Abstract:
A horizontal shaft impact rock crusher having breaker plates which are coupled to a shaft or pins which rest in voids along an edge of the crusher and are held in place by a retainer device, such that the breaker plates with the shaft or pins still attached can be removed from the crusher by releasing the retainer devices.

Description:
BACKGROUND OF INVENTION 
     In the past, rock crusher designers have endeavored to improve the ease of maintaining horizontal shaft impact rock crushers. While many improvements have been made to reduce the expense associated with repair and maintenance of such crushers, removal of all of the breaker plates on such crushers remains a non-trivial task. Most crushers usually have two breaker plates. A primary breaker plate is disposed nearest the feed opening and nearest the top of the crusher. These crushers typically have a secondary or rear breaker plate, which is generally located lower in the crusher and more toward the rear of the crusher. Some attempt has been made to reduce the removal time for the primary breaker plates. One example is the crusher shown in U.S. Pat. No. 6,089,481 entitled APPARATUS FOR RELIEVING THE LOAD ON ADJUSTING RODS OF A CRUSHER, issued to Gregory A. Young. This patent shows a primary breaker plate pivot shaft disposed near a front edge of the tiltable portion of the crusher. When the crusher housing is tilted for repair, the pivot shaft of the primary breaker plate can be lifted out of the crusher while the breaker plate is still attached. Another example of an attempt to reduce the removal time for primary breaker plates (or curtains, as they are sometime called) has been to hang one or more of them on a single cradle. However, it is typical that when a repair is needed on any of the breaker plates, the breaker plate pivot shaft, which is typically directly coupled to each of the breaker plates and typically extends wall-to-wall across the crusher, (a directly coupled trans-crusher pivot shaft) is either driven or pulled from the crusher, and then the breaker plates may be removed. 
     While this approach of driving or pulling the pivot shaft prior to breaker plate removal has been used extensively in the past, it does have some drawbacks. First of all, depending upon the condition of the breaker plate pivot shaft (which can be bent), or any distortion of the breaker plate itself, or the crusher frame, this can involve significant effort and can leave the crusher out of service for an extended time period. 
     Consequently, there exists a need for improved methods and systems for rapidly removing and replacing all of the breaker plates in horizontal shaft impact rock crushers in an efficient manner. 
     SUMMARY OF INVENTION 
     It is an object of the present invention to provide a system and method for repairing and maintaining a horizontal shaft impact rock crusher in an efficient manner. 
     It is a feature of the present invention to utilize directly coupled trans-crusher pivot shafts mounted in slots with movable structures for permitting rapid access to the shafts and thereby permitting rapid removal of all breaker plates, with the breaker plate pivot shaft remaining therein. 
     It is another feature of the present invention to utilize short pivot shafts or pins mounted in slots with movable structures for permitting rapid access to the pins or shafts and thereby permitting rapid removal of all breaker plates, with the breaker plate pin or shaft remaining coupled thereto. 
     It is an advantage of the present invention to achieve improved efficiency in replacing the entire complement of breaker plates in horizontal shaft impact rock crushers. 
     The present invention is an apparatus and method for repairing and maintaining horizontal shaft impact crushers which are designed to satisfy the aforementioned needs, provide the previously stated objects, include the above-listed features, and achieve the already articulated advantages. The present invention is carried out in a “wasted time-less” manner in a sense that the time consumed with separating (driving or pulling apart) a breaker plate and its associated pivot shaft prior to removal of a breaker plate from a crusher, has been eliminated. 
     Accordingly, the present invention is a system and method including a horizontal shaft impact crusher having a movable breaker pivot shaft slot cover or retaining member which permits access to and removal of a pivot shaft from a void near a periphery of the crusher while the pivot shaft remains directly coupled to the breaker plate. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     The invention may be more fully understood by reading the following description of the preferred embodiments of the invention, in conjunction with the appended drawings wherein: 
     FIG. 1 is a schematic sectional view of a horizontal shaft impact crusher of the present invention, employing a removable pivot shaft slot cover. 
     FIG. 2 is an elevational view of a horizontal shaft impact crusher of the present invention, in which the housing has been tilted and where the removable pivot shaft slot cover has been removed, exposing the pivot shaft slots. 
     FIG. 3 is an enlarged elevational view of a portion of the top of the crusher of FIG. 2, showing the configuration of pivot shaft slots in more detail. 
    
    
     DETAILED DESCRIPTION 
     Now referring to the drawings wherein like numerals refer to like matter throughout, and more specifically referring to FIG. 1, there is shown a system of the present invention generally designated  100 , including a horizontal shaft rotor  10 , a feed opening  12 , a primary breaker plate  14 , a secondary breaker plate  16  and a discharge opening  18 . Primary breaker plate  14  is coupled to the crusher  100  by primary breaker plate pivot shaft  24 . Primary breaker plate pivot shaft  24  is preferably a trans-crusher directly coupled pivot shaft which extends from wall-to-wall of the crusher  100  and extends directly through a portion of primary breaker plate  14 . Similarly, secondary breaker plate pivot shaft  26  is preferably a trans-crusher directly coupled pivot shaft which extends from wall-to-wall of the crusher  100  and extends directly through a portion of secondary breaker plate  16 . Primary breaker plate pivot shaft  24  and secondary breaker plate pivot shaft  26  are preferably disposed in a pivot shaft-mounting slot  30  (FIG. 3) which are covered by removable top shaft slot cover  20 . It should be understood that primary breaker plate pivot shaft  24  or secondary breaker plate pivot shaft  26  as shown in FIG. 1 could be trans-crusher shafts or short shafts or pins which merely extend from the respective breaker plate to the housing of the crusher  100 . 
