Abstract:
In certain embodiments, the improved safety ladder and harness assembly described herein incorporates a harness coupling designed to slide freely within the vertical member of a safety ladder so long as the forces exerted on the coupling are small. Any significant external force applied to the coupling, such as the application of a worker&#39;s weight, will result in a braking and holding action by the coupling until the external force or weight is removed. In one embodiment, the apparatus incorporates a substantially cylindrical coupling body having a braking lever extending from the front side, an upper braking nub extending from the upper portion of the coupling body in the same direction as the braking lever, and a lower braking nub extending from the lower portion of coupling body in the opposite direction as the braking lever.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to the field of construction scaffolding, and in particular to a ladder and safety harness assembly incorporating a set of features designed to improve both the functionality of the ladder and harness assembly and the safety characteristics thereof. 
     BACKGROUND OF THE INVENTION 
     In various applications, it is necessary to provide safe and structurally-sound support apparatus in order to give workers safe access to elevations above ground. For example, in the course of repairs to the outside surface of a building, modifications of the same, window washing, painting, cleaning, or installation of siding on the exterior of a building, ladders and scaffolds are commonly used to enable workers to move up and down adjacent the side of the building. Such devices are well known and take a wide variety of forms. 
     Although there are a number of ladder designs known in the construction art, most conventional ladders include a pair of vertical rails that are interconnected by horizontal rungs. Certain ladders are designed to be free-standing, while others are designed to rely on an external support surface. Either of these designs may be fixed to an external support by braces or other structural members, in order to increase their rigidity, stability, and structural integrity. 
     With respect to scaffolds, although scaffolding designs encompass a wide variety of geometries, most conventional forms of scaffolding ordinarily include a set of vertical posts or columns that are interconnected by horizontal rails and often cross-braces for added structural integrity. Generally, these assemblies may be stacked on top of each other so as to permit workmen to work at high elevations. 
     In order to provide workers access to multiple levels of the scaffolding, most scaffold installations incorporate ladders either integrally as part of the scaffold structure, or mounted to the scaffold structure by some form of attachment means. 
     Hazards to workers associated with scaffolds in general, and scaffold ladders in particular, are well known. These hazards include loss of balance and slippage. These hazards can be exacerbated by movement of workers on the scaffold, wind, and other environmental factors. In order to protect the workers against falls, safety structures and devices may be incorporated into the structure of the scaffolding and/or the scaffold ladders. 
     Although certain devices have been developed to improve the level of safety of workers performing tasks at high elevations, there remains a need in the art for a safety device that allows for a secure attachment between the worker and the structure while at the same time allowing the worker to move freely along the structure and quickly engage or disengage from the structure. Furthermore, there is a need for a safety device that is easy to use, reliable, and easy to manufacture. 
     SUMMARY OF THE INVENTION 
     The following summary of the invention is provided to facilitate an understanding of some of the innovative features unique to the present invention, and is not intended to be a full description. A full appreciation of the various aspects of the invention can be gained by taking the entire specification, claims, drawings, and abstract as a whole. 
     The present invention relates generally to the field of construction scaffolding, and in particular to a scaffold ladder and harness assembly incorporating a set of features designed to improve both the functionality of the ladder and the safety characteristics thereof. In its various embodiments, the present invention includes a number of novel structures and assemblies to facilitate safe and efficient use of scaffold ladders as well as improve the safety of workers using such ladders. 
     In one embodiment, the invention comprises a safety harness coupling having a substantially cylindrical coupling body having a front side, a back side, a center of rotation, and a braking lever extending from the front side having an attachment feature disposed therein. The coupling has a braking nub extending from one side of the coupling body and disposed about an axis non-coincident to the center of rotation of the coupling body. 
     In a second embodiment, the present invention comprises a safety harness and ladder assembly including a ladder having a vertical rail having a substantially cylindrical internal surface and a vertical slot disposed therein. A substantially cylindrical coupling body is disposed inside the vertical rail having a front side, a back side, a center of rotation. The coupling incorporates a braking lever extending from the front side of the coupling body and through the vertical slot and a braking nub extending from one side of the coupling body and disposed about an axis non-coincident to the center of mass of the coupling body. The braking lever has an attachment feature disposed therein for attachment to a safety harness. 
