Abstract:
Impact bed assemblies are provided, both static and dynamic, for absorbing impact forces taken by conveyor belts. The static and dynamic bed assemblies generally are constructed to optimize their impact absorption capacities while minimizing their space requirements under the belt.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of PCT Application No. PCT/US2008/088489, filed Dec. 29, 2008, which claims priority to U.S. Provisional Patent Application No. 61/017,473, filed Dec. 28, 2007, both of which are incorporated herein by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to an impact bed for a conveyor belt and, more particularly, to impact bed assemblies that are conventionally known as static and dynamic-type impact beds. 
       BACKGROUND OF THE INVENTION 
       [0003]    Conveyor belts are used in a variety of industries to transport goods and materials from one place to another. Generally, goods are deposited at one end of a conveyor and are transported to the other end, where they are discharged or otherwise removed from the conveyor belt. The belts used are often robust, but are susceptible to damage from a variety of sources. While the discharge of the goods from a conveyor belt does not usually cause damage to the belt, the act of depositing goods and materials onto a conveyor belt has the potential to cause damage. In this regard, when a belt is being used to transport coal, aggregate and other coarse and heavy material, the deposit of these types of rocks onto the belt can generate tremendous impact forces on the belt. For instance, with a 100 lb mass having drop distance of 10 feet from a discharge chute onto a conveyor belt, there is 1,000 ft-pounds of force impacting the belt. 
         [0004]    An impact bed is an apparatus which is installed below the area of a conveyor belt on which heavy loads are deposited for absorbing the impact forces generated thereby, as discussed above. Generally, impact beds can be classified as either static or dynamic. Static impact beds have resilient impact bars and an underlying bed framework that includes rigidly connected frame members. For instance, static impact beds typically include at least two support members for supporting the resilient impact bars thereon with the support members extending from either side of the belt inwardly and toward the middle of the belt. The support members are rigidly secured on cross members that span the width of the belt to be rigidly secured to stringers of the conveyor belt frame. 
         [0005]    By contrast, dynamic impact beds differ from static impact beds in the manner in which impact forces are absorbed since, rather than using resilient impact bars, dynamic impact beds have torsion bias units mounted under an impact cradle upon which the belt is supported. In this regard, unlike static beds, the bed framework underlying the impact cradles includes frame members resiliently connected together via the torsion bias units secured therebetween. 
         [0006]    Generally, there is a trade off between increasing the capacity of the bed to absorb impact forces, such as by using thicker impact bars with static impact beds, and the size of the impact bed. In other words, an impact bed having a compact size for fitting under the belt generally sacrifices in its ability to absorb high impact forces. Given that an impact bed is meant to be installed under the upper or carry run of a belt, a location often without an excess of space, balancing the size and strength of the bed is important. Generally, the vertical height between the carry run of the belt and the upper surface of the conveyor frame stringer member currently is approximately 8.5 to approximately 9.0 inches and cost constraints may tend to shrink the size of this space even further. 
         [0007]    In typical static impact beds, several sets of support members will be longitudinally spaced from each other under the area of the belt where materials are deposited thereon for being conveyed thereby. The longitudinally spaced support members have the resilient bars secured thereto to extend thereacross running lengthwise in the belt travel direction and which are operable to absorb the impact forces and to decrease the acceleration of the materials or rocks dropped onto the belt. The resilient bars are subject to wear and damage over repeated impacts with the belt and thus need to be serviced and/or replaced on a regular basis. 
         [0008]    In many static impact beds, servicing of the impact bars, particularly for those in the lower central area under a troughed belt, requires that the loading on the impact bed by the heavy conveyor belt thereon be relieved. This allows an operator to unfasten the support members from the cross members so that the support members and impact bars thereon can be removed out from under the belt for servicing. 
         [0009]    In some prior static impact beds, the support members upon which the impact bars are secured can be slid in and out from under the conveyor belt along the cross members. However, when the support members are slid out from under the conveyor belt, the relatively heavy support members and impact bars thereon, e.g. approximately 100 to 200 lbs., must be supported, such as by heavy equipment like a crane or other lifting or support mechanism, which allows an operator to safely replace the impact bars. 
         [0010]    In prior static impact beds, the support members are secured in their operative positions under the belt by being bolted to the cross members. This requires that an operator reach or climb under the belt to access the bolt locations, which can be of particular difficulty when the bolting needs to occur centrally under a troughed belt at which the belt is at its lowest height and where there is very little work space available between the upper and lower runs of the belt. Similar problems are presented when servicing of the impact bed is necessary and the securing bolts need to be removed. 
         [0011]    Thus, prior static impact beds suffer from problems with optimizing size of the bed and their impact absorption capacity, and from difficulty in servicing the resilient impact bars. 
