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CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority from U.S. Provisional Application No. 61/775,911 filed Mar. 11, 2013, which is hereby incorporated herein by reference in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not applicable. 
       NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       REFERENCE TO A COMPACT DISC 
       [0004]    Not applicable. 
       BACKGROUND 
       [0005]    This disclosure relates to a stairway safety and mobility assistance apparatus. 
         [0006]    Prior art includes devices intended to help people traverse stairs. Certain issues with these devices inhibit full and effective use by mobility impaired persons. U.S. Pat. No. 7,950,498 by Stair Climbing Aid issued to Yang is an example of an assistance rail that spans the width of a stairway. Assistance rails that span across the stairs and attach to each side of the stairway create a barrier preventing the user from exiting the stairway. 
         [0007]    U.S. Pat. 7,870,695 Support Apparatus and Method for Assisted Traversal of a Structure issued to Manson is an example of an assist rail attached to a single side of a stairway. In this and other prior art, rails that are attached to only one side of the stairway may be too weak to handle the full load of a falling person, and they often bind or get stuck during use. 
         [0008]    Existing stairway assistance devices require a degree of muscle strength or fine motor manipulation that is beyond the ability of many mobility impaired individuals. The rails or barrier devices constructed are heavy and difficult for children or elderly users to manipulate. 
         [0009]    Much of the prior art requires the user to exercise precise control of a stopping mechanism. The user may stop in a position that is either too far away, causing a dangerously extended reach, or too nearby, blocking full movement to the next step. Some devices have built-in stopping positions to overcome this problem, but those positions are not adjustable for ease of installation and for re-use on another stairway. 
       SUMMARY 
       [0010]    A stairway assist apparatus helps mobility impaired individuals to walk up and down stairs. A low-friction, high strength track is attached to a wall or banisters running parallel to the rise of the stairs. A cross rail assembly serves as a grip to hold onto and a barrier to prevent falling. It includes upper and lower rails to provide a larger barrier and unique grips for walking up and down. The cross rail slides along the track on a high strength, low-friction carriage. A counterweight is attached to the carriage so that the cross rail assembly is easy to move. The cross rail moves one full step at a time and locks into place for travel to the next step. The stop positions are fully adjustable to accommodate differences in stair construction. A self-retracting lifeline is attached to lock the cross rail if it accelerates quickly when a user trips or falls. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of an apparatus being used by a person. 
           [0012]      FIG. 2  is a perspective view of a track and adjustable stops. 
           [0013]      FIG. 3  is a perspective view of a cross rail assembly. 
           [0014]      FIG. 4  is a perspective view of a carriage. 
           [0015]      FIG. 5  is a front view of the counterweight and self-retracting lifeline assemblies. 
           [0016]      FIG. 6  is a front view of the telescoping cross rail. 
           [0017]      FIG. 7A  is a side view of a wheeled carriage and separate stop. 
           [0018]      FIG. 7B  is a front view of a wheeled carriage and separate stop. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    Several embodiments of the assist apparatus are shown and described in relation to the drawings. Referring to  FIGS. 1 and 3 , the cross rail assembly can be moved along the length of a stairway  10  by a user  11  moving either up or down stairs. The apparatus includes a low-friction track  14  mounted parallel to the rise of the stairs. The apparatus includes a cross rail assembly to be gripped by the user. The cross rail assembly consists of at least two bars or rails  12  that are parallel with the steps. A lower bar or rail is gripped to walk up the stairs,  4  while an upper bar or rail is gripped for descent. The cross rail assembly is attached to a carriage  13 . In some embodiments, a cross rail base  23  will be used to join the carriage to the cross rail assembly. The carriage  13  includes bearings, wheels or low friction material so that it slides freely along the track. A plunger-lock  15  engages with adjustable stops  16  to prevent movement of the cross rail assembly down the stairs. The plunger-lock is disengaged by the user to initiate movement to the next step. One lock position exists for each step. 
         [0020]    Referring to  FIG. 2 , the preferred embodiment includes a track  14  and adjustable stops  16 . The track is securely attached to the wall and/or banister either with through bolts or with a bracket. The adjustable stops  16  may be attached to the track, or to the wall, or to a bracket attached to either the wall or track. One embodiment uses an extruded aluminum t-track rail. 
         [0021]    Referring to  FIG. 3 , the preferred embodiment includes a cross rail assembly with upper and lower cross rails  12 . The cross rail assembly includes a carriage  13 . The cross rail and base may be attached to the carriage in any manner sufficient to handle the usage loads, including welding, bolts, and other attachment means. The cross rail assembly includes a sliding plunger-lock mechanism  15 . The preferred embodiment includes a support bar  22  for strength and a base  23  to join the cross rails  12  to the carriage  13 . The upper cross rail will be above the lower cross rail. 
         [0022]    The sliding plunger-lock mechanism  15  includes a shaft that penetrates the cross rail assembly base  23  and the carriage  13  so that it can engage against  5  the adjustable stops  16 . This prevents sliding of the cross rail assembly down the track  14 . The plunger-lock mechanism also includes a handle and positive engagement device  26 . In this embodiment, a spring is used for positive engagement; positive pressure will always push the mechanism into locked position unless the handle portion of the lock mechanism  15  is used to retract it. The handle can be moved by the user, away from the track, to unlock the cross rail assembly. The lock mechanism can include a key and slot to prevent unwanted rotation of the lock mechanism. The apparatus may also include a strap to keep the assembly in the unlocked mode. 
         [0023]    The stop release mechanism may be intended for use by individuals that lack fine motor skills. A slap or swipe at the release handle may be sufficient to release the cross rail assembly for movement to the next step. 
