Dragline bucket

Abstract

The invention provides for the design of a dragline bucket of the type where there are separate front and rear hoist ropes attached to front mounting points and rear mounting points respectively. The front and rear hoist ropes can be independently operated to vary the horizontal attitude of the bucket. The bucket design methodology seeks to equalize the loads in the front and rear hoist ropes during the major phases of the operating cycle such as digging, hoisting and dumping, and this is typically achieved by providing a bucket with comparatively shallow side walls compared with the overall length of the bucket and the positions at which the front and rear hoist ropes ultimately join onto the bucket. The bucket typically has a flat floor and relatively shallow side walls which may in some embodiments taper downwardly from the rear section to the front section.

1 - 12 . (canceled)  
   
   
       13 . A method of designing a bucket for a dragline of the type wherein the attitude of the bucket is controllable by differential movement of front and rear hoist ropes attached to front and rear portions of the bucket respectively, said method including the steps of: analysing the loads in both the front and rear hoist ropes during digging, hoisting and dumping phases of the dragline operating cycle; and optimising bucket parameters such that the respective loads are equalized as far as possible over as much of the cycle as possible.  
   
   
       14 . A method as claimed in  claim 13 , when performed on a dragline having two spaced apart boom point sheaves located at or adjacent the distal end of a boom assembly, one sheave being positioned closer to the distal end of the boom assembly than the other.  
   
   
       15 . A method as claimed in  claim 13 , wherein the bucket parameters are optimised such that the respective front and rear hoist rope loads are within 30% of their mean value during a major part of the hoisting phase of the operating cycle, being the time between the point of disengagement of the bucket from the ground, and dumping of the payload.  
   
   
       16 . A method as claimed in  claim 15 , wherein the bucket parameters are optimised such that the respective front and rear hoist rope loads are within 20% of their mean value during a major part of the hoisting phase of the operating cycle.  
   
   
       17 . A method as claimed in  claim 13  whereby the bucket parameters include the positions at which the front and rear hoist ropes ultimately join onto the bucket.  
   
   
       18 . A bucket for a dragline assembly when designed in accordance with the method as claimed in  claim 13 .  
   
   
       19 . A bucket for a dragline assembly as claimed in  claim 18 , including a base and side walls extending upwardly therefrom, wherein the bucket has a height dimension shorter than a length dimension, and wherein the height dimension at a front part of the bucket is less than or equal to the height dimension at a rear part of the bucket.  
   
   
       20 . A bucket for a dragline assembly as claimed in  claim 18 , wherein the bucket has a substantially flat base with two tapering side walls along its length dimension.  
   
   
       21 . A bucket for a dragline assembly as claimed in  claim 18 , wherein the overall length dimension of the bucket is at least twice the overall height dimension.  
   
   
       22 . A bucket for a dragline assembly as claimed in  claim 21 , wherein the length dimension is at least three times the height dimension.