Abstract:
A mining shovel including a frame having an upwardly support member. A boom extends upwardly and forwardly from the frame from a connecting end toward a distal end along a boom longitudinal axis. At least one first suspension cable has one end attached to the boom proximal the boom distal end and an opposing end attached to the support member. The at least one first suspension cable defines an angle relative to the boom longitudinal axis, wherein in tension, the at least one first suspension cable resists a first side load imposed on the boom.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
         [0001]    This application claims the priority benefit of U.S. Provisional Patent Application No. 60/238,065 filed on Oct. 5, 2000.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH  
         [0002]    Not Applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    This invention relates to mining shovels, and more particularly to a knee-action mining shovel with an boom supported by suspension cables.  
           [0004]    A conventional mining shovel generally includes a base supported by ground engaging tracks. The base rotatably supports a frame on which is mounted a housing for protecting mining shovel components, such as power generation equipment, electrical equipment, a dipper hoist, and controls. The frame also supports a dipper assembly and boom. The dipper assembly includes a dipper which engages the ground.  
           [0005]    The boom on a rope hoist mining shovel locates and supports boom point sheaves, over which pass hoist ropes from the hoist machinery to the dipper. When viewed from the side, the conventional boom structure generally lies on a line between the boom lower end connected to the frame, and the center of the boom point sheaves. Suspension cables support the angular position of the boom, and also aligned with the boom.  
           [0006]    The boom must be designed to withstand side loads imposed upon the load during mining operation. This requires a heavy boom formed from expensive material to withstand the side loads. A need exists for a boom suspension system which can counteract side loads on the boom to provide a mining shovel with a lighter weight boom which is less expensive to produce.  
         SUMMARY OF INVENTION  
         [0007]    The present invention provides a mining shovel including a frame having an upwardly support member. A boom extends upwardly and forwardly from the frame from a connecting end toward a distal end along a boom longitudinal axis. At least one first suspension cable has one end attached to the boom, proximal the boom distal end and an opposing end attached to the support member. The at least one first suspension cable defines an angle relative to the boom longitudinal axis, wherein in tension, the at least one first suspension cable resists a first side load imposed on the boom.  
           [0008]    In another aspect of the invention, a boom suspension assembly for supporting a distal end of a boom includes a boom point box having a longitudinal axis. The longitudinal axis is parallel to a longitudinal axis of the boom when the boom point box is fixed to the distal end of the boom. A first lug is fixed to the boom point box, and defines an angle greater than 0 degrees relative to the boom point box longitudinal axis.  
           [0009]    A general objective of the present invention is to provide side load stability to the boom while reducing the boom weight. This objective is accomplished by providing suspension cables which counteract side loads imposed on the boom during operation, thus allowing a reduction in the weight of the boom.  
           [0010]    Another objective of the present invention is to reduce the weight of the boom point box. This objective is accomplished by aligning the lugs connected to the angled suspension cables to reduce the side loads on the lugs imposed by the angled suspension cables.  
           [0011]    The foregoing and other objects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is a perspective view of a mining shovel incorporating the present invention;  
         [0013]    [0013]FIG. 2 is a perspective view of boom point box of the mining shovel of FIG. 1; and  
         [0014]    [0014]FIG. 3 is a top view of the boom point box of FIG. 2. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0015]    A knee-action mining shovel  10 , shown in FIGS.  1 - 3 , includes a base  12  supported by ground engaging tracks  14 . The base  12  rotatably supports a frame  16  on which is mounted a housing  18  for protecting mining shovel components, such as power generation equipment, electrical equipment, a dipper hoist, and controls. The frame  16  also supports a gantry  20 , dipper assembly  22 , and overhead boom  24 . A dipper assembly  22  is pivotally connected to the frame  16 , and supports a dipper  26  for engaging the ground. A gantry  20  is fixed to the frame, and extends above the housing  12 . An overhead boom  24  is pivotally connected to the gantry  20 , and extends over the dipper assembly  22 . The boom  24  supports hoist rope sheaves  25  which guide hoist ropes  28  attached to the dipper  26 .  
         [0016]    The dipper assembly  22  includes a stiff leg  48  having a lower end  50  pivotally connected to the frame  16  with pins  49  and an upper end  54  pivotally connected to a dipper handle  52 . The stiff leg  48  is pivoted about the pins  49  by a crowd handle  53  to move the dipper handle in a forwardly or rearwardly direction.  
         [0017]    The dipper handle  52  is a beam extending forwardly from the stiff leg  48  having a connecting end  70  pivotally connected to the stiff leg upper end  56 , and a dipper end  72 . The dipper end  72  extends away from the frame  12  below the boom  24 , and is connected to the dipper  26 . Preferably, the dipper handle connecting end  70  is connected to the stiff leg upper end  56  by a universal joint to allow rotation about the dipper handle longitudinal axis.  