     The novel features of the present invention will become apparent to those of skill in the art upon examination of the following detailed description of the invention or can be learned by practice of the present invention. It should be understood, however, that the detailed description of the invention and the specific examples presented, while indicating certain embodiments of the present invention, are provided for illustration purposes only because various changes and modifications within the spirit and scope of the invention will become apparent to those of skill in the art from the detailed description of the invention and claims that follow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention. 
     FIG. 1 is an isometric view of a scaffolding system incorporating certain embodiments of the present invention; 
     FIG. 2A is a top view of a ladder mounting clamp according to one embodiment of the present invention; 
     FIG. 2B is a top view of a ladder mounting clamp according to one embodiment of the present invention; 
     FIG. 3 is a perspective view of a scaffold ladder incorporating certain embodiments of the present invention; 
     FIG. 4 is a detailed isometric view of a scaffold ladder incorporating certain embodiments of the present invention; 
     FIG. 5 is a top view of a vertical ladder member incorporating certain embodiments of the present invention; 
     FIGS. 6A-6C are top section views of a safety ladder showing the manner of insertion of a safety harness coupling according to one embodiment of the present invention; 
     FIGS. 7A-7C is a side section view of a safety ladder showing the manner of engagement and locking of the safety harness coupling according to certain embodiments of the present invention; 
     FIGS. 8A and 8B are isometric views of showing the safety harness coupling assembly according to certain embodiments of the present invention; 
     FIGS. 9A-9C are principle axis views of a safety harness coupling body according to certain embodiments of the present invention; 
     FIGS. 10A and 10B are principle axis views of a safety harness coupling locking lever according to certain embodiments of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. 
     The present invention relates to a safety ladder and harness assembly designed to facilitate safe movement of workers between various portions of an elevated structure, such as, for example, a building face or scaffold. The following discussion of the safety ladder and harness assembly of the present invention is described in detail in connection with a scaffold structure, but it will be appreciated by one of skill in the art that the teachings of the present invention are applicable in any context wherein worker safety due to high elevation is a cause for concern. 
     As noted, one area in which the ladder and harness assembly of the present invention is readily employed is in connection with scaffolding. Referring to FIG. 1, one configuration of a scaffolding system  10  is depicted. In scaffolding system  10 , posts  12  provide vertical support and may be supplied with bases  14 . Bases  14  may be stable platforms that function as an interface between the posts  12  and the ground or other supporting surface. In certain embodiments, bases  14  may incorporate screw-type leveling mechanisms  15  that allow the scaffolding system  10  to be erected on uneven terrain. Alternatively, bases  14  may incorporate numerous other forms of leveling mechanisms, including hydraulic mechanisms and telescoping sections secured by pins. 
     In certain embodiments, rails  16  may be secured to the posts  12  by couplings  18 . Rails  16 , as with the other portions of the scaffold, may be made of any one of a variety of materials used in structural applications, including steel, aluminum, and composite materials. The rails  16  may have any of a number of cross-sectional shapes commonly used in structural applications, including square and round tubes, I-beams, and wide-flange sections. In certain designs, the couplings  18  may be generally conical sections connected to the posts  12 , though other coupling styles may be employed without departing from the spirit and scope of the present invention. 
     In the embodiment shown in FIG. 1, tabs  20  may be rigidly attached to the rails  16 . The tabs  20  may be attached to the ends of the rails  16  by, for example, welding, bolting, or forging the tabs  20  as an integral part of the rails  16 . Other methods of joining the tabs  20  to the rails  16  will be apparent to one of ordinary skill in the art. 
     In one embodiment of the present invention, the tabs  20  may be a part of a flange that is attached to the rail  16 . Alternatively, the tabs  20  may be, for example, individual pieces of metal or other materials, such as composites, that are formed from, or attached to, the end of the rails  16 . The tabs  20  may be formed from the end section of a metal rail  16 , welded, screwed, or assembled in manners known to those of skill in the metalworking art. The tabs  20  may also be designed to conform to the radius of the post  12 , which results in a more stable interface between the post  12  and the tabs  20 . 
