Patent Publication Number: US-8112912-B2

Title: Dump block with improved assembly features

Description:
FIELD 
     The present disclosure relates to equipment for use in excavation or mining processes, and dump blocks in particular. 
     BACKGROUND 
     Dragline excavation systems comprise heavy equipment that can remove materials from the ground, such as overburden, in surface mining or other civil engineering projects where large volumes of material must be removed in an efficient manner. A typical dragline excavation system includes a large bucket that is suspended from a boom (a large truss-like structure) with wire ropes. The bucket is maneuvered by means of a number of ropes and chains. The hoist rope, typically powered by large diesel or electric motors, supports the bucket and hoist-coupler assembly from the boom. The dragline is used to draw the bucket assembly horizontally to scoop up and remove material from the ground. By skillful maneuver of the hoist and the dragline, the bucket can be controlled for various operations. 
     Dragline excavation systems provide several advantageous features over other earthmoving equipment, including a long reach for both digging and dumping, the ability to dig below their tracks (or base), and a high cycle speed. However, the loads and stresses applied to the various parts of the dragline excavation system are massive and the parts associated with the system must be able to withstand such stresses. In addition, the harsh environment in which a dragline excavation system operates can further contribute to increased wear of the various parts of the dragline excavation system. Because of the tremendous size and weight of the various parts of these systems, failure of a single part can result in significant down-time. 
     SUMMARY 
     In a first embodiment, a dump block comprises a housing with two side sections, a sheave, a bearing assembly, and a sheave pin. Each side section has an opening extending therethrough. The sheave has a peripheral groove shaped to receive a rope and a central bore. The bearing assembly is positioned within the central bore. The sheave pin rotatably supports the sheave. The sheave pin has a first end with a shoulder portion, a second end with a threaded portion, a support section of a predetermined length extending between the first and second ends, and a fastener coupleable to the second end at the threaded portion. When the sheave pin is assembled with the housing, the first and second ends of the sheave pin extend into the respective openings in the side sections. The bearing assembly is installed within the sheave and adjusted by urging the sheave pin to translate in the direction of the second end and securing the fastener to the threaded section at a location between the two side sections. 
     In one specific implementation, the housing comprises substantially solid side sections. In another specific implementation, the fastener is secured to the threaded section with a force sufficient to cause the shoulder portion to bear against the bearing assembly until the predetermined length of the support section is fully seated. In another specific implementation, the portions of the first and second ends that extend through the respective openings in the side sections each comprise an extending threaded portion, and a securing mechanism is coupled to each extending threaded portion to secure the sheave pin to the two side sections. 
     In another specific implementation, the bearing assembly comprises an outer surface and the sheave comprises an inner surface that defines the central bore, and the outside surface of the bearing assembly is secured to the inner surface of the sheave with an interference fit. In another specific implementation, the inner surface of the sheave comprises first and second indentations to facilitate positioning of the bearing assembly within the central bore, and a first ring is positioned within the first indentation and a second ring is positioned within the second indentation, and at least a portion of the bearing assembly is positioned between the first and second rings. 
     In another specific implementation, the bearing assembly comprises an open-ended cylindrical member with two tapered cone members positioned within the cylindrical member and spaced apart by at least one spacer member. In another specific implementation, the first end further comprises a lubrication port in fluid communication with a lumen that extends at least partially through the sheave pin for delivering lubrication to the bearing assembly. 
     In another embodiment, a dump block includes a housing comprising two side sections, a sheave, a bearing assembly, and a shaft. Each side section comprising an opening extending therethrough and the sheave has a peripheral groove shaped to receive a rope. The sheave has a central bore and the bearing assembly is positioned within the central bore. The shaft rotatably supports the sheave and has an asymmetrical configuration dimensioned to positively locate the shaft pin within the bearing assembly. 
     In one specific implementation, when the shaft is assembled with the housing, the first and second ends of the shaft extend into the respective openings in the side sections. In another specific implementation, the shaft comprises a first end with a shoulder portion sized to contact the bearing assembly and a second end with a threaded portion sized to receive a fastener, and the position of the shaft relative to the bearing assembly can be adjusted by applying a torque to the fastener. In another specific implementation, the bearing assembly is substantially sealed after installation in the dump block. 
