Patent Publication Number: US-9890589-B2

Title: Step adapter for rung ladders

Description:
RELATED APPLICATION 
     The present application claims benefit of U.S. Provisional Patent Application Ser. No. 62/167,013 filed May 27, 2015, which is incorporated herein by reference. 
    
    
     FIELD OF INVENTION 
     Step adapters for rung ladders are described which provide for increased step or support area on a ladder rung. The step adapters are structurally simple for ease of manufacture and use, and which provide safety in use of both the step adapter and a rung ladder. Further, a tray overlay in combination with a step adapter serving as a support element is described to provide a platform for holding work items on a rung ladder. 
     BACKGROUND OF THE INVENTION 
     The step adapter of the invention is useful with rigid ladders having rungs or steps for ascending the ladder and standing on while performing work from the ladder. The rungs are supported by two vertical side members called rails or stringers or stiles. Rung ladders can be made of metal, wood, fiberglass or tough plastic. The rungs can be round, semi-round with the flat side facing upward, or flat. 
     Rung ladders of popular use are rigid ladders for leaning against another structure during use, for example, an extension ladder for leaning against a building. Leaning ladders for safety purposes need to be placed at a proper angle to reduce risk of falling. The safest angle for a ladder has been considered to be 75.5°. If the angle is too shallow, the bottom of the ladder is at the risk of sliding. If the angle is too steep, the ladder is at the risk of falling backwards. 
     Due to the (1) nature of the angle of work when a user is on a leaning ladder, (2) limited space on a rung of the ladder, and (3) need to stand in one place to maintain stability, standing on a ladder for an extended period of time, especially on a narrow rung is tiring and stressful to the feet and legs. This is especially true when the rungs are round (so as to be useful regardless of the angle of the ladder). Accordingly, a need is present to increase the support area of a rung for safety and to reduce stress on the feet and legs. 
     In the past, various devices have been developed to extend the size of the rungs or steps of a ladder. Generally, however, such have been complex as to structure and, thus, more difficult to use and manufacture. 
     SUMMARY OF INVENTION 
     Step adapters for a rigid rung ladder are described which are safe in use and provide an increased support surface to a user to reduce stress on the feet and lower legs of a user, especially over a period of extended use. 
     The step adapters are structured for attachment to a rung ladder by engagement with a rung of the ladder. 
     A first and preferred embodiment of the step adapter includes a brace element, a platform element, a lock element and a safety element. At least the brace, platform and lock elements are of one piece. Alternatively, all of the brace, platform, lock and safety elements are of one piece. The step adapter is preferably made from a metal, such as aluminum or aluminum alloy, or is an injection molded piece of tough plastic, both of which provide a lightweight structure with weight-bearing strength. 
     The step adapter of the first embodiment includes as a top portion the platform element from which the brace element extends downward from the front of the platform section and from which the lock element extends downward from the back of the platform section. The safety element extends from the underside surface of the platform element. The safety element may be one piece with the platform element or may be a separate piece fastened to the underside of the platform element, such as by a rivet, screw and bolt, or other suitable fastening structure. The fastener(s) are preferably countersunk into the upper surface of the platform element to maintain an essentially level top surface of the platform. 
     The platform, lock and safety elements are sized to have a width and structure to pass between the rails of a rung ladder and over a rung to engage the rung. The brace element has a width sufficient to extend across and abut the upper or outer exposed surface of the rails of the rung ladder. The lock element and safety element partially surround a selected rung and in conjunction with the brace element secure the step adapter to the rung ladder, providing the platform element as an extended surface to the rung and, thus, an increased support area for the user of the rung ladder. In use, a user selects any rung on the ladder based on the height desired to attach the step adapter and provide an increased support area for the user. The platform element has a length that extends outward left and right toward the rails, but not engaging the rails, and is supported by the brace element engaging the rails. 
     A second embodiment of the step adapter includes a brace element, a platform element, and a lock element. A separate safety element as present in the first embodiment, however, is not required. Rather, the platform element has side edges which are of a different configuration and serve to hold the step adapter in place in relation to the rails of a rung ladder to block the step adapter from moving forward through the ladder rails. The brace element and lock element are of the same structure in the second embodiment as described above in relation to the first embodiment. If desired, the second embodiment of the step adapter can also include the safety element of the first embodiment to provide the step adapter with redundant features for maintaining the step adapter securely in place on a ladder rung. 
