Abstract:
A retractable stair system for vehicles. The apparatus includes stairs which are retractable into a frame, or extendable to provide a set of stairs with relatively uniform height therebetween. Indexing plates with locking notches and companion latches with latch tongues to fit in the notches enable adjustment of the height of a top step S 1  in a set of steps in an extensible-retractable stairs assembly. Extensible legs are provided which are individually vertically adjustable to provide secure engagement with an uneven substrate such as rocky ground or a sloping surface. Foot pads are pivotally attached to the extensible legs. The combination of vertical adjustability, the selection of a desired number of stairs, and individual top stair height adjustability, make the unit adaptable for use in a variety of vehicles.

Description:
RELATED PATENT APPLICATIONS 
     This application claims priority from prior U.S. Provisional Patent Application Ser. No. 62/246,601, filed Oct. 26, 2015, entitled RETRACTABLE STAIR SYSTEM FOR VEHICLE, the disclosure of which is incorporated herein in its entirety, including the specification, drawing, and claims, by this reference. 
    
    
     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 retractable stairs, and in particular, to stairs configured for use with driven or towed vehicles, such as trucks, trailers, (including semi-trailer truck tractor units, or other over-the road rigs or specific purpose vehicles such as earth movers or large dump trucks), campers on pickup trucks, towed camper doorways, motor homes, 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 may be facilitated by the availability of a stair system. Further, quite often a vehicle is 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 I am 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 reasonable height for users to access existing stairs to a camper. 
     A common problem encountered in prior art stair systems is that when operating on uneven ground, such structures are often not uniformly adjustable (often are not even variably adjustable) to provide a secure final level platform near the ground. Thus, such prior art stair structures inevitably leave a gap of a few inches between a desirable stair platform height and the actual stair platform height which may be achieved. Also, it is often rather difficult to achieve a quick adjustment in any of the available stair designs. Often, the result is a vehicle located a particular site, such as a campsite or jobsite with an entrance/exit stairs/platform which does not provide adequate safety in terms of providing an even distance between stairs, vertically, or with respect to providing stable contact with the ground below. 
     Thus, there remains a continuing unmet need for a retractable stairs system for a vehicle in which the total stair height is adjustable, and in which stable ground contact is provided via support pads, with individually adjustable heights between the stairs and the support pads on opposing sides of the stairs. 
     SOME OBJECTS, ADVANTAGES, AND NOVEL FEATURES 
     An objective of our invention is to provide a design for a retractable stair system in which a varying number of steps may be provided. 
     Another objective of our invention is to provide a design for a retractable stair system in which the support pad distance below the bottom step is individually adjustable at either side of the step. 
     Another important objective is to provide a retractable stair system which is easily and rapidly adjustable in total stair height, yet retains the ability to evenly space the stair steps which are provided. 
     Another important objective is to provide retractable stair system in which the distance from the top of the stair assembly to the level of the first step is adjustable in selectable increments of height. 
     A related and important objective is to provide a retractable stair system in which the stairs are sturdy and of high strength. 
     A related and important objective is to provide a retractable stair system in which the length of support to ground contact pads is quickly adjustable, individually, on each side of the retractable stair system. 
     Another important objective is to provide a compact retractable stair system structure and frame design in which the stairs may be easily installed in existing or new vehicles, and in which the retractable stairs are neatly and securely stowed when not in use, and thus, when the vehicle is in service over the road. 
     Finally, another important objective is to provide a high strength retractable stair system which can be conveniently and easily built with conventional manufacturing processes, so that manufacturing costs are minimized. 
     SUMMARY 
     We have now invented a retractable stair system for vehicles which provides for stowage of stairs when not in use, and which provides convenient, adjustment of the height or level of the first step, and then equal spacing between stair steps when the stair system is deployed. This is important since it enhances the safety of access to and from a vehicle (e.g., a camper mounted on the back of a pickup truck). Further, individually adjustable foot pads enable secure support of the stairs, even when the stair system is deployed on uneven ground. 
     The retractable stair system disclosed herein includes four major components. These major components are (a) a frame, (b) an extensible-retractable scissors stair assembly, (c) a manually adjustable latching system for locking the extensible-retractable scissors stair assembly in a particular position, and (d) individually adjustable foot pads. For the latter item, in an embodiment a detent system is utilized, where a spring loaded pin is adjustably locatable to any one of a plurality of latch hole locations along an extensible support tube, so that when a detent is pressed inward, an adjustment may be made, and when the detent protrudes through a specific latch hole, the height of the foot pad is secured at such location. In this manner, foot pads at either side of the stairs may be individually adjusted when the retractable stair system is located above uneven ground. 
     Moreover, the retractable stair system with precision elevation control needs no extra parts, bolts, or other components for on-site assembly and deployment. Resultantly, the retractable stair system with precision elevation control 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) will be described by way of exemplary embodiments, using for illustration the accompanying drawing in which like reference numerals denote like elements, and in which: 
         FIG. 1  is a rear elevation view of a camper situated in a conventional arrangement on the bed of a pickup truck, showing mounted thereon an embodiment for a retractable stair system in which four stair steps are provided. 
         FIG. 2  is an elevation view of an embodiment for a retractable stair system as just depicted in  FIG. 1  above, and in which four stair steps are retracted into the mounting frame. 
         FIG. 3  is a detail (Detail M from  FIG. 2 ) of an embodiment for a foot pad for use with an exemplary retractable stair system, providing a view looking down at a pair of coupled tubes which may be deployed in a nested, telescoping fashion for adjustment of height of the foot pad below a bottom stair step and above a substrate. 
