certain terminology is used in the following description for convenience only and is not considered limiting . words such as “ front ”, “ back ”, “ top ” and “ bottom ” designate directions in the drawings to which reference is made . this terminology includes the words specifically noted above , derivatives thereof and words of similar import . additionally , the terms “ a ” and “ one ” are defined as including one or more of the referenced item unless specifically noted . in the drawings , “( typ )” has been used to indicate that an element number is “ typical ” for all instances of a particular element where more than one of the elements are shown ( for example the opening 20 designated as “( typ )” in fig1 ). the preferred embodiments of the present invention will be described with reference to the drawing figures where like numerals represent like elements throughout . referring to fig1 - 4 , a portable step 10 in accordance with the first preferred embodiment of the present invention is shown . as can be seen most clearly in fig1 and 2 , the step 10 includes a right sidewall 12 and a left sidewall 14 , each having a plurality of connection openings 20 extending therethrough . two individual treads 22 and two risers 40 are connected between the sidewalls 12 , 14 using pegs 34 , 54 , respectively , which extend from each side of the treads 22 and risers 40 that engage in the openings 20 . additionally , as shown in detail in fig2 , a support bar 60 with pegs 61 is connected between the sidewalls 12 and 14 at the back , bottom corner of each for additional support . as shown in fig1 , preferably the treads 22 are angled downwardly between an angle of approximately 5 ° and 15 °, more preferably between an angle of 8 ° and 12 °, and most preferably at an angle of 10 ° with respect to horizontal . additionally , the treads 22 preferably have a depth of approximately twice the height of a riser 40 . in the first preferred embodiment , the risers 40 are approximately five inches tall and the treads have a depth of approximately 10 inches or more . this ratio can vary such that the depth of the tread 22 is preferably between 1 . 5 and 2 . 5 times a height of the riser 40 . preferably , the risers 40 and treads 22 have a curved profile at the front of each step to allow for easier use . referring to fig6 - 9 , the construction of the tread 22 is shown in detail . the tread 22 is preferably formed from a blow molded polymeric material and includes a top skin 24 and a bottom skin 26 . a depression 25 is preferably provided in the top skin 24 for mounting of an anti - slip material 30 , such as a piece of carpet , rubber , or any other suitable material . in a preferred embodiment , the anti - slip material 30 is attached through hook and loop type textile fastening strips , such as velcro ®, with the hook and loop textile fastening strips of one type 29 being located on the top skin 24 , preferably in further recesses 33 , and opposing hook and loop type textile fastener strips 32 being located on the anti - slip material 30 . the pegs 34 preferably extend from the edge walls 28 on either side of the tread 22 . the pegs 34 are preferably constructed with an enlarged cylindrical shoulder 35 adjacent to the base and include an enlarged diameter end section 36 having tabs 37 located at approximately the 3 o &# 39 ; clock and 9 o &# 39 ; clock positions . preferably , two pegs 34 are provided on each side of the tread 22 . referring to fig7 - 9 , the bottom skin 26 of the tread 22 preferably includes stiffening depressions 27 located therein . the stiffening depressions 27 provide support for the top skin 24 as shown most clearly in fig9 and provide additional stiffness for the tread 22 . while the preferred embodiment of the tread 22 is preferably blow molded from polypropylene , those skills in the art will recognize that the tread 22 could be formed from other materials and by other means , and that one key feature of the present invention is to provide the releasably engageable pegs 34 , preferably having the indicated configuration for assembly of the treads 22 with the sidewalls 12 , 14 . referring to fig1 - 13 , the sidewalls 12 , 14 are shown in detail . the sidewalls 12 , 14 each include an outer skin 15 and an inner skin 16 . the openings 20 are defined through the outer and inner skins 15 , 16 of both sidewalls 12 , 14 . the openings have a continuous wall that extends between the inner and outer skins 15 , 16 . as shown in fig1 and 12 , recesses 