     In another embodiment, a method of assembling a dump block is provided. The method comprises: providing a sheave with a peripheral groove and having a central bore; providing a bearing assembly; and providing a sheave pin with a first end that with a shoulder portion, a second end with a threaded portion, and a support section between the first and second ends. The method comprises positioning the bearing assembly within the central bore; inserting the second end of the sheave pin into the bearing assembly and securing a fastener to the second end of the sheave pin; and adjusting the position of the sheave pin relative to the bearing assembly by causing the shoulder portion to bear against the bearing assembly until the support section is fully seated. The method further comprises providing a first side section and a second side section; and securing the first and second side section to the sheave pin. 
     In one specific implementation, the act of positioning the bearing assembly within the central bore comprises heating the sheave and positioning the bearing assembly within the heated sheave. In another specific implementation, the act of positioning the bearing assembly within the central bore comprises positioning at least one ring in at least one indentation in an inner surface of the central bore; and positioning the bearing assembly adjacent to the at least one ring. 
     In another specific implementation, the act of securing the first and second side sections comprises providing two fasteners, securing one of the two fasteners to a portion of the first end that extends out of an opening in the side of the first side section, and securing the other of the two fasteners to a portion of the second end that extends out of an opening in the side of the second side section. 
     In another specific implementation, the method further comprises securing the first and second side sections to one another at locations radially outside of the location of the sheave. In another specific implementation, the method further comprises lubricating the bearing assembly by delivering lubricant through a port located at the first end of the sheave pin, with the port being in fluid communication with a lumen that extends at least partially through the sheave pin. 
     The foregoing and other objects, features, and advantages of the embodiments disclosed herein will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a dragline excavation system with a dump bucket. 
         FIG. 2  illustrates an enlarged view of a portion of the dragline excavation system, showing the use of two dump blocks. 
         FIGS. 3A-3F  illustrate enlarged views of a portion of a dragline excavation system as the system is operated to scoop up material from a surface. 
         FIG. 4  is a front isometric view of a dump block. 
         FIG. 5  is a front view of the dump block of  FIG. 4 . 
         FIG. 6  is a side view of the dump block of  FIG. 4 . 
         FIG. 7  is an exploded isometric view of the dump block of  FIG. 4 . 
         FIG. 8  is an exploded side view of a bearing assembly. 
         FIG. 9  is an enlarged, side cross-sectional view of a portion of the dump block of  FIG. 4 . 
         FIG. 10  is a front isometric view of a dump block with opposite-plane extension members. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, example embodiments in which the subject matter may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the subject matter. The embodiments may be combined, other embodiments may be used, or structural and other changes may be made without departing from the scope of the present subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present subject matter is defined by the appended claims and their equivalents. 
     As used in this application and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the terms “coupled” and “secured” generally mean electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or secured items absent specific contrary language. 
     Although the operations of exemplary embodiments of the disclosed method may be described in a particular, sequential order for convenient presentation, it should be understood that disclosed embodiments can encompass an order of operations other than the particular, sequential order disclosed. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Further, descriptions and disclosures provided in association with one particular embodiment are not limited to that embodiment, and may be applied to any embodiment disclosed. 
     Referring to  FIG. 1 , the major components of a dragline excavation system  10  include a powerplant  100 , a boom  102 , a hoist cable  104 , a bucket  106 , hoist chains  108 , drag chains  110 , dump cables  112 , drag cables  114 , and respective dump blocks  115 . Powerplant  100  can be mounted on a rotary base  117 , allowing the boom to swing in the horizontal plane. Smaller draglines typically employ sets of tracks for moving the machine, while larger draglines use a “walking” mechanism. These larger machines are typically referred to as walking draglines. Hoist cable  104  can be retracted or extended by means of a hoist drum (not shown) that is located in the powerplant. Likewise, drag cable  114  can be retracted and extended by means of a drag drum (not shown) located in the powerplant. 
     As shown in  FIG. 2 , drag cable  114  can be connected to a pair of drag sockets  116 . Drag sockets  116  can be connected through drag devises  118  to the drag chains  110 . Drag chains  110  can be connected to the bucket  106  at hitch devises  120 . Drag sockets  116  can also be respectively connected to a pair of dump sockets  122  at dump devises  124 . A second pair of dump sockets  126  can be connected to the front of bucket  106  at anchor links  128 . The dump sockets  122  and  126  are commonly connected to a respective pair of dump cables  112 , which ride on one or more sheaves of dump blocks  115 . Although the system  10  of  FIG. 1  illustrates the use of two dump blocks  115 , it should be understood that fewer (i.e., one dump block) or more dump blocks can be used. As discussed in more detail below, dump block  115  is a pulley-like device that functions to change the direction of forces exerted on bucket  106  so that bucket  106  can be filled and emptied. 
