Patent Publication Number: US-2022219613-A1

Title: Quick disconnect for detachable stair system

Description:
RELATED PATENT APPLICATIONS 
     This is a divisional application and claims priority under 35 USC § 121 of U.S. patent application Ser. No. 16/878,435 filed May 19, 2020, which matures into U.S. Pat. No. 11,292,391 on Apr. 5, 2022. That application claimed priority under 35 USC. § 119(e) from U.S. Provisional Patent Application Ser. No. 62/910,628 filed Oct. 4, 2019, entitled QUICK DISCONNECT FOR DETACHABLE STAIR SYSTEM. U.S. patent application Ser. No. 16/878,435 also claimed the benefit of priority from U.S. Provisional Patent Application Ser. No. 62/850,531, filed May 20, 2019, entitled RETRACTABLE STAIR SYSTEM. U.S. patent application Ser. No. 16/878,435 additionally cross-referenced and incorporated by reference U.S. Non-Provisional patent application Ser. No. 16/878,404, filed May 19, 2020, entitled RETRACTABLE STAIR SYSTEM. 
    
    
     STATEMENT OF GOVERNMENT INTEREST 
     Not Applicable. 
     COPYRIGHT RIGHTS IN THE DRAWING 
     A portion of the disclosure of this patent document contains material that is subject to copyright protection. The patent owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. 
     TECHNICAL FIELD 
     This disclosure relates to adjustable stairs, and in particular, to adjustable stairs configured for use with driven or towed vehicles, and especially, motor homes and recreational vehicles, including campers on pickup trucks, or on towed campers, or the like. 
     BACKGROUND 
     A continuing need exists for improvements in stair systems for use in accessing a variety of driven or towed vehicles. Often, vehicles of various types park at locations where an entrance door or platform is at a level above the ground where ease and/or safety of access to the vehicle would be facilitated by the availability of a stair system. Further, quite often a vehicle may be parked over sloping or uneven ground, so placement of legs on the ground, for support or stability, is often problematic in prior art designs of which we are aware. A wide variety of stair structures have been known and utilized as appropriate for various applications. And, although many of such prior art stair structures have been constructed which in some limited fashion enable a user to effect or provide some adjustment in the stairs, at least in the case of campers used on pickup trucks, adjustment is generally only with respect to extension from the camper. Thus, often a separate stool, block of wood, or other structure is necessary for placement on the ground in order to provide a reasonable height for users to access many prior art stair designs for campers. 
     A common problem encountered in prior art stair systems is that such stairs often are provided as a part of a structure, similar to an outward opening door on an aircraft, which leaves the stair system in place, even when not in use, and after it has been folded or retracted. Alternately, in many prior art designs the stairs become permanently affixed to a doorway opening when installed, so that they are always in the doorway, whether in use or folded up. Thus, such prior art stair structures inevitably interfere from time to time with the full use and enjoyment of the doorway area just interior to the doorway in a vehicle, e.g., the doorway of a camper trailer, or the entry/exit door provided on a pickup truck camper. 
     A previous retractable stair system design owned by the applicant herein, namely Torklift International, Inc. provided some advantages over various prior art stair systems for vehicles, and such details were disclosed in prior U.S. Pat. No. 9,527,448 B1, issued to Jack KAY and Joel CRAWFORD, on Dec. 27, 2016, entitled RETRACTABLE STAIR SYSTEM WITH PRECISION ELEVATION CONTROL. The disclosure of the just mentioned patent is incorporated herein in its entirety, including the specification, drawing, and claims, by this reference. 
     Nevertheless, there remains a continuing and unmet need for a detachable stair system which may be quickly and easily installed in, and quickly and easily removed from, a vehicle doorway. It would be advantageous, especially in vehicles such as in a camper in which a stair system is mounted, that the stairs are easily deployed, and easily removed, for out-of-the-way storage when not in use. It would be particularly advantageous if the weight of the detachable stairs allowed easy extension for use, removal when not in use, and installation when use is desired, by a single adult without resort to tools or lifting devices. 
     Some Objects, Advantages, and Novel Features 
     An objective of our invention is to provide a design for a detachable stair system in which it is easy for user to install and remove the stairs, without the necessity of use of lifting devices or tools of various sorts. 
