You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the field of safety gates commonly mounted on catwalks, walkways, and the like, and more particularly to a toe board attachment for improving the safety of a gate that is used to close an opening in a guard rail of a walkway for ladders and stairs leading to and from the walkway. 
       BACKGROUND OF THE INVENTION 
       [0002]    In a typical industrial plant, there are walkways and catwalks from which a worker could fall to a lower level. For safety&#39;s sake, these walkways are usually provided with guard rails to help prevent a worker from accidentally stepping off the side of the walkway and falling. Guard rails also often include a toe board to prevent tools and other items from falling off the walkway. For various reasons, however, it is necessary to provide openings in the guard rails. For example, one or more ladders or stairs may lead from the walkway to another level. Openings are provided in the guard rails so that one can move from the ladders or stairs onto the walkway and vice versa. Such openings in the guard rails are a danger to personnel using the walkway. 
         [0003]    U.S. Pat. No. 3,866,356 described a safety gate specifically designed to keep personnel from inadvertently falling from the walkway into the openings for the stairs or ladders, hereinafter “stairwells”. The safety gate of the &#39;356 patent has enjoyed tremendous commercial success and can be found throughout the industrial world protecting workers from inadvertently falling through the stairwells in catwalks. 
         [0004]    The gate of the &#39;356 patent is positioned approximately waist high to an average size worker standing on the catwalk. As a result, there exists an opening between the gate and the catwalk through which it is possible for a worker to slide under the gate into the stairwell. No such accident has been reported to date although these gates have been in use throughout the world for many years. 
         [0005]    Nevertheless, an attachment for these gates extending the gate downwardly to a position closer to the catwalks reduces the chances of a worker slipping under the gate into a stairwell. This improvement was shown and described in U.S. Pat. No. 6,094,863. However, the attachment of the &#39;863 patent left a gap between the bottom of the attachment and the upper surface of the walkway. That gap has sometimes provided an egress for tools and other objects, which can then fall down the stairwell and perhaps strike a worker below the gate. Thus, there remains a need for a toe board which extends the bottom of the gate to a position close to the top surface of the walkway. The toe board attachment described herein fulfills this and other needs in the art. 
       SUMMARY OF THE INVENTION 
       [0006]    The safety gate and its attachment described herein provides a toe board which may be attached during manufacture of the gate, or it may be attached as a retrofit to a gate that is already installed. The attachment comprises a pair of spaced-apart mounting adapters, preferably in the form of loops of a flat plate workpiece, to which vertical supports are secured. A butt plate is mounted to the vertical supports, and the butt plate preferably includes two or more joining holes so that the attachment may be secured to one of several widths of safety gate. The safety gate also includes an adjustable plate so that the safety gate may be mounted in line with a hand rail or perpendicular to the hand rail. 
         [0007]    These and other objects, advantages, and features of this invention will be apparent to those skilled in the art from a consideration of this specification, including the attached drawings and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of a safety with an attached toe board. 
           [0009]      FIG. 2  is a rear view of a toe board and a presently preferred structure of attaching the toe board to a safety gate. 
           [0010]      FIG. 3  is a side view in partial section of a presently preferred attaching structure for mounting a toe board to a gate. 
           [0011]      FIG. 4  is a top view of a toe board strike plate, enabling the toe board to be attached to safety gates of various sizes. 
           [0012]      FIG. 5  is a perspective view of a reversible butt plate, enabling the safety gate to be attached in-line with a hand rail or perpendicular to the hand rail, simply by reversing the butt plate. 
           [0013]      FIG. 6  is a top view of the butt plate of  FIG. 5 , depicting the closure biasing means of the safety gate. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0014]      FIG. 1  depicts a gate  10  comprising a frame  12  having horizontal members  14   a ,  14   b ,  14   c , and  14   d . In an alternative embodiment, the frame  12  may include more or fewer horizontal members, but in no case fewer than two such members, as will be explained in further detail below. The horizontal members are joined by a first vertical plate  16   a  and a second vertical plate  16   b  to form a substantially rigid frame  12 , capable of withstanding normal wear and tear of a safety gate. The frame  12  is preferably formed from an elongated flat plate about two inches wide that is bent into the shape shown in  FIG. 1 , and then the additional members welded to the bent form. 
