Abstract:
A spring loaded double plunger track fitting for use in securing a wheelchair or the like to a floor track mounted in a vehicle. The track fitting includes at least four track engaging lugs on each side thereof and a pair of spring loaded plungers between adjacent pairs of lugs to lock into the floor track when the fitting slides therealong. A visual means to indicate when the plungers are in the locked position may be provided.

Description:
FIELD OF INVENTION 
   This invention relates to wheelchair restraint systems and more particularly to an improved spring-loaded track fitting for adjustably securing a wheelchair tie down strap to a floor track mounted in a vehicular conveyance. 
   BACKGROUND OF INVENTION 
   Conventionally, buses and vans equipped to carry wheelchairs and the like are provided with a pair of parallel slotted floor tracks into which one or more strap anchor fittings can be inserted and secured at any selected position therealong. Usually such anchors are provided with a spring-loaded plunger, the lower end of which can be passed through an opening in the track and, upon release of the spring, the sides of the plunger releasably engage with the track at any selected position therealong. While such fittings are generally effective they are not without their disadvantages. The fact that they are secured to the track at substantially one end of the anchor fitting implies that there is a considerable moment of force applied to the fitting when a heavy load, as in a sudden deceleration or crash situation, is applied thereto and this can cause bending or twisting of the fitting or of the track itself so that the fitting jams in the track and no longer slides freely therealong. There is a need, therefore, for an improved track fitting that spreads the applied load along a longer length of the fitting and track so as to prevent or at least minimize such bending or twisting of the fitting and/or the track. 
   OBJECT OF INVENTION 
   An object of the present invention is to provide a track plunger fitting that engages two adjacent holes in a conventional floor track so as to eliminate or reduce any twisting action on the fitting. In order to accommodate two plungers without increasing the overall height of the device, a split plunger with overlapping heads in employed. 
   BRIEF DESCRIPTION OF INVENTION 
   By one aspect of this invention there is provided a double plunger track fitting comprising: 
   a body member including means to secure a restraining strap thereto, and at least four track engaging lugs on each side of said body and extending laterally therefrom when in operative position;
     spring loaded means on each side of said body member, each having a pair of plungers longitudinally from each other and adapted to slide, when in operative position, between two adjacent pairs of said track engaging lugs between a raised unlocked position and a lowered locked position; and   finger grip means on each said spring loaded means arranged in overlying relationship to each other.   

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is an isometric view of a plunger type track fitting according to the prior art and provided with a single plunger; 
       FIG. 2  is an isometric view of one embodiment of the track fitting and double plunger of the present invention; 
       FIG. 3  is an isometric enlarged view of the plunger of the embodiment of  FIG. 2 ; 
       FIG. 4  is an isometric view of the plunger of  FIG. 2  as inserted into a floor track; 
       FIG. 5  is an isometric view of the embodiment of  FIG. 2  incorporating one type of locking indicator; 
       FIG. 6  is an isometric view, similar to  FIG. 5 , showing an alternative type of locking indicator; 
       FIG. 7  is an isometric view of the embodiment of  FIG. 2 , in the unlocked position, incorporating a slide mechanism to lock said plungers into locked position; 
       FIG. 8  is an internal view of  FIG. 7  illustrating the slide mechanism; 
       FIG. 9  is a plan view of the slide of  FIG. 8 ; and 
       FIG. 10  is an enlarged view of the plunger of FIG.  8 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   In  FIG. 1  there is shown a conventional floor track  1 , generally formed from extruded aluminum and provided with a C-shaped track  2  and a plurality of slots  3 , uniformly spaced along the length thereof. A die cast or forged metal track fitting  4  having a pair of outwardly extending lugs  5 , which can be inserted in any adjacent pair of slots  3 , and so that the tops of the lugs  5  engage the underside of the C-shaped section of track  2 , is locked into any selected position along the length thereof by means of a spring loaded plunger  6  which engages a selected slot  3 . It will be appreciated that the fitting is relatively short and only two lugs on each side engage with the track so that there is some tendency to twist when a load is applied upwardly, which can occur in an emergency crash or stop situation. 