     The tabs  20  may be fixed to the rails  16  at a variety of different angles so that the scaffolding system  10  may be built to accommodate structures having irregular shapes. For example, one section of the scaffolding system  10  may be oriented at an angle greater or less than ninety degrees to the adjoining section. Varying the angles that the tabs  20  are formed or fixed to the rails  16  and varying the lengths of the rails  16  allows the scaffolding system  10  to be assembled to conform to different buildings that have a variety of shapes. As another example, various lengths of rails  16  have angled tabs  20  that allow the scaffolding system  10  to be assembled to conform to round structures, such as storage tanks. 
     It will be understood to one of skill in the art that the type of scaffolding system described above is only one of a number of different styles of scaffolding suitable for use in connection with the present invention. Known scaffolding designs making more extensive use of welded sections and/or bolted connections are equally suitable for use with the present invention. In fact, any structurally-sound vertical structure having some form of feature or structure suitable for attachment is suitable for use in connection with the present invention. These types of structures may include, but are certainly not limited to building frames, bridges, broadcasting towers, and petroleum drilling platforms. 
     Safety ladder  22 , attached to scaffolding system  10  by mounting clamps  24 , is designed to facilitate safe movement of workers between various portions of the scaffold system  10 . In the embodiment shown in FIG. 1, safety ladder  22  is attached to post  12  using the existing couplings  18 , but it will be understood by one of skill in the art that the mounting clamps  24  could be attached to posts  12  in the vertical portion between couplings  18  without departing from the spirit and scope of the present invention. 
     FIGS. 2A and 2B are detail views of a mounting clamp  24  of the scaffolding system incorporating certain embodiments of the present invention. Mounting clamp  24  includes strut  30 , inner jaw  32 , outer jaw  34 , threaded shank  36 , and nut  38 . In FIG. 2A, clamp  24  is shown fastened to ladder  22 . In FIG. 2B, mounting clamp  24  is shown in its open condition, ready to receive ladder  22  and be fastened to it. 
     In various embodiments, the mounting flange  40  at the opposite end of clamp  24  may be fastened to post  12  or other portions of the scaffold  10 , depending on the application. Various geometries for mounting flange  40  will be dictated by the application and the structure to which it is to attach. In certain embodiments, mounting flange  40  may be designed to be a mirror image of the structure at the opposite end of strut  30 , to facilitate attachment to vertical structural members. In other embodiments, mounting flange  40  may have this same structure disposed 90 degrees to the structure at the opposite end, so as to facilitate solid attachment to horizontal structural members. 
     In order for mounting clamp  24  to be secured to ladder  22 , mounting clamp  24  must first be disposed in the open position shown in FIG.  2 B. Once mounting clamp  24  is placed in the open position, the inner jaw  32 , which is sized to receive ladder  22 , can be moved into position around ladder  22 . After inner jaw  32  is placed around ladder  22 , outer jaw  34  is moved into position on the other side of ladder  22 , thereby completely capturing ladder  22  between inner jaw  32  and outer jaw  34 . The final steps in securing mounting clamp  24  to ladder  22  are to swing threaded shank  36  into position and to tighten nut  38 , thereby securely fastening mounting clamp  24  around ladder  22 . 
     FIG. 3 is a perspective view of a safety ladder  22  incorporating certain embodiments of the present invention. Ladder  22  is constructed of a pair of vertical rails  50  connected by a set of rungs  52 . Vertical rails  50  and rungs  52  may be made of any number of materials known to those of skill in the art, including steel, aluminum, and composite materials. Rungs  52  may be connected to vertical rails  50  by any number of methods known to those of skill in the art, including welding, fastening, and adhesive bonding. 
     One or both of vertical rails  50  incorporate a vertical slot  54  in one portion of the sidewall of a vertical rail  50 . In the embodiment shown in FIG. 3, ladder  22  incorporates one vertical slot  54  in each of the vertical rails  50 . Although ladder  22  incorporates vertical slots  54  on opposite sides of vertical rails  54 , there is nothing within the spirit and scope of the present invention necessitating such an arrangement. In various embodiments, the vertical slots  54  may be oriented on the same side of ladder  22 . Similarly, while the vertical slots  54  of ladder  22  are disposed on the left side of a worker standing on ladder  22 , nothing within the spirit and scope of the present invention prevents the rails from being disposed on the right side. 