         [0012]    Known dynamic impact beds differ from static beds by the provision of torsion bias units, such as Rosta mounts, between the cross members and the upper impact cradles of the beds. In one known dynamic impact bed, the Rosta mounts are secured on elevated platforms extending up from the cross member and connected to outer ends of the support members thereover. In another known dynamic impact bed, a pair of Rosta mounts are linked together, with the lower unit secured to the cross member and the upper unit secured to the impact cradle. In both instances, the profile of the dynamic impact bed above the cross members is undesirably increased due to the location of the Rosta mounts under the belt and over the cross members. In this regard, the impact cradles typically need to have a very low profile and thus utilize low profile impact plates that engage under the belt instead of the thicker, resilient impact bars used with static impact beds. 
       SUMMARY OF THE INVENTION 
       [0013]    In accordance with one aspect of the invention, an impact bed assembly is provided that provides simpler and easier replacement of impact bars connected to the support members of the impact bed assembly. In this regard, the impact bed assembly has a slide interface between a cross member and a support member for allowing the support member, with impact bars mounted thereon, to translate along the cross member from an operative position under the belt to a predetermined service position on the cross member at which the impact bars can readily be serviced. In the predetermined service position, the support member and impact bars thereon are still securely supported on the cross member thus allowing an operator to replace the impact bars by only sliding the support member out from under the belt to the predetermined service position. In this manner, the securely supported support member on the cross member when in the service position permits safe and easy changing of the impact bars without the need for employing heavy equipment to support or lift the support member for servicing of the impact bars thereon. Accordingly, the slide interface and predetermined service position provided for the present impact bed assembly allows for easier and faster servicing of the impact bars in terms of shifting of the support member in a direction out from under the belt, replacement of the impact bars connected thereto, and shifting of the support member back to its operative position. 
         [0014]    Preferably, there are multiple support members that are spaced in the longitudinal, belt travel direction and which have the impact bars extending transversely thereacross and rigidly secured thereon to form one of two identical side impact bed subassemblies that are slid on corresponding cross members from either side of the belt. The support members and impact bars are configured to remain securely upright on the cross members when in the predetermined service position. In particular, when in the predetermined service position the center of mass of the combined mass of the interconnected support members and impact bars is located vertically above the cross members laterally inward from the outer ends thereof so that the support members and resilient bars are securely balanced on the cross members and will not tip over the ends of the cross members. 
         [0015]    The predetermined service position can be defined by stops between the cross members and abutment portions of the support members so that when stop members are engaged with the abutment portions, the side impact bed subassemblies are in their predetermined service positions. Further, once in the above-described predetermined service position, the subassemblies can be shifted slightly back toward their operative positions so that the stop members and abutment portions are slightly spaced from each other with apertures of the support members and cross members aligned to allow the subassemblies to be positively secured or fixed to the cross members as by bolting to resist any shifting of the support members while the impact bars are being replaced in a preferred predetermined service position of the subassemblies. Manifestly, the apertures also may be arranged in the support members and cross members so that they are aligned with the stop members and abutment portions engaged. 
         [0016]    In another aspect, an impact bed assembly is provided for a troughed belt and has support members that can be slid on underlying cross members to an operative position under the belt via an outer slide interface between the support members and the cross members. However, rather than having to reach or climb under the belt to bolt inner portions of the support members to inner portions of the cross members in the operative position generally under a lowered, central area of the troughed belt so that the greater impact loads received thereat are transferred from the impact bars secured to the support members to the cross members bolted thereto, the present impact bed assembly has automatically operable inner load bearing mechanisms. The inner load bearing mechanism is automatically operable to transfer loading once the support members are slid to their operative positions without the need for bolting thereof to the cross members. This makes the installation of the support members and impact bars easier and faster than the prior bolted support members and cross members. 
         [0017]    In another aspect, an impact bed assembly is provided that provides additional capacity for impact absorption without increasing the height of the impact bed assembly. In this regard, the impact bed assembly includes resilient impact bars each having an elongate resilient body and a backing plate connected under the resilient body with the backing plate having depending legs extending away from the resilient body and being configured to be mounted on rigid mounting pads spaced along the support members. In this manner, the depending legs of the backing plate do not restrict the compression of the resilient body as impact forces are absorbed thereby so as to maximize the impact absorption capacity of the resilient impact bars. Further, the spacing of the pads along the support members and gaps provided therebetween into which the depending legs are fit minimize the height of the impact bed assembly. 
         [0018]    In another aspect of the invention, a dynamic impact bed assembly is provided that has increased impact absorption capacity over prior dynamic impact bed assemblies without requiring an increase in profile thereof and thus more space therefor under the belt. In prior dynamic bed assemblies, a cross member is rigidly connected to the conveyor frame structure and has a support member for an impact cradle resiliently mounted thereto so that the cross member generally provides a floor that limits the potential downward movement of the support members upon the application of impact forces thereto. Since the space between the conveyor frame members or stringers to which the cross member is secured is typically only approximately 8.5 to approximately 9.0 inches in vertical height, the vertical space for prior dynamic bed assemblies has been even further limited due to the fixed cross beams on the stringers. 