   In  FIG. 2  there is shown a track fitting  7  according to one embodiment of the present invention which is designed so that four lugs  5  can be inserted into four adjacent slots  3  in a conventional floor track  2 , and slid therealong until two spring loaded plungers  8  drop into a pair of adjacent slots  3  on each side of the track  2 , as seen most clearly in FIG.  4 . It will be appreciated that, as lugs  5  are inserted into slots  3 , the lower surfaces of plungers  8  engage the top surface of the track  1 , the internal compression springs (not shown) therein are compressed when the lugs  5  are fully inserted in the slots  3 , the fitting  7  can then slide along the track  2  until the plungers  8  are exactly located over an adjacent pair of slots  3 , whereupon the compressed springs force the plungers  8  downwardly into the slots  3 , thereby locking the fitting  4  securely in a selected position along the track  1 . Usually, but not essentially, the plungers  8  are fabricated in any conventional thermoplastic or thermosetting plastic material, such as glass filled nylon or similar abrasion resistant material. For ease of manufacture, it has been found preferable to make the plungers  8  in two parts  9 ,  10 , each having a pair of plungers  8  in spaced longitudinal alignment to each other, and interconnected by a side body member  11 ,  12  respectively. Each part  9 ,  10  is provided with a substantially oval shaped planar finger grip  13 ,  14 , in overlying relationship to each other, as shown in  FIGS. 2 and 3 . In order to release the fitting  4  from track  1 , upward finger pressure is applied to grips  13 ,  14  to raise the plungers  8  out of their respective slots  3  so that fitting  4  can slide along track  1  until the lugs  5  are aligned with an adjacent pair of slots  3  and can be removed therefrom. Because the track fitting of the present invention is considerably longer than that of the prior art, as exemplified in  FIG. 1 , there is far less tendency for the fitting  4  to twist and bind in the track  1 . 
   It will, of course, be appreciated that a strap engaging lug  15  may be secured by a bolt  16  (as seen in  FIG. 1 ) insertable in threaded bore  17  ( FIG. 2 ) in conventional manner. 
   It has also been found that, in the event dirt enters the track or a track bolt is loose, the plungers  8  may appear to be locked in place but are in fact not securely locked and it is possible that, in the event of a sudden stop or accident, the track fitting will separate from the track thereby releasing the restraint system to the danger of the wheelchair passenger. It is advisable, therefore, that the the double plunger system should also incorporate a visual indicator to show that the plungers  8  are in the fully locked position. One such indicator  18  is shown in FIG.  5  and comprises a multi-coloured pin which extends through a cover  19  on plungers  8 . The top of the pin  18  may be coloured, say red on the top and along part of the sides  20  thereof, but green along the lower sides  21  thereof. The green lower portions are, of course, only visible when the plungers  8  are fully engaged and locked in place on the track. 
   In  FIG. 6  there is shown an alternative embodiment of the visual indicator described with reference to FIG.  5 . Track fitting  7  is provided with finger grips  13 ,  14 , plungers  8  and lugs  5  as in other embodiments, and the rear of fitting  7  is provided with a finger  21 , forming part of the housing  22  of fitting  7 , and extending longitudinally into a cover  23  forming part of finger grips  13 ,  14 , such that when the plungers  8  are in the fully depressed and locked position, the top surface of finger  21  is flush with the top surface of cover  23 . It will be appreciated that if plungers  8  are not fully locked, then the surface of cover  23  will be above the surface of finger  21  and the difference therebetween will provide a clear visual indication that the fingers are not locked. 
   In some circumstances it may also be desirable to provide a visual indication of locking and to secure the plungers in the locked position by a positive locking mechanism. One such lock is illustrated in  FIGS. 7 and 8 , in which the pin  18  and finger  21  of  FIGS. 5 and 6  are replaced by a slide  24 , projecting rearwardly from the cover  23  and movable from an extended unlocked position, shown in  FIG. 7 , to a closed locked position (not shown) in which the slide engages plungers  8  so as to hold them in the locked position and prevent lifting of finger grips  13 ,  14  until the lock slide  24  is extended rearwardly. As seen more clearly in  FIG. 9 , slide  24  is provided with a narrow slot  26  which engages in slot  25  in the plungers  8  and a wider slot  27  which disengages from slot  25  when the slide  24  is pulled outwardly to the unlocked position.