     Another objective of our invention is to provide a design for a detachable stair system in which the support pad distance below the bottom step is individually adjustable, to accommodate uneven ground at either side of the step. 
     Another important objective is to provide a quickly removable detachable stair portion in a detachable stair system which is easily and rapidly adjustable in total stair height, yet retains the ability to evenly space the height between individual stair steps. 
     Another important objective is to provide a detachable stair system in which the stairs are sturdy and of high strength, especially when quickly removable and easily portable. 
     Yet another important objective is to provide a compact detachable stair system structure and mounting hardware design in which the stairs may be neatly and securely stowed inside the vehicle when not in use, for example when the vehicle is in service over the road. 
     Finally, another important objective is to provide a compact detachable stair system structure and mounting hardware design in which the stairs may be easily and quickly installed in existing or new vehicles, and may be easily and quickly removed for storage. 
     SUMMARY 
     We have now invented a detachable stair system for vehicles which provides for easy removal and stowage of stairs when not in use, and which provides convenient, easy installation of stairs when they need to be deployed for use in a vehicle. This is important since it enhances ease of use of the doorway space in a vehicle (i.e. minimizes lost space occupied by a permanently mounted stair system), and thus increases the ease of access to and from a vehicle (e.g., a camper mounted on the back of a pickup truck) when the use of stairs is not needed or desired. Moreover, the design provides for a quick pivot disconnect structure for ease of deployment and ease of removal, so that the detachable stair system can be easily and quickly installed by or removed by a user, without the necessity for tools. 
     In various embodiments, a quick disconnect for a detachable stair system as disclosed herein may include four major components. These major components are (a) a pair of mounting brackets for use at a first and second side of a doorway in a vehicle for pivotally deploying a detachable stair portion in a detachable stair system, each of the mounting brackets including an inwardly extending pivot stud for pivotally supporting a detachable stair system, (b) a sill cover plate, (c) a pair of open jaw brackets affixed to the ends of the sill cover plate, wherein the open jaw of each of the brackets is sized and shaped for secure pivotable motion about the pivot studs, and (d) a latch assembly, the latch mounted on a stair assembly and configured for movement into and out of a latch slot on one or more of the mounting brackets. The latch assembly may be a manually adjustable latching system, configured for locking the extensible-retractable scissors stair assembly in a closed position in a vehicle doorway. In an embodiment, a manually deployable locking tab and receiving slot system may be used, where a sliding locking tab is adjustably locatable into or out of one or more latch holes configured as a receiving slot in a mounting bracket, so that when the manually deployable locking tab is adjusted, the locking tab can be configured for secure interfitting engagement with the edges of the receiving slot. In this manner, a latch at one or both sides of the stairs may secure a detachable stair portion in a stowed position, when desired. 
     Moreover, the quick disconnect for detachable stair system described herein, after initial installation of mounting brackets, needs no tools, or extra or loose parts, bolts, or other components for on-site assembly, installation, use, or removal. Resultantly, the pivotably deployable quick disconnect for detachable stair system disclosed herein is easy to use, since all necessary components are already on board and readily available. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The present invention(s) are fully described herein by way of exemplary embodiments, using for illustration the accompanying drawing in which like reference numerals denote like elements in the various figures of the drawing, and in which: 
         FIG. 1  is a perspective view of an embodiment for a pivotably stowable detachable stair system, in a fully retracted configuration, and having a quick disconnect pivot mechanism, showing mounting brackets for mounting in a doorway, and showing one of a pair of open jaw brackets affixed to the ends of a sill cover plate, wherein the open jaw of each one of the open jaw brackets is sized and shaped for secure pivotable motion about pivot studs provided on the mounting brackets. 
         FIG. 2  is a partial perspective view of the right side mounting bracket, showing one of the open jaw brackets affixed to an end of the sill cover plate, wherein the open jaw of the right end open jaw bracket is engaged with the right side pivot stud, showing how the right end open jaw bracket is sized and shaped for secure pivotable motion about the right side pivot stud, and wherein a latch tab in the latch assembly is engaged with latch hole in a mounting bracket. 
         FIG. 3  is a partial perspective view of the right side of the detachable stair system, similar to the view just depicted in  FIG. 2 , but now showing the right side mounting bracket with the right end open jaw bracket disengaged from the right side pivot stud, and wherein the latch has been disengaged from the right side mounting bracket, as occurs when the stairs are removed for storage. 