     The step adapter of either the first or the second embodiment can also be provided with a service table or tray overlay. In this embodiment, the step adapter serves as a support element to provide a surface area for holding items being used by a person while the person is working on the ladder, e.g., paint can, tools, drink container, etc. Preferably, one or more edges of the overlay will include an upraised wall portion or curb to keep items from sitting over (or going over) the edge of the overlay. The overlay can be made of metal or plastic. When the overlay is made of plastic, the overlay can be provided with recessed areas of different geometric configurations suitable for holding a drink container, paint can, tools, etc. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of the step adapter of a first embodiment of the invention positioned in use on a rung of a leaning rigid rung ladder. 
         FIG. 2  is an underside rear perspective view of the step adapter shown in  FIG. 1 . 
         FIG. 3  is a front plan view of the step adapter of the first embodiment. 
         FIG. 4  is a top plan view of the step adapter of the first embodiment. 
         FIG. 5  is a rear plan view of the step adapter of the first embodiment. 
         FIG. 6  is a first side view of the step adapter of the first embodiment where the opposite side view is a mirror image thereof. 
         FIG. 7  is a top plan view of a sheet format which will form a step adapter of the first embodiment once the sections are angled appropriately. 
         FIG. 8  is a side perspective view of a one-piece injection molded step adapter of the first embodiment. 
         FIG. 9  is a side view of the step adapter of the first embodiment engaged on a rung of a ladder leaning at a 78° angle. 
         FIG. 10  is a side view of the step adapter of the first embodiment engaged on a rung of a ladder leaning at a 73° angle. 
         FIG. 11  is a side view of the step adapter of the first embodiment engaged on a rung of a ladder leaning at a 68° angle. 
         FIG. 12  is a side view of the step adapter of the first embodiment, where the opposite side view is a mirror image thereof, and where the bottom edge of the brace element is curled. 
         FIG. 13  is a front view of the step adapter of the first embodiment positioned on a rung ladder. 
         FIG. 14  is a top plan view of a sheet format similar to that shown in  FIG. 7  and shows certain alternative features. 
         FIG. 15  illustrates an embodiment of a modified step adapter of the first embodiment used in weight bearing tests which are described below. 
         FIG. 16  is a top plan view of a sheet format which will form a step adapter of a second embodiment once the sections are angled appropriately. 
         FIG. 16 a    is a side view of the sheet format of  FIG. 16  angled to form the step adapter of the second embodiment wherein the opposite side view is a mirror image thereof. 
         FIG. 17  is a plan view of the outside surface of the lock section of the step adapter of the second embodiment. 
         FIG. 18  is a plan view of the top surface of the platform section of the step adapter of the second embodiment. 
         FIG. 19  is a plan view of the outside surface of the brace section of the step adapter of the second embodiment. 
         FIG. 20  is a side view of the step adapter of the second embodiment positioned in use on a rung of a leaning rigid rung ladder. 
         FIG. 21  is a top plan view of a service table or tray overlay which can be attached to either the first or the second embodiment of the step adapter. 
         FIG. 22  is a side view of the service table or tray overlay of  FIG. 21  attached to the top surface of the step adapter of the first embodiment when in place on a rung of a leaning rung ladder. 
         FIG. 23  is a front view of a step adapter with a service table or tray overlay thereon, where the step adapter is positioned on a rung ladder. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The step adapters will be described with reference to the drawings. 
     As to the first embodiment, the step adapter  10  is shown in  FIG. 1  positioned for use on a rung  12   a  of a ladder  14  and against a rail  16 . Rail  16  is cut away at rung  12   a . Other rungs  12   b  are shown in dashed lines where rail  16  is not cut away. The step adapter in use can be positioned for engagement with any rung in accordance with the level at which work is to be conducted. The rungs can be round, semi-round with a flat side facing upward, or flat. 