         [0015]    The horizontal member  14   b  extends to define a horizontal extension  18   b  and the horizontal member  14   c  extends to define a horizontal extension  18   c . An axle  20  spans the space between the extensions  18   b  and  18   c  and the axle  20  is rotatably held by upper and lower hollow tubular spacers  22   a  and  22   b . The tubular spacers  22   a  and  22   b  are secured to a handrail  24 , such as by welding, bolting, or other secure means. In this way, the safety gate  10  is operably mounted to the handrail  24 . A coil spring  26  is positioned on the axle  20  between the two tubular spacers. The spring urges the gate to the closed position. In most respects, the safety gate  10  is similar to that shown and described in U.S. Pat. No. 6,094,863; assigned to the same assignee as the present improvement. 
         [0016]    The toe board attachment of this invention is indicated in  FIG. 1  by the number  30 . Additional details of the attachment are shown in  FIGS. 2 through 4 . The toe board  30  comprises a pair of spaced-apart mounting loops  32   a  and  32   b , each of which may be formed of a single flat of stock, roughly the same width as the horizontal members  14   a ,  14   b ,  14   c , and  14   d . However, as shown in  FIG. 3 , the mounting loop  32   b  is preferably formed of an upper loop section  32   b ′ and a lower loop section  32   b ″. The loop  32   a  is also formed of upper and lower loop section in a similar fashion. The loops  32   a  and  32   b  are illustrated in  FIG. 1  as looped around the horizontal members  14   c  and  14   d , and these loops are preferably looped around the bottom two horizontal members, however many horizontal members form the safety gate  10 . Preferably, the loops are not immovably secured to the horizontal members; rather, they are slidingly mounted to the horizontal members so that the toe board  30  may be mounted to any of a varying width of gate. 
         [0017]    Once the loops  32   a  and  32   b  are placed on the horizontal members  14   c  and  14   d , a vertical support  34   a  is mounted to the loop  32   a , preferably with a bolt  36   a  and nuts  38   a  and  38   a ′ and a vertical support  34   b  is mounted to the loop  32   b , preferably with a bolt  36   b  and nuts  38   b  and  38   b ′, shown in greater detail in  FIG. 3 . A first butt plate  38   a  is secured to the vertical support  34   a  and a second butt plate  38   b  is secured to the vertical support  34   b , preferably with a plurality of bolt/nut combinations  40 . The butt plates  38   a  and  38   b  are jointed together with a bolt/nut combination  42 , at one of a plurality of bolt holes  44 . This feature enables the same elements of the attachment to be adapted to a range of widths of safety gate. 
         [0018]      FIG. 2  shows a similar feature in respect of the height of the attachment in respect of a walkway. A first pair of elongate bolt holes  46   a  and  46   b  define a first height for the attachment above a walkway  60 , while a second pair of elongate bolt holes  48   a  and  48   b  define a second height, wherein the first height is higher than the second height, providing even more flexibility for the adaptation of the safety gate to a particular installation. 
         [0019]    Finally,  FIGS. 5 and 6  illustrate another feature of the safety gate described herein. A vertical structural member  62  extends between the horizontal extension  18   b  and the horizontal extension  18   c . A contact plate  64  is mounted to the structural member  62 , such as for example with bolts  66 . Similarly, an adjustable plate  68  is mounted to a vertically depending portion  70  of the handrail  24 , such as for example with bolts  72 . With the adjustable plate  68  in the position as shown in  FIGS. 5 and 6 , the adjustable plate  68  abuts the contact plate  64  so that the rest position of the safety gate is in line with the hand rail  24 . However, the bolts  72  are off center in the adjustable plate  68 , so by rotating the adjustable plate by 180°, the safety gate is permitted to swing 90° out of the plane of  FIG. 5 , so that the safety gate is perpendicular to the hand rail  24 , in applications where this orientation is desired. 
         [0020]    From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus and structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. Because many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Summary:
An attachment is provided for a safety gate that is positioned to close the opening in a catwalk to allow access to and from a ladder or stairs. The gate is urged to the closed position by springs. The improvement is an attachment for connecting to the lower side of existing gates to prevent workmen using the catwalk from slipping under the gate and falling into the opening for stairs or a ladder.