Anchor Cable Release Mechanism for a Guardrail System

Abstract

A highway guardrail terminal having horizontally extending guardrail elements mounted on a plurality of vertical posts. An anchor cable release mechanism having a cable release bracket attached to a W-beam rail element by cable release bolts has an arrangement of tapered slots and elongated openings to quickly release the cable release bracket from the W-beam rail element upon end-on vehicular impact to the terminal. The tapered slots have a geometry which lifts the bracket away from and out of a parallel alignment with the W-beam rail element.

1 . An anchor cable release mechanism in combination with a guardrail system, said guardrail system having a W-beam rail element, an anchor impact surface, and an anchor cable comprising:
 a first set and a second set of cable release bolts connected to a first section of said W-beam rail element of said guardrail system, said first set and said second set of cable release bolts aligned in separate rows along a top side and a bottom side of said W-beam, respectively;   a cable release bracket releaseably attachable to said cable release bolts, said bracket having a first side with a plurality of enlarged openings slidingly engageable on said first set of said bolts along said top side of said W-beam rail element, said bracket having a second side with a plurality of tapered slots, said tapered slots slidingly engageable on said second set of bolts along said bottom side of said W-beam rail element, each of said tapered slots having a flat, bolt-slide surface intersecting with an angled, release surface, the length of said flat, bolt-slide surface increasing progressively from a upstream most slot to a downstream most slot, said bracket adapted to move away from and out of parallel alignment with said W-beam rail element beginning at a downstream end of said bracket as tension is released from said cable of said guardrail system and said bracket is urged downstream by impacting forces.   
     
     
         2 . The anchor cable release mechanism of  claim 1  wherein the angled release surface of each tapered slot increases progressively from said upstream most slot to said downstream most slot. 
     
     
         3 . The anchor cable release mechanism of  claim 1  wherein said anchor impact surface has a tapered leading edge for increasing the moment of said cable release bracket away from said W-beam rail element 
     
     
         4 . The anchor cable release mechanism of  claim 1  wherein each of said cable release bolts further comprises:
 a shank having a first threaded end extendable through an opening is said W- beam rail element; 
 a head rigidly attached to a second end of said shank; 
 a fixed spacer rigidly attached to a middle portion of said shank and spaced apart from said head providing a space for releasable retaining said anchor cable release bracket; and 
 an internally threaded locknut adapted to be received on said first threaded end of said shank to retain said cable release bolt to said W-beam rail element. 
 
     
     
         5 . The anchor cable release mechanism of  claim 4  wherein said head has two, flat, opposing edges and two, radiused opposing edges.