     The step adapter is preferably formed from a sheet of metal  18 , preferably a sheet of aluminum alloy from which the body of the step adapter is stamped out of such as shown in  FIG. 7 . The sheet preferably has a thickness in a range of about ⅛ to about 7/32 inches (about 3.175 to about 5.556 mm), with the preferred thickness of a metal sheet being ⅛ inch (3.175 mm) thick. Alternatively, the step adapter can be injection molded using a plastic to provide a rigid plastic structure. The preferred thickness of an injection molded structure is in a range of from about ¼ to about ⅝ inches (about 6.35 to about 15.875 mm), with the preferred thickness being ¼ inch (6.35 mm). The final interior surface structure of the injection molded step adapter, i.e., the surfaces coming into contact with the rung and rails of the ladder, is otherwise the same as the step adapter made from sheet metal. The corners of both the sheet metal embodiment and the injection molded embodiment are preferably rounded for enhanced safety purposes. 
     The structure of the step adapter includes a lock element  20 , a platform element  22 , a brace element  24  and a safety element  26 . 
       FIG. 7  shows a sheet metal format for the step adapter shown in  FIG. 2 . As shown in  FIG. 7 , the lock section  20  and platform section  22  in a preferred embodiment have a common width. As used herein the width is the measurement from left to right when viewing the step adapter from the front, i.e., facing the brace element. The length is thus the measurement from front to back of an element or section. As seen in  FIG. 7 , the length of the lock section is less than the length of the platform section. The brace section has a greater width than each of the platform and lock sections wherein the width of the brace section is sufficient to extend across both rails of a ladder and to abut against each rail of the ladder in use. The dashed lines A and B in  FIG. 7  indicate the transition or bend points between the lock, platform and brace sections. At the transition or bend point (line A) between the platform section  22  and brace section  24 , the point of intersection between the side edge of the platform element and the top free edge of the brace element is preferably a rounded 90° angle (such as angle  27  shown in  FIG. 14 ). However, in an alternative embodiment, notches  28  can be present as an added safeguard against tearing of the metal sheet during bending in the manufacturing process of the adapter which may occur due to the difference in width. Notches  28  do not have to be too deep to provide this effect, e.g., a depth of about ⅛ to about ¼ inch (about 3.175 to about 6.35 mm) is sufficient. As shown in  FIG. 7 , notch  28  can have a greater depth in relation to the shoulder  29   a , or the notch can be reduced in depth resulting in a lower shoulder  29   b  (shown in dashed lines). The same effect is achieved and no difference in strength, i.e., weight bearing capacity, of the step adapter occurs. A shallow depth of the notch is preferred for safety purposes, i.e., to provide a space which decreases the chance of or prevents catching anything associated with a user within the space during use of the step adapter, such as a loose shoe lace. 
     Lock section  20  is bent at line B to provide a downward extending section in relation to the top surface of platform section  22 . The angle at which lock section  20  is bent is sufficient for lock section  20  to extend around and beyond a rung of a ladder. The preferred bend angle provided is 90°. Lock section  20  works in conjunction with safety section  26  to engage a rung and hold the step adapter in place around the rung. Safety section  26  has a downward extending bar  26   a . In the step adapter embodiment made from sheet metal, the safety section will be a separate element such as a corner or L-shaped element having downward extending bar  26   a  and extension  26   b  which is secured by a suitable fastener to the underside of platform section  22 . This may entail providing holes  30  in platform section  22  which receive suitable fasteners which in turn extend through holes (not shown) in the extension  26   b  of safety section  26 . The fasteners may be rivets, screw and bolt combinations, lock-screws or the like. The holes are preferably such that the head of the fasteners are countersunk in the platform section so as to provide an essentially level top surface to platform section  22 . In the alternative embodiment of an injection molded step adapter, as shown in  FIG. 8 , the safety section  26  may be simply a downward extending bar  26   a  since no fastener is necessary since the structure is preferably one piece. In either embodiment, the angle of downward extending bar  26   a  and lock section  20  is preferred to be 90° in relation to platform section  22  so as to readily and securely encompass a rung to hold the step adapter in place thereon. 
     An optional feature for inclusion in lock section  20  is a cutout  44  (see  FIG. 15 ). This cutout results in reducing the overall weight of the step adapter due to less material being present. The step adapter will thus be lighter and easier to handle in use. This is more notable in the metal embodiment of the step adapter than the plastic embodiment. The provision of cutout  44  in lock section  20  does not have an effect on the weight bearing capacity of the step adapter. 