         FIG. 4  is a perspective view of an embodiment for a retractable stair system as just depicted in  FIGS. 1 and 2  above, and in which four stair steps are retracted into the mounting frame, and further showing first and second slide plates at first and second sides of the frame, between first and second longitudinally extending frame members, as well as the first and second latch handles which enable locking and unlocking of latches which secure the first step of the stair system at a selected height with respect to the top of the mounting frame, as well as lock the stairs when in a retracted, stowed configuration as illustrated in this  FIG. 4 . 
         FIG. 5  is an enlarged perspective view of a detail (Detail H from  FIG. 4 ) for portions of an embodiment for a slide plate, including one of the attachments of the slide plate to a first longitudinally extending frame member. 
         FIG. 6  is an elevation view of an embodiment for a retractable stair system similar to that just depicted in  FIG. 1  above, but now showing portions of a retractable stair system embodiment in which two stair steps are provided. 
         FIG. 7  is a side elevation view of portions of an embodiment for the working components of a retractable stair system as just depicted in  FIG. 6  above, now showing a retractable stair system embodiment depicted in a compact arrangement as if the two stair steps were retracted into at least a portion of the frame and substantially between opposing first and second slide plates. 
         FIG. 8  is a perspective view of portions of an embodiment for a retractable stair system as just depicted in  FIGS. 6 and 7  above, and in which two stair steps are depicted in a retracted position, and further showing first and second adapter brackets which are used to mount the extensible-retractable scissors stair assembly to a frame. 
         FIG. 9  is an enlarged perspective view of a detail (Detail A from  FIG. 8 ) of an embodiment for portions of an adapter bracket, and depicting, in part, hardware used in assembly, including use of a nylon spacer between two thin washers. 
         FIG. 10  is an enlarged perspective view of a detail (Detail B from  FIG. 8 ) of an embodiment for portions of a first end of a latch pipe, and depicting, in part, hardware used in assembly. 
         FIG. 11  is an elevation view of an embodiment for a retractable stair system similar to that just depicted in  FIGS. 1 and 6  above, but now showing a retractable stair system embodiment in which three stair steps are retracted into the mounting frame. 
         FIG. 12  is a side elevation view of an embodiment for a retractable stair system as just depicted in  FIG. 11  above, now showing a retractable stair system embodiment depicted as if the three stair steps are retracted into at least a portion of the frame and substantially between opposing first and second slide plates. 
         FIG. 13  is an elevation view of an embodiment for portions of a retractable stair system similar to that just depicted in  FIGS. 1, 6, and 11  above, but now showing a retractable stair system embodiment in which four stair steps are provided. 
         FIG. 14  is a side elevation view of an embodiment for portions of a retractable stair system as just depicted in  FIG. 13  above, now showing a retractable stair system embodiment depicted in a compact arrangement as if the four stair steps were retracted into at least a portion of the frame and substantially between opposing first and second slide plates. 
         FIG. 15  is a perspective view of an embodiment for a retractable stair system as just depicted in  FIGS. 13 and 14  above, and in which four stair steps are shown in a retracted position, and further showing first and second adapter brackets which are used to mount the extensible-retractable scissors stair assembly to a frame (not shown in  FIG. 15 ). 
         FIG. 16  is an enlarged perspective view of a detail (Detail AB from  FIG. 15 ) for portions of an embodiment for an adapter bracket, and depicting, in part, hardware which may be used in assembly, including a nylon spacer between two thin washers. 
         FIG. 17  is an exploded perspective view of a detail (Detail AC from  FIG. 15 ) for portions of an embodiment for the first end of a latch pipe, and depicting, in part, hardware which may be used in assembly. 
         FIGS. 18 through 29  of the drawing are provided to illustrate the operation of an embodiment for a retractable stair system for a vehicle. At least a portion of the various components of retractable stair system may appear in various  FIGS. 18 through 29 , and thus the overall components of the retractable stair system are described to assist in understanding the various drawing figures. Generally, a frame is depicted including first and second upper longitudinal members which extend between first and second side plates. Also, the frame includes a third lower longitudinally extending member extending between the first and second side plates (see also  FIG. 30 ). In these drawing  FIGS. 18 through 29 , a three step extensible-retractable scissors stairs assembly is provided disposed between a first keeper plate and a second keeper plate. Between a first keeper plate and a first slide plate is located a first indexing plate. Between a second keeper plate and a second slide plate is located a second indexing plate. A first latch is provided mounted for pivotable movement to allow releasable locking engagement of a latch tongue of the first latch with one of the plurality of tongue receiving recessed notches in the first indexing plate. A second latch is provided mounted for pivotable movement to allow releasable locking engagement of a latch tongue of the second latch with one of the plurality of tongue receiving recessed notches in the second indexing plate. The height of the uppermost step is adjustably positionable by selecting one level of the sets of companion notches in the indexing plates. A first longitudinal stiffener runs between the first latch and the second latch (see  FIGS. 22-23 ). A second longitudinal stiffener runs between the first keeper plate and the second keeper plate (see  FIGS. 22-27 ). The entire stair assembly is mounted for pivotable movement between first adaptor bracket and first flat bar arm, and between a second adaptor bracket and second flat bar arm. The first flat bar arm is pivotably mounted to the first side plate; the pivot extends through the first keeper plate and the first indexing plate. Likewise, the second flat bar arm is pivotably mounted to the second side plate; the pivot extends through the second keeper plate and the second indexing plate. The first flat bar arm has a first guide attached for arcuate movement in a guide track of the first side plate. The second flat bar arm has a second guide attached for arcuate movement in a guide track of the second side plate. 
