Patent Publication Number: US-7219766-B2

Title: Mid-span fall protection system

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to safety devices, and more particularly, to a fall protection system for providing fall protection to persons working mid-span on horizontal structures, such as a horizontal strand. 
   2. Description of the Prior Art 
   Workers, such as linemen, employed to perform operations on horizontally extending lines typically prop a ladder adjacent a location of the line requiring work, where the line is used as an upper support for the ladder. The danger inherent in climbing and working on lines using a ladder is well known, in that the ladder may shift while in use, and particularly when the worker is ascending or descending the ladder. In addition, such lines are subject to oscillating movement which can cause instability in the ladder and increased danger to a worker due to movement of the line. 
   Generally, the prior art has recognized the importance of providing a secure connection between a ladder and a line providing a support for the ladder. See, for example, U.S. Pat. Nos. 5,054,581 and 5,529,145. Further, it should be noted that some known worker support constructions rely on a connection to the ladder to support the worker, and thus the degree of safety provided to the worker will vary with the integrity of the ladder construction and will further depend on the reliability of the connection between the ladder and the supporting elevated line. 
   Although several prior art devices suggest constructions for maintaining a desired position for ladders utilized in combination with elevated lines, and devices for attachment to workers for securing the worker in various ways to the ladder structure, there remains a need for providing fall protection to a worker in situations where the worker is climbing a ladder, as well as when the worker is in position to perform a task at an elevated location. In particular, there is a need for a fall protection system which directly associates a worker with the elevated support line and which ensures that the connecting components of the fall protection system connecting the worker to the elevated line meet or exceed fall protection standards, such as the ANSI Z.359 or ANSI A-14.3 standards, which relate to loads applied against the system in the event a fall by the worker is arrested by the system. There is a further need for providing a fall protection system which can be secured prior to the worker ascending to the elevated work location, such that the fall protection system may be implemented throughout the time a worker is at risk. 
   SUMMARY OF THE INVENTION 
   In accordance with one aspect of the invention, a mid-span fall protection system is provided comprising a remotely attachable fall protection latching mechanism for attachment to an elevated horizontal strand. The fall protection latching mechanism may be used with an elongated rigid structure for extending between a support surface and the elevated horizontal strand, where the fall protection latching mechanism is attached to an upper end of the elongated rigid structure. The fall protection latching mechanism includes a hook portion for engaging over the elevated horizontal strand to provide a support for the fall protection latching mechanism, and a fall protection line coupling structure attached to the hook portion for providing a direct connection between the hook portion and a fall protection line. A fall protection line is also provided having an upper end attached to and supported by the coupling structure, and includes a lower end located adjacent a lower end of the elongated rigid structure at the support surface. The fall protection line provides a connection between the fall protection latching mechanism and a worker moving vertically along the elongated rigid structure. 
   In accordance with another aspect of the invention, a mid-span fall protection system is provided comprising first and second remotely attachable fall protection latching mechanisms for attachment to an elevated horizontal strand. The fall protection latching mechanisms may be used with an elongated ladder structure for extending between a support surface and the elevated horizontal strand. The first and second fall protection latching mechanisms may be attached to opposing sides of an upper end of the ladder structure. The fall protection latching mechanisms include a hook portion for engaging over the elevated horizontal strand to provide a support for the fall protection latching mechanism and to provide a support for the ladder structure, and include a fall protection line coupling structure connected to the hook portion of at least one of the fall protection latching mechanisms for providing a direct connection between the hook portion and a fall protection line. A fall protection line is also provided having an upper end attached to and supported by the coupling structure, and includes a lower end located adjacent a lower end of the ladder structure at the support surface. The fall protection line provides a connection between at least one of the fall protection latching mechanisms and a worker moving vertically along the ladder structure. 
