Coil car structure

Abstract

A railcar unit has a pair of deep sidewalls and a cradle mounted between the sidewalls for carrying coils. The sidewalls span the distance between the two railcar trucks, and act as a pair of deep beams for carrying vertical loads. The deep sidewalls are arranged to extend above and below the centre sill of the cradle and to give vertical stiffness to the car. The centre sill is a straight through sill for carrying buff and draft loads between the couplers. The cradle is made from a set of cross bearers welded to the centre sill to form a series of segmented beams, covered by plating. The cross bearers are welded to the sidewalls at lap joints. The cross bearers are all of the same design and can be made from a rolled beam. The sidewalls have their deepest section at mid-span, and are tapered to a thinner section toward the end structure of the cars. The tapering includes provision of an access way between the railcar truck wheels and the sidewall to permit brake maintenance.

I claim:  
     
         1 . A rail car for carrying metal coils, comprising: 
 a pair of end structures each mounted on a rail car truck;    a pair of side beams extending between said end structures;    a transverse cradle, for cradling metal coils, mounted between said side beams;    said cradle having a longitudinally extending low central portion;    the lowest point of said low central portion lying at a height that is at least as high as the lowest extremity of said side beams.    
     
     
         2 . A railcar as claimed in  claim 1  wherein said railcar has, at a transverse-section between said trucks, a second moment of area about a horizontal neutral axis, and said side beams contribute at least half of said second moment of area of said section.  
     
     
         3 . The rail car of  claim 2  wherein said side beams contribute at least three quarters of said second moment of area of said section.  
     
     
         4 . The railcar of  claim 3  wherein said side beams contribute at least 90% of said second moment of area.  
     
     
         5 . The rail car of  claim 1  wherein at a transverse section between said trucks the location of maximum longitudinal tensile stress under a gravity load is in the lowest chord of one of said side beams.  
     
     
         6 . The rail car of  claim 5  wherein at a transverse section between said trucks the location of maximum longitudinal compressive stress under a gravity load is in the highest chord of one of said side beams.  
     
     
         7 . The rail car of  claim 1  wherein said cradle has a center sill extending longitudinally along said low central portion.  
     
     
         8 . The rail car of  claim 7  wherein said central sill has a top flange and a bottom flange, said rail car has, at a transverse section between said trucks, a neutral axis for bending under gravity loads, and said neutral axis lies at a height that is between the height of said top and bottom flanges.  
     
     
         9 . The rail car of  claim 1  wherein said cradle includes cross-bearers connected to said side beams.  
     
     
         10 . The rail car of  claim 9  wherein in at least a medial portion of said rail car between said trucks, said cross bearers are of substantially uniform design.  
     
     
         11 . The rail car of  claim 10  wherein at least a medial portion of said rail car between said trucks is of the type chosen from the set of rail car types consisting of 
 (a) rail car portions that are free of cross-ties; and  
 (b) rail car portions in which the number of cross ties is fewer than two thirds as many as cross bearers.  
 
     
     
         12 . The rail car of  claim 1  wherein said rail car has a through centre sill of substantially constant cross-section.  
     
     
         13 . The rail car of  claim 12  wherein over at least the medial portion of rail car said cross-bearers are of substantially uniform design.  
     
     
         14 . The rail car of  claim 12  wherein at least the medial portion of said rail car is of a type chosen from the set consisting of 
 (a) types that are free of cross-ties; and  
 (b) types that have less than two-thirds as many cross-ties as cross-bearers.  
 
     
     
         15 . A rail car for carrying metal coils comprising: 
 a pair of end structures each mounted on a rail car truck;    a pair of side beams extending between said end structures;    a transverse sling, for cradling metal coils, slung between said side beams said rail car having a set of brakes;    at least one of said side beams having a relief permitting access to said brakes.    
     
     
         16 . The rail car of  claim 15  wherein said relief is located adjacent said truck.  
     
     
         17 . The rail car of  claim 15  wherein said one beam has a relief adjacent each of said trucks.  
     
     
         18 . The rail car of  claim 15  wherein both said beams have reliefs adjacent said trucks.