       In  FIG. 18 , an embodiment for a retractable stair system having three stair steps is shown in a fully retracted position, wherein the stair steps are secured for over-the-road movement. 
       In  FIG. 19 , an embodiment for a retractable stair system having three stair steps as just shown in  FIG. 18  above is now shown with the latch handle in a slightly raised position, wherein the latch tongue on the latch handle is beginning to disengage from the first locking recessed notch in the first indexing plate; in this  FIG. 19 , the first side plate is depicted in broken lines in a “see-though” configuration, so the view is as if looking through the first side plate to see the first indexing plate and the first latch handle. 
       In  FIG. 20  an embodiment for a retractable stair system having three stair steps is provided as just shown in  FIGS. 18-19 , but now shown with the latch handle in a slightly further partially raised position, wherein the latch tongue on the latch handle is still in the process of disengaging from the first locking recessed notch in the first indexing plate; in this diagram, the first side plate is depicted in broken lines in a “see-though” configuration, so the view is as if looking through the first side plate to see the first indexing plate and the first latch handle. 
       In  FIG. 21  an embodiment for a retractable stair system having three stair steps is provided as just shown in  FIGS. 18-20 , but now shown with the latch handle in a raised position, wherein the latch tongue on the latch handle has disengaged from the first locking recessed notch in the first indexing plate, so that the extensible-retractable scissors stairs assembly may begin to be extended outward as the first indexing plate also pivots outwardly and downwardly (i.e. clockwise to the right in this  FIG. 21 ). 
       In  FIG. 22  an embodiment for a retractable stair system having three stair steps is provided as just shown in  FIGS. 18-21 , but now shown with the latch handle in a lowered, second position, wherein the latch tongue on the latch handle has engaged a second locking recessed notch in the first indexing plate to place the top stair at a first position having a selected stair height H SA , and wherein the extensible-retractable-scissors stairs assembly is provided ready for extension; again in this diagram, the first side plate is depicted in broken lines in a “see-though” configuration, so the view is as if looking through the first side plate to see the first indexing plate and the first latch handle. 
       In  FIG. 23  an embodiment for a retractable stair system having three stair steps is provided as just shown in  FIGS. 18-22 , but now shown with the first latch handle in a raised position, wherein the latch tongue on the first latch handle has disengaged from the first locking recessed notch in the first indexing plate, so that the first stair in the extensible-retractable scissors stairs assembly may be further lowered to a selected stair height as the first indexing plate pivots outwardly and downwardly (i.e. clockwise to the right in this  FIG. 23 ). 
       In  FIG. 24 , the embodiment for a retractable stair system having three stair steps as just shown in  FIGS. 18-23  above is now shown with the first latch handle in a lowered, third position, wherein the latch tongue on the first latch handle has engaged a third locking recessed notch in the first indexing plate to place the top stair at a second position having a selected stair height H SB , and wherein the extensible-retractable scissors stairs assembly is provided ready for extension; again in this diagram, the first side plate is depicted in broken lines in a “see-though” configuration, so the view is as if looking through the first side plate to see the first indexing plate and the first latch handle. 
       In  FIG. 25  an embodiment for a retractable stair system having three stair steps is provided as just shown in  FIGS. 18-24 , but now shown with the first latch handle in a lowered, fourth position, wherein the latch tongue on the first latch handle has engaged a fourth locking recessed notch in the first indexing plate to place the top stair at a third position having a selected stair height H SC , and wherein the extensible-retractable scissors stairs assembly is provided ready for extension. 
       In  FIG. 26  an embodiment for a retractable stair system is provided having three stair steps as just shown in  FIGS. 18-25 , now shown in the same position as just depicted in  FIG. 25  above, but without the use of broken lines to provide a “see-through” first side plate as was provided in  FIG. 25  above. 
       In  FIG. 27  an embodiment for a retractable stair system is provided having three stair steps as just shown in  FIGS. 18-26 , but now additionally showing the method of extension of the extensible-retractable scissors stairs assembly and independently adjustable legs and their supporting pivotably mounted foot pads. 
       In  FIG. 28  an enlarged portion of an embodiment for a retractable stair system having three stair steps as was just shown in  FIGS. 18-27  above is now shown in a position similar to the position as just depicted in  FIG. 27  above, but now additionally showing details which allow independent extension or retraction of legs supporting the foot pads by way of holes in a tube which may be selected for use of a detent, and in which a spring loaded detent securely holds the foot pad at a selected distance below the bottom step. 
       In  FIG. 29  an enlarged portion of an embodiment for a retractable stair system having three stair steps as just shown in  FIGS. 18-28  above is now shown in a position wherein a first foot pad and a second foot pad are independently deployed at different heights above a substrate surface above which the stair system is located. 
         FIG. 30  provides a bottom perspective view of the frame and some of the operational mechanisms of an embodiment for a retractable stair system having four steps, and further shows the location of a shelf to secure stair steps during storage, i.e., when the extensible-retractable scissors stairs assembly has been retracted. 
         FIG. 31  provides details of an embodiment for a shelf for storage of steps, especially as useful in an embodiment having four steps, as generally depicted in  FIG. 30  above. 
         FIG. 32  is similar to  FIG. 30 , and provides a bottom perspective view of the frame and some of the operational mechanisms of an embodiment for a retractable stair system having five steps, and further shows the location of a shelf to secure stair steps during storage, i.e., when the extensible-retractable scissors stairs assembly has been retracted. 