         FIG. 4  is a partial perspective view of the right side mounting bracket, and the locking tab in the unlocked position, showing one of the open jaw brackets affixed to the right end of the sill cover plate, wherein the open jaw of the right end open jaw bracket is engaged with the right side pivot stud, showing how the right end open jaw bracket is sized and shaped for secure pivotable motion about the right side pivot stud, and wherein the detachable stairs have been pivoted outwardly and downwardly toward a working position, wherein the sill cover plate is substantially horizontal in position, and also showing an arcuate slot provided to engage a locking stud, and where the arcuate slot has a proximal, closed end and a distal, open end, with the arcuate slot defined between a curved base edge and the inner edge of a curved finger that extends outwardly from the open jaw bracket, and wherein the arcuate slot is sized and shaped for secure sliding engagement therein of the locking stud. 
         FIG. 5  is a perspective view of the inside of the right side mounting bracket, showing the locking tab receiving slot at the top, and the pivot stud for supporting the right end open jaw bracket, and the locking stud for interfitting sliding engagement with and sliding containment in the arcuate slot in the open jaw bracket. 
         FIG. 6  is a perspective view of the outside of the right side mounting bracket, showing a locking tab receiving slot at the top, and the mounting hardware for the pivot stud for supporting the right end open jaw bracket, and the mounting hardware for the locking stud. 
         FIG. 7  is a partial perspective view of the backside of the right side mounting bracket and a partial cutaway of the detachable stairs, showing the locking tab receiving slot at the top, and sliding action for locking and unlocking the stairs by having the tab engage and disengage the locking tab receiving slot. 
         FIG. 8  is a perspective view of the inside of the right side mounting bracket, similar to the view shown in  FIG. 5  above, but now showing the mounting bracket installed in the door frame of a recreational vehicle, ready for receiving a detachable stair portion, and utilizing a quick connect bracket system. 
         FIG. 9  is a partial perspective view of the right side of the detachable stair system, similar to the view depicted above in  FIG. 3 , showing the right side mounting bracket with the right end open jaw bracket disengaged from the right side pivot stud, but aligned with and ready to be lowered to the right side pivot stud, so the right end open jaw bracket rests on the pivot stud ready for pivoting action thereon. 
         FIG. 10  is a partial perspective view of the right side mounting bracket, similar to the view just depicted in  FIG. 9  above, showing the right side mounting bracket in place in a doorway of a recreational vehicle, with the right end open jaw bracket pivotally connected to the and engaged with the right side pivot stud, showing how the right end open jaw bracket is sized and shaped for secure pivotable motion about the right side pivot stud. 
         FIG. 11  is a perspective view of the right side mounting bracket, with the detachable stair system with quick disconnect mounted for use, showing the sill cover plate in a substantially horizontal position, ready for extension of stairs outward and downward for use. 
         FIG. 12  is a perspective view of a detachable stair system in use, showing the right end open jaw bracket in place on the right side pivot stud, and showing the sill cover plate in a substantially horizontal position, so that a door of the vehicle may be closed over the sill cover plate, and with the stairs extended outward and downward into an operating position, ready for use. 
     
    
    
     The foregoing figures, being merely exemplary, contain various elements that may be present or omitted from a final configuration for an embodiment of a quick disconnect apparatus for a detachable stair system, where quick disconnect brackets are pivotably mounted to pivot studs extending inwardly from left and right mounting brackets. Other variations in quick disconnect components for detachable stair systems for vehicles may use other mechanical structures, mechanical arrangements, or size and shape of components, and yet employ the principles described herein and as generally depicted in the drawing figures provided, and as more specifically called out in the claims set forth below. In particular, although various dimensions may be utilized by those of skill in the art to make and use the claimed invention, and there is no intention to limit the claimed invention to dimensional data, any of which is exemplary rather than mandatory. Thus, quick disconnect components for a detachable stair system may be provided which is sized up or down from any dimensions depicted, without affecting the scope of the appended claims. An attempt has been made to draw the figures in a way that illustrates at least those elements that are significant for an understanding of exemplary quick disconnect apparatus for detachable stair systems which may be used in various types of vehicles. 