     A further support and securing element of the step adapter operating in conjunction with the lock and safety elements is brace element  24  which includes a bottom edge  32  which abuts or rests on the top exposed surface of the pair of rails of a rigid ladder. Brace element  24  is bent at line A in relation to platform section  22  so as to be angled downward in a manner to allow the top of platform section  22  to be a support area and the bottom edge  32  to rest on rails  16  of the ladder. 
     Generally, in use, rigid ladders are angled against another structure in a range of about 65° to about 85°, i.e., the base  34  of the rails  16  rest flat on a ground surface  36  while an upper section of the ladder abuts the structure the ladder is positioned to lean against. The lean angle cannot be too shallow (since the ladder may slide back) or too great (since the ladder may fall backwards) due to safety issues. The step adapter provides an acceptable safe support surface at preferred angles in a range of about 68° to about 78° as shown in  FIGS. 9, 10 and 11  when the brace section is bent at an angle in a range of about 70° to 75° and most preferably at about 73°. As shown in  FIG. 9 , when the ladder is positioned at a 78° angle to the ground and the angle between the platform and brace sections is 73°, a 0° slope is present in the top surface of platform section  22 .  FIG. 10  shows that when the ladder is positioned at a 73° angle to the ground, a 73° angle between the platform and brace sections results in a 5° slope of the top surface of the platform element where the slope is downwards when moving from front (the brace section end) to back (the lock section end). In  FIG. 11 , it is shown that when the ladder is positioned at a 68° angle to the ground, a 73° angle between the platform and brace sections results in a 10° slope from front to back. Thus, the angle between the platform section  22  and brace section  24  is significant in controlling the level or slope of the support or step surface provided by platform section  22 . 
     To prevent damage to rails  16  of a ladder (e.g., by gouging), the bottom edge  32  of the brace element can include one or more plastic bumpers  38  (as shown in  FIG. 2 ) or be provided with a curled edge  40  (as shown in  FIG. 12 ). The curled edge may curl inward or outward. The bumper(s)  38  can be one continuous strip across the bottom edge  32  or be two strips positioned on the bottom edge for alignment with the rails of a ladder. A preferred plastic is polyethylene or the like as shown to have enduring protective strength. 
     Examples of preferred dimensions of the elements or sections of the step adapter are described below. These dimensions are such as to allow the step adapter to be useful with various conventional commercially available rigid rung ladders. The lengths (i.e., front to back measurements as described above) are the inside measurements of the described element or section after the bends or angles along line A or line B are provided in the device. 
     The brace element or section has a width of about 17 inches (43.18 cm) to about 20 inches (50.8 cm) and a length of about 5 inches (12.7 cm) to about 7 inches (17.78 cm). A most preferred embodiment based on sizing the range of commercial rung ladders is a width of about 19 inches (48.26 cm) wide by 6 inches (15.24 cm) in length. The bottom free edge of the brace element can be curled outward or inward to prevent the edge from gouging, marking or otherwise damaging the rails of the ladder in use. The curl can be continuous across the bottom edge or non-continuous wherein the curl preferably extends at least about 3 inches (7.62 cm) inward from each side edge of the brace element, see for example  FIG. 14  wherein the curl  40  extends inward as denoted by dashed line  40   a . In providing for the curl in the sheet metal format, extensions of desired width and length are provided extending from the free end of the brace section and curled inward or outward as desired. Alternatively, one or more slip covers can be placed on the bottom edge at least at the point the brace will abut the rails so as to protect the rails. The slip covers are preferably made of a durable plastic, e.g., polyethylene, and have a width of about 3 inches (7.62 cm) to about 4 inches (10.6 cm) in width, or can be sized to extend substantially along or along the entire width of the bottom edge. Additionally, the brace element may include openings of a desired shape, preferably circular as shown at  31  in  FIG. 14  (preferably of about ⅜ inch (9.525 mm) diameter) for receiving a clip attachment by which the step adapter could be carried and clipped to another structure for carrying or storage. Necessarily, such an opening could also be placed in another section of the step adapter (e.g., the platform section or lock section). However, since the brace section has the greater width, the opening(s) are preferably in the extended end(s) to allow for easier access to the openings in use and storage. 
     The platform element or section has a width of about 11 inches (27.94 cm) to about 13 inches (33.02 cm) in width and about 5 inches (12.7 cm) to about 7 inches (17.78 cm) in length. In a most preferred embodiment the platform element has a width of about 12½ inches (31.75 cm) by 5⅜ inches (13.6525 cm) in length. 