         [0019]    Instead of rigidly mounting the cross members to conveyor frame members, the cross members of the preferred dynamic bed assemblies herein are incorporated in a dynamic frame assembly that is mounted to the conveyor frame members via resilient mounts so that the entire dynamic frame assembly including the cross members shifts downwardly when impact forces are received thereby. In this manner, the movement of the dynamic frame assembly is only limited by the freedom provided by the resilient mounting mechanisms, as there are no structural members rigidly connected to the conveyor frame structure extending below the dynamic frame assembly to limit the downward movement thereof. This allows the preferred dynamic bed assemblies to utilize more of the space between the carry and return runs of the conveyor belt which includes not only the space between the upper belt run and the upper surface of the stringers, but also the height of the stringers themselves, e.g. approximately 6 inches to approximately 8 inches. 
         [0020]    In another aspect, the present dynamic impact bed assembly has bed frame members or support members that are resiliently mounted to the conveyor frame structure via outer resilient torsion mounts therebetween. The resilient torsion mounts are preferably located laterally beyond the support members. In this manner, when impact forces are taken by the dynamic impact bed assembly causing the support members to resilient shift downward, the outer resilient torsion mounts do not interfere with the range of resilient downward shifting that can be provided thereby. Accordingly, the range of travel for the dynamic impact bed assembly provided by the torsion mounts can be maximized. In addition, since space under the belt is not needed for the outer resilient torsion mounts, impact bars having relatively thick bodies of resilient material, e.g. approximately 3.0 to 4.5 inches thick, and preferably 3.5 to 4.5 inches thick, such as typically used in static impact bed assemblies, can be employed in the present dynamic impact bed assembly to further maximize the impact absorption capacity provided thereby. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a perspective view of an impact bed assembly showing the conveyor belt in phantom supported on impact bars extending thereunder with the impact bars secured to support members and the support members secured on cross members; 
           [0022]      FIG. 2  is an end elevational view of another, larger impact bed assembly having a greater number of impact bars for larger width belts and showing one of the cross members mounted to conveyor frame structure on either side of the conveyor belt; 
           [0023]      FIG. 3  is an enlarged elevational view of the impact bed assembly of  FIG. 2  showing in phantom depending fin projections of the support members in their operative positions on the cross-member with pins of the cross member engaged in notches of the fin projections; 
           [0024]      FIG. 4  is an elevational view similar to  FIG. 3  but showing the smaller impact assembly of  FIG. 1  with one of the support members slid to a predetermined service position on the cross member; 
           [0025]      FIG. 4A  is a perspective view of the impact bed assembly of  FIG. 4  showing a pair of identical side impact bed subassemblies each including multiple support members and impact bars secured thereon with one of the subassemblies slide to the predetermined service position with a securing fastener connecting one of the support members of the assembly to the cross beam thereunder; 
           [0026]      FIG. 5  is a perspective view showing a cross member having transverse, end mounting brackets for securing the cross member to conveyor frame side members with resilient pads therebetween; 
           [0027]      FIG. 5A  is a perspective view of the cross member of  FIG. 5  having the mounting brackets reversed when resilient pads are not used; 
           [0028]      FIG. 6  is an enlarged, perspective view of the mounting bracket configured as in  FIG. 5  showing raised side plate portions under which the resilient pads are fastened; 
           [0029]      FIG. 7  is a perspective view of the cross member; 
           [0030]      FIG. 8  is a side elevational view of the cross member; 
           [0031]      FIG. 9  is side elevational view of the support member showing a lowered central portion and an outer lateral portion having an inclined configuration up from the central portion; 
           [0032]      FIG. 10  is a perspective view of the support member of  FIG. 9  showing raised pad members spaced therealong; 
           [0033]      FIG. 11  is a perspective view of the underside of one the impact bars showing an elastomeric body, a hard covering including a tapered upstream end, a rigid insert, and a backing plate with depending legs with notches for receiving the pad members of the support members; 
           [0034]      FIG. 12  is an a fragmentary perspective view of one of the side impact bed subassemblies showing the resilient impact bars secured on the support member with the legs of the backing plates extending down into gaps between the spaced raised pads of the support member; 
           [0035]      FIG. 13  is a plan view of an anti-rotation washer for being disposed about a polygonal portion under heads of fasteners that secure the impact bar insert to the backing plate thereof with the washer fitting between and closely adjacent to upstanding side walls of the impact bar inserts; 
           [0036]      FIGS. 14A and 14B  are perspective views of a dynamic impact bed assembly having a dynamic mounting frame including rigidly connected cross members and support members, and torsion bias units for resiliently mounting the dynamic frame to the conveyor frame members; 
