Energy absorbing system

Abstract

A heavy duty ground retractable automobile barrier for a railroad crossing. Concrete bunkers are placed at each side of a roadway. An upstanding concrete-filled steel pipe fixed in each bunker has a sleeve for rotational and axial movement. Shock absorbers are mounted on each sleeve. A net extends across the road and is attached to the opposite ends of the shock absorbers. Collision of an automobile with the net creates tensile forces in the net. The shock absorbers expand while rotating about the pipe's axis in response to tensile forces from the net that meet or exceed a minimum threshold. Forces from the net pass through the axis of the steel pipe. The net is stored in a pit transverse the roadway parallel to the railroad tracks and is raised and lowered as appropriate. The net includes a cable that extends across the road in a wave pattern, having peaks, valleys and midpoints, wherein tangents of the wave midpoints are at least 90 degrees from tangents of the peaks and valleys.

We claim:  
     
         1 . An energy absorbing system comprising: 
 a stanchion;    a bearing sleeve rotatable and vertically slidable on the stanchion;    a hydraulic shock absorber in its compressed state connected to the sleeve;    a threshold force securing mechanism connected to the shock absorber; and    a ground retractable restraining net connected to the shock absorber;    wherein the securing mechanism prevents expansion of the shock absorber until acted upon by tensile forces of at least a minimum threshold force;    wherein the minimum threshold force exceeds a static tensile force exerted by the restraining net in a quiescent state upon the shock absorber; and    wherein the minimum threshold force is less than dynamic tensile forces that the net would exert on the shock absorber when an automobile collides with the net at substantial speed.    
     
     
         2 . An energy absorbing system comprising: 
 a fixing means for fixing a vertical axis;    a shock absorbing means connected to the fixing means, for absorbing tensile forces while rotating around the vertical axis; and    a threshold force securing means connected to the shock absorbing means, for preventing expansion of the shock absorbing means until acted upon by tensile forces of at least a minimum threshold force.    
     
     
         3 . The energy absorbing system according to  claim 2 , wherein the shock absorbing means is linearly translatable in a direction parallel to the vertical axis.  
     
     
         4 . The energy absorbing system according to  claim 2 , wherein the shock absorbing means is expandable in a substantially orthogonal direction relative to the vertical axis.  
     
     
         5 . The energy absorbing system according to  claim 3 , wherein the shock absorbing means is expandable in a substantially orthogonal direction relative to the vertical axis.  
     
     
         6 . The energy absorbing system according to  claim 2 , wherein the shock absorbing means is connected to a rotating means for rotating about the fixing means.  
     
     
         7 . The energy absorbing system according to  claim 2 , wherein the shock absorbing means has a 50,000 pound resistance.  
     
     
         8 . The energy absorbing system according to  claim 7 , wherein the shock absorbing means has a twelve inch stroke.  
     
     
         9 . The energy absorbing system according to  claim 7 , wherein the shock absorbing means has an accumulator with a 5,000 pound return force.  
     
     
         10 . The energy absorbing system according to  claim 9 , wherein the shock absorbing means has a 20,000 pound resistance.  
     
     
         11 . The energy absorbing system according to  claim 10 , wherein the shock absorbing means has a four foot stroke.  
     
     
         12 . The energy absorbing system according to  claim 11 , wherein the shock absorbing means has an accumulator with a 5,000 pound return force.  
     
     
         13 . The energy absorbing system according to  claim 6 , wherein the rotating means is mounted on the fixing means.  
     
     
         14 . The energy absorbing system according to  claim 6 , wherein the rotating means comprises a bearing sleeve.  
     
     
         15 . The energy absorbing system according to  claim 2 , further comprising a torque protection means for adding structural strength to the shock absorbing means to resist deformation due to the torque upon the shock absorbing means.  
     
     
         16 . The energy absorbing system according to  claim 6 , further comprising a torque protection means for adding structural strength to the shock absorbing means to resist deformation due to the torque upon the shock absorbing means.  
     
     
         17 . An energy absorbing system according to  claim 2 , comprising a restraining means connected to the shock absorbing means, for absorbing forces and for transferring forces to the shock absorbing means, and through the shock absorbing means to the support means.  
     
     
         18 . An energy absorbing system according to  claim 6  comprising a restraining means connected to the shock absorbing means, for absorbing forces and for transferring forces to the shock absorbing means, and through the shock absorbing means to the support means.  
     
     
         19 . An energy absorbing system according to  claim 18 , wherein the restraining means comprises a restraining net means.  
     
     
         20 . An energy absorbing system according to  claim 18 , wherein the restraining means comprises horseshoe cable.  
     
     
         21 . An energy absorbing system according to  claim 18 , wherein the restraining means comprises cable extending substantially horizontally in a wave pattern with vertical amplitude, having peaks, valleys and midpoints, wherein tangents of the wave midpoints are at least 90 degrees from tangents of the peaks and valleys.  
     
     
         22 . An energy absorbing system according to  claim 6 , further comprising: 
 a torque protection means for adding structural strength to the shock absorbing means to resist deformation due to the torque upon t he shock absorbing means, and    a restraining means connected to the shock absorbing means, for absorbing forces and for transferring forces to the shock absorbing means, and through the shock absorbing mean s to the support means.    
     
     
         23 . An energy absorbing system comprising: 
 a stanchion;    a bearing sleeve rotatable and vertically slidable on the stanchion;    a shock absorber connected to the sleeve; and    a shear pin connected to the shock absorber which prevents expansion of the shock absorber until acted upon by tensile forces of at least a minimum threshold force.    
     