     Vertical slots  54  within vertical rails  50  are designed to accommodate safety harness couplings  60 , which are shaped and sized to slide freely inside vertical rails  50 . A worker climbing on safety ladder  22  may insert one or more of safety harness couplings  60  into one or more of vertical rails  50 . In certain embodiments, each safety harness coupling  60  is attached to one or more safety harnesses (not shown) the other end of which is securely attached to the worker. In the event of a slip or loss of balance, the safety harness coupling  60  is designed to slow or stop the descent of the worker. The manner of operation of the safety harness coupling  60  is described in detail below. 
     Certain embodiments of the present invention may incorporate one or more insertion windows  56  in the sidewall of a vertical rail  50 . These insertion windows  56  enable the safety harness couplings  60  to be quickly and easily inserted and removed at a number of points along vertical rails  50 . 
     FIG. 4 is a detailed isometric view, and FIGS. 6A-6C are top section views, of a scaffold ladder vertical rail  50  showing the manner of insertion of safety harness coupling  60  through an insertion window  56  according to one embodiment of the present invention. It can be seen in these views that the insertion window  56  is designed to be a relatively close fit to the safety harness coupling  56 , so as to prevent accidental disengagement from the vertical rail  50  of safety ladder  22 . It can also be seen that the body of the safety harness coupling  60  is non-circular owing to the presence of two flats on the body, making the coupling significantly wider in one axis than the other. 
     Insertion of a safety harness coupling  60  into a vertical rail  50  of a safety ladder  22  begins with alignment of the safety harness coupling  60  with the window  56 , as shown in FIGS. 4 and 6A. After proper alignment, the safety harness coupling  60  will slide readily into the center of vertical rail  50  of safety ladder  22 . Once inserted into the vertical rail  50  as seen in FIG. 6B, the safety harness coupling  60  is designed to rotate within the vertical rail  50  until the protruding portion of safety harness coupling  60  is aligned with the vertical slot  54  in vertical rail  50 . 
     FIG. 5 is a top view of a safety ladder  22  incorporating certain embodiments of the present invention. Safety ladder  22  is shown having two safety harness couplings  60  installed, one disposed in each of vertical rails  50  and protruding through vertical slots  54 . 
     FIGS. 7A-7C are side section views of a safety ladder  22  showing the manner of engagement and locking of the safety harness coupling  60  according to certain embodiments of the present invention. Safety harness coupling  60  is disposed within vertical rail  50  and under normal light-load conditions is able to slide freely in the vertical axis. Safety harness coupling  60  comprises coupling body  62 , lower braking nub  64 , upper braking nub  66 , and braking lever  68 . Braking lever  68  protrudes through vertical slot  54  and incorporates a hole  70  or other feature designed to accept a safety harness  72 . Although the embodiment shown in FIGS. 7A-7C makes use of a loop geometry, it will be understood by one of skill in the art that any of the various structures known to be useful for the connection of safety devices may be employed in this capacity without departing from the spirit and scope of the present invention. 
     FIG. 7A depicts safety harness coupling  60  as it appears in use under a neutral or light downward load imparted by safety harness  72 . As seen in this figure, safety harness coupling  60  is disposed essentially coaxially with the inner surface of vertical rail  50  and is able to slide freely within vertical rail  50  without interference. 
     FIG. 7B depicts safety harness coupling  60  as it appears in use under a heavy downward load imparted by safety harness  72 . This is the condition to which the safety harness coupling  60  would be subjected if a worker lost his balance or slipped on a ladder rung, for example. The worker&#39;s weight is applied to braking lever  68  through safety harness  72 , imparting a moment to safety harness coupling  60 . 
     The moment applied to braking lever  68  will tend to cock safety harness coupling  60  within vertical rail  50 , forcing lower braking nub  64  and upper braking nub  66  into high-pressure contact with the inner surface of vertical rail  50 . As braking nubs  64  and  66  are constructed of a relatively high-friction material, this high pressure contact between the braking nubs  64  and  66  and the inner surface of vertical rail  50  will tend to brake the safety harness coupling  60  against further movement in the downward direction within the vertical rail  50 . The braking nubs  64  and  66  may be constructed of any of a number of materials known to those of skill in the art as being useful in braking applications, including but not limited to certain appropriate polymers, elastomers, metals, ceramics, and composite materials. 
