Abstract:
The invention is a mobile maintenance stand that combines the function of an adjustable stairway and hydraulic scissor lift that independently elevates and descends an access work platform to support maintenance tasks on commercial and military aircraft. The elevating access work platform has an extended reach of 144′ and is initiated by a secondary hydraulic scissor lift that promotes upward extension beyond the parameters of the adjustable stairway reach, to provide further maintenance access. The additional extension range of the access work platform with a hydraulic scissor device, provides vertical movement to the work deck at all check levels. Further, this invention is self-contained that collapses to a compact dimension and be transported on an air cargo pallet. Thus, the invention&#39;s mechanical scheme of the scissor lift to extend access work platform beyond the adjustable stairway is novel and, is unlike any existing articulating stairway and, or scissor embodiments.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention arose out of the necessity to create a mobile elevating access work platform with easier accessibility and expanding repair range that prior or present platform system failed to provide in support of maintenance task upon aircraft. This mobile elevating access platform invention with a second hydraulic scissor lift and an independent operating device addressed this particular problem. Prior maintenance stands had stairways without an adjustable access work platforms to add extra height range for maintenance service. Further, the articulating stairway has an independent operating scissor device separate from the access work platform. As a result, this second hydraulic scissor lift device helps to expand the height range of the access work platform which is mandatory and useful for maintenance repairs in the aviation industry. Thus, the Mobile Access Maintenance Stand will be filed under the United States Patent Code definition as a Machine. 
       SUMMARY OF THE INVENTION 
       [0002]    The invention relates to Mobile Maintenance Stand which uniquely combined functions of an articulating stairway and access work platform both powered and operated by hydraulic scissor devices and controls. Further, the access work platform has an added dimension with the capability to lift vertically above the expanding stairway structure and provides an add advantage to aircraft repair that other maintenance stands failed to offer. A further advantage of Mobile Maintenance Stand invention is its capability of being collapsible to an appreciable small envelope designed to fit within the allowable limits of a standard military transport pallet HCU-6/E 463L. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0003]    Referring to  FIG. 1 , this drawing illustrates one embodiment of the present invention in a non-collapsed configuration;  FIG. 2 , illustrates one embodiment of the invention in a collapsed and deployable configuration. The present invention which is referred to as a deployable combination mobile elevating access platform comprises in one embodiment of a chassis element  29  connected to and supporting a height adjustable stairway element  30 , which in turn is connected to and supports an elevating platform element  31 . 
         [0004]    The elevating platform element  31  in one embodiment is comprised of a lower rail assembly  34 , a deck assembly  35  and opposing scissor frames  36  &amp;  37  which in a preferred embodiment have rollers  38  to allow roll movement in the lower rail assembly  34  and the deck assembly  35 . In a preferred embodiment the lower rail assembly  34  is designed to articulate and remain substantially parallel with the steps  39  of the height adjustable stairway element  30  by means of a designed geometrically appropriate telescoping support trestle element  33  which is also attached to the chassis element  29 . 
         [0005]    The chassis element  29  in a preferred embodiment is supported on at least  4  suitably sized wheels or caster wheels  40 . The invention is further adapted to include at least 1, but the preferred embodiment having 4 mechanical screw type stabilizer leg assemblies  41 . In the preferred embodiment the forward 2 mechanical screw type stabilizer assemblies  41  are fitted to outriggers  42  which enhance the stability of the invention when in use. In one embodiment the outriggers  42  are stowed for transportation or when not in use by folding back parallel with the chassis frame element  29  and winding the stabilizer leg assembly  41  under and into the capture cleat  52 . 
         [0006]    In one embodiment, the height adjustable stairway element  30  is comprised of steps  39 , stringers  43 , tie rod  44 , telescoping support trestle element  33 , pivoting hand rail  45 , rotating handrail posts  46  and pivoting hardware  47 . In a preferred embodiment the height adjustable stairway element  30  is articulated in a controlled radially up and down movement initiated by a suitably sized hydraulic piston ram  48  located and attached between the telescoping trestle element  33  and the chassis element  29 . In a preferred embodiment the hydraulic piston ram  48  is actuated by a manually operated oil pump  49 . Similarly the elevating platform element  31  is in one embodiment operates by a second independent hydraulic piston ram  50 . In a preferred embodiment the hydraulic ram assembly is actuated by means of a manually operated hydraulic pump  51 , that controls vertically up and down movement of the elevating platform element  31 . 
         [0007]    In one embodiment, the height adjustable stairway element  30  is further adapted to incorporate a mechanical lock out feature  52 , comprising of a pivoting ridged fixed length mechanical lock out leg  53 , a multi-position glide cleat assembly  54 , a lubricated low friction glide shoe  55 , lock out glide rail  56 , and locking pin  57 . 
         [0008]    The mechanical lockout feature  52  functions in the presented preferred configuration as follows: when the height adjustable stairway element  30  is in a static position, the multi-position glide cleat  54 , being mechanically connected to the pivoting ridged fixed length mechanical lock out leg  53 , is secure to prevent movement within the lock out glide rail  56  located on chassis element  29  by locking pin  57 . 
         [0009]    Inversely when the height adjustable stairway element  30  is required to articulate, the locking pin  57  is temporarily removed and the height adjustable stairway element  30  acted upon by the hydraulic cylinder  48 . The multi-position glide cleat assembly  54  being mechanically connected to the pivoting ridged fixed length mechanical lockout leg  53  is forced to travel along the lockout glide rail  56  as the angle of the pivoting ridged fixed length mechanical lockout leg  53  changes and the distance from the pivot point  32  to the lockout glide rail  56  increases or decreases as a consequence of a change in elevation of the height adjustable stairway element  30 . When a desired height is attained the multi-position glide cleat assembly  54  is again secured in position by the locking pin  57  in the lockout glide rail  56 . Guaranteeing an infinite number of height positions for the height adjustable stairway element  30  is possible due to the suitably dimensioned slots  58  in the lock out glide rail  56  and the appropriately spaced array of pin positions  59  provided in the multi-position glide cleat assembly  54 . 
         [0010]    Similarly the elevating platform element  31  is adapted to incorporate a mechanical lock out feature  60 , comprising of mechanical lock out pin  61 , threaded support let  62 , hollow guardrail gate post  63 , actuating stop nut  64  and articulating cleat and pin  65 . 
         [0011]    The mechanical lock out feature  60  functions in the presented preferred embodiment. When the elevating platform element  31  in a static position is prevented from collapsing by the mechanical lock out pin  61  placed through pre-drilled holes in the threaded support leg  62  secures the threaded support leg  62  from sliding inside the hollow guardrail gate post  63 , and thereafter, prevents movement of the connected elevating platform element  31 . Additionally the articulating stop nut  60  being set to any desired height along the threaded support leg prevents the elevating platform element  31  from collapsing and can be set to an infinite number of height positions. The threaded support let  62  is connected to the lower rail assembly  34  by articulating cleat and pin  65 . This arrangement ensures that the threaded support let  62  is always coaxial with hollow guardrail gate post  63  during adjustment of height adjustable stairway element  30  and or elevating platform element  31 . 
         [0012]    In a preferred embodiment invention is enhanced with the inclusion of OSHEA &amp; ANSI compliant adjustable stairway handrails  60 , which by means of a pivoting joint are connected to fixed guardrail post  66  which is part of chassis element  29 , and pivoting guardrail post  67 . The arrangement ensures that the handrails  60  are always parallel to the height adjustable stairway element  30 . 
         [0013]    The invention and this embodiment is further adapted with the inclusion of OSHA &amp; ANSI compliant fall protection removable guardrails  68 , on all sides of the elevating platform element  31  deck assembly  35 . The invention is further enhanced with the inclusion of a positive locking swing gate  69  and integrated drop ladder  70 . 
         [0014]    In one embodiment the guardrails  68  are located into arranged pockets  71  located on the deck assembly  35  and secured in position using locking pins  72 . The swing gate  69  and integrated drop ladder  70  are fitted to the egress side of the elevating platform element  31  and provide safety for the operator while elevated and emergency ingress from the elevating platform element  31  in an emergency. 
         [0015]    In a preferred embodiment a folding lower step  73  is included and fitted to the chassis element  29  for the purposes of compacting for the collapsed configuration ( FIG. 2 ). The invention is further adapted by the inclusion of at least 1 suitably sized tie down pin  74  and at least one lifting point  75 . The invention is adapted to include an integrated stowed towing element  76 , which is located onto arranged and suitably sized spigots  77  located on the chassis element  29 . The towing element  76  is adapted with telescoping members  78  to increase its size and is fitted using retaining pins  79  to cleats  80  fitted to the chassis element  29 . In one embodiment the towing element  76  can be used as a winch point and a secondary winch point  81  is provided on the front of the chassis element  29 . 
         [0016]    The following text describes a preferred sequence of procedures associated with the invention to configure it from an operation to a collapsed configuration; the description is offered as one possible sequence and not the only possible sequence. 
         [0017]    In one embodiment, the invention is configured from an operational configuration ( FIG. 1 ) to collapsible configuration ( FIG. 2 ) by first collapsing the elevating platform element  31  to its lowest position. Then by lowering the height adjustable stairway element  30  to its minimum height position and removing temporarily guardrails  68 , swing gate assemblies  69  &amp;  70  and mechanical lock out feature  60 . In a preferred embodiment un-couple the manual pump  51  used to actuate the elevating platform element  31 . 
         [0018]    Next lock the elevating platform element  31  assembly together using hood straps  82  to prevent unwanted actuation and raise the deck assembly back to approximately  72 ″ above ground using the manually operated oil pump  49 . 
         [0019]    Next release a temporarily remove securing pins  83  secured from locating holes  84  found on the inner slide frame  85  of the telescoping support trestle element  33  and locating holes  86  on the outer slide frame  87  of the telescoping support trestle element  33 . 
         [0020]    Using the manually operated oil pump  49  reverse the hydraulic piston ram  48  to rotate downward the elevating platform element  31  until the inner slide frame  85  of the telescoping support trestle element  33  travels downward along the outer slide frame  87  until the 2 nd  set of locating holes  88  on the outer slide frame  87  align with the locating holes  84  of the inner slide frame  85 . Replace securing pins  83  to locating holes  88  to lock the geometry. 
         [0021]    Now remove hydraulic piston ram securing pin  89  and using manually operated oil pump  49  extend again the hydraulic piston ram  48  until it aligns and can be secured using the removed securing pin  89  to the lowering cleats  90  located on the outer slide frame  87 . 
         [0022]    Next temporarily remove securing pins  83  again. Once again using manually the manually operated oil pump  49  reverse the hydraulic piston ram  48  to continue to rotate downward the elevating platform element  31  until the outer slide frame  86  of the telescoping support trestle element  33  slides downward until 3 nd  set of locating holes  91  found on outer slide frame  87  align with locating holes  84  found on inner slide frame. Replace securing pins  83  into locating holes  91  to lock the geometry. 
         [0023]    Extend pivoting mechanical actuator jack  92  by releasing locking pin  57  and winding actuator using handle  93  until inner leg  94  extends sufficiently and can be secured using locking pin  57  and multi-position glide cleat assembly  54  to lock out glide rail  56 . Next remove hydraulic piston ram securing pin  89  and rotate downward the hydraulic piston ram  48  until it can be located in the stowing cleat  95  located on the chassis element  29 . 
         [0024]    Next remove the locating pins  83  and allow the elevating platform element  31  to swing in until the 4 th  set of locating holes  96  found on the outer slide frame  87  align with the locating holes  84  found on the inner slide frame  85 . Replace securing pins  83  to the 4 th  set of locating holes  96  to lock the geometry. 
         [0025]    Using the handle  93  wind and retract the inner leg  94  of the pivoting mechanical actuator jack  92  until the entire assembly comes to rest on angle shelf  97 . Release locking pin  57  and continue to retract until aligned with pivoting ridged fixed length mechanical lock out leg  53  replace lock out pin  57 . 
         [0026]    Unbolt OSHEA &amp; ANSI compliant adjustable stairway handrails  60  form and the pivoting guardrail post  67  located height adjustable stairway element  30  and allow both to hang down freely. 
         [0027]    Replace 2 of the guardrails  68  inverted in the arranged pockets either side of the elevating platform element  31 , and replace inverted the swing gate assemblies  69 . Next locate mechanical lock out features assembly  60  into provided storage location  98 . Locate 3 rd  guardrail to sockets  99  provided on chassis element  29 . Retract outriggers  42  by folding back parallel with the chassis frame element  29  and winding the stabilizer leg assembly  41  under and into the capture cleat  52 . 
         [0028]    In the above preferred sequence and embodiment the preceding instructions are reversed to reconfigure into the operational configuration. 
     
    
     LIST OF FIGURES 
       [0029]      FIG. 1  General Isometric views of device in maximum extended configuration 
         [0030]      FIG. 2  Elevation and isometric views of device in collapsed deployable configuration 
         [0031]      FIG. 3  Detail view from under side of scissor deck extended 
         [0032]      FIG. 4  Detail view from under side of chassis frame and stairway 
         [0033]      FIG. 5  Detail view of sliding and locking mechanisms 
         [0034]      FIG. 6  Detail view of scissor deck access and locking mechanisms 
         [0035]      FIG. 7  Elevation views od benchmark range of motions