Patent Publication Number: US-7913981-B2

Title: Cable release lever

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 60/628,213 filed on Nov. 16, 2004. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     BACKGROUND 
     Cable systems have often been used as safety systems for roadside barriers or as tie-down measures for securing equipment such as antennas, towers, or safety fences/netting. Using cable systems for these purposes requires that the cables be maintained in constant tension and not break loose. If not, they would fail as a securing mechanism. The cable used in these systems is typically manufactured from heavy gauge steel wire, rated to maintain a desired loading. Unexpected failure of the cable safety system can result in significant property damage to the item being secured, as well as potential injury or fatality to bystanders. 
     Prior art mechanisms that release a cable from its anchor have traditionally relied on the fracture of a post or support. In these mechanisms, the cable is passed through the base of a post such that when the post fractures on impact, the cable is freed from its anchor. 
     As previously mentioned, roadside barriers have been known to use cable safety systems as guardrails. In such an arrangement, at least one cable is supported by relatively weak steel posts. The steel cables are pre-tensioned with an initial load, and are anchored at both ends of the system. The anchoring typically occurs along a surface such as the roadside or ground. When an errant vehicle obliquely impacts the system, which is most commonly a three cable system, the cables have sufficient tension in them to absorb the impact and redirect the vehicle back towards the driving surface, effectively shielding the roadside hazard and increasing the safety of the vehicle operator. This is especially important on roads that do not have other types of barriers that could perform similar functions (i.e. curbs, concrete walls). Numerous fatalities and injuries have been attributed to vehicles leaving the road and either rolling or entering opposing traffic lanes, thereby potentially endangering other motorists, as well as the occupants of the errant vehicle. The support posts alone offer very little resistance to the impacting vehicle. 
     While these conventional systems have proven successful, they also possess shortcomings. For example, these systems are typically employed where deemed necessary by traffic officials or government regulations. As a result, they are not used along all roadsides, but instead in sections. At the ends of these sections, the cables are anchored to the surface. Accordingly, the cables taper from their maximum height between the support posts to their minimum height at the surface. Since these conventional cable systems are not designed to give way, a vehicle striking the cable system longitudinally, or in line with the taper of the cables, is likely to ride up the tapered cables and initiate a rollover, thereby causing serious damage to the vehicle and severe, if not fatal, injuries to any passengers. This has become a more prevalent event as more roadside cable systems are now being installed with ends tangent to the roadway, instead of being flared away from it. 
     SUMMARY 
     The present invention is defined by the claims below. Embodiments of the present invention solve at least the above problems by providing a system and method for a device for releasing a cable of a safety system. The system and method disclose various features of the safety system as it applies to a roadway barrier system and other applications in the event that the cables are impacted proximate the region they are secured to the surface. 
     In a first aspect, a device for releasing a cable is disclosed comprising primarily an anchor bracket and a release lever. The release lever is located proximate the anchor bracket such that the release lever can pivot, upon impact of a load, to disengage one or more cables from the anchor plate. 
     In a second aspect, a device for releasing tension within a roadside safety system is disclosed. This system incorporates the aspects of an anchor bracket and release lever as previously described, but also includes other features of a roadside safety system such as vertically extending support posts, one or more cables extending between the support posts, and end terminals. 
     In a third aspect, a method of releasing one or more cables of a safety system is disclosed. This method discloses the steps necessary to release the one or more cables. This method is applicable to a variety of cable safety systems, including, but not limited to a roadside safety system. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein and wherein: 
         FIG. 1A  is a side elevation view of a roadside safety system in accordance with an embodiment of the present invention. 
         FIG. 1B  is a top elevation view of a roadside safety system in accordance with an embodiment of the present invention. 
         FIG. 2  is an side elevation view of an end terminal and cable release device in accordance with an embodiment of the present invention. 
         FIG. 3  is an end elevation view of the cable release device in accordance with an embodiment of the present invention. 
         FIGS. 4A ,  4 B, and  4 C are various views of a release lever in accordance with an embodiment of the present invention. 
         FIGS. 5A ,  5 B, and  5 C are various views of an anchor bracket in accordance with an embodiment of the present invention. 
         FIGS. 6A and 6B  are top elevation and side elevation views, respectively, in accordance with a single cable embodiment of the present invention. 
         FIG. 7  is a side elevation view of a cable release device in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present invention provide systems and a method for releasing a cable of a safety system. Under certain circumstances, it may be necessary to release a cable, in tension, that is otherwise intended to serve as a safety system. Under these circumstances, it is desirable to provide such a system and method that is relatively simple, reliable, and reusable. 
     Referring now  FIGS. 1A and 1B , a roadside safety system  10  in accordance with the present invention is shown in detail.  FIG. 1A  shows a side elevation view of safety system  10  along a surface  12 .  FIG. 1B  shows a top elevation view of roadside safety system  10  adjacent a two-lane road  14 . Roadside safety system  10  can be secured to a surface  12 , which may be the ground, or asphalt/concrete covered shoulder of road  14 . The exact location varies and typically depends on the surrounding terrain and available property. As previously mentioned, roadside safety systems, such as the one depicted in  FIGS. 1A and 1B , have ends,  16  and  18  respectively, and also a plurality of vertically extending support posts  20 . Extending between support posts  20  are one or more cables  22 , which are preferably constructed of steel. In the illustrated embodiment of the invention, three cables are utilized. The cables are anchored at ends  16  and  18  to surface  12 . Further understanding of this transition region and anchoring region is shown in  FIG. 2 . 