         FIG. 33  provides details of an embodiment for a shelf for storage of steps, especially as useful in an embodiment having five steps, as generally depicted in  FIG. 32  above. 
         FIG. 34  is similar to  FIGS. 30 and 32 , and provides a bottom perspective view of the frame and some of the operational mechanisms of an embodiment for a retractable stair system having six steps, and further shows the location of a shelf to secure six stair steps during storage, i.e., when the extensible-retractable scissors stairs assembly has been retracted. 
         FIG. 35  provides details of an embodiment for a shelf for storage of steps, especially as useful in an embodiment having six steps, as generally depicted in  FIG. 34  above. 
         FIG. 36A  provides a perspective view of an embodiment for an adapter bracket, one of which is used on each side of the retractable stairs to attach opposing side of the extensible-retractable scissors stairs assembly to flat bar arms. 
         FIG. 36B  provides a side view of an embodiment for an adapter bracket. 
         FIG. 36C  provides a top view of an embodiment for an adapter bracket. 
         FIG. 36D  provides a front end view of an embodiment for an adapter bracket. 
         FIG. 37  provides a perspective view of an embodiment for an extensible-retractable scissors stairs assembly having four stairs, and shows adapter brackets mounted thereon. 
         FIG. 38  provides a perspective view of a portion of an embodiment for a retractable-extensible scissors stairs assembly having four stairs, taken as detail L from  FIG. 37 , and now shows details for an embodiment of a latching stud, as may be used on either side of an extensible-retractable scissors stairs assembly. 
         FIG. 39A  provides a perspective view of an embodiment for a side plate, two of which are used to provide sides of a frame for an extensible-retractable scissors stairs assembly. 
         FIG. 39B  provides a side view of an embodiment for a first side plate. 
         FIG. 39C  provides a side view of an embodiment for a second side plate. 
         FIG. 39D  provides a top view of an embodiment for a side plate. 
         FIG. 39E  provides an end view of an embodiment for a side plate. 
         FIG. 40A  provides a perspective view of an embodiment for an indexing plate, two of which are used to provide recessed notches for accepting locking latches at each side of the frame of the retractable stairs system. 
         FIG. 40B  provides a side view of an embodiment for an indexing plate. 
         FIG. 40C  provides a top view of an embodiment for an indexing plate. 
         FIG. 40D  provides a front end view of an embodiment for an indexing plate. 
         FIG. 41A  provides a perspective view of an embodiment for a keeper plate, two of which are used to provide a rotatable assembly, one of which is used at each side of the frame of the retractable stairs system. 
         FIG. 41B  provides a side view of an embodiment for a keeper plate. 
         FIG. 41C  provides a top view of an embodiment for a keeper plate. 
         FIG. 41D  provides a front end view of an embodiment for a keeper plate. 
         FIG. 42A  provides a perspective view for a latch handle, two of which are used to provide latches with latch tongues for locking engagement with recessed notches in indexing plates at both first and second sides of a frame for the extensible-retractable scissors stairs assembly. 
         FIG. 42B  provides a side view of an embodiment for a latch handle. 
         FIG. 42C  provides a side view of an embodiment for a latch handle, before final fabrication by bending the handle ninety degrees. 
         FIG. 42D  provides a top view of an embodiment for a latch handle. 
         FIG. 42E  provides an end view of an embodiment for a latch handle. 
         FIG. 43A  provides a perspective view of an embodiment for a latch pipe, used to provide a latching mechanism for the extensible retractable scissors stairs assembly. 
         FIG. 43B  provides a side view of an embodiment for a latch pipe. 
         FIG. 43C  provides a top view of an embodiment for a latch pipe. 
         FIG. 43D  provides an end view of an embodiment for a latch pipe. 
         FIG. 44A  provides a perspective view of an embodiment for a flat bar arm, used to mount an extensible-retractable scissors stairs assembly to a keeper plate. 
         FIG. 44B  provides a side view of an embodiment for a flat bar arm. 
         FIG. 44C  top view of an embodiment for a flat bar arm. 
         FIG. 44D  provides an end view of an embodiment for a flat bar arm. 
     
    
    
     The foregoing figures, being merely exemplary, contain various elements that may be present or omitted from a final configuration for an embodiment of a retractable stair system with precision elevation control, or that may be implemented in various embodiments described herein for a retractable stair system for a vehicle. Other variations in retractable stair systems for vehicle 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 specific dimensions have been provided in many of the drawing figures, such dimension are provided merely to enable those of skill in the art to make and use the claimed invention, and there is no intention to limit the claimed invention to such dimensional data, which is exemplary rather than mandatory. Thus, a retractable stair system with precision elevation control may be provided which is sized up or down from any such dimensions provided, 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 retractable stair system with precision elevation control 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 retractable stair systems for vehicles, depending upon the specific requirements (such as typical height of the bottom of a vehicle door above the road) within the scope and coverage of the teachings herein as defined by the claims. Further, like features in various embodiments for retractable 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 , where rear elevation view of a pickup truck  50  having a camper  52  thereon is provided, illustrating the use of an embodiment of a retractable stair system  54  having four stair steps (S 1 , S 2 , S 3 , and S 4 , respectively) is provided mounted thereon. As will be further noted below, a retractable stairs system may, in various embodiments, be provided with a number N of stairs S, wherein N is a positive integer. In various embodiments illustrated, the number N of stairs S ranges from 2 to 6, inclusive. 
