Drop-Arm Barrier

Abstract

A drop-arm barrier features an elongate arm supported on a shaft. The shaft and the arm rotate as a unit. At its opposite ends, the shaft is supported at an elevated position by a pair of vertical and hollow columns. A bearing within each column supports the shaft. Also received within the column are a plurality of shear-resistant structures. These structures help to dissipate shear energy that might be transmitted to the shaft as a result of a vehicular collision with the arm. The shear-resistant structures include first and second shear plates, which are threaded onto the shaft, and a shear pin, which extends orthogonally through the shaft.

1 . A kit, comprising: 
 an elongate arm;   a shaft extendable through the arm in orthogonal relationship thereto, the shaft being rotatable with the arm as a unit;   a column from which the shaft is supportable, the column having an internal chamber through which a portion of the shaft is extendable; and   at least one shear-resistant structure positionable within the internal chamber in shear-receiving relationship to the shaft.   
     
     
         2 . A barrier, comprising: 
 the kit of  claim 1  in which: 
 the shaft extends through the arm in orthogonal relationship thereto; 
 the column supports the shaft; and 
 the at least one shear-resistant structure is positioned within the internal chamber in shear-receiving relationship to the shaft. 
   
     
     
         3 . The barrier of  claim 2  in which the column is supported by a footing embedded within a terrain. 
     
     
         4 . The kit of  claim 1  in which the at least one shear-resistant structure comprises: 
 a solid shear pin extendable through the shaft in orthogonal relationship thereto. 
 
     
     
         5 . A barrier, comprising: 
 the kit of  claim 4  in which: 
 the shaft extends through the arm in orthogonal relationship thereto; 
 the column supports the shaft; and 
 the shear pin is positioned within the internal chamber in shear-receiving relationship to the shaft; and 
 the shear pin extends through the shaft in orthogonal relationship thereto. 
   
     
     
         6 . The kit of  claim 1  in which the at least one shear-resistant structure comprises: 
 a solid shear plate through which the shaft is extendable. 
 
     
     
         7 . A barrier, comprising: 
 the kit of  claim 6  in which: 
 the shaft extends through the arm, in orthogonal relationship thereto, and through the shear plate; 
 the column supports the shaft; 
 the shear plate is positioned within the internal chamber in shear-receiving relationship to the shaft. 
   
     
     
         8 . The kit of  claim 1  in which the column comprises a wall that bounds an internal chamber, and further comprising: 
       
         a bearing positionable within the internal chamber in supported relationship to the column and supporting relationship to the shaft; 
         and in which the at least one shear-resistant structure comprises: 
 a solid first shear plate through which the shaft is extendable. 
 
       
     
     
         9 . A barrier, comprising: 
 the kit of  claim 8  in which: 
 the shaft extends through the arm, in orthogonal relationship thereto, and through the first shear plate; 
 the column supports the shaft; 
 the first shear plate is positioned within the internal chamber in shear-receiving relationship to the shaft; and 
 the first shear plate is interposed between the bearing and the wall. 
   
     
     
         10 . The kit of  claim 8  in which the at least one shear-resistant structure further comprises: 
 a solid second shear plate through which the shaft is extendable. 
 
     
     
         11 . A barrier, comprising: 
 the kit of  claim 10  in which: 
 the shaft extends through the arm, in orthogonal relationship thereto, and through the first and second shear plates; 
 the column supports the shaft; 
 the first and second shear plates are positioned within the internal chamber in shear-receiving relationship to the shaft; 
 the first shear plate is interposed between the bearing and the wall; and  
 the second shear plate is situated on the opposite side of the bearing from the first shear plate. 
   
     
     
         12 . The kit of  claim 2  in which the at least one shear-resistant structure further comprises: 
 a solid shear plate through which the shaft is extendable. 
 
     
     
         13 . A barrier, comprising: 
 the kit of  claim 12  in which: 
 the shaft extends through the arm, in orthogonal relationship thereto, and through the shear plate; 
 the column supports the shaft; 
 the shear pin and the shear plate are positioned within the internal chamber in shear-receiving relationship to the shaft; and 
 the shear pin extends through the shaft in orthogonal relationship thereto. 
   
     
     
         14 . The kit of  claim 2  in which the column comprises a wall that bounds an internal chamber, and further comprising: 
       
         a bearing positionable within the internal chamber in supported relationship to the column and supporting relationship to the shaft; 
         and in which the at least one shear-resistant structure further comprises: 
 a solid first shear plate through which the shaft is extendable. 
 
       
     
     
         15 . A barrier, comprising: 
 the kit of  claim 14  in which: 
 the shaft extends through the arm, in orthogonal relationship thereto, and through the first shear plate; 
 the column supports the shaft; 
 the shear pin and the first shear plate are positioned within the internal chamber in shear-receiving relationship to the shaft;  
 the shear pin extends through the shaft in orthogonal relationship thereto; and  
 the first shear plate is interposed between the bearing and the wall. 
   
     
     
         16 . The kit of  claim 14  in which the at least one shear-resistant structure further comprises: 
       
         a solid second shear plate through which the shaft is extendable. 
       
     
     
         17 . A barrier, comprising: 
 the kit of  claim 16  in which: 
 the shaft extends through the arm, in orthogonal relationship thereto, and through the first and second shear plates; 
 the column supports the shaft; 
 the shear pin and the first and second shear plates are positioned within the internal chamber in shear-receiving relationship to the shaft;  
 the shear pin extends through the shaft in orthogonal relationship thereto; 
 the first shear plate is interposed between the bearing and the wall; and  
 the second shear plate is situated on the opposite side of the bearing from the first shear plate. 
   
     
     
         18 . The barrier of  claim 17 in which the column is supported by a footing embedded within a terrain.