     It should be understood that various features may be utilized in accord with the teachings hereof, as may be useful in different embodiments as useful for various sizes and shapes of quick disconnect components for detachable stair systems for vehicles, depending upon the specific requirements (such as typical height of the bottom of a vehicle door above a road, or doorway dimensions, or vehicle door sill configuration) within the scope and coverage of the teachings herein as defined by the claims. Further, like features in various embodiments for a quick disconnect apparatus for detachable stair systems may be described using like reference numerals, or other like references, without further mention thereof. 
     DETAILED DESCRIPTION 
     Attention is directed to  FIG. 1 , which provides a perspective view of a detachable stair system  20 , with a detachable stair portion  21  (also see  FIG. 3 ) in an inverted position with feet  22  pointing upward, as if mounted above floor  24  in a recreational vehicle doorway (doorway details not shown). In various embodiments, a recreational vehicle doorway may have a left side door frame adjacent the left side mounting bracket  31 . Similarly, a right side door frame may be provided adjacent the right side mounting bracket  32 . As illustrated in  FIG. 1 , the detachable stair portion  21  includes a retractable stair assembly RSA which is folded into a compact position  30  for storage. In this position, the detachable stair portion  21  is pivotally supported between the left side mounting bracket  31  and the right side mounting bracket  32 . In an embodiment, the detachable stair portion  21  may include most or all components other than bracket  31 , bracket  32 , a floor plate  33  which extends between bracket  31  and bracket  32 , and the pivot studs, mounting hardware, and adjustment hardware on the brackets  31  and  32 , all of which is further discussed below. The floor plate  33  may be affixed to (e.g. by using fasteners), or integrally provided with (e.g. by welding or mechanical interlock), and located between the left side mounting bracket  31  and the right side mounting bracket  32 . As seen in  FIG. 6 , in an embodiment, the bottom  32   B  of mounting bracket  32  is affixed to an upper surface  33   U  of the floor plate  33 . As seen in  FIG. 5 , a floor plate  33  may be provided having a depth D 33 . In an embodiment the depth D 32  of bracket  32  may be the same as the depth D 33  of floor plate  33 . In an embodiment, as seen in  FIG. 1 , the overall width of floor plate  33  may be sized as the overall width Do available for mounting the detachable stair system  20  in a recreational vehicle. For standard recreational vehicle doorway widths, it has been found convenient to provide floor plates  33  having an overall width Do of about twenty three and seven sixteenths of an inch (23 7/16″) for narrow doors, and about twenty seven and seven sixteenths of an inch (27 7/16″) for wider doors. Importantly, the use of a floor plate  33  simplifies installation, and thus reduces installation time, and may also avoid or at least minimize the use of intrusive fasteners otherwise necessary in order to securely place the detachable stair system  20  in the doorway of a recreational vehicle. 
     In an embodiment, the detachable stair portion  21  may be latched (details below) to the right mounting bracket  32 . A sill cover plate  34  is provided, having a right end  36  and a left end  38 . The sill cover plate  34  may have a sill cover plate base  34   B  that is configured to be deployed in a substantially horizontal configuration when the detachable stair assembly RSA is in use (see  FIGS. 4 and 12 ) so that a door of a recreational vehicle (e.g. trailer door, pickup camper door, or motorhome door, not shown) may be closed above the sill cover plate  34 . Additionally, the sill cover plate  34  may include additional panels, such as panels  34   A ,  34   C    34   D , and  34   E , and  34   F  in the configuration depicted in  FIGS. 1 and 4 . In an embodiment, a sill cover plate  34  may be sized, shaped, and structurally suited for support of a right end pivot bracket, such as the right end open jaw bracket  40  and for support of a left end pivot bracket, such as the left end open jaw bracket  42 . 
     When a quick disconnect mechanism is used, as described herein, a right end open jaw bracket  40  and a left end open jaw bracket  42  (in an embodiment, a mirror image of right end open jaw bracket  40 ) are provided. The right end open jaw bracket  40  may be affixed to the right end  36  of the sill cover plate  34 , and the left end open jaw bracket  42  may be affixed to the left end  38  of the sill cover plate  34 . In an embodiment, the right end open jaw bracket  40  (and mirror image left end open jaw bracket  42 ) may be affixed to panels  34   A  and  34   B  of the sill cover plate  34 . In order to facilitate a suitable clearance for pivoting motion, the sill cover plate  34  may include cutout portions  34   Z  in the ends of sill cover plate adjacent the right end and left end open jaw brackets  40  and  42 . In an embodiment, cutouts  34   Z  may be provided in the thickness of the right end and left end open jaw brackets  40  and  42 . In an embodiment, the right end open jaw bracket  40  (and mirror image left end open jaw bracket  42 ) may be affixed to panels  34   A  and  34   B  of the sill cover plate  34  via welds  34   1  and  34   2 , as seen in  FIG. 4 . In any event, the right end open jaw bracket  40  (and mirror image left end open jaw bracket  42 ) are operably connected to the retractable stair assembly RSA in a manner that the retractable stair assembly RSA may be placed into a stairs deployed condition as indicated in  FIG. 12 , or alternately placed into a retracted positon as seen in  FIG. 1 . 
     As better seen in  FIG. 2 , in an embodiment, the right end open jaw bracket  40  (and mirror image left end open jaw bracket  42 ) may be provided as a fixed plate having a thickness T. In various embodiments, thickness T may be about one-quarter inch (¼″). In an embodiment, the thickness T may be in the range of from about 0.20 inches to about 0.30 inches. As may be appreciated from  FIG. 3 , in an embodiment, each of the fixed plates that provide right and left end open jaw brackets  40  and  42  may include a pivot end  44  in which a generally U-shaped pivot stud receiver  46  is defined by an interior sidewall  48  having a proximal end  50 . The pivot stud receiver  46  in left end open jaw bracket  42  may be sized and shaped for interfitting pivotal engagement with a pivot stud  52   1  on the left side mounting bracket  31 . Similarly, the pivot stud receiver  46  in right end open jaw bracket  40  may be sized and shaped for interfitting pivotal engagement with a pivot stud  52   2  on the right side mounting bracket  32 . In an embodiment, a left side mounting bracket  31  (see  FIG. 6 ) may be provided as a mirror image of the right side mounting bracket  32  that was just illustrated in  FIG. 5 , and vice versa. 
     In an embodiment, the right end open jaw bracket  40  and the left end open jaw bracket  42  may each further include an arcuate shaped guide slot  60 , which is spaced radially outwardly from the center of rotation of right end and left end open jaw brackets  40  and  42  about pivot studs  52   1  and  52   2  respectively. The guide slot  60  may include a proximal end  62  and a curved opening extending away therefrom. The arcuate shaped guide slot  60  may thus be defined between an interior guide slot edge  64  and an extending finger  66  reaching out to a distal end  68  and having an inside edge  70 . 
     As seen in  FIG. 1 , the left side mounting bracket  31  is configured for location at and/or attachment to a left side frame of a doorway (not shown). Similarly, the right side mounting bracket  32  is configured for location at and/or attachment to a right side frame of a doorway. The left mounting bracket  31  includes a left pivot stud  52   1 . The right side mounting bracket  32  includes a right pivot stud  52   2 . As noted above, the right end open jaw bracket  40  and the left end open jaw bracket  42  are sized and shaped for interfitting pivotal engagement with and pivoting movement about the left pivot stud  52   1  and the right pivot stud  52   2 , respectively. As shown in  FIGS. 3 and 5 , in an embodiment, the left pivot stud  52   1  and the right pivot stud  52   2  may each include an alignment groove  71  which is sized and shaped to accommodate the pivot stud receiver  46  of the right end open jaw bracket  40  and of the left end open jaw bracket  42 , respectively. 
     In an embodiment, a quick disconnect mechanism may be provided wherein the left side mounting bracket  31  and the right side mounting bracket  32  additionally include left and right locking studs,  72   1  and  72   2 , respectively. The locking studs  72   1  and  72   2  are sized and shaped for secure interfitting sliding motion within the arcuate shaped guide slots  60  in the right end open jaw bracket  40  and the left end open jaw bracket  42 , respectively. 
     In an embodiment, the left and right locking studs  72   1  and  72   2  may be provided as threaded bolts and thus may be secured to left  31  and right  32  mounting brackets via use of nuts as indicated by fasteners  74   1  and  74   2 , as seen for example in  FIG. 6  showing fastener  74   2 . Likewise, in an embodiment the left and right pivot studs  52   1  and  52   2  may be provided as threaded bolts and thus may be secured to left  31  and right  32  mounting brackets via use of nuts as indicated by fasteners  53   1  and  53   2 , as seen for example in  FIG. 6  with respect to fastener  53   1 . In order to maintain radial spacing between the pivot studs  52   1  and  52   2  and their adjacent locking studs  72   1  and  72   2 , respectively, alignment bars  76   1  and  76   2  may be provided, as also seen in  FIG. 6 . Further, as seen in  FIGS. 2, 3 , and  5 , mounting slots  77   1  in bracket  31  and  77   2  in bracket  32 , as defined by slot edgewalls  77   E , may be provided to enable adjustment of the location of locking studs  72   1  and  72   2  so that alignment of the detachable stair portion  21  between brackets  31  and  32  (in a recreational vehicle doorway) is provided. 
     As can be appreciated from  FIG. 1 , in an embodiment, the inside surface  31   I  of bracket  31  and the inside surface  32   I  of bracket  32  may be spaced apart by a distance D S . In an embodiment the alignment grooves  71  in the pivot studs  52   1  and  52   2  provide for spacing of the right outside surface  40   0  and a left outside surface  42   0  of the fixed plates provided by right end open jaw bracket  40  and a left end open jaw bracket  42  away from the inside surface  31   I  of bracket  31  and the inside surface  32   I  of bracket  32  by a clearance distance C. In an embodiment, clearance distance C may be larger than zero and up to about one quarter of an inch (¼″). In an embodiment, clearance distance C may be at least one eighth inch (⅛″). Thus, the overall width Wo of the detachable stair portion  21 , at least in that portion between brackets  31  and  32 , is the combination of the distance D S  less two times the clearance distance C. Thus, in an embodiment, the right outside surface  40   0  of the right end open jaw bracket  40  and the left outside surface  42   0  of the left end open jaw bracket  42  (see  FIG. 1 ) are spaced apart by width Wo. 
     The left locking stud  72   1  and the right locking stud  72   2  each have an interior distal end,  72   1-E  and  72   2-E  respectively. When the detachable stair system  20  is assembled and installed in a recreational vehicle doorway, the interior distal ends  72   1-E  and  72   2-E  of said left locking stud  72   1  and the right locking stud  72   2  are spaced apart a distance D D , where D D  is less than the width of the sill cover plate  34  (e.g. at edge  79  as seen in  FIGS. 2, 3, and 4 ) adjacent the arcuate shaped guide slots  60  provided in the right end open jaw bracket  40  and the left end open jaw bracket  42 . Importantly, the interior distal ends  72   1-E  and  72   2-E  of the left locking stud  72   1  and of the right locking stud must be sufficiently long that they extend well into, or in an embodiment actually fully occupy the lateral thickness of the right end and left end open jaw brackets  40  and  42  and thus fit fully and snugly in guide slots  60 , but are not so long that they extend too far toward each other (i.e. do not extend very far inwardly past—if at all inwardly past—an interior edge  42   I  of left end open jaw bracket  42  and interior edge  40   I  of right end open jaw bracket  40 ), where they would tend to interfere with or prevent rotating passage of the adjacent end  79  of the sill cover plate  34  (see  FIG. 2, 3 or 4 ), when the detachable stair portion  21  is moved from a closed, upward stored position as seen in  FIG. 1 , to a outwardly and downwardly extended working position as seen in  FIG. 12 . When so constructed, and a suitable distance is provided between the interior distal ends  72   1-E  and  72   2-E  of the left locking stud  72   1  and of the right locking stud, the detachable stair portion  21 , including the sill cover plate  34  and the right end and left end open jaw brackets  40  and  42  are freely pivotable on the left pivot stud  52   1  and the right pivot stud  52   2 , while the locking studs  72   1  and  72   2  snugly fit and move in the arcuate shaped guide slots  60 , to rotatably secure the detachable stair portion  21 . 
     Also, in order to enable the detachable stair portion  21  to pivot outward and downward (see  FIGS. 11 and 12 ), and inward and upward when the detachable stair portion  21  is returned to the stored position  30  as seen in  FIG. 1 , the distance D S  (between the inside edge  31   I  and  32   I  and of brackets  31  and  32  respectively) is larger than the distance Wo (the overall width of the detachable stair portion  21  at the outside edge  40   0  and  42   0  of right end open jaw and left end open jaw brackets  40  and  42  respectively). Thus, the clearance distances provided enable the detachable stair portion  21 , including a quick disconnect upper end assembly with the sill cover plate  34  and the right end and left end open jaw brackets  40  and  42  which are freely pivotable on and between the left pivot stud  52   1  and the right pivot stud  52   2 . 
     As more clearly seen in  FIGS. 5 and 6 , in various embodiments, one or both of the mounting brackets  31  and  32  further include a latch slot  80  defined by slot interior edge walls  82 . As seen in  FIGS. 2 and 3 , the detachable stair system  20  further includes at least one latch  84 . In an embodiment, latch  84  may be a slide latch. In an embodiment, latch  84  may include a body  86  having a latch tongue  88  portion sized and shaped for mating engagement with the latch slot  80 . An embodiment for suitable structure and operation for latch  84  may be seen in  FIGS. 2, 3, 4, and 7 . Threaded studs  85   1  and  85   2  may be provided on the rear  34   R  of sill plate  34  portion  34   F . In an embodiment, the threaded studs  85   1  and  85   2  may be used to slidably secure latch  84  to the rear  34   R  of sill plate  34 , using washers  85   W  and fasteners such as nuts  85   N . 
     As seen at reference arrow  87  in  FIG. 7  (or reference arrow  87   L  in  FIG. 3  and reference arrow  87   U  in  FIG. 2 ) the latch tongue  88  portion is moveable into or out of the latch slot  80 . Elongated slots  85   s  (which may be oval in shape) are provided through which threaded studs  85   1  and  85   2  extend, for maintaining the latch  84  in a working position with respect to latch slot  80 . The latch tongue  88  may be insertable into the latch slot  80  (see tongue  88  at the tongue  88 ′ position shown in  FIGS. 2 and 7 ). Thus, the lock the detachable stair portion  21  of the detachable stair portion  21  is retained in place in a rolled up, stored configuration as seen in  FIG. 1 , and removable from said latch slot  80  to allow the detachable stair portion  21  to be rolled down and out for deployment, as seen in  FIG. 12 , or for removal, as demonstrated in  FIG. 3  (see removal reference arrow  89 ). In an embodiment, the slide latch  84  may include an ear portion  90  adapted for manual manipulation of the slide latch  84 . Accordingly, when the latch is engaged, the brackets  40  and  42  are hooked over and secured against (and to) the left and right pivot studs  52   1  and  52   2 . Consequently, the brackets  40  and  42  cannot lift off of the left and right pivot studs  52   1  and  52   2  when the latch  84  is engaged securely within latch slot  80 . However, when the latch  84  is disengaged from latch slot  80 , the brackets  40  and  42 , and the entire detachable stair portion  21 , may be lifted off of the left and right pivot studs  52   1  and  52   2  when the detachable stair portion  21  is tilted-up into a stored position as shown in  FIG. 1 . 
     Attention is now directed to  FIGS. 8, 9, and 10 , where a perspective view of the right side mounting bracket  32  is provided, similar to the view shown in  FIG. 5  above, but now showing the mounting bracket installed in the door frame of a recreational vehicle, ready for receiving a detachable stair portion  21 , utilizing the quick connect bracket and pivot system described herein. Pivot stud  52   2  and pivot lock  72   2  are seen in  FIGS. 8, 9 and 10 , ready to receive right end open jaw bracket  40  (not shown, but see  FIG. 9 ). In an embodiment, the left side mounting bracket  31  and left end open jaw bracket  42  may be provided as mirror images of the configurations illustrated in  FIGS. 8, 9, and 10 . Floor plate  33  extends between left side mounting bracket  31  and the right side mounting bracket  32 . In an embodiment, the floor plate  33  may extend under the left side mounting bracket  31  and under the right side mounting bracket  32 . In an embodiment, the left side mounting bracket  31  may include a foot  31   F  configured to stand on and be supported by, and affixed to the floor plate  33 . In an embodiment, the right side mounting bracket  32  may include a foot  32   F  configured to stand on and be supported by, and affixed to the floor plate  33 . 
     Existing door sill  100 , stop  102 , and exterior structural features  104 ,  106 , and  108 , as well as door  110 , are all portions of an existing recreational vehicle in which the detachable stair system  20  is installed. In an embodiment, a suitably shaped sill cover plate  34  may be provided so that when the detachable stair portion  21  is deployed outward and downward, the sill cover plate  34  covers the existing door sill  100 , the stop  102 , and the exterior structural features  104 ,  106 , and  108 , while allowing door  110  to be easily opened and closed. 