21 are provided on both sides of the openings 20 in corresponding positions to the tabs 37 of the pegs 34 for a first set of the openings , and in corresponding positions to the tabs 57 of the pegs 54 for a second set of the openings . as shown in fig1 and 13 , each of the openings 20 has a circular shoulder 19 defined therein which corresponds to the shoulder 35 at the base of the pegs 34 of the tread as well as to the shoulders 55 and 62 on the pegs 54 and 61 of the risers 40 and support bar 60 , which are described in further detail below . the circular shoulder 19 in the opening 20 preferably provides a snug fit for the pegs 34 , 54 , 61 so that a good weight transferring connection is provided . preferably , the pegs 34 , 54 , 61 can be pressed through the openings 20 and the tabs 37 , 57 and 64 can engage behind the shoulder 19 in the openings 20 to hold the treads 22 , risers 40 and support bar 60 to the sidewalls 12 , 14 , as shown in fig5 . the sidewalls 12 , 14 are preferably also blow molded from polypropylene , although other materials and / or methods of fabrication can be utilized . the blow molded configuration allows the continuous wall defining the openings 20 between the inner and out skins 15 , 16 to flex for assembly and disassembly . referring to fig1 - 17 , one of the risers 40 is shown in detail . the risers 40 are preferably also formed from blow molded polymeric material , preferably polypropylene , and include a front skin 42 and a back skin 44 , shown best in fig2 , with an edge wall 46 extending between the front skin 42 and back skin 44 . pegs 54 , which are similar to the pegs 34 as described above , extend from both sides of the riser 40 . the peg 54 includes the circular shoulder 55 located at the base and an enlarged end 56 having tabs 57 located at the 12 o &# 39 ; clock and 6 o &# 39 ; clock positions . the openings 20 in the sidewalls 12 and 14 include corresponding recesses 21 , as indicated in detail in fig1 and 12 . the shoulders 55 provide a snug fit with the circular recesses that define the shoulder 19 in the inner skins 16 of the side walls 12 and 14 , as discussed above . preferably , as shown in fig2 , the back skin 44 of the riser 40 includes stiffening depressions 45 to provide added stiffness to the risers 40 . it is envisioned that these stiffening elements , including those formed on the sidewalls and treads , are not limited to being formed as depressions . similar contours including ribs , protrusions , and other suitable forms may be utilized to accomplish the desired stiffening effect . while it is preferred that the risers 40 are formed from blow molded polymeric material , those skilled in the art will recognize that the risers 40 can be formed from other suitable materials and / or other construction methods . referring to fig1 and 19 , the support bar 60 is shown in detail . the support bar 60 preferably includes pegs 61 at each end . the pegs 61 have the same configuration as the pegs 34 and 54 for the treads 22 and risers 40 , respectively . this includes the shoulder 62 which is adapted to fit into the circular recess formed by the shoulder 19 of the openings 20 in the inner skin 16 of the sidewalls 12 , 14 . an enlarged end 63 with tabs 64 is similarly provided for engagement through the openings 20 . preferably , the support bar 60 is formed from a polymeric material , such as polypropylene , and may include stiffening ribs or recesses 66 which extend longitudinally along the support bar 60 for added stiffness . in the preferred embodiment , the material used for the treads , sidewalls , risers and support bar is polypropylene having a wall thickness of about 0 . 1 inches . however , other polymeric or non - polymeric materials could be utilized , and the hollow wall construction is not required , although preferred . other light - weight solid or sandwiched panel constructions could also be employed . in order to assemble the portable step 10 , preferably sidewalls 12 and 14 are provided along with two of the treads 22 , two of the risers 40 and one support bar 60 . preferably , the pegs 34 of each tread 22 are pressed into the corresponding openings 20 of the left sidewall 14 and the pegs 54 of the risers 40 are similarly pressed into the openings 20 of the left sidewall 14 . one end of the support bar 60 is similarly inserted into the corresponding opening 20 in the left sidewall 14 . the right side wall 12 is then positioned over the pegs 34 , 54 and 61 of the treads 22 , risers 