     As seen in  FIG. 4  and similar figures of the drawing, generally, a frame  60  is providing including first  62  and second  64  upper longitudinal members which extend between first  66  and second  68  side plates. Also, the frame  60  includes a third lower longitudinally extending member  70  extending between the first  66  and second  68  side plates (e.g., see  FIG. 24 ). In some of the drawing figures, a two step (S 1 , S 2 ) or three step (S 1 , S 2 , S 3 ), or four step (S 1 , S 2 , S 3 , and S 4 ) configurations are provided for an extensible-retractable scissors stairs assembly RSA. As noted above and with configurations as noted, for example in  FIGS. 30, 32, and 34 , four step, five step, and six step configurations may be utilized. A keeper longitudinal stiffener  72  is provided disposed between a first keeper plate  74  and a second keeper plate  76 . Between a first keeper plate  74  and a first slide plate  66  is located a first indexing plate  80 . Between the second keeper plate  76  and a second side plate  68  is located a second indexing plate  90 . A first latch  92  is provided mounted for pivotable movement to allow releasable locking engagement with the first indexing plate  80 . A second latch  94  is provided mounted for pivotable movement to allow releasable locking engagement with the second indexing plate  90 . A latch longitudinal stiffener  96  runs between the first latch  92  and the second latch  94  (see  FIGS. 22-23 ). A keeper longitudinal stiffener  72  runs between the first keeper plate  74  and the second keeper plate  76  (see  FIGS. 22-27 ). The entire retractable stair assembly RSA is mounted for pivotable movement between first adaptor bracket  100  and first flat bar arm  102 , and between a second adaptor bracket  104  and second flat bar arm  106  (see  FIG. 19  or  FIG. 25 ). The first flat bar arm  102  is pivotably mounted to the first side plate  66 ; a pivot P 1  extends through the first keeper plate  74  and the first indexing plate  80 . Likewise, the second flat bar arm  106  is pivotably mounted to the second side plate  68 ; a pivot P 2  extends through the second keeper plate  76  and the second indexing plate  90 . The first flat bar arm  102  has associated therewith or attached thereto a first guide G 1  positioned for arcuate movement in guide track T 1  of the first side plate  66 . The second flat bar arm  106  has associated therewith or attached thereto a second guide G 2  attached for arcuate movement in a guide track T 2  of the second side plate  68 . Note from  FIGS. 41A and 41B  that the first keeper plate  74  and second keeper plate  76  may each include keeper cutout  75 , to allow each of the first keeper plate  74  and the second keeper plate  76  to clear the respective pivots P 1  and P 2  when the retractable stair system  54  is in a retracted, stair stowed configuration as discussed below. 
     The top stair S 1  in any group of stairs S 1 , S 2 , S 3 , etc. may be secured at a selected height H SA , H SB , H SC , etc. below the top of the frame of the retractable stair system. In an embodiment, once the top stair S 1  is secured by use of the locking latch system just described, the retractable-extensible stair assembly RSA may be pulled out to extend the set of stairs to a desired overall height, while the scissors construction provides for uniform spacing distance D between each of the stairs (S 1 , S 2 , S 3 ) in a selected set of stairs, as illustrated in  FIG. 29 . 
     Still referring to  FIG. 29 , for ground support, a first extensible support leg  109 A and second extensible support leg  109 B may be provided. In various embodiments, the first extensible support leg  109 A and the second extensible support leg  109 B include an upper support member  112  having an interior channel defined by interior sidewalls  110 , which provides a receiver for passage therethrough of a lower support member  114  which can be adjusted upwardly or downwardly as it nests in the upper support member  112 . A plurality of holes  115  defined by edgewalls  116  in the upper tubular member  112  provides locking locations for detents  120  which may be spring loaded outwardly toward the upper tubular member  112 , so that the height of the lower support member  114  is easily adjusted. The detents  120  are sized and shaped for close fitting mating engagement with each of the holes  115  in the upper support member  112 . In an embodiment, the upper support member  112  may be provided in the configuration of a square tubular member. 
     As further seen in  FIG. 29 , extensible foot pads or plates  122   A  and  122   B  may be sized and shaped for transmitting a portion of a load from the stairs to a substrate  124  below (such as the ground or a parking lot) may be pivotably secured (at pivot  126 ) to the lower support member  114 . In an embodiment, the foot pads  122 A and  122 B may be affixed to the lower support member  114  so that a majority of said substrate engaging surface of foot pad  122 A and  122 B is located inwardly toward the stairs, and thus away from first frame side  67  and from second frame side  69 . Where uneven ground is encountered in a substrate  124 , such as represented by rock  128 , the overall extended height H F1  of the first foot pad  122   A  and the overall extended height of a second foot pad  122   B  may be independently adjusted to assure firm support even though the substrate  124  includes uneven ground. The first extensible support leg  109   A  is extendable to a selected height H F1 , and the second extensible support leg  109   B  is extendable to a selected height H F2 . The first extensible support leg  109   A  and the second extensible support leg  109   B  are independently extendable, so that selected height H F1  and selected height H F2  may be the same or different. 
     Further details of construction of an embodiment for a retractable stair assembly  54  will now be addressed. Attention is directed to  FIG. 18 , where an embodiment for a retractable stair system  54  is provided. The retractable stair system  54  includes a frame  60  having a first side plate  66  and a second side plate  68 . The first  66  and second  68  side plates located at a first frame side  67  and at a second frame side  69 , respectively, and spaced apart by one or more longitudinal structural members, for example first upper longitudinal member  62  and second upper longitudinal member  64 . The first side plate  66  and the second side plate  68  each further include first edgewalls  82  defining an annular arc slide guide cutout  84  therein, and second edgewalls  86  defining a recessed latch finger cutout  88  therein. 