     In  FIG. 9  again a partial perspective view of the right side of the detachable stair system, is shown, similar to the view depicted above in  FIG. 3 , showing the right side mounting bracket  32  with the right end open jaw bracket  40  disengaged from the right side pivot stud  52   2 , but aligned with and ready to be lowered to the pivot stud  52   2 , so the right end open jaw bracket  40  rests on the pivot stud  52   2  ready for pivoting action thereon. 
     Then, as shown in  FIG. 10 , the right side mounting bracket  32  is shown with the right end open jaw bracket  40  resting on the right side pivot stud  52   2 , and aligned with and ready to be locked in place in an upright, position as illustrated in  FIG. 1 , using latch  84  (not shown in  FIG. 10 , but see  FIG. 7 ) when lowered to the pivot stud  52   2 , so the right end open jaw bracket  40  rests on the pivot stud  52   2  ready for pivoting action thereon. 
     As seen in  FIGS. 11 and 12 , a detachable stair system may be conveniently deployed for use on a vehicle, using an extensible-retractable scissors stair assembly RSA, which may include a first scissors assembly on the left side L and a second scissors assembly on the right side R, as is visible in  FIG. 12 . In various embodiments, the first scissors assembly and said second scissors assembly each includes a plurality of outward elements and a plurality of downward elements, and wherein the first scissors assembly and the second scissors assembly are spaced apart by a number N of stairs S in a series of stairs Si to SN, wherein N is a positive integer. In an embodiment, N may be between two (2) and six (6) inclusive. Each of the stairs S should be securely affixed between selected elements of the first scissors assembly and the second scissors assembly. In various embodiments, one or more of the stairs S, or each of the stairs S in a series of stairs Si to SN may further include an upper surface having a non-skid surface portion. In various embodiments, the materials used and the structural elements provided enable the provision of a detachable stair portion  21  which is removable by a single adult human individual without the use of a helper, or lifts or tools. As an example, it has been found that when the number N of stairs S in a series of stairs Si to SN is three, a three step system may be provided having a weight of about forty two (42) pounds. When the number N of stairs S in a series of stairs Si to SN is four, a four step system may be provided having a weight of about forty eight (48) pounds. When the number N of stairs S in a series of stairs Si to SN is five, a five step system may be provided having a weight of about fifty five (55) pounds. When the number N of stairs S in a series of stairs Si to SN is six, a six step system may be provided having a weight of about sixty one (61) pounds. 
     It is to be appreciated that the quick disconnect system for a detachable stair system which may be mounted in the doorway of a vehicle as disclosed herein is an appreciable improvement in the art of stairs for recreational vehicles. The novel design for a quick disconnect mechanism for a detachable stair system with precision elevation control addresses the problem of how to conveniently detach and store a stair system for recreational vehicles, while providing a way to eliminate or minimize space occupied by stairs during those times when stairs are not required. The embodiments have been thoroughly described to enable those of ordinary skill in the art to make and use the invention. Further, embodiments which utilize aircraft grade aluminum components, and stainless steel components are provided, for corrosion resistance during years of outdoor use, such as on various camp trailers or on pickup camper designs. 
     Although only a few exemplary embodiments have been described in detail, various details are sufficiently set forth in the drawings and in the specification provided herein to enable one of ordinary skill in the art to make and use the invention(s), which need not be further described by additional writing in this detailed description. It will be readily apparent to those skilled in the art that the quick disconnect system for a detachable stair system may be modified from those embodiments provided herein, without materially departing from the novel teachings and advantages provided. 
     The aspects and embodiments described and claimed herein may be modified from those shown without materially departing from the novel teachings and advantages provided by this invention, and may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Therefore, the embodiments presented herein are to be considered in all respects as illustrative and not restrictive. As such, this disclosure is intended to cover the structures described herein and not only structural equivalents thereof, but also equivalent structures. Numerous modifications and variations are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention(s) may be practiced otherwise than as specifically described herein. Thus, the scope of the invention(s), as set forth in the appended claims, and as indicated by the drawing and by the foregoing description, is intended to include variations from the embodiments provided which are nevertheless described by the broad interpretation and range properly afforded to the plain meaning of the claims set forth below.