           [0037]      FIG. 14C  is an end elevational view of the dynamic impact bed assembly of  FIGS. 14A and 14B  showing the travel range of the dynamic impact bed assembly with the bottom of the cross members capable of traveling downward from just below the top of the stringer members of conveyor frame to approximately the center thereof; 
           [0038]      FIG. 15  is a perspective view of longitudinal beam members of the dynamic bed frame assembly including outbound mounting plates for pairs of linked torsion bias units to be mounted to the stringer members; 
           [0039]      FIG. 16  is an enlarged perspective view of one of the pairs of linked torsion bias units showing the units being vertically offset and interconnected by diagonal link members; 
           [0040]      FIG. 17  is a perspective view of a vibration mounting plate having the resilient pads secured thereto; and 
           [0041]      FIG. 18  is a perspective view of another support member having a single mounting plate with fastener receiving lugs for mounting the resilient impact bars thereto. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    In  FIGS. 1-3 , static impact bed assemblies  2  are shown used for a conveyor belt  6  having a troughed configuration as provided by belt supports mounted to conveyor frame structure  4 , such as idler rollers, that can be located both upstream and downstream along the longitudinal, belt travel direction  13  from the impact bed assembly  2 . To accommodate the troughed configuration, the static impact bed assembly  2  includes a pair of identical side impact bed subassemblies  20 ,  22  supported on cross beam members  100  under the conveyor belt  6  in the area where items are typically dropped thereon. The impact bed assembly  2  is operable to absorb the impact forces so as to avoid damage to the conveyor belt  6  in the impact receiving area thereof. For this purpose, the side bed subassemblies  20 ,  22  each includes support members  200  on which resilient impact bars  300  are mounted. Although troughed belt configurations are far more common, it is conceivable that with untroughed belts only a single subassembly  20  would need to be used and it would not need outer inclined portions thereof as described hereinafter for the pair of bed subassemblies  20 ,  22 . 
         [0043]    The number and transverse spacing of the impact bars  300  as well as the sizing of the support members  200  and cross members  100  can vary as the width of the belt  6  varies.  FIG. 1  illustrates a smaller impact bed assembly  2  for smaller width belts  6 , e.g. 24 inch and 30 inch wide belts, with each subassembly  20 , 22  having three impact bars  300 , while  FIGS. 2-4  illustrate a larger impact bed assembly  2  for larger width belts  6  with each subassembly  20 , 22  having five impact bars  300 . It is contemplated that subassemblies  20 , 22  could carry up to seven impact bars  300  for very wide belts e.g. seventy-two inches in width. Also, for certain applications it may be desirable to have one of the subassemblies  20 , 22  carry more impact bars  300  then the other subassembly  20 , 22 . 
         [0044]    As seen best in  FIG. 9 , the support members  200  of the side bed subassemblies  20 ,  22  each include a generally lowered central portion  210  configured to be positioned below the central trough portion  6   a  of the belt  6  and a raised and inclined outer lateral portion  230  under inclined side portions  6   b  of the belt  6  configured to generally maintain the troughed configuration of the conveyor belt  6  as the conveyor belt  6  has impact forces applied thereto. Both the lowered central and raised outer lateral portions  210 ,  230  include impact bars  300  mounted thereon, as will be discussed further hereinafter. 
         [0045]    To service and maintain the impact bed assembly  2  the support members  200  of the side impact bed subassemblies  20 ,  22  each are mounted on corresponding underlying cross members  100  via a slide interface  12  therebetween. The slide interface  12  allows an operator to slide the subassemblies  20 ,  22  from one side of the belt  6  in a lateral direction  11  generally orthogonal to the longitudinal, belt travel direction  13 . 
         [0046]    As shown in  FIGS. 4 and 4A , the slide interface  12  is preferably formed between upper surfaces  111  of the cross members  100  and wing portions  280  extending laterally from either side of the support members  200  at the lower end of the outer portions  230  thereof so that the lower surfaces  281  of the lateral wing portions  280  can slide along the upper surfaces  111  of the cross members  100 . The lower surfaces  281  of the lateral wing portions  280  preferably include a low friction coating, such as of a low friction plastic material, to reduce friction between the lower surfaces  281  of the lateral wing portions  280  and the upper surfaces  111  of the cross members  100  and to ease translation of the subassemblies  20 ,  22  along the cross member  100  between the operative and service positions thereof. 
         [0047]    Guide structure  60  is provided between the support members  200  and cross members  100  to guide the support members  200  along the upper surface  111  of the cross members  100 . As shown, the guide structure  60  includes guide channels  128  extending centrally along the cross members  100 , and depending fin portions  282  of the support members  100  received in the guide channels  128 . The depending fin portions  282  extend generally from forward operative abutment portions  209  located under the lower central portions  210  of the support members  200  to rearward service abutment portions  131  located at a predetermined lengthwise position below the raised outer portions  230  of the support members  200 . 