     
         24 . An energy absorbing system according to  claim 23 , further comprising a bunker into which said stanchion is secured.  
     
     
         25 . An energy absorbing system according to  claim 23 , further comprising a foundation and a pipe embedded in the foundation.  
     
     
         26 . An energy absorbing system according to  claim 23 , wherein the shock absorber is a hydraulic shock absorber.  
     
     
         27 . An energy absorbing system according to  claim 23 , wherein the minimum threshold force is about 3,000 to about 15,000 pounds.  
     
     
         28 . An energy absorbing system according to  claim 23 , wherein the minimum threshold force is about 5,000 to about 10,000 pounds.  
     
     
         29 . An energy absorbing system according to  claim 23 , wherein the shock absorber comprises a torque protective sleeve comprised of a material selected from the group consisting of aluminum and steel.  
     
     
         30 . An energy absorbing system according to  claim 23 , further comprising wheels and a cross-bar between at least two shock absorbers on a stanchion, supporting the shock absorbers.  
     
     
         31 . A shock absorbing system, comprising: 
 a stanchion;    a bearing sleeve rotatable and vertically slidable on the stanchion;    a shock absorber connected to the sleeve;    a restraining net connected to the shock absorber; and    a shear pin connected to the shock absorber which prevents expansion of the shock absorber until acted upon by tensile forces of at least a minimum threshold force.    
     
     
         32 . An energy absorbing system according to  claim 31 , wherein the restraining net in a quiescent state exerts a static tensile force upon the shock absorber, and the minimum threshold force exceeds the static tensile force.  
     
     
         33 . An energy absorbing system according to  claim 31 , further comprising a torque protective sleeve attached to the shock absorber.  
     
     
         34 . An energy absorbing system according to  claim 31 , wherein the net extends across a roadway and is ground retractable.  
     
     
         35 . An energy absorbing system according to  claim 31 , wherein the net is adjacent to and approximately parallel to railway tracks.  
     
     
         36 . An energy absorbing system according to  claim 31 , wherein the net comprises horseshoe cable.  
     
     
         37 . An energy absorbing system according to  claim 36 , wherein the horseshoe cable comprises wire rope.  
     
     
         38 . An energy absorbing system according to  claim 37 , wherein the horseshoe cable is substantially unitary.  
     
     
         39 . An energy absorbing system according to  claim 31 , wherein the restraining net comprises cable extending substantially horizontally in a wave pattern with vertical amplitude, having peaks, valleys and midpoints, wherein tangents of the wave midpoints are at least 90 degrees from tangents of the peaks and valleys.  
     
     
         40 . A restraining net comprising: 
 top, middle and bottom horizontally extending structural cables; and    horseshoe cable extending along and between the horizontally extending structural cables.    
     
     
         41 . The restraining net according to  claim 40 , wherein the structural cables comprise wire strand.  
     
     
         42 . The restraining net according to  claim 40 , wherein the top and bottom structural cables comprise wire strand, and the middle horizontal cable comprises wire rope.  
     
     
         43 . The restraining net according to  claim 40 , wherein the horseshoe cable comprises wire rope.  
     
     
         44 . The restraining net according to  claim 40 , wherein the top and bottom structural cables comprise wire strand, the middle horizontal cable comprises wire rope, and the horseshoe cable comprises wire rope.  
     
     
         45 . The restraining net according to  claim 44 , wherein the horseshoe cable is secured to the structural cables by wire rope cable clamps.  
     
     
         46 . A restraining net comprising: 
 top, middle and bottom horizontally extending structural cables; and    cable extending substantially horizontally along the horizontally extending structural cables in a wave pattern with vertical amplitude, having peaks, valleys and midpoints, wherein tangents of the wave midpoints are at least 90 degrees from tangents of the peaks and valleys.    
     
     
         47 . The restraining net according to  claim 46 , wherein the structural cables comprise wire strand.  
     
     
         48 . The restraining net according to  claim 46 , wherein the top and bottom structural cables comprise wire strand, and the middle horizontal cable comprises wire rope.  
     
     
         49 . The restraining net according to  claim 46 , wherein the horseshoe cable comprises wire rope.  
     
     
         50 . The restraining net according to  claim 46 , wherein the top and bottom structural cables comprise wire strand, the middle horizontal cable comprises wire rope, and the horseshoe cable comprises wire rope.  
     
     
         51 . The restraining net according to claim  50 , wherein the horseshoe cable is secured to the structural cables by wire rope cable clamps.  
     
     
         52 . A railroad crossing safety system, comprising: 
 first and second energy absorbing systems installed respectively on each side of a roadway that intersects railroad tracks;    ground retractable restraining means for restraining automobiles from crossing the railroad tracks, the restraining means extending across the roadway between the first and second energy absorbing systems on each side of the railroad tracks;    each of the first and second energy absorbing systems comprising: 
 supporting means for providing a rigid support for a fixing means;  
 fixing means for rigidly fixing a vertical axis relative to the supporting means;  
 shock absorbing means for absorbing forces applied to the restraining means, the shock absorbing means being mounted on the fixing means to rotate around the vertical axis; and  
 a threshold force securing mechanism connected to the shock absorber preventing expansion of the shock absorber until acted upon by tensile forces of at least a minimum threshold force;  
   wherein the restraining means comprises horseshoe cable.