Abstract:
The present invention relates to a roof adapted to cover a manure storage tank. The roof comprises a plurality of trusses and sheeting members. The roof is constructed so as to minimize the lateral forces on the manure storage tank and to eliminate vertical forces on the centre point of the floor of the storage tank.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     A number of covers for manure storage tanks are known in the art. A number of these are inflatable covers which do not provide for ventilation of the storage tank. Access to the manure storage tank for emptying of the storage tank, for example, is difficult. Furthermore, the life span of inflatable cover members is limited. Such covers also need to be secured to the storage tank. These are often secured to the tank in such a fashion that forces on the cover are transmitted laterally to the tank which could lead to cracking of the said tank.  
         [0002]     Other non-inflatable domes have a very complex structure. By way of example, Canadian patent application 2,220,382 provides a ventilated flexible dome. The dome includes a circular base, a rigid ridge pole, support cables connecting the base to the ridge pole, a cover and a flexible membrane arranged on the support cables, a ventilation cone with a rigid ridge pole. The construction of such a dome cover is complex and a cable arrangement is necessary to support the structure. Furthermore, the cover attaches to the outside of the storage tank and, as such, any pressure applied to the cover would create lateral forces on the storage tank which increases the risk of cracking of the storage tank.  
         [0003]     The roof of the present invention has a structure which affords it flexibility to withstand the forces applied thereon. Furthermore, the structure of the roof is such as to minimize lateral forces applied to the storage tank thus minimizing the risk of cracking thereof. It is important to minimize the risk of cracking of the manure storage tank which could result environmental damage and in costly clean-up operations.  
       BRIEF SUMMARY OF THE INVENTION  
       [0004]     The invention relates to a roof for a generally cylindrical wall structure. The roof has a frusto-conical configuration and comprises a central, tubular hub and a plurality of trusses extending radially outwardly therefrom. Each of said trusses has a proximal end and a distal end. The proximal ends of the trusses are connected to the central, tubular hub. The trusses comprise parallel upper and lower beams spaced apart and secured together by generally V-shaped chord members and intermittent vertical connecting members extending normally to said upper and lower beams. A plurality of support beams extend between adjacent trusses. The trusses and the support beams form the upper surface of the roof. A covering for the roof comprises sheeting members which are secured to the upper surface of the roof. Plate members having low frictional surfaces are located intermediate a lower edge of the roof and an upper surface of the cylindrical wall structure covered by the roof. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0005]     The foregoing summary, as well as the following detailed description of preferred embodiments of the invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings embodiments which are presently preferred. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.  
         [0006]     In the drawings:  
         [0007]      FIG. 1  is a top view of the said roof;  
         [0008]      FIG. 2  is a vertical cross-section of the roof of the present invention;  
         [0009]      FIG. 3  is a perspective view of the roof of the present invention without the sheeting members;  
         [0010]      FIG. 4  is a perspective view of the roof of the present invention without the sheeting members and wherein the support beams have been secured to only one portion of the roof;  
         [0011]      FIG. 5  is an enlarged view of one the means for securing the roof to the cylindrical structure; and  
         [0012]      FIG. 6  is an enlarged view of the reinforcement member of the roof. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0013]     The roof  10  is adapted to cover manure storage tank  12  having a generally cylindrical wall structure. The roof  10  has a frusto-conical configuration. As illustrated in  FIG. 2 , it comprises a central, tubular hub  14 . The hub  14  comprises an upper ring  16  and a lower ring  18  spaced from one another by members  20  which are disposed perpendicularly to the rings  16  and  18 . The hub  14  can be made of steel.  
         [0014]     As seen in FIGS.  2  to  4 , the roof  10  also comprises a plurality of trusses  22  which extend radially outwardly therefrom. The trusses  22  are made of steel or of other suitable material having comparable strength characteristics. Each truss  22  has a proximal end  24  and a distal end  26 . The proximal end  24  of each truss  22  is connected to the hub  14 . The hub  14  serves to anchor all of the trusses  22  and allows for the roof to be constructed without a central support post. This avoids the disadvantages associated with a central support post, namely the transmission of vertical forces to the floor of the tank  12  and the associated risks of cracking of the tank  12  which could result therefrom. The hub  14  also allows for ventilation of the gases emanating from the storage tank  12 .  
         [0015]     Each truss  22  comprises parallel upper beams  28  and lower beams  30  spaced apart and secured together by V-shaped chord members  32  and intermittent vertical connecting members  34  which extend perpendicularly to the upper  28  and lower  30  beams. Support beams  36  interconnect the upper beams  28  of the adjacent trusses  22 . The support beams  36  can be secured to the upper beams  28  of the trusses  22  by means of screws. The upper beams  28  of the trusses  22  and the support beams  36  form the upper surface  38  of the roof  10 .  
         [0016]     A post member  40  extends perpendicularly to the distal end  26  of each parallel upper beam  28  and lower beam  30 . In a preferred embodiment as illustrated, the post member  40  is an I-shaped beam. The post member  40  has an upper end  42  and a lower end  44 . The lower ends  44  of the post members  40  form the periphery  46  of the roof  10 .  
         [0017]     Sheeting panels  48  serve as a covering for the roof  10 . The sheeting panels  48  are preferably made of steel. They can also be made of any other suitable material such that the panels have sufficient strength and are impermeable, such as corrugated tar paper panels and the like. The sheeting panels  48  are secured to the upper surface  38  of the roof  10 . In a preferred embodiment, the sheeting panels  48  are secured by means of screws to the support beams  36 .  
         [0018]     Plate members  50  having low frictional surfaces are secured to the lower end  44  of the post members  40 . In a preferred embodiment, the plate member  50  is made of polyethylene such as UHMW polyethylene. The plate members  50  minimize the lateral forces which will be transmitted from the roof  10  to the manure storage tank  12 .  
         [0019]     As seen in  FIG. 5 , the lower ends  44  of the post members  40  are secured to the storage tank  12  by means of brackets  52  which will prevent the roof  10  from lifting off the storage tank  12 . The brackets  52  do not prevent the movement back and forth of the post members  40 .  
         [0020]     As seen in  FIG. 6 , a reinforcement belt  54  comprising a plurality of interconnected units  56  is secured about the outer surface of the post members  40 . The reinforcement belt  54  will prevent the post members  40  from being displaced off the surface of the storage tank  12  by the forces being exerted on the roof  10 , such as the weight of snow during the winter, which could result in the collapse of the roof  10 .  
         [0021]     In a preferred embodiment which is not illustrated, an access door can be constructed in the roof  10  by making an opening between two adjacent trusses  22  in one of said sheeting panel  48  and through the support beams  36  and securing a door in said opening. The door can be used to gain access to the storage tank  12  without having to remove the roof  10  from the tank  12 .  
         [0022]     In use, the roof  10  is placed on the manure storage tank  12 . It is secured to the storage tank  12  by means of the brackets  52 . The construction of the roof  10  is such that it can withstand forces applied thereon, such as the weight of snow during the winter time. The plate members  50  minimize the transmission of lateral forces from the roof  10  to the storage tank  12  which could possibly lead to the cracking of the tank  12 . The reinforcement belt  54  is secured about the outer surface of the post members  40  to prevent their displacement off the surface of the storage tank and the resulting collapse of the roof  10 .  
         [0023]     It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.