         [0048]    As best seen in  FIGS. 5 and 7 , the cross members  100  can each include a pair of adjacent channel members  700  that are connected so that their web walls  702  are spaced from each other to form the guide channel  128  therebetween. The channel members  700  have a generally C-shape cross sectional configuration so that upper and lower flanges  704  and  706  extend orthogonal to the web wall  702  thereof. The upper flanges  704  are level with each other and together form the upper surface  111  of each of the cross members  100  with each wing portion  280  of the support members  200  riding on the underlying upper flange member  704 . To provide additional strength, the channel members  700  of the cross members  100  include rib portions  124  extending between the upper and lower flanges  704 ,  706  and rib portions  126  extending from the service stop members  130  to the upper flange  104 . 
         [0049]    The side impact bed subassemblies  20 ,  22  are configured to be translated along the cross members  100  between a predetermined operative position  8  and a predetermined service position  10 . The predetermined service position  10  is located so that with the subassemblies  20 ,  22  slid from their operative positions  8  to their predetermined service positions  10 , the center of mass  24  of the subassemblies  20 ,  22  will be located laterally inward from the outer ends  150 ,  152  of the cross members  100 , as shown in  FIG. 4 . As a result, the subassemblies  20 ,  22  are securely balanced on the cross members  100  when shifted to their predetermined service positions. To keep an operator from shifting the subassemblies  20 ,  22  too far laterally outward, a stop  800  is formed between the cross members  100  and support members  200 , as shown in  FIG. 4 . Each cross member  100  includes a pair of stop members  130 , one at either end  150 ,  152  of the cross member  100 , and the support members  200  include the service abutment portions  131  at the rear of the depending fin projections  282  of the support members  200 . The service abutment portions  131  and service stop members  130  are arranged so that they will engage with one another with the subassemblies  20 , 22  slid laterally outward beyond their predetermined service positions but before the subassemblies  20 ,  22  reach a point where their center of mass  24  is positioned beyond the ends  150 ,  152  of the cross member  100 . In this regard, the impact bars  300  can be serviced with the stop members  130  engaged with the abutment portions  131  to form a predetermined service position thereat. 
         [0050]    In the more laterally inward predetermined service position, the subassemblies  20 ,  22  preferably are positively secured to the cross members  100 , such as by bolting. As shown in  FIGS. 4 ,  4 A and  5 , in the predetermined service position  10  notch openings  284  of the depending fin projections  282  correspond to and are aligned with web throughbores  134  of the cross members  100 . In addition, inner wing throughbores  290  of the wing portions  280  of the support members  200  correspond to and are aligned with upper surface throughbores  121  ( FIG. 7 ) of the cross members  100 . As shown, the notches  284  are aligned with the web throughbores  134  and the inner wing throughbores  290  are aligned with the upper surface throughbores  121  when the abutment portions  131  of the depending fin projections  282  are slightly spaced from the stop members  130  of the cross members  100 . 
         [0051]    In the predetermined service position  10 , impact bars  300  will be vertically spaced from the conveyor belt  6  to provide an operator access to the impact bars  300  so that they can remove and replace the impact bars  300  without adjusting the conveyor belt  6 . In particular, the laterally outermost impact bars  300  will be pulled out from under the belt  6  while the inner impact bars  300  will be pulled out from under the central lower belt portion  6   a  to be under the inclined belt portion  6   b . The impact bars  300  mounted on the raised outer lateral portions  230  of the support members  200  are shifted out from under the conveyor belt  6  to permit an operator to remove and replace these impact bars  300 . Further, at least one impact bar  300  mounted on the raised outer lateral portions  230  is positioned vertically above the cross members  100 . The impact bars  300  mounted on the lowered central portions  210  of the support members  200  are positioned above the cross members  100  and generally under the inclined portion of  6   b  of the conveyor belt  6 , as shown in  FIG. 4 . Generally, as shown in  FIG. 4 , the conveyor belt  6  will maintain a trough configuration after the subassemblies  20 ,  22  are translated toward the predetermined service position  10 . As a result, a vertical spacing separates the conveyor belt  6  and the upper surfaces  301  of the impact bars  300  mounted on the lowered central portions  210  that is larger than the vertical spacing when the bars  300  are in their operative position, permitting an operator to remove and replace the impact bars  300  without having to adjust the conveyor belt  6 . 
         [0052]    The subassemblies  20 ,  22  are further configured to be secured to the cross members  100  in the operative position  8  so as to transfer impact forces applied to the impact bars  300  mounted on the subassemblies  20 ,  22  to the cross members  100 . In particular, the subassemblies  20 ,  22  are automatically secured to the cross members  100  via automatically operable load bearing mechanisms  133  when they are slid to their operative positions. The automatically operable load bearing mechanisms  133  are positioned adjacent the centers  112  of the cross members  100  so that an operator need not reach under the lowered center  6   a  of the belt  6  to secure the subassemblies  20 ,  22  in the operable position  8 . As is apparent, the lowered central area  6   a  of the belt receives the greatest impact loading applied to the conveyor belt  6 . Thus, the load bearing mechanisms  133  are positioned to transfer a high level of the impact loading from the impact bars  300  mounted on the support members  200  to the cross members  100  therebelow. 