     A pair of upper hoist chains  132  are commonly connected to the bottom of a pickup link  134  at their top ends, and to opposing sides of a spreader  136  at their bottom ends. A pair of lower hoist chains  138  are connected to the spreader  136  at their top ends, and are connected at their bottom ends to the bucket  106  at trunnions  139 . The pickup link  134  is connected to a hoist equalizer  140 , which in turn is connected to hoist sockets  142 . Hoist sockets  142  can be connected to the hoist cables  104 . Hoist equalizer  140  can also be connected to a pickup link  144 , which is connected to the dump block  115 . 
     The loads on the hoist and drag chain links are massive. It is common for the largest draglines to employ hoist and drag cables or ropes that are 5 inches in diameter. These cables are typically made out of very high strength steels, and can support suspended loads of upwards of 750,000 lbs. The loads placed on the hoist chains and drag chains are equally impressive. These loads dictate the use of specialized chain links made from ultra-high-strength alloyed steels. In addition, these chains and chain links are preferably designed to endure a tremendous amount of wear. 
     A typical dragline digging cycle is shown in  FIGS. 3A-3F . As shown in  FIG. 3A , the digging cycle begins by lowering the bucket into the mine pit (or other suitable location) with both the hoist cable  132  and the drag cable  114  nearly taut until the bucket contacts the pit surface. At this point, hoist cable  132  is slightly slackened and drag cable  114  is pulled towards powerplant  100 .  FIGS. 3B-3E  illustrate how bucket  106  scoops up material from the surface of the mine pit while it is dragged towards across the surface towards powerplant  100 . The movement of bucket  106  causes the bucket teeth to dig into the surface of the ground, cutting into the ground surface, and forcing material to pile up inside bucket  106  as the bucket moves horizontally. The depth and angle of the cut may be controlled by varying the hoist cable length as the drag cable is pulled. 
     Once bucket  106  is filled or otherwise moved through the desired surface area, the orientation of bucket  106  can be adjusted so that at least a substantial portion of the material will remain in bucket  106  while it is transported (generally via a swing operation) to a different location for dumping. At the dumping location, drag cable  114  can be slackened (e.g., released) while hoist cable  104  is held taut, causing bucket  106  to tilt and empty (as shown in  FIG. 1 ). 
     During the dragging and dumping operations, dump block  115  desirably allows for the smooth transition of forces between the hoist cables and drag cables. Like the other parts of the excavation dragline system, however, dump blocks are subjected to high forces, stresses, and harsh conditions. In addition, because dump blocks  115  contain moving parts (e.g., a rotatable sheave as discussed in more detail below), dump blocks  115  can be particularly susceptible to failure or malfunction. 
     Referring to  FIGS. 4-7 , dump block  115  comprises a sheave (pulley)  150  that is rotatably mounted around a shaft (e.g., sheave pin)  151 . Shaft  151  defines an axis of rotation about which sheave  150  rotates. Sheave  150  comprises a wheel or roller with a peripheral grooved section  153  for receiving or holding a rope, and a central bore  158  for receiving a bearing assembly. As used herein, rope generally refers to any elongate flexible material suitable for use with a dump block operation, including, for example, wires, cables, chains, and other braided fibers or materials. 
     A first side frame  152  and a second side frame  154  collectively define a housing that at least partially encloses the sides of sheave  150 . Preferably, first and second side frames  152 ,  154  are substantially solid sections that restrict contaminants from entering the housing and causing damage to the internal structure of the dump block. Shaft  151  is positioned within a bearing assembly  156 , which in turn is positioned within central bore (aperture/opening)  158  of sheave  150 . To facilitate smooth operation of the sheave  150 , bore  158  is preferably located at a substantially central location with respect to a diameter of sheave  150 . 