     As better seen in  FIG. 19  and following figures, and as may be further understood by reference to  FIGS. 41A and 41B , a first keeper plate  74  and a second keeper plate  76  are provided, and are pivotally affixed to the said frame  60  at the first frame side  67  and at the second frame side  69 . As may be more clearly understood by further reference to  FIGS. 30, 32, and 34 , the first keeper plate  74  is pivotally affixed at a first pivot P 1  on the first frame side  67 , and the second keeper plate  76  is pivotally affixed at a second pivot P 2  on the second frame side  69 . 
     As may be understood by reference to  FIGS. 19-25  and to  FIGS. 40A and 40B , a first indexing plate  80  and a second indexing plate  90  are provided. The first indexing plate  80  and the second indexing plate  90  are pivotally affixed to the frame  60  at P 1  to first side plate  66  on first frame side  67  and at P 2  to second side plate  68  on the second frame side  69 , respectively. 
     Each of the first indexing plate  80  and the second indexing plate  90  may include a generally arcuate upper surface  81  and  91 , respectively. In the arcuate upper surface  81  and  91  of the first indexing plate and of the second indexing plate  90 , a plurality of locking notches LN are provided downwardly recessed therein. In an embodiment, locking notches LN may be provided in a series of locking notches LN 1 , LN 2 , LN 3  and LN 4  as seen in  FIGS. 19, 40A , and  40 B. In an embodiment, a first locking notch LN 1  may be provided for use in locking the retractable-extensible scissors stairs assembly RSA in a stowed and locked position, as seen in  FIGS. 4 and 19 . 
     As seen in  FIG. 19  and as may be further understood by reference to  FIGS. 42A, 42B, 42C, and 42D , a first latch  92  and a second latch  94  are provided. The first latch  92  and the second latch  94  are pivotally affixed at a pivot necks  92   P  and  94   P  respectively via pivot P 3  and P 4 , to frame  60  at first side plate  66  on first frame side  67  and at second side plate  68  on second frame side  69 , respectively. The first latch  92  and the second latch  94  each further include a downwardly extending latch tongue  92   T  and  94   T , respectively, which is sized and shaped for interfitting locking engagement with locking notches LN (e.g., LN 1 , LN 2 , LN 3  and LN 4 ) in the first indexing plate  80  and in the second indexing plate  90 , respectively.  15 . In an embodiment, the first latch  92  and the second latch  94  may each include a body  93  and  95 , respectively, which has a concave lower portion  92   C  and  94   C , respectively, from which their respective latch tongue  92   T  or  94   T  protrudes. In an embodiment, the concave lower portion  92   C  and  94   C  of first latch  92  and second latch  94 , respectively, may substantially conform in shape to said arcuate upper surface  81  or  91  of the first indexing plate  80  or the second indexing plate  90 , respectively. In an embodiment, the first latch  92  and the second latch  94  each may further have a distal end  92 D or  94 D, respectively, having a latch handle  98  thereon. In an embodiment, the latch handle  98  may be oriented substantially transverse to the body  93  or  95  of the first latch  92  and/or of the second latch  94 , and in a direction outwardly from the first side plate  66  and/or the second side plate  68 , respectively. 
     In an embodiment, a retractable stair system  54  may further include the use of at least one latch longitudinal stiffener  96 . In such an embodiment, the least one latch longitudinal stiffener  96  extends between said first keeper plate and said second keeper plate; and 
     In an embodiment, a retractable stair system  54  may further include the use of at least one latch longitudinal stiffener  96 . In such an embodiment, the least one latch longitudinal stiffener  96  extends between a proximal end  92   X  of the first latch  92  and a proximal end  94   X  of the second latch  94 . The at least one latch longitudinal stiffener  96  provides for coordination of movement between first latch  92  and second latch  94 , so that movement of either the first latch  92  or of the second latch  94  is transferred to the other. 
     Similarly, a retractable stair system  54  may further include at least one keeper longitudinal stiffener  72 . The at least one keeper longitudinal stiffener  72  is oriented to extend across the retractable stair system  54  between the first keeper plate  74  and the second keeper plate  76 . In order to assure locking, the keeper longitudinal stiffener  72  is sized and shaped to keep the first  74  and second  76  keeper plates against or at least adjacent the first  80  and second  90  indexing plates, respectively, sufficiently so that slippage of latch tongue  92 T of the first latch  92  with respect to the first indexing plate  80 , and of the latch tongue  94 T of said second latch  94  with respect to the second indexing plate  90  when the latch tongue  92 T of the first latch  92 , and the latch tongue  94 T of the second latch  94 , are latched in one of said recessed locking notches LN in the first indexing plate  80  and in the second indexing plate  90 , respectively. 
     In an embodiment, a retractable stair system  54  may further include a latch pipe  108  having first a first end  108   A  and a second end  108   B . The first end  108   A  and the second end  108   B  of the latch pipe  108  are configured for secure mating engagement with the recessed latch finger cutout  88  defined by sidewalls  86  in the first side plate  66  and in the second side plate  68 . In this manner, the latch pipe  108  vertically supports the extensible-retractable scissors stair assembly RSA when the extensible-retractable stair assembly RSA is placed in a storage position as shown in  FIG. 2, 4 , or  19 . In an embodiment, the latch pipe  108  may be provided using a material with adequate strength properties for the service (e.g., inch schedule  40  pipe). In an embodiment, the latch pipe  108  may be provided in a selected stainless steel. Various fabrication techniques such as use of welding in a jig may be selected by those of skill in the art and to whom this disclosure is directed, without need for additional details. However, attention is drawn to  FIG. 10 , showing Detail B of  FIG. 8 , which further illustrates assembly location and identifies suitable additional components such as large spacer  118   L  and small spacer  118   S , as well as use of suggested hardware including capping the ends  108   A  and  108   B  with a pan head machine screw  118   M . One latch pipe  108  may be provided for each retractable stair system  54 . 
     Attention is directed to  FIG. 26 , which provides details which may be utilized in an embodiment of a retractable stair system  54  for attachment of the extensible-retractable stair assembly RSA to the frame  60  via first keeper plate  74  and second keeper plate  76 . As noted above, in an embodiment, the entire retractable stair assembly RSA may be mounted for pivotable movement between first adaptor bracket  100  and first flat bar arm  102 , and between a second adaptor bracket  104  and second flat bar arm  106  (see  FIG. 19 ). Note that a first flat bar arm  102  is pivotally mounted to the first side plate  66  at pivot P 1 , which extends through the first keeper plate  74  and the first indexing plate  80 . Likewise, the second flat bar arm  106  is pivotably mounted to the second side plate  68 ; a pivot P 2  extends through the second keeper plate  76  and the second indexing plate  90 . The first flat bar arm  102  has a first guide G 1  attached for arcuate movement in guide track T 1  which may be defined by an annular arc shaped slide guide  84  which may be in the shape of an annular arc shaped slide guide  84  as defined by first edgewalls  82  in the first side plate  66 . The second flat bar arm  106  has a second guide G 2  attached for arcuate movement in a guide track T 2  which may be in the shape of an annular arc shaped slide guide  84  as defined by first edgewalls  82  in the second side plate  68 . The guides G 1  and G 2  may be attached through a medial hole  102   M  in the first flat bar arm  102  and a medial hole  106   M  in the second flat bar arm  106 , respectively, as may be appreciated by reviewing  FIGS. 44A and 44B . Thus, the first flat bar arm  102  has a proximal end  102   P  which is securely attached at the first keeper plate  74  and configured for pivoting motion about pivot P 1 . Likewise, the second flat bar arm  106  has a proximal end  106   P  which is securely attached at the first keeper plate  74  and configured for pivoting motion about pivot P 1 . The first flat bar arm  102  and the second flat bar arm  106  are configured for arcuate movement in concert with the first keeper plate  74  and the second keeper plate  76 , respectively. The first flat bar arm  102  has a distal end  102   D  that extends outwardly from the first keeper plate  74 . The second flat bar arm  106  has a distal end  106   D  that extends outwardly from the second keeper plate  76 . 
     As seen in  FIGS. 19 and 25 , a retractable stair system  54  may be provided where the extensible-retractable stair assembly RSA is attached at pivots P 5  and P 6  at or near the distal ends  102   D  and  106   D  of first flat bar arm  102  and second flat bar arm  106 , respectively to the first adapter bracket  100  and to the second adapter bracket  104 . In an embodiment, the first adapter bracket  100  includes a proximal end  100   P  which is pivotally attached at or near the distal end  102   D  of the first flat bar arm  102 . The first adapter bracket  100  also includes a distal end  100   D  that extends outwardly from the first flat bar arm  102 . In an embodiment, the second adapter bracket  104  includes a proximal end  104   P  which is pivotally attached at or near the distal end  106   D  of the second flat bar arm  106 . The second adapter bracket  104  also includes a distal end  104   D  that extends outwardly from the second flat bar arm  106 . In an embodiment, the first adapter bracket  100  and the second adapter bracket  104  each includes a generally L-shaped ear portion  100   E  or  104   E , respectively, at said proximal end  100   P  or  104   P , respectively. In such an embodiment, the first adapter bracket  100  is pivotally attached to the first flat bar arm  102  at the ear shaped portion  100   E  of the first adapter bracket  100 . Likewise, the second adapter bracket  104  is pivotally attached to the second flat bar arm  106  at the ear shaped portion  104   E  of the second adapter bracket  104 . 
     As seen in  FIGS. 19 and 29 , a retractable stair system  54  may be provided which includes an extensible-retractable scissors stair assembly RSA. The extensible-retractable stair assembly RSA includes a first scissors assembly  118   A  and a second scissors assembly  118   B . The first scissors assembly  118   A  and the second scissors assembly  118   B  are affixed to the first adapter bracket  100  and to the second adapter bracket  104 , respectively. In an embodiment, the first scissors assembly  118   A  and the second scissors assembly  118   B  each includes a plurality of outward elements  130  (which when extended may be oriented substantially horizontally) and a plurality of downward elements  132  (which when extended may be oriented substantially vertically). Suitable means for providing the first scissors assembly  118   A  and the second scissors assembly  118   B  are set out in various drawing figures, such as  FIGS. 27, 28, and 29 . The first scissors assembly  118   A  and the second scissors assembly  118   B  are spaced apart by a number N of stairs S in a series of stairs S 1  to S N , wherein N is a positive integer between two and six inclusive, and wherein each of the stairs S is securely affixed between selected outward elements of the first scissors assembly  118   A  and the second scissors assembly  118   B . As seen in  FIGS. 9, 16, 18, 22 , one or more of the stairs S in the series of stairs S 1  to S N  further includes an upper surface S 1S , S 2S , etc., which includes thereon a non-skid surface portion  140 . 
     Attention is now directed to  FIGS. 21, 22, and 40B, and 42C . In order to provide easy deployment and stowage of the extensible-retractable stair assembly RSA, the first indexing plate  80 , the second indexing plate  90  may be provided with low friction surface pads  150 . In an embodiment, the first indexing plate  80  has an outer side  80   O  and an inner side  80   I . Low friction surface pads  150  are affixed to the outer side  80   O  of the first indexing plate  80 . This technique decreases the friction between inner side  66   I  of the first side plate  66  and the outer side  80   O  of the first indexing plate  80 , to facilitate arcuate movement of the first indexing plate  80  with respect to the first side plate  66 . For the same reasons, the second indexing plate  90 , may be provided with low friction surface pads  150 . In an embodiment, the second indexing plate  90  has an outer side  90   O  and an inner side  90   I . Low friction surface pads  150  are affixed to the outer side  90   O  of the second indexing plate  90 . This technique decreases the friction between inner side  681  of the second side plate  68  and the outer side  90   O  of the second indexing plate  90 , to facilitate arcuate movement of the second indexing plate  90  with respect to the second side plate  68 . As seen in  FIGS. 20 and 42C , for the same reasons, an inward side of first latch  92  and of second latch  94  may also be provided with a strip of low friction surface pad  150 . 
     In operation, the retractable stair assembly  54  is adjusted via the moving the first  92  and second  94  latches to remove latch tongues  92   T  and  94   T  from the then utilized working recessed locking notch LN in the respective first indexing plate  80  and in the second indexing plate  90 . This can be seen in the series of drawing figures, namely  FIGS. 19 through 25 . The first side plate  66  has a top  66   T , and the second side plate has a top  68   T . In an embodiment, the adjustment of the latch tongue  92 T of the first latch  92  and of the latch tongue  94   T  of the second latch  94  to one of the plurality of working recessed locking notches LN adjusts said stair S 1  to a height H S  below the top  66   T  of the first side plate  66  and below the top  68   T  of the second side plate  68 . 
     In an embodiment, as seen in  FIG. 19 , wherein the first  80  and second  90  indexing plates include a first recessed locking notch LN 1 , a second recessed locking notch LN 2 , a third recessed locking notch LN 3 , and a fourth recessed locking notch LN 4 , the placement of the latch tongues  92   T  and  94   T  in the first locking notch LN 1  may be used to secure the retractable stair system  54  in a secure stair S 1  in a stowed position, wherein the stair S 1  is substantially secured between the first side plate  66  and the second side plate  68 . 
     In an embodiment, as seen in  FIG. 22 , wherein the first  80  and second  90  indexing plates include a first recessed locking notch LN 1 , a second recessed locking notch LN 2 , a third recessed locking notch LN 3 , and a fourth recessed locking notch LN 4 , the placement of the latch tongues  92   T  and  94   T  in the second locking notch LN 2  may be used to secure the retractable stair system  54  in a first stair height configuration, wherein the stair S 1  is adjusted to a height H SA  below the top  66   T  of said first side plate  66  and below the top  68   T  of the second side plate  68 . 
     In an embodiment, as seen in  FIG. 24  wherein the first  80  and second  90  indexing plates include a first recessed locking notch LN 1 , a second recessed locking notch LN 2 , a third recessed locking notch LN 3 , and a fourth recessed locking notch LN 4 , the placement of the latch tongues  92   T  and  94   T  in the third locking notch LN 3  may be used to secure the retractable stair system  54  in a second stair height configuration, wherein the stair S 1  is adjusted to a height H SB  below the top  66   T  of said first side plate  66  and below the top  68   T  of the second side plate  68 . 
     In an embodiment, as seen in  FIG. 25  wherein the first  80  and second  90  indexing plates include a first recessed locking notch LN 1 , a second recessed locking notch LN 2 , a third recessed locking notch LN 3 , and a fourth recessed locking notch LN 4 , the placement of the latch tongues  92   T  and  94   T  in the fourth locking notch LN 4  may be used to secure the retractable stair system  54  in a third stair height configuration, wherein the stair S 1  is adjusted to a height H SC  below the top  66   T  of said first side plate  66  and below the top  68   T  of the second side plate  68 . In this example, the adjustment of height H S  of the stair S 1  below the top  66   T  of the first side plate  66  and below the top  68   T  of the second side plate  68  may be about seven (7) inches. In other embodiments, as just noted above, the adjustment of height H S  of the stair S 1  below the top  66   T  of the first side plate  66  and below the top  68   T  of the second side plate  68  may be as much as about seven (7) inches, or less. 
     Attention is directed to  FIGS. 30 through 35 , where the use of shelf brackets  160 , or  162 , or  164  are illustrated. The shelf brackets  160  may be utilized when four steps S are provided. The shelf brackets  162  may be utilized when five steps S are provided. The shelf brackets  164  may be provided when six steps S are provided. As illustrated in  FIGS. 30 through 35 , although similar shelf brackets  160 ,  162  or  164  may be provided, the use of a larger number of steps requires lower mounting of the shelf brackets  160 ,  162  or  164 , which may be facilitated by changing the configuration utilized for mounting brackets  161 ,  163 , and  165 , respectively. 
     It is to be appreciated that the retractable stair system with precision elevation control as disclosed herein is an appreciable improvement in the art of stairs for vehicles. The novel design for a retractable stair system with precision elevation control addresses the problem of how to provide for service above differing or uneven substrates, such as rocky ground located below the stairs at the location of a parked vehicle. The embodiments have been thoroughly described to enable those of ordinary skill in the art to make and use the invention, including embodiments which utilize aircraft grade aluminum and stainless steel components, for corrosion resistance during years of outdoor use, such as on various 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 retractable stair system with precision elevation control 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.