         [0053]    As previously discussed, the support members  200  include lateral wing portions  280  which ride on the upper surfaces  111  of the cross members  100 . Accordingly, the wing positions  280  also transfer impact loading received by the impact bars  300  to the cross members  100 . However, since the wing portions  280  are at the laterally outer inclined portions  230  of the support members  200 , laterally inner load bearing mechanisms such as the automatically operable load bearing mechanisms  133  herein are desirable where the impact loading is greatest on the impact bed assembly  2 . Further, the illustrated wing portion  280  are formed as lower leg portions  280  of right angle members  900  that have upright leg portions  902  welded to vertical plate portions  271  of the support members  200 . Accordingly, the laterally inner load bearing mechanisms  133  ensure most of the impact loading is transferred to the cross members  100  and then to the conveyor frame stringer members  4  thereby rather than being transferred at the welds between right angle members  900  and the support member  200 . 
         [0054]    As shown in  FIGS. 3 ,  4  and  8 , the automatically operable load bearing mechanisms  133  include pins  135  extending across the guide channel  128  of the cross members  100  and the forward notch openings  284  of the abutment portions  209  of the depending fin projections  282  configured to receive the pins  135  therein. The notch opening  284  is tapered for smoothly receiving the pin  135  therein as the subassemblies  20 , 22  are slid to their operative positions so that there is an overhang portion  140  that engages and extends over the pin  135 . The tapered notch opening  284  is configured to orient the subassemblies  20 ,  22  so that the pins  135  engage and bottom out in the notch opening  284  and are fully received therein thereby limiting the laterally inward translation of the subassemblies  20 ,  22 . The overhang portions  140  engage on the pins  135  and transfer impact forces applied to the subassemblies  20 ,  22  to the cross members  100 . 
         [0055]    In their operative positions, the subassemblies  20 ,  22  are positively secured to the cross members  100 , such as by bolting. In particular, the lateral wing portions  280  of the subassemblies  20 ,  22  each include an outer lateral throughbore  291  that will be aligned with throughbores  121  of the cross members  100  to accept a bolt  292  extending therethrough. In the operative position, the support members  200  of the subassemblies  20 ,  22  are further secured to the cross members  100  via outer fin throughbores  286  of each of the support members  200  aligned with the web throughbores  134  of the cross members  100 . 
         [0056]    The cross members  100  are configured to be secured to the belt frame structure in the form of the side stringer members  4  extending parallel to the conveyor belt  6  along each side thereof for transferring the loading transferred to the cross members  100  to the belt frame stringers  4 . The cross members  100  include end mounting brackets  120  at either end  150 ,  152  of the cross members  100  for mounting the cross members  100  to the stringers  4 . Preferably, the mounting brackets  120  include a central, lower portion  120   a  that extends across the guide channel  128  to form the stop member  130 . The channel members  700  each include end cut-outs in their web walls  702  to form end raised portions  710  with the bracket central portion  120   a  spanning and interconnecting the adjacent raised portions  710 , as seen best in  FIG. 6 . In this manner, with the brackets  120  secured to the stringers  4 , the main, central portion  712  of the channel members  700  will extend down from the end raised portions  710  so that the cross members  100  are hung from the stringer members  4  to extend below the upper surfaces thereof to keep the profile of the static impact bed assembly  2  to a minimum. 
         [0057]    The mounting brackets also preferably include a pair of upwardly extending steps  122  so that there are raised side plate portions  120   b  on either side of the lowered central portion  120   a  to permit resilient pads  12   a  mounted to the vibration mounting plate  121  ( FIG. 17 ) to be fastened between the mounting brackets  120  and the stringers  4  without increasing the height of the impact bed assembly  2 . The resilient pads  12   a  absorb impact forces transferred to the cross members  100  from the subassemblies  20 ,  22  to reduce wear and damage to the conveyor belt  6  upon the application of impact forces thereto. 
         [0058]    The impact bars  300  are configured to absorb the impact forces applied thereon to minimize any damage to the conveyor belt  6 . The impact bars  300  are mounted to the support members  200  to extend in the travel direction  13  of the conveyor belt  6 . The impact bars  300  include an elastomeric body  302  extending the length of the impact bars  300  and include a metal insert  340  therein, as shown in  FIGS. 11 and 12 . The metal insert  340  includes an upper wall  348 , sidewalls  350  and spaced lower flanges  344  defining a longitudinal slot  345  extending the length of the impact bars  300 . 