40 and support bars 60 , respectively . by pressing the sidewalls 12 , 14 , toward one another , the pegs 34 , 54 , 61 pass through the inner shoulders 19 of the openings 20 and the tabs 37 , 57 , 64 engage behind the shoulder 19 and are aligned in the recesses 21 , visible in the outer skins 15 of the sidewalls 12 , 14 . the anti - slip material 30 , such as pieces of carpet can be applied to the treads 22 using the hook and loop type textile fastening strips 29 , 32 . this provides a light weight step which is suitable for use by pets for climbing to and from an elevated surface , with the extended treads which are sloped downwardly providing ease of use and creating less trepidation in the pet as it moves up and down the portable step 10 . referring now to fig2 - 24 , a second embodiment of a step 100 in accordance with the present invention is shown . the second embodiment of the step 100 has three treads 122 and three risers 140 located between two sidewalls 112 , 114 . the second embodiment of the step 100 is similar to the first embodiment of the step 10 in its construction and similar parts have been identified with similar element numbers for ease of reference . fig2 and 22 show rear perspective views of the step 110 indicating the location of the sidewalls 112 , 114 , the treads 122 , the risers 140 and the support bar 160 connected at the rear bottom corners of the sidewalls 112 , 114 . as shown , the sidewalls 112 , 114 , treads 122 and risers 140 are all preferably formed of a polymeric material , preferably by blow molding , and include stiffening depressions in the inner skins which are not apparent in normal use . as shown in fig2 , preferably anti - slip material 130 , such as pieces of carpeting are affixed to the treads 122 , preferably using hook and loop type textile fastening strips 129 , shown in fig2 and corresponding strips on the underside of the anti - slip material 130 , similar to the strip 32 described above in connection with the first preferred embodiment . referring to fig2 , a partially assembled right side elevational view of the second embodiment of the step 100 is shown . specifically , the left sidewall 114 is shown with the treads 122 , risers 140 and support bar 160 connected via the respective pegs 134 , 154 and 161 inserted in the corresponding openings 120 in the sidewall 114 . as discussed above in connection with the first embodiment of the step 10 , the right sidewall 112 is then placed over the partially assembled step as shown in fig2 with the upwardly directed pegs 134 , 154 and 161 being aligned with the corresponding openings 120 in the right side wall 112 , and the assembly is then pressed together such that the pegs 134 , 154 , 161 extend through the openings 120 and the enlarged diameter ends 136 , 156 , 163 with the tabs 137 , 157 and 164 engage behind the shoulders 119 of the openings . referring to fig2 and 26 , the right sidewall 112 is shown in detail with the outer skin 115 shown in fig2 and the inner skin 116 shown in fig2 . stiffening depressions 117 are provided in the inner skin 116 for added stiffness to the sidewall 112 . the recesses 121 for the tabs of the pegs are shown in fig2 and the shoulders 119 in the openings 120 are shown most clearly in fig2 . fig2 illustrates the left sidewall 114 with the outer skin 115 . the inner skin 116 of the left sidewall 114 is similar to the inner skin 115 of the right sidewall 112 , as shown in fig2 as well . fig2 - 30 show the construction of the tread 122 which includes the hook and loop type textile fastening strips 129 located in recesses 133 as well as the recess 125 in the upper skin 124 for the anti - slip material 130 . the construction of the pegs 134 with the circular shoulder 135 at the base along with the enlarged diameter end 136 with tabs 137 is also clearly illustrated . the construction of the tread 122 is similar to the tread 22 and preferably the ratios of tread depth to riser height are as discussed above , although in the second preferred embodiment , the tread 122 is only approximately 9 inches deep at the sidewalls as opposed to the tread 22 of the first embodiment of the invention being approximately 11 inches deep at the sidewalls . the construction of the risers 140 is the same as that of the risers 40 discussed above and accordingly has not been repeated . referring to fig3 and 32 , an enlarged detail of a portion of a sidewall 12 , 14 , 112 , 114 is shown in the area of an opening 20 , 120 . fig3 shows the outer skin of the sidewall 12 , 14 , 112 , 114 , wherein the shoulder 19 , 119 within the opening 20 , 120 is clear as well as the recesses 21 , 121 for receiving the tabs located at the ends of the pegs 34 , 54 , 61 , 134 , 154 , 161 . referring to fig3 , the inner skin of the sidewalls 12 , 14 , 112 , 114 is illustrated at the opening 20 , 120 . here the enlarged diameter of the opening 20 which corresponds to the diameter of the shoulder 35 , 55 , 63 , 135 , 155 , 163 at the base of the pegs 34 , 54 , 61 , 134 , 154 , 161 is shown . in the preferred embodiment , the shoulder 35 , 55 , 63 , 135 , 155 , 163 at the base of the peg has a diameter of about 0 . 