         [0018]    The dipper  26  is pivotally connected to the dipper end  72  of the dipper handle  52 , and engages the ground to extract minerals and the like. The dipper  26  is a bucket, such as well known in the art for mining shovels. The dipper  26  is guided in the forwardly and rearwardly directions by the dipper handle  52 , and is raised and lowered by the hoist ropes  28  suspended from the boom  24 . Although pivotally connecting the dipper  26  to the dipper handle  52  is preferred, the dipper  26  can also be rigidly connected to the handle  52  without departing from the scope of the present invention.  
         [0019]    The hydraulic crowd handle  53  pivots the stiff leg  48  about the pins  49  to move the dipper handle  52 , and thus the dipper  26 , in a forwardly and rearwardly direction. The crowd handle  53  has one end  55  pivotally connected to the gantry  20  and an opposing end  57  pivotally connected to the stiff leg  48  proximal the stiff leg upper end  54 . Actuation of the hydraulic crowd handle  53  pivots the stiff leg about the pins  49 . Although a hydraulic crowd handle is disclosed, other crowd handles known in the art, such as a rack and pinion driven crowd handle, a rope driven crowd handle, and the like, can be used without departing from the scope of the present invention.  
         [0020]    The boom  24  is an overhanging structure pivotally connected to the gantry  20 , and supports the dipper  26  above the ground. The boom  24  has left and right legs  94 ,  96  pivotally connected to the gantry  20  above the stiff leg lower end  50 , and has a distal end  86  extending forwardly over the dipper  26 . An area  98  between the left and right legs  94 ,  96  is open, which allows the stiff leg upper end  54  to slip between the side legs  94 ,  96  when the stiff leg upper end  54  is pulled by the crowd handle  53  to a maximum rearward position. A boom point box  42  welded to the legs  94 ,  96  at the boom distal end  86  ties the legs  94 ,  96  together.  
         [0021]    The boom  24  extends upwardly from the gantry  20  along a longitudinal axis  87 , and is held in its angular position by left and right upper suspension cables  88 ,  89 . Each suspension cable  88 ,  89  has one end  90  attached to a lug  36  fixed to the gantry  20  and an opposing end  92  (shown in FIGS. 2 and 3) attached to a lug  38  fixed to the boom point box  42 .  
         [0022]    Importantly, the suspension cables  88 ,  89  are strung at an angle relative to the boom longitudinal axis  87  to provide boom side stability. In particular, two cables  88 ,  89  are strung at an angle outwardly from each boom point box lug  38  toward one of the lugs  36  fixed to the gantry  20 . The gantry lugs  36  are spaced further apart than the boom point box lugs  38  to cause the cables  88 ,  89  to form an angle B with the boom longitudinal axis  87  which is greater than 0 degrees, such as greater than 5 degrees. Preferably, angle B is greater than 7 degrees.  
         [0023]    In tension, the angled cables  88 ,  89  counteract side loads imposed on the boom  24  during the operation of the shovel  10 . In particular, the left suspension cables  88  counteract a side load imposed on the boom which is in a direction opposite to a side load counteracted by the right suspension cables  89 . Advantageously, stringing the suspension cables  88  at an angle to the boom  24  minimizes the potential for interference between the suspension cables  88  and the hoist ropes  28 . Preferably, the angled cables  88 ,  89 , and thus the boom point lugs  38 , define lines  91 ,  93  which intersect within the perimeter of the boom point box structure to avoid inducing a moment on the boom  24 .  
         [0024]    As shown in FIGS. 2 and 3, the welded-on boom point box  42  incorporates both the boom point sheaves  25  and suspension cable lugs  38  to reduce the bending moment on the connection between the boom point box  42  and legs  94 ,  96 , and has a longitudinal axis substantially parallel to the boom longitudinal axis  87 . The boom point box lugs  38  are fixed, such as by welding to a top surface  44  of the boom point box  42 , at the angle B aligned with the cables  88  attached thereto to eliminate side loads on the lug  38 , and thus reduce the structural weight of the lug  38 . The cables  88  are attached to the lugs using methods known in the art, such as yokes  46  fixed to a cable end and bolted to the lug  38 .  
         [0025]    The boom point sheaves  25  are rotatably mounted to the boom point box  42  above the dipper  26 . Each sheave  25  supports one of the hoist ropes  28  attached to the dipper  26 . Each rope  28  is attached to a dipper side, passes over one of the boom point sheaves  25 , and is wound up on a dipper hoist. The hoist winds and unwinds the hoist rope  28  to raise and lower the dipper  26  using a single part hoist reeving method. Preferably, each hoist rope  28  is a wire rope sized using methods known in the art, for the particular application, which depends upon the dipper duty and capacity rating.  
         [0026]    While there has been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention defined by the appended claims.