     A more detailed understanding of the present invention can be achieved by now referring to FIG. 2, which shows the crusher  100  after the housing has been tilted for maintenance and the removable top shaft slot cover  20  has been removed. Additionally, the present invention would preferably include pivot shaft end caps disposed at the ends of each pivot shaft. These end caps (not shown) could be any structure designed to keep primary breaker plate pivot shaft  24  and secondary breaker plate pivot shaft  26  from sliding out of the pivot shaft-mounting slot  30 . The end caps could be held in place with clamps, pins, bolts, rivets, welding or any suitable structure or process. Primary breaker plate pivot shaft  24  and secondary breaker plate pivot shaft  26  are each shown in a pivot shaft-mounting slot  30  in a reinforcing plate  25  on the crusher  100 . 
     An even more detailed understanding of the present invention may be achieved by now referring to FIG. 3, which shows an enlarged view of a portion of the top side of the crusher  100  with one of the pivot shaft-mounting slots  30  empty and the other pivot shaft mounting slot  30  occupied by primary breaker plate pivot shaft  24 . The shape of a pivot shaft-mounting slot  30  is shown as being slanted with respect to the top of the crusher  100 . A force vector  34  is shown which represents the primary direction of impact forces upon primary breaker plate  14  during operation. The slanted shape of pivot shaft-mounting slot  30  helps to retain the primary breaker plate pivot shaft  24  and secondary breaker plate pivot shaft  26  in place during operation when the primary breaker plate  14  and secondary breaker plate  16  are experiencing forces, such as shown by force vector  34 . The slanted shape of pivot shaft-mounting slot  30  also permits much of the impact forces during operation of the crusher  100  to be absorbed by crusher housing and reinforcing plate  25  in lieu of additional operational impact forces being absorbed by retainer bars  22 , removable top shaft slot cover  20 , the pivot shaft end caps or any other structure designed to keep the primary breaker plate pivot shaft  24  and the secondary breaker plate pivot shaft  26  in place in the pivot shaft-mounting slot  30 . Pivot shaft-mounting slot  30  is shown having a depth axis  35  which is substantially orthogonal to force vector  34 . Retainer bars  22  are designed to be removable and when in place, prevent the pivot shaft  26  from exiting the slot  30 . 
     In operation, the apparatus and method of the present invention as described in FIGS. 1-3, could function as follows: 
     A rock crusher  100  is provided with a removable primary breaker plate which can be removed without driving or pulling the shaft from the primary breaker plate. 
     The crusher  100  is also provided with a secondary breaker plate which can be removed without driving or pulling the shaft from the secondary breaker plate. 
     The primary breaker plate is removed. (Note: this could be using the same method as described below or with a known prior art method using cradles.) 
     A mechanism holding the secondary pivot shaft for the secondary breaker plate is manipulated to permit removal of the secondary pivot shaft from a void. 
     The secondary breaker plate is removed, with the secondary breaker plate pivot shaft still directly coupled thereto. 
     Throughout this description, reference is made to secondary breaker plates, because it is believed that the beneficial aspects of the present invention would be most readily apparent when used in connection with crushers using two breaker plates; however, it should be understood that the present invention is not intended to be limited to merely dual breaker plate designs and should be hereby construed to include other multiple breaker plate crushers as well. In such crushers, all non-primary breaker plates may be viewed as secondary and may be able to employ the innovative aspects of the present invention. In all designs, it should be understood that if two or more breaker plates are used in the crusher, their associate pivot shafts need not necessarily be located in close proximity to each other. As is shown in FIGS. 1-3, other locations could be used especially for additional breaker plates beyond the second breaker plate. 
     Additionally, throughout this description, the pivot shafts are described as trans-crusher wall-to-wall pivot shafts where the breaker plates pivot about the pivot shaft. It should be understood that the pivot shafts herein need not be trans-crushers; i.e., they need not extend across the crusher. Each breaker plate could be supported by two or more pins, at least on each side acting as pivot shafts. It also should be understood that the breaker plate may preferably pivot with respect to said pivot shaft or pins; they need not. The breaker plates could be firmly fixed to the pivot shafts or pins, and the pivot shafts or pins could pivot with respect to the crusher housing. 
     It is thought that the method and apparatus of the present invention will be understood from the foregoing description and that it will be apparent that various changes may be made in the form, construct steps, and arrangement of the parts and steps thereof, without departing from the spirit and scope of the invention or sacrificing all of their material advantages. The form herein described is merely a preferred exemplary embodiment thereof.