     Bore  158  is preferably sized to receive the bearing assembly  156  with an interference fit. If desired, during dump block assembly, sheave  150  can be heated to slightly enlarge bore  158  to facilitate the receipt of bearing assembly  156  within bore  158 . Thus, the temperature of sheave  150  can be increased causing bore  158  to expand slightly, bearing assembly  156  can be inserted into bore  158 , and, as sheave  150  cools, bore  158  will decrease slightly in size causing an interference fit between an inner surface of sheave  150  (which defines bore  158 ) and an outer surface of bearing assembly  156 . 
     Bearing assembly  156  is preferably a bearing assembly that does not require adjustment at installation (i.e., a self-adjusting bearing).  FIG. 8  illustrates a bearing assembly  156  that comprises a cup member  160  (e.g., an open-ended cylindrical member), a first cone member  162 , and a second cone member  164 . A cone spacer  166  can be positioned between the first and second cone members  162 ,  164 . As shown in  FIG. 8 , seals  168 ,  170  can be provided adjacent to the cone members  162 ,  164  (respectively) to maintain the lubrication of bearing assembly  156 . In addition, seal wear rings  172 ,  174  can be positioned adjacent the seals  168 ,  170 , as shown in  FIG. 8 . A bearing assembly as described in  FIG. 8  can be obtained from the Timken Company, which provides so-called “AP Bearings for Industrial Applications.” 
     Referring to  FIG. 9 , the assembly of dump block  115  is described in more detail. Bearing assembly  156  (comprising cup member  160 , cones  162 ,  164 , cone spacer  166 , seals  168 ,  170 , and seal rings  172 ,  174 ) is shown positioned within bore  158 . Bore  158  is defined by an inner surface  180  of the sheave  150 . As discussed above, inner surface  180  and an outer surface of the bearing assembly  156  (i.e., the outer surface of cup member  160 ) preferably form an interference fit to secure the two surfaces together. In order to facilitate positioning of the bearing assembly  156 , snap rings  176  can be positioned on either side of cup member  160  and received into indentations  178  in surface  180 . One or both of rings  176  can be used to guide or otherwise facilitate positioning of the bearing assembly  156  within bore  158 . 
     After bearing assembly  156  is secured to sheave  150 , shaft  151  can be inserted through bearing assembly  156  to occupy the assembled position as shown in  FIG. 9 . Shaft  151  preferably has a first support end that has a shoulder portion (e.g., a radially enlarged section)  190 , a support second end with a threaded portion  201 , and a support section  191  between the first and second support ends. Thus, shaft  151  is configured to be inserted through bearing assembly  156  in only one direction (i.e., from right to left as viewed in  FIG. 9 , before the side plates  152 ,  154  and fastener  194  are installed). The threaded portion  201  of the second support end can be configured to receive a fastener or other securing mechanism. The fastener is preferably received on the shaft at a location that is between first and second side frames  152 ,  154  (e.g., within the housing). For example, a washer  192  and fastener (locknut)  194  combination can be secured to shaft  151  within the housing as shown in  FIG. 9 . 
     Bearing assembly  156  can be assembled and adjusted by urging shaft  151  to translate in the direction of the second support end. Thus, bearing assembly  156  can be fully adjusted by securing the fastener  194  to threaded portion  201  and providing a force sufficient to cause the shoulder portion  190  to bear against bearing assembly  156  until the predetermined length of support section  191  is fully seated. 
     The second end of shaft  151  can comprise an extending section  193  configured to extend through an opening in second side frame  154  and an extending threaded portion  195 . The extending threaded portion  195  extends outside of second side frame  154  and a securing mechanism (e.g., nut  202  as discussed below) can secure extending threaded portion  195  to second side frame  154 . Thus, second end of shaft  151  comprises threaded portion  201 , extending section  193 , and extending threaded portion  195 . 
     First end of shaft  151  can further comprise an extending section  197  that extends beyond the shoulder portion  190  (i.e., further from the second end). Extending section  197  can be a section with a smaller diameter than shoulder portion  190  and can extend through an opening in first side frame  152 , as shown in  FIG. 9 . A further extending section can comprise a threaded portion  199  that is configured to receive a securing mechanism (e.g., nut  202  as discussed below) to secure threaded portion  199  to the first side frame  152 . Thus, first end of shaft  151  comprises shoulder portion  190 , extending section  197 , and threaded portion  199 . 
     As shown in  FIG. 9 , a lubricant entry area (port)  196  and a lubricant pathway (lumen)  198  through shaft  151  can be provided to deliver grease or other lubrication to bearing assembly  156 . Dust caps  200  can optionally be used to cover the shoulder portion  190  and the washer/locknut  192 ,  194  combination as shown in  FIGS. 7 and 9 . Bearing assembly  156  is preferably prefilled (i.e., factory filled) with lubricant. If desired, however, additional lubricant can be added to completely fill the bearing assembly during assembly to help prevent contamination of the bearing assembly. Preferably, sufficient lubrication is used so that further lubrication is not required over the life of the dump block assembly. 
     After bearing assembly  156  is positioned within bore  158 , and shaft  151  is positioned and secured to bearing assembly  156  (as discussed above), first side frame  152  and second side frame  154  can be secured to shaft  151 . To secure first side frame  152  and second side frame  154  to shaft  151 , nuts  202  (or other fasteners) can be screwed onto the respective threaded portions  195 ,  199  that extend out of the openings in the first and second side frames  152 ,  154  (as shown in  FIG. 9 ). If desired, nut locks  204  can be secured to nuts  202  to further secure first and second side members  152 ,  154  to each other (through shaft  151 ). Nut locks  204  can optionally be welded in place. 
     First and second side frames  152 ,  154  can be additionally secured to one another by using fasteners, such as bolts  206  and nuts  208  as shown in  FIG. 7 . Bolts  206  and nuts  208  are preferably received in recesses in first and second side frames  152 ,  154  to protect them from exposure or impact with the outside environment during use of the dump block. If desired, sleeves  210  can be positioned within the opening for receiving bolts  206 . Sleeves  210  can be constructed of rubber or other similar resilient materials. 
     It should be understood that the order in which the various parts of the dump block are installed can vary. For example, it can be preferable to insert the shaft into the bearing assembly before inserting the bearing assembly into the bore. Thus, the assembly of the various parts of the dump block can be achieved using the same steps described above but performed in a different order. Such variations fall within the scope of the disclosed embodiments. 
     As shown in  FIG. 4 , for example, dump block  115  can comprise one or more extensions  212  that are configured with apertures  214  to receive pins (not shown) to couple dump block  115  to hoist cables  104  (either directly or indirectly). In  FIG. 4 , extensions  212  are shown as being in the same general plane as the first and second side frames  152 ,  154 ; however, it should be understood that other configurations can be used. For example,  FIG. 10  illustrates a dump block  115  that has extensions  212  that are configured out-of-plane (e.g., perpendicular) relative to a plane of the first and second side frame members  152 ,  154 . 
     Preferably, the tolerances between the sheave and extensions are sufficient to permit rope for a ferrule socket to pass through the dump block while the dump block is assembled. Thus, a ferrule socket (or becket end) of a rope can pass through the dump block when changing or adding a rope system without any disassembly or alteration of the dump block. 
     The bearing assemblies described herein provide for more efficient and more accurate assembly and rebuilds of dump blocks. For example, when using conventional bearing assemblies with a dump block, significant adjustment is required during assembly and rebuilding. Fasteners must be carefully adjusted at both ends of the bearing assembly in order to ensure that the shaft and bearing assembly are appropriately centered during assembly to achieve the desired amount of end-to-end movement (i.e., “end play”) of the shaft. Generally, this means that the end fasteners must be repeatedly adjusted, which may require repeated assembly and disassembly of the side plates, until the bearing assembly and shaft are correctly positioned. Such careful adjustment is necessary both during initial assembly and during any necessary rebuilds during the life of the dump block. 
     In contrast, the bearing assemblies of the dump block configurations disclosed herein are substantially self-centering. By providing a shaft with a positive positioning feature, such as a shoulder portion as described above, the shaft and bearing assembly can be assembled (or rebuilt) quickly and with little, if any, adjustment to align the shaft and the bearing assembly. In addition, the bearing cavity is substantially protected from material intrusion due to its enclosed design. Conventional bearing assemblies often require o-rings to facilitate sealing the assembly from the environment. However, o-ring seals are often susceptible to failure. The use of bearing assemblies as disclosed herein can eliminate the need for an o-ring, thereby providing a better sealing environment. 
     In addition, because the sides of the housing are substantially solid, the internal portions of the housing are further protected from rough service environments, which can further increase service life of the dump block. 
     In view of the many possible embodiments to which the disclosed principles may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting in scope. Rather, the scope of protection is defined by the following claims. We therefore claim all that comes within the scope and spirit of these claims.