         [0024]    Referring to  FIG. 4 , the carriage  13  may take a range of shapes. It is the connection point between the track  14  and the cross rail assembly. The carriage will match the low friction design of the track, and will have sufficient strength to support the usage loads.  FIG. 4  shows a carriage that is an H-shape profile, with threaded holes  29  so that the base  23  of the cross rail assembly may be bolted to it. The other T-shape engages the track  14 . 
         [0025]    Referring to  FIGS. 1 and 5 , a counterweight  31  reduces the force needed for a user to move the cross rail  12  up the stairs. The counterweight  31  slides in a slide-way  32  that is fastened to the wall at an angle so that it is steeper than the stairway. The counterweight  31  is attached to the carriage  13  by a cable  33  that runs through a pulley  34 . 
         [0026]    Referring to  FIGS. 1 and 5 , one embodiment includes a self-retracting lifeline  37  to prevent rapid acceleration of the cross rail  12 . In one embodiment, the self-retracting lifeline  37  is attached to the carriage  13  by a cable  36  that runs through a pulley  35 . The pulling force is up the stairs, and the self-retracting lifeline  37  will lock movement of the carriage  13  if it accelerates due to the fall of a user. In an embodiment, cable  36  runs through an anchored centrifugal brake mechanism so that the brake locks if the cable is moved very quickly, as in a fall. 
         [0027]    The apparatus may also include a retrieval system. The purpose of the retrieval mechanism is to move the cross rail assembly toward the user if the assembly was last left at the other end of the stairs. A reel is attached to one end of a cable. The other end of the cable is attached to the carriage  13 . The reel is turned manually to retrieve the assembly. Reels are positioned at the top and bottom of the track. A strap can be used to keep the locking mechanism in the unlocked mode for retrieval. The cables for the retrieval system and for the braking system can ride inside of a cableway that runs parallel to the track. 
         [0028]    A child barrier attachment can be used in some embodiments. The child barrier attachment attaches to the cross rail assembly so that it extends to the nose of a step, and across the width of the stairway. One embodiment uses hooks to hand the child barrier from the top or bottom rail. Another embodiment uses screws to attach the child barrier to the cross rail assembly. Another embodiment uses a hook and loop system such as Velcro™ to attach the child barrier to the cross rail assembly. 
         [0029]    Referring to  FIG. 6 , one embodiment includes a cross-rail that telescopes to reduce the width of the apparatus across the entrance to a stairway when it is not in use. The fixed cross-rail  38  and support bar  22  are joined together and attached in a fixed way to the base  23 . Fixed cross-rail  38  has a through-hole for spring-loaded location pin  39 . Telescoping cross-rail  40  has an outside diameter that fits within the inside diameter of fixed cross-rail  38  and has a through-hole for spring-loaded location pin  39 . The spring-loaded location pin  39  is fixedly attached to the inside of telescoping cross-rail  40  with constant outward pressure. A user pushes down the pin  39  and pushes telescoping cross-rail  40  to retract inside of fixed cross rail  38 . 
         [0030]    Referring to  FIG. 7A  and  FIG. 7B , in one embodiment, the track may be split into two parallel sections. The main track  42  provides a guide for wheels  44 . The adjustable-stop track  41  is parallel with the main track  42  and the adjustable stops  16  are attached to track  41 . The wheels  44  are attached to carriage  43  by axles  45 . 
         [0031]    Other embodiments may include various features. 
         [0032]    In one embodiment, the apparatus can be used to move up or down a ramp instead of stairs. 
         [0033]    In one embodiment that does not use stop blocks, the lock mechanism penetrates stop holds in the track, the wall, or an attachment that runs parallel to the track. The lock shaft engages with the downhill side of the stop hold to prevent movement. 
         [0034]    One embodiment includes a stainless steel track and ball bearing carriage. One embodiment uses two parallel tracks to support the cross rail assembly. 
         [0035]    One embodiment of the cross rail assembly includes additional parallel rails between the upper and lower rails to accommodate users of different heights. One embodiment includes a hinge so that the cross rail may swing out of the way. One embodiment includes a bracket and pocket/slot so that the cross rail may be removed from the carriage when not in use. 
         [0036]    One embodiment of the cross rail omits the end section, the support bar, or both. 
         [0037]    Other embodiments may use alternative locking/unlocking mechanisms and include actuators, including a cable and lever arrangement. 
         [0038]    Other embodiments achieve the unlocked position by use of alternative restraints to hold the lock mechanism in the unlocked positions, such as a slide, or clip. 
         [0039]    Other embodiments attach the base to the carriage using a different number of bolts, use pins, or use a welded or chemically joined attachment. 
         [0040]    In one embodiment, the carriage is fabricated so that the base is not used and the cross rails attach directly to the carriage. 
         [0041]    In one embodiment, a different brake mechanism is used to stop movement of the cross rail assembly if a fall is detected. 
         [0042]    In one embodiment, electronic gauges sense a fall and force the lock mechanism to engage, so that the lock mechanism doubles as a brake. 
         [0043]    In one embodiment, the retrieval reel is turned by a motor. In one embodiment, the cable is a continuous loop and is grasped directly by the user to manage the retrieval without a reel.

Summary:
This apparatus helps mobility impaired individuals to walk up and down stairs and can reduce the incidence of stairway falls. A low-friction, high strength track is attached to a wall or banisters, running parallel to the rise of the stairs. A perpendicular cross rail assembly serves as a grip and a barrier to prevent falling. The cross rail slides along the track on a low-friction carriage. The user moves the cross rail up or down along the stairway one full step at a time. The cross rail locks into a fixed stopping position for travel to the next step. The fixed positions are adjustable. A counterweight reduces the force required for users to move the cross rail up or down stairs. A braking system is in place to lock the cross rail if a user falls.