   Other features and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the fall protection system in accordance with the present invention illustrated incorporated on a ladder in association with a horizontal strand; 
       FIG. 2  is a side elevational view of one of the latching mechanisms showing the latch member in cross-section; 
       FIG. 3  is a front elevational view of the fall protection system illustrated incorporated on a ladder with the hook portions positioned for engaging a horizontal strand; and 
       FIG. 4  is a front elevational view of the fall protection system illustrated incorporated on a ladder with the hook portions positioned  90  relative to the position shown in  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring to  FIG. 1 , a mid-span fall protection system  10  in accordance with the present invention is shown in combination with an elongated rigid structure illustrated in the form of a ladder  12  having a pair of side rails  14 ,  16  and a plurality of rungs  18  extending horizontally between the side rails  14 ,  16 , the ladder  12  being adapted to extend between a substantially horizontal surface and a vertically spaced, horizontally extending strand  20 , such as a cable or power line. However, it should be understood that the concept embodied by the illustrated fall protection system  10  may be incorporated with other rigid structures for extending vertically to a horizontal strand  20  in order to locate the fall protection system  10  in an operable position. The fall protection system  10  is shown attached to the upper end of the elongated rigid structure whereby remote attachment of the fall protection system  10  to the horizontal strand  20  is facilitated. 
   Referring to  FIG. 2 , the fall protection system  10  comprises a latching mechanism  22  including a hook portion  24  for engaging over the horizontal strand  20  to provide a support for the fall protection system  10 . In one embodiment, the hook portion  24  comprises a unitary member, such as may be formed of a metal bar, i.e., 6061-T6 aluminum round bar, bent approximately 180 to define substantially parallel legs where one of the legs comprises a long leg  26  and the other of the legs comprises a short leg  28 , and a concave interior area  30  is defined between the two legs  26 ,  28  for receiving the horizontal strand  20 . 
   The hook portion  24  is attached to a ladder side rail  14  by a bracket  32  which bolts to an inside portion of the ladder side rail  14 . Referring further to  FIG. 3 , the bracket  32  generally defines a U-shaped member including an upper wall  34  and a lower wall  36  and a side wall  38  spanning between and connecting the upper and lower walls  34 ,  36 . The upper wall  34  includes an upper flange portion  40  for receiving bolts  42  to connect the upper wall  34  to the ladder side rail  14 , and the lower wall  36  includes a lower flange portion  44  for receiving bolts  46  to connect the lower wall  36  to the ladder side rail  14 . Connection of the upper and lower walls  34 ,  36  of the bracket  32  to the ladder side rail  14  positions the side wall  38  of the bracket  32  parallel to the inside portion of the ladder side rail  14 . 
   The upper and lower bracket walls  34 ,  36  include respective apertures  48 ,  50  sized to receive the long leg  26  of the hook portion  24 . The long leg  26  of the hook portion  24  extends downwardly through the apertures  48 ,  50  in the bracket  32  and includes a lower end comprising a lower threaded portion  52  extending downwardly from the lower wall  36  of the bracket  32 . A nut  54  is threaded on the lower threaded portion  52  and is adapted to engage a lower surface of the lower wall  36  of the bracket  32 . An intermediate portion  56  of the long leg  26  of the hook portion  24  is located between the upper and lower walls  34 ,  36  of the bracket  32 , and a spring seat comprising a square nut  58  is rigidly attached to the intermediate portion of the long leg  26 . The square nut  58  is positioned such that a side  60  of the square nut  58  is normally parallel and closely adjacent to the side wall  38  of the bracket  32 , preventing rotation of the square nut  58  and thus preventing rotation of the hook portion  24 . A spring  62  located between the square nut  58  and the lower wall  36  of the bracket  32  acts on the nut  58  to bias the hook portion  24  upwardly relative to the bracket  32  to a rest position for the nut  58  ( FIG. 3 ). 
   The bracket  32  includes a cut-out or slot area  64  ( FIG. 2 ) below the rest position, and the hook portion  24  may be pushed into the bracket  32  to align the square nut  58  with the slot  64 , as illustrated by the dotted line position of the nut  58  in  FIG. 4 , which provides clearance for the sides of the nut  58  to permit the nut  58  to rotate relative to the bracket  32 . Accordingly, the hook portion  24  may be rotated relative to the bracket  32  and the ladder side rail  14 , and may be pivoted about an axis generally parallel to the direction of elongation of the ladder  12 . The spring force applied to the square nut  58  on the hook portion  24  normally biases the hook portion  24  and associated nut  58  to its rest position whereby the hook portion  24  is maintained in a desired rotational position. The square nut  58  permits the hook portion  24  to be located at different positions oriented  90  from each other. For example, the hook portion  24  may be rotated such that a plane defined by the hook portion legs  26 ,  28  is parallel to the plane of the ladder side rail  14  when the fall protection system  10  is positioned for use to engage the horizontal strand  20 , and the hook portion  24  may be rotated  90  to extend perpendicular to the use position for transportation of the fall protection system  10  when not in use, as illustrated in  FIG. 4 . 