     One feature depicted in  FIG. 2  is an end terminal  24 . It is at this location that cables  22  are directed towards an anchor plate  26  which is itself fixed to surface  12 . As can be seen in  FIG. 2 , anchor plate  26  and support posts  20  are secured beneath surface  12  in order to provide the necessary structural support to absorb the load caused by a vehicular impact as well as to maintain the cables in tension. End terminals  24  are positioned at each end of safety system  10  as shown in  FIG. 1A . 
     Referring now to  FIGS. 3-5C , additional aspects of the present invention are disclosed in greater detail. An anchor bracket  26  comprises a base portion  28  and an end plate  30  that extends generally vertically from base portion  28  and has an upper edge  32 . One or more slots  34 , designed for receiving one or more cables  22  in tension, are positioned in end plate  30 , along upper edge  32 . The cables secured in slots  34  are shown in  FIG. 3 . Base portion  28  also has a plurality of openings  36  for securing anchor bracket  26  to surface  12 . This securing is accomplished by a plurality of fasteners  38  (see  FIG. 5B ). 
     Another feature of the safety system is a release lever  40  which comprises at least one first leg  42  that is secured to a second leg  44 . In the embodiment shown in  FIGS. 3-4C , at least one first leg  42  comprises two generally parallel legs. Second leg  44 , which is shorter than first leg  42 , is positioned at an angle α relative to first leg  42 . In order to minimize the time required for the release of cables  22  from the time of impact of lever  40 , it has been determined that the angle α should be only slightly obtuse—approximately 90-105 degrees. To provide additional structural support to lever  40 , the lever further comprises a plurality of gussets  46  that reinforce said first and second legs. 
     Release lever  40  is positioned proximate said anchor bracket  26  such that release lever  40  can pivot to disengage one or more cables  22  from anchor plate  26  by releasing nuts  41  from slots  34 . In the example of a roadside safety system, upon impact with first leg  42 , lever  40  pivots about a point A (see  FIG. 4B ) thereby raising second leg  44  to a height sufficient to raise ends of cables  22  from slots  34  in end plate  30 . Once the cables are raised to the point that their securing means, E.g. nuts  41 , clear slots  34 , the contraction of the one or more cables  22  from its built-in tension allows the cables to collapse. 
     The means by which the collapse of cables  22  for a roadside safety system is possible is by means of a vehicle striking lever  40  at first leg  42 . Depending upon the type of vehicle, most likely it will be the vehicle bumper which will strike first leg  42 . After the cables  22  become disengaged from anchor plate  26 , due to a vehicle striking lever  40 , support posts  20  will breakaway from surface  12  as they are impacted by the vehicle. 
     While the system described up to this point, that provides the best understanding of the present invention, has been a roadside safety system, the present invention is not intended to be limited to that type of technology. On the contrary there are other fields in which a cable safety system is utilized, such as a mechanism for releasing securing cables for other structures. For example, with reference now to  FIGS. 6A ,  6 B, and  7 , a single-cable safety system  60  is shown in detail. In this arrangement, the same features as described above are utilized herein, including lever  40  and anchor plate  26 . However, in this arrangement only, a single cable  22  is required. This type of cable safety system can be utilized for securing vertically extending structures, such as antennas, radio towers, safety fencing, etc. An example of such an arrangement is shown in  FIG. 7 . The lever in such a system is similar to the one shown in  FIGS. 1-6  except that it only requires one slot. 
     The present invention also provides a method of releasing one or more cables of a safety system comprising the steps of providing an anchor bracket and a release lever as previously disclosed and impacting the release lever. The impact on the release lever causes a pivoting of the release lever such that the second leg of the lever pushes the ends of the one or more cables out of the slots in the anchor bracket, thereby releasing the tension in the one or more cables. 
     This method is applicable to a variety of cable safety system applications including a roadside safety system as well as the other applications previously discussed such as antennas, radio towers, fencing, to name a few generally vertically extending structures often requiring securing mechanisms. 
     This system and method as it applies to roadway safety systems was simulated and tested through careful experimentation by the inventors. Through computer simulations and scaled testing, they were able to verify that the cable ends of a three-cable system would properly release from an anchor bracket upon longitudinal impact of a moving vehicle (at approximately 45 mph), thus eliminating the tension in the cables and preventing the vehicle from climbing the inclined cables proximate the end terminal. For the system tested, it was determined from photographic evidence that the cables were released from the anchor bracket approximately 8 milliseconds after the vehicle impacted the first leg of the release lever. Significant reduction in cable tension was seen by approximately 18 milliseconds after vehicle impact. In this scaled testing, the release lever incorporated an angle α between its first leg and second leg of approximately 97.5 degrees. Reductions in vehicular velocity were detected at impact with the releasing lever as well as with each support post. Although the support posts did slow the vehicle they provide minimal resistance to an impact load and typically fractured. 
     Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of the present invention. Embodiments of the present invention have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from its scope. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from the scope of the present invention. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.