjusted relative to the other to control the angle of inclination of the bucket in a vertical plane. 
     
     
         41 . A control system for a dragline as claimed in  claim 30 , wherein one said hoist rope is wound on to a first drum located on the base, and the other said rope is wound on to a second drum located on the base, the first and second drums being independently rotatable. 
     
     
         42 . A control system for a dragline as claimed in  claim 30 , wherein said first and second drums are mounted adjacent one another with their inner ends substantially adjacent to one another, each being driven by a motor located respectively on the outer ends of the drums.