   In a typical configuration of the fall protection system  10 , first and second latching mechanisms  22 ,  22 ′ are provided attached to opposing side rails  14 ,  16  of a ladder  12 , where elements of the second latching mechanism  22 ′ corresponding to elements of the first latching mechanism  22  are labeled with the same reference numerals. A coupling mechanism comprising a lateral bar  66  is further provided having ends  68 ,  70  extending through apertures in the side walls  38  of the brackets  32 . Each end  68 ,  70  of the lateral bar  66  is threaded and receives a respective nut  72 ,  74 , such that the first and second latching mechanisms  22 ,  22 ′ and the lateral bar  66  comprise a structural unit. The lateral bar  66  is adapted to receive a worker safety line, such as by attachment of a fall protection line  76  to the lateral bar  66 . Thus, the fall protection system  10  provides a direct connection between a fall protection line  76  for a worker and the horizontal strand  20 , which is typically a mid-span location on a line for conducting power or electrical signals, requiring maintenance or other operations by the worker at an elevated location. 
   The latching mechanism  22  comprising the hook portion  24 , and including the coupling for the safety line  76 , is rated to withstand a dynamic force which may occur in the event of a fall by a worker attached to the fall protection system  10 , such as a fall from a ladder  12  associated with the fall protection system  10 . Specifically, the fall protection system  10  is constructed to withstand a 2500 lb. stress test force, as required by the ANSI Z.359 and ANSI A-14.3 standards, and is accomplished in the illustrated construction by avoiding intermediate structural connections between the hook portion  24  and the coupling structure for the safety line  76 . In particular, the connection to the safety line  76  does not depend on an intermediate connection to a ladder  12  or similar structure. 
   As seen in  FIG. 2 , the latching mechanism  22  of the fall protection system  10  may further include a latch member  78  for closing the passage to the interior area  30  between the two legs of the hook portion  24 . The latch member  78  is supported at a pivot point  80  defined on a support block  82  on the long leg  26 , and the latch member  78  pivots about the pivot point  80 . The latch member  78  comprises a first side  84 , a second side  86  and a third side  88  connected to each other to define a triangular shaped member. The first side  84  defines an outer surface extending from a location near the pivot point  80  to a distal point  90  for cooperating with the short leg  28  of the hook portion  24 . The second side  86  defines an interior surface adjacent the interior area  30  extending from the distal point  90  toward a leverage point  92 , and the third side  88  extends between the pivot point  80  and the leverage point  92 . The first, second and third sides  84 ,  86 ,  88  are defined by first and second parallel plates  94 ,  96  ( FIG. 3 ) which are spaced apart to receive the lateral sides of the hook portion legs  26 ,  28  therebetween. The plates  94 ,  96  are held in spaced relation by a connecting wall  98  ( FIG. 2 ) integrally connected to the first and second plates  94 ,  96  and extending along a portion of the first side  84 . In addition, the leverage point  92  is defined by a laterally extending pin element  100  ( FIG. 3 ) connecting the first and second plates  94 ,  96  and located on a side of the long leg  26  opposite from the interior area  30 . 
   The outer surface of the first side  84  is adapted to engage the horizontal strand  20  when locating the fall protection system  10  in place, such as by positioning the hook portion  24  over the horizontal strand  20 , causing the latch member  78  to pivot inwardly to permit movement of the horizontal strand  20  into the interior area  30 . The interior surface of the second side  86  is adapted to engage the horizontal strand  20 , when the horizontal strand  20  is located within the interior area  30 , and prevent the horizontal strand  20  from becoming disengaged from the interior area  30 . The first and second plates  94 ,  96  are located on either lateral side of the short leg  28  of the hook portion  24  when the latch member  78  is in the closed position to prevent the horizontal strand  20  from passing out of engagement with the interior area  30 , and a spring  99  is provided at the pivot point  80  for biasing the latch member  78  toward the closed position. 
   Movement of the latch member  78  toward the closed position is limited by engagement of the connecting wall  98  with the short leg  28 , which also prevents the latch member  78  from opening the interior area  30  in response to engagement of the horizontal strand  20  on the second or interior surface  86 . Thus, the latch member  78  is movable to allow the hook portion  24  to be remotely engaged on the horizontal strand  20 , and the latch member  78  prevents removal of the hook portion  24  from the horizontal strand  20  during engagement of the horizontal strand  20  against the inside surface of the latch member  78 . 
   When disengagement of the hook portion  24  from the horizontal strand  20  is required, such as when disengaging the fall protection system  10  from the horizontal strand  20 , the latch member  78  may be manually pivoted to the open position. Specifically, a rope  101  or other actuating structure may be attached to the latch member  78  at or adjacent to the leverage point  92 . A force applied downwardly to the leverage point  92 , such as by pulling the rope  101 , causes the distal point  90  of the latch member  78  to pivot upwardly and into the interior area  30 , opening the interior area  30  to permit passage of the horizontal strand  20  out of engagement with the hook portion  24 , as illustrated by the dotted line position of the latch member  78  in  FIG. 1 . Thus, the fall protection system  10  may be remotely detached from the horizontal strand  20  by actuation of the rope  101  attached to the latch member  78 , such as may be actuated by a person standing on the ground below the mounting location of the system. 
   In one application of the fall protection system  10 , a latching mechanism  22  may be provided adjacent the upper end of each side rail  14 ,  16  of the ladder  12 . One of the latching mechanisms  22  may be provided with a latch member  78 , while the other latching mechanism  22 ′ may include the hook portion  24  without a latch member. In the illustrated embodiment, the above-described lateral bar  66  is shown extending between the two latching mechanisms  22 ,  22 ′ and provides a safety line attachment location, where a worker may attach a security device  102  to the safety line  76  for securing the worker to the safety line  76  and for permitting the worker to move vertically along the safety line  76 . Such a security device preferably is auto-latching/locking for gripping the safety line  76 , and which requires manual release for removal. An example of such a security device  102  is described in U.S. Pat. No. 5,855,251, which patent is incorporated herein by reference. It should be noted that the one latch member  78  on the first latching mechanism  22  is sufficient to ensure fall protection in that, even if the second latching mechanism  22 ′ should become disengaged from the horizontal strand  20 , the safety line  76  will remain connected to the horizontal strand  20  through the connection of the first latching mechanism  22  on the horizontal strand  20 . Further, the direct connection of the safety line  76  to the latching mechanism  22  ensures that the maximum rating fall protection provided through the present system is available at the safety line  76 , avoiding weak points that may occur through attachment of the safety line  76  via the ladder  12  or other intermediate structures. 
   The fall protection system  10  may further be provided with a brace member  104  for engaging vertical structures, such as utility poles. The brace member  104  extends laterally between the latching mechanisms  22 ,  22 ′, and is attached to the brackets  32  of the latching mechanisms  22 ,  22 ′ above the lateral bar  66 . The brace member  104  is formed of a bar or strap in a generally V-shape for accommodating the curved outer surface of the vertical structure. The rigid brace may be secured to the vertical structure by a cable extending around the vertical structure and attached to the latching mechanisms  22 ,  22 ′. 
   From the above-description, it should be understood that the hook portions  24  and lateral bar  66  operate to provide an independent fall protection anchorage connector that can be used in conjunction with a vertical safety or life line to facilitate an OSHA/ANSI load rated fall protection system. 
   It should be understood that the latching mechanism  22  could be attached to the end of a pole to enable the latching mechanism  22  to be connecting to an elevated location, and that the climbing structure, such as a ladder, may be provided separately. For example, the lower end of the hook portion  24  of the latching mechanism  22  may be provided with an eye-ring (not shown) receiving the safety line of a worker, permitting independent attachment of the latching mechanism  22  to an elevated location prior to the worker ascending to the elevated location. 
   While the form of apparatus herein described constitutes a preferred embodiment of this invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.