     The lock element or section has a width of about 11 inches (27.94 cm) to about 13 inches (33.02 cm) and a length of about 2 inches (5.08 cm) to about 4 inches (10.6 cm). In a most preferred embodiment, the lock element has a width of about 12½ inches (31.75 cm) and a length of about 3 inches (7.62 cm). As set forth above, the platform element and the lock element preferably are of the same width so as to provide the step adapter with clean lines with minimum corners or cuts. This contributes to allowing for simple fabrication of the step adapter and ease of use. 
     The safety element is positioned inward from line B on the underside of the platform element about 2 inches (5.08 cm) to about 4 inches (10.6 cm), most preferably about 2⅜ inches (6.0325 cm). The safety element includes a bar portion extending downward from the underside of the platform element. The distance between the lock element  20  when extended downward and the downward extending bar  26   a  of the safety element  26  is to be sufficient to position a ladder rung (whether round, semi-round or flat) therebetween. The bar portion is about 3 inches (7.62 cm) to about 6 inches (15.24 cm) in length and about ¾ inch (1.905 cm) to about 3 inches (7.62 cm) high. In the most preferred embodiment the bar portion is about 4 inches (10.6 cm) long and about 1¾ inches (4.445 cm) high. When the step adapter is a one piece injection molded structure, the safety element only requires the bar portion since, preferably, it is an integral part of the whole structure. When the step adapter is made from sheet metal, the safety element includes an extension or leg portion with the bar portion, preferably at a 90° angle to the bar portion. The leg portion will abut the underside of the platform and be fastened thereto by appropriate fastening means, such as rivets, screws, or the like. Preferably the fastening means are countersunk in the top surface of the platform so as to maintain an essentially uniform level in the top surface of the platform element since this is the surface a user will be stepping and standing on in use of the step adapter on a rung ladder. The leg portion will preferably have the same length as the bar portion, i.e., about 3 inches (7.62 cm) to about 6 inches (15.24 cm), and a width of about ¾ inch (1.905 cm) to about 1¼ inches (3.175 cm), with the preferred being about 4 inches (10.6 cm) to about 1 inch (2.54 cm). 
     Preferably two or three rivets are used to fasten the safety element to the platform element. Two rivets are adequate to provide sufficient fastening. In the absence of computer-controlled assembly or other assembly safeguard, three rivets can be used to prevent accidental mismounting, i.e., the bar portion of the safety element is to abut the rung of the ladder. This is achieved by having the two end rivets aligned with each other and the third rivet centered therebetween and out of alignment with the other two rivets. As an example of the spacing of the fastening elements, e.g., rivets, in a safety bar having dimensions of 1½ inches (3.81 cm) for the downward extending bar  26   a  and 4 inches (10.6 cm) in width, 3 inches (7.62 cm) preferably is between the two outermost rivets which should be evenly spaced from the ends. A third rivet, if desired, is then spaced between the two outermost rivets. 
     A further benefit in maintaining a level top surface to the platform element is the desirability of providing a non-skid surface to the top of the platform element. This can be provided by adhering to the surface an adhesive-backed non-skid material, e.g., rubber with grit provided thereon. Preferably, the non-skid material is permanently adhered to the top surface of the platform element. The non-skid material preferably has dimensions of about 4 inches (10.6 cm) in length by about 12⅜ inch (31.4325 cm) in width when used with the most preferred embodiment of the platform element of about 12½ inches (31.75 cm) in width and about 5⅜ inches (13.6525 cm) in length. The length and width of a non-skid surface can be adjusted as appropriate based on the size of the top surface of the platform element. Further, the non-skid material can be provided as a single strip or piece, or can be multiple small strips or pieces (of the same or different configuration) spaced over the width of the top surface of the platform section. 
     The choice of metal or injection molded plastic, thickness of metal or plastic, bend angles present are all selected for strength and stability, preferably so as to bear a weight of at least about 300 pounds (136.078 kg). 
     Tests were conducted on a step adapter as shown in  FIG. 14  to show weight bearing capacity of the step adapter. The step adapter tested was made of sheet aluminum having a ⅛ inch (3.175 mm) thickness. Measurements taken at 200 pounds (lbs.), 300 lbs. and 400 lbs. (up to and including 432.6 lbs.) were identical throughout at a depression value of 10 mm for a first adapter tested and a value of 8.8 mm for a second adapter tested. The difference in values was attributed to the second step adapter being tested using more sensitive equipment. That the depression value did not rise with increasing weight in either case, indicates that 400 lbs. was tolerated with no physical change in weight bearing capacity. No permanent depression was found to be present in the step adapter. 
     To further show the significance of the structure of the step adapter, another step adapter structure was tested. This step adapter was as shown in  FIG. 15  having a ⅛ inch (3.175 mm) thickness was identical to that tested and described above except that the platform section  24  had a rectangular cutout  42  with rounded corners 6 inches (15.24 cm) by 1¾ inch (4.445 cm) (such as could be used as a hand hold and/or to lessen the amount of aluminum used) and a cutout  44  in lock section  20  of 6½ inch (16.51 cm) by 2 inch (5.08 cm) to decrease the amount and weight of the aluminum used. A depression of 15 mm was shown at both of 200 lbs. and 300 lbs. This same step adapter structure with cutouts as in  FIG. 15  but of a 1/10 inch (2.54 mm) thickness, was also tested. A 16 mm depression was observed at both 200 lbs. and 300 lbs. The test equipment used in the tests of the step adapters with two cutouts was the same as used for the first tests above on the step adapter with no cutouts. 
     A step adapter as shown in  FIG. 15  except not containing cutout  42  (i.e., only containing cutout  44 ) was also tested as to weight bearing capacity at each of 200 lbs., 300 lbs., and 400 lbs. (up to and including 433.6 lbs.). The depression value of this step adapter was 8.8 mm. and did not rise throughout, even upon increasing the weight up to the tested amount of 433.6 lbs. The tests on this embodiment of the strip adapter were conducted using the same equipment used for the second tests described above on the step adapter with no cutouts. Accordingly, the results of tests on the step adapter embodiment with a single cutout in the lock section were equivalent to the results of the step adapter with no cutout, thereby indicating no physical change in weight bearing capacity even in the presence of cutout  44 . These test results as compared to those of the step adapter containing both cutouts  42  and  44  indicate that cutout  42  in the platform section is the feature causing a decrease in weight bearing capacity. 
     A second embodiment of the step adapter is shown in  FIGS. 16-20 . The second embodiment is similar to the first embodiment in that it contains a brace element  124 , a platform element  122 , and a lock element  120 . However, the second embodiment of the step adapter does not include a safety element  26 . Rather, in order to maintain the step adapter in place on a selected rung on a ladder, the second embodiment has a modified platform element in the nature of differently configured side edges  132  made up of edge sections  126 ,  127  and  128 . Edge section  128  transitions to edge section  127  through an angle  130 , which is preferably a rounded 90° angle. Edge section  127  than at corner  131  transitions to edge section  126 , where corner  131  is preferably a rounded 90° corner. 
     The step adapter of the second embodiment is bent along lines A and B in the same manner as the step adapter of the first embodiment.  FIG. 16 a    shows the step adapter of the second embodiment bent along lines A and B at the preferred angle of 73° as between the brace element  124  and the platform element  122 , and the preferred angle of 90° as between the platform element  122  and the lock element  120 . 
     When in place on a rung of a leaning ladder, edge section  128 , which is the same width as lock section  120 , extends through the rails of a ladder, and edge section  127  abuts the front of the rails of the ladder. With brace section  124  and edge section  127  abutting the rails of the ladder and lock section  120  around a rung between the rails, edge section  127  serves to keep the step adapter from moving forward through the rails thereby maintaining the step adapter in place on the ladder. The length of the edge section  126  is critical for blocking forward/inward motion of the step adapter when in place on a ladder. The length of edge section  126  is preferably about 2.6 inch (6.604 cm) to about 3 inches (7.62 cm), and most preferably about 2.875 inches (7.3025 cm). The total length of the edge section  132  is the same as in the platform element of the first embodiment, i.e., about 5 inches (12.7 cm) to about 7 inches (17.78 cm). The preferred total length of edge  132  is 5.625 inches (14.2875 cm) when edge section  126  is the preferred 2.875 inches (7.3025 cm). The length of edge section  128  is necessarily the difference between the total length of edge section  132  and the length of edge section  126 . The width of edge section  127  preferably is the same as the plastic bumper  38  (when not continuous such as shown in  FIG. 5 ) or curled edge  40 . The most preferred width is about 3 inches (7.62 cm). The thickness of the format, whether metal or plastic, is the same for both the first and second embodiments. Further, the width of brace element  124 , lock element  120  and platform section  122  is the same as in the first embodiment. The lock section preferably has a cutout  144  the same as cutout  44  in the first embodiment of the step adapter. The second embodiment of the step adapter can have additional features, such as openings  31 , non-skid surface(s) on platform  122 , curled edges  140 , etc., in the same manner as described in relation to the first embodiment of the step adapter. 