     FIG. 7C depicts safety harness coupling  60  as it appears under the application of a strong upward load. It can be seen in this figure that the rotation of safety harness coupling  60  under an upward load is such that the braking nubs  64  and  66  are moved completely out of contact with the inner surface of vertical rail  50 , so that little or no braking is exhibited under these conditions. 
     FIGS. 8A and 8B are isometric views of showing the safety harness coupling  60  according to certain embodiments of the present invention. In this embodiment, coupling body  62 , containing braking nubs  64  and  66 , is attached to braking lever  68  by threaded fasteners  74  and  76 . In alternate embodiments, coupling body  62  and braking lever  68  may be formed as one piece, or may be attached using any one of a number of methods known to those of skill in the art, including welding, brazing, or adhesive bonding. In certain embodiments, braking lever  68  may be assembled to coupling body  62  using an interference fit. Other methods of assembly will be apparent to one of skill in the art. 
     FIGS. 9A-9C are principle axis views of a safety harness coupling body according to certain embodiments of the present invention. As seen in these figures, coupling body  62  has a generally cylindrical shape with a channel  80  formed therein approximately transverse to the principal axis of the coupling body  62 . In alternate embodiments, channel  80  may have alternate shapes depending upon the shape of the braking lever  68  employed. For example, channel  80  may in certain embodiments be a smooth wall cylindrical hole or a threaded hole designed to accept a threaded braking lever  68 . 
     In the embodiment shown in FIGS. 9A-9C, the coupling body  62  incorporates two threaded holes  82  and  84  disposed within channel  80 . Holes  82  and  84  are sized and positioned to accept threaded fasteners for fastening braking lever  68  to coupling body  62 . Alternate embodiments may incorporate more or fewer threaded holes without departing from the spirit and scope of the present invention. 
     In the embodiment shown in FIGS. 9A-9C, coupling body  62  incorporates flats  86  and  88  to provide a narrowed cross-section width. This narrowed cross-section width allows the coupling body  62  to be removed from a window  56  in the side of a safety ladder vertical rail  50 . Various embodiments may incorporate flats  86  and  88  or not, as requirements dictate. 
     FIGS. 10A and 10B are principle axis views of a safety harness coupling braking lever  68  according to certain embodiments of the present invention. Braking lever  68  is designed to assemble to coupling body  62 , thereby forming a complete safety harness coupling  60 . A safety harness is attached through hole  70 , which is disposed in the portion of the braking lever  68  designed to protrude through vertical slot  54  in vertical rail  50 . 
     Braking lever  68  incorporates fastener holes  90  and  92  sized and positioned to correspond to threaded holes  82  and  84  in the coupling body  62 . Alternate embodiments may incorporate more or fewer holes as requirements dictate. Certain embodiments of the present invention may use non-threaded attachment schemes, in which case fastener holes  90  and  92  would not be necessary. In this embodiment, the shank  94  of the braking lever  68  has a generally rectangular shape, but nothing within the spirit and scope of the present invention necessitates such a geometry. In alternate embodiments, braking lever  68  may have a cylindrical shape and be designed to mate with a hole in the body of coupling body  62 . 
     The embodiments and examples set forth herein are presented to best explain the present invention and its practical application and to thereby enable those skilled in the art to make and utilize the invention. Those skilled in the art, however, will recognize that the foregoing description and examples have been presented for the purpose of illustration and example only. Other variations and modifications of the present invention will be apparent to those of skill in the art, and it is the intent of the appended claims that such variations and modifications be covered. The description as set forth is not intended to be exhaustive or to limit the scope of the invention. Many modifications and variations are possible in light of the above teaching without departing from the spirit and scope of the following claims. It is contemplated that the use of the present invention can involve components having different characteristics. It is intended that the scope of the present invention be defined by the claims appended hereto, giving full cognizance to equivalents in all respects.