70 inches and corresponds to the diameter of the opening in the inner skin of the sidewall 12 , 14 , 112 , 114 . the shoulder 19 , 119 in the opening 20 , 120 has an inside diameter of approximately 0 . 68 inches . the peg has a diameter of approximately 0 . 62 inches at the intermediate portion and the enlarged diameter end of the peg has a diameter of approximately 0 . 65 inches . the tabs 37 , 57 , 64 on the ends of the peg extend to an effective diameter of approximately 0 . 69 inches . while the approximate dimensions from the preferred embodiments of the steps 10 , 100 have been given , those skilled in the art will recognize that other dimensions can be utilized in order to form the connections between the treads , risers , support bars and sidewalls in order to form the steps 10 , 100 . fig3 and 34 provide enlarged detail cross - sections of the openings 20 , 120 and the pegs 34 , 54 , 134 , 154 . the pegs 61 , 161 are of the same construction as well . an advantage of the steps 10 , 100 according to the present invention is that the treads and sidewalls are generally flat and can be easily flat packed and the risers are only slightly curved also allowing for generally flat packing for shipping . due to the hollow wall construction , the steps 10 , 100 according to the invention provide exceptional strength while maintaining a light weight that allows not only for lower costs for shipping but also easier handling by the ultimate end user . additionally , the peg and opening connection used by the steps 10 , 100 according to the invention allow for repeated assembly and disassembly for cleaning and / or storage . the removable anti - slip material 30 , 130 is also easily removable for cleaning and / or replacement . while the preferred embodiments have been described with two or three steps , the invention can be applied to steps having a different number of treads and risers , and for steps of various widths and heights , and the invention is not limited to the two preferred configurations noted above . the present invention is also not limited to a step assembly for use by pets , and combinations described herein may be used with any construction that aids in moving between different heights . having thus described in detail several embodiments the present invention , it is to be appreciated and will be apparent to those skilled in the art that many physical changes , only a few of which are exemplified in the detailed description of the invention , could be made without altering the inventive concepts and principles embodied therein . it is also to be appreciated that numerous embodiments incorporating only part of the preferred embodiment are possible which do not alter , with respect to those parts , the inventive concepts and principles embodied therein . the present embodiment and optional configurations are therefore to be considered in all respects as exemplary and / or illustrative and not restrictive , the scope of the invention being indicated by the appended claims rather than by the foregoing description , and all alternate embodiments and changes to this embodiment which come within the meaning and range of equivalency of said claims are therefore to be embraced therein .
a step assembly that is specifically adapted to assist pets in reaching and / or descending from elevated surfaces is provided . the step assembly has two sidewalls having a plurality of openings in which pegs formed on the sides of individual treads and risers are engaged . the pegs are removably insertable into the openings and include protrusions which create an interference fit upon insertion . because the treads , risers and side walls are joined by interlocking pegs and openings , the step assembly can be flat packed for shipping , and is easily assembled and disassembled for transportation and / or cleaning .