     The advantages of the step adapters of the invention include the absence of moving parts, simplicity and low cost of manufacture, simplicity of use with no known way of misuse, and safety features. The step adapters can be sized to use with various commercially available rigid rung ladders. The width of the ladder from rail to rail is important since the width provided in the brace element must be sufficient to extend from rail to rail and abut the rails. The widths of the lock element and the platform element are selected so that they pass between the rails to engage and rest upon a selected rung of the ladder. The diameter or circumference of the rung is significant since size and spacing of the lock element and the safety element must be such so that the rung is engaged between the lock element and safety element so as to retain the rung therebetween when a step adapter is positioned for use on a rung ladder. Accordingly, ranges and preferred embodiments of sizes of the elements/sections of the step adapters are preferably selected to be useful with various commercially available rigid rung ladders or may be adjusted to be customized to a particular ladder structure. 
     The step adapter in addition to being a support for a user of a rung ladder, may also serve as a support for a table or tray overlay to provide for a work area on which a user of a rung ladder can hold items, such as a paint can, tool(s), drink container, etc. The table or tray overlay is shown in  FIGS. 21-23 . 
     The overlay  141  is a one piece substrate which can be made of metal or plastic, and preferably is made of aluminum metal of a thickness which is preferably about 1/10 inch (2.54 mm) to about ⅛ inch (3.175 mm). The preferred thickness of a metal overlay is ⅛ inch (3.175 mm). 
     The overlay includes a first section bounded by sides  148   a ,  148   b , and  148   c . The width of this first section is preferably the same as the width of the platform element of the step adapter and is dimensioned to pass through the interior space between the rails of the ladder. The length is such that it may extend beyond the step adapter platform element as shown in  FIG. 22 . The overlay also includes a second section  150  having a width greater than the width of the first section and, preferably, the same as brace section  24  or  124 . Transition angles  152  are present to provide a continuous structure between sides  148   a  and  148   c  and wing sides  150   a  and  150   b , respectively, of the second section  150 . At this point, wing sides  150   a  and  150   b  and sides  148   a  and  148   c  each abut the rails of the ladder when a step adapter containing an overlay thereon is seated upon a rung of a ladder. The overlay  141  preferably is attached by one or more suitable fastening elements, e.g., rivet(s), screw(s), bolt(s), or the like, through openings  142  and/or  142   a . The table or tray overlay  141  will then be attached to the step adapter  10  as shown in  FIGS. 22 and 23 . Preferably, the openings are recessed so that when a fastening element is placed therein, the head will be countersunk to provide a uniform top surface to overlay  141 . 
     Preferably, the overlay  141  has an upraised wall or curb  146  on one or more edges of the overlay. More preferably, curbs  146  are on all edges except the front edge of the second section  150 . Curbs  146  and  146   a  can be present in a height of 0 to about ¼ inch (6.35 mm) or of a sufficient height generally to avoid items being positioned over an outer edge of the overlay and to avoid items falling off the overlay. 
     The top surface of the overlay may be provided with a non-skid surface, e.g., a grit material adhered to the top surface. Further, when the overlay is made of molded plastic, recessed areas may be formed therein to aid maintenance of items in place on the overlay, e.g., a circular recess of appropriate size to hold a drink container or paint container, a rectangular recess for holding one or more tools or the like, etc. 
     The exemplary embodiments herein disclosed are not intended to be exhaustive or to unnecessarily limit the scope of the invention. The exemplary embodiments were chosen and described in order to explain the principles of the present invention so that others skilled in the art may practice the invention. As will be apparent to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.