         [0059]    The impact bars  300  include backing plates  360  for securing the elastomeric bodies  302  to the support members  200  of the subassemblies  20 ,  22  and maximize the impact absorption thereof. The backing plates  360  extend along the lower surface  308  of the elastomeric bodies  302 . The backing plates  360  include a series of apertures  361  extending therethrough aligned with the slot  345  of the metal insert  340  for securing the impact members  300  to the support members  200 , as will be described more fully hereinafter. 
         [0060]    The backing plates  360  preferably include an upstanding tab  362  extending from a downstream end  363  of the backing plates  360  and generally orthogonal to the length of the impact bars  300 . The upstanding tabs  362  engage downstream ends of the elastomeric bodies  302  to resist migration of the elastomeric bodies  302  as the conveyor belt  6  travels therealong. 
         [0061]    As shown in  FIGS. 11 and 12 , the impact bars  300  further include connection mechanisms  316  to mount the elastomeric bodies  302  to the backing plates  360  and the support members  200  of the subassemblies  20 ,  22 . In particular, the connection mechanisms  316  are a bolt  312  having a head portion  314 , a polygonal shank portion (not shown) and a threaded shank portion  318 . The head portion  314  is configured to be received in the space defined by the upper wall  348 , sidewalls  350  and spaced lower flanges  344  of the metal insert  340 . Further, the polygonal shank portion is configured to be received closely between the spaced lower flanges  344  so as to resist rotation of the bolt  312 . The threaded shank portion  318 , which extends from the shank portion, extends through the apertures  361  of the backing plates  360 . Further, each securing mechanism  316  includes an anti-rotation member  324 , such as a washer, having straight inner edges  328  configured to receive the polygonal shank portion therein and a flat outer edge  326  configured to engage the sidewalls  350  of the metal insert  340  to resist rotation of the bolt  312  during conveyor belt operations. 
         [0062]    As best seen in  FIG. 11 , the backing plates  360  preferably have a generally inverted U-shaped configuration including depending legs  364  extending generally orthogonally to the length of the backing plates  360  and away from the elastomeric bodies  302 . The legs  364  do not extend up alongside the elastomeric bodies  302  so as to not restrict the compression of the elastomeric bodies upon the application of impact forces thereto. Further, by not positioning the legs  364  adjacent the elastomeric body  302  debris and other particulate will not settle therebetween. 
         [0063]    As previously discussed, the support members  200  of the subassemblies  20 ,  22  have the impact bars  300  mounted thereon. As shown in  FIGS. 9 and 10 , the support members  200  preferably include vertical plate portions  271  having upper edges  216 ,  232  of the lowered central and raised outer lateral portions  210 ,  230  with mounting pads  270  extending generally normal to the vertical plate portions  271  and parallel to the direction of travel  13  of the conveyor belt  6 . The mounting pads  270  each extend longitudinally along a longitudinal axis  273  and have a fastener receiving slot  272  formed by spaced lugs  272   a  on either side thereof with both the pads  270  and slots  272  extending parallel to the direction of travel of the conveyor belt  13 . The lugs  272   a  and slots  272  formed thereby are configured to extend from the upstream ends  138  of the mounting pads  272  and receive a bolt  312  therein. 
         [0064]    In addition, the mounting pads  272  are spaced from each other to receive the depending legs  364  of the backing plates  360  therebetween. As shown in  FIG. 11 , the depending legs  364  of the backing plate  360  preferably include notches  366  therein configured to guide the impact bars  300  onto the mounting pads  270 . Further, the notches or cut-outs  366  are configured to extend beyond the adjacent upper surfaces  216 ,  232  of the support members  200 . 
         [0065]    The impact bars  300  are further configured so as to minimize wear and damage to the conveyor belt  6  as the belt  6  travels thereacross in the operable orientation  8 . Preferably the impact bars  300  include a relatively thin, wear resistant plastic covering  304  atop the elastomeric body  302  and configured to be engaged by the conveyor belt  6 . Further, the plastic covering  304  includes a tapered upstream end  306  configured to urge the conveyor belt  6  upward as the conveyor belt  6  travels thereacross. 
         [0066]    Further, the impact bars  300  are configured to ease translation of the subassemblies  20 ,  22  toward a position under the belt  6 . As shown in  FIGS. 2 and 9 , the impact bars  300  are mounted at an angle relative to the upper surface  111  of the cross member  100  to urge the conveyor belt  6  upwardly upon translation of the subassemblies  20 ,  22  toward the center  112  of the cross members  100 . In particular, the upper surfaces  232  of the support members  200  are configured to define an angle A. Additionally, upper edge surfaces  216  of the lower central portions  210  are configured to mount the impact bars  300  thereon at an angle B less than the angle A defined by the raised upper portion  230 , e.g. such as 3 degrees off the upper surfaces  111  of the cross members  100 . 
         [0067]    In another aspect of the invention, a dynamic impact bed assembly  400  is provided to transfer impact loading applied to the conveyor belt  6  to the stringer members  4 . The dynamic impact bed assembly  400  includes a dynamic frame assembly  401  which has structural components configured to extend below the belt  6  and be resiliently mounted on either side of the belt  6  to the conveyor frame stringer members  4 . The dynamic frame assembly  401  is resiliently mounted to the conveyor frame stringer members  4  so that the entire dynamic frame assembly  401  shifts as a single unit as impact forces are applied to the conveyor belt  6  thereabove. 
         [0068]    Accordingly, the dynamic frame assembly  401  herein forms an integrated bed. As illustrated in  FIGS. 14A-14C  and  15 , the dynamic frame assembly  401  preferably includes longitudinal members  402  extending parallel to the direction of travel  13  of the conveyor belt  6  and cross stabilization beams  404  rigidly connected to the ends  450  of the longitudinal members  402  extending below and transverse to the direction of travel  13  of the conveyor belt  6 . The longitudinal members  402  preferably each include a tab mount  458  at each end  450  thereof to which the stabilization beams  404  are secured. 
         [0069]    As shown in  FIGS. 14A-14C , the dynamic frame assembly  401  further includes cross members  100  and support members  200  rigidly connected together to form a rigid support grid for the impact bars  300 , which are preferably substantially of the same construction as the corresponding components of the static bed assemblies  2  so as to be interchangeable therewith. The cross members  100  are configured to be mounted on the lower flange  452  of the longitudinal members  402 , with the ends  150 ,  152  of the cross members  100  positioned adjacent the web  454  of the longitudinal members  402  and below upper flange  456  of the longitudinal members. 
         [0070]    The dynamic frame assembly  401  further includes outboard mounting plates  413  of the longitudinal members  402  configured to extend transversely outward from the longitudinal members  402  and above the conveyor frame stringers  4 . The outboard mounting plates  413  are connected to a resilient mount assembly  408 , which is further connected onto the conveyor frame stringers  4 . As a result, as shown in  FIGS. 14A-14C , the resilient mount assemblies  408  are positioned above the conveyor frame stringers  4  at a height that is generally aligned with the cross members  100 . 
         [0071]    The resilient mount assemblies  408 , as shown, preferably include offset upper torsion bias units  420  and lower torsion bias units  430  interconnected by diagonal torsion links  409 . The resilient mount assemblies  408  are configured such that, upon the application of an impact force to the dynamic frame assembly  401 , the upper torsion bias units  420 , which are connected to and under the outboard mounting plate  413  of the longitudinal member  402 , are urged downward toward but offset from the lower torsion bias units  430 . As a result, the entire dynamic frame assembly  401  travels downward between the conveyor frame stringers  4  and thereby absorbs impact forces applied to the conveyor belt  6 . 
         [0072]    The torsion bias units  430  are preferably standard Rosta units that include an outer housing  432  in which rubber or resilient material  434  is provided at the corners for urging a central bar connected to the link members  409  back to the rest position when the bar is turned in the housing  432  due to impact forces applied to the dynamic frame assembly  400 . 
         [0073]    The bottoms of cross members  100  can travel from just below the upper surface  5  of the conveyor frame stringers  4  in the absence of impact loading to a maximum travel distance when high impact loads are received that is at approximately the center of the vertical height of the stringer members  4 , as shown in  FIG. 14C . Preferably, the maximum travel distance of the dynamic bed assembly  400  is at least approximately 0.875 inches. In cooperation with the impact bars  300 , the elastomeric bodies of which provide approximately 0.625 inches of compression travel distance, the conveyor belt  6  is allowed a travel distance of at least 1.5 inches. 
         [0074]    In a further preferred embodiment, the maximum deceleration distance travel is about 2.5 inches. While a larger deceleration distance is possible, the benefits of the increased deceleration distance are marginal after 2.5 inches. In addition, the increased distance contributes to stretching of the belt  6 , thereby increasing the likelihood of damage. Additionally, given the space constraints created by the stringer members  4 , and the belt  6 , in particular the return section of the belt  6 , and any other rigid obstructions a maximum distance of 2.5 inches is preferred. 
         [0075]    To ensure a proper trough configuration, the dynamic bed assembly  400  includes rigid lateral support assemblies  410  mounted along each side of the belt  6  on the conveyor frame structure  4 . The rigid lateral support assemblies  410  include at least impact bar  300  mounted thereon and cooperate with the dynamic frame assembly  401  to define the trough configuration with the impact bars  300  mounted on the dynamic frame assembly  401 . 
         [0076]    Preferably, the dynamic impact bed  400  includes a plurality of resilient mount assemblies  408  along each longitudinal member  402 . As illustrated, the number of resilient mounts  408  connected to each longitudinal member  402  is less than the number of ends  150 ,  152  of the cross members  100  mounted to the longitudinal member  402 . Preferably, the resilient mounts  408  are positioned between the ends  150 ,  152  of adjacent cross members  100 . 
         [0077]    While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled in the art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention.