Abstract:
A passenger seat having a walk-over seat back mounted for movement on a pair of rotatable shafts through a pair of of levers mounted on each end of the shafts. The levers contact each other at opposite seat positions to support the seat back. The pair of shafts include a torsion section at each end portion capable of undergoing plastic deformation upon a lock mechanism detecting predetermined deceleration forces. A lever and link element are operatively connected between the seat cushion frame to permit movement. The seat cushion is removable secured to the seat cushion frame.

Description:
This application claims benefit of priority date of provisional application, Ser. No. 60/284,995 filed Apr. 19, 2001. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to railcars and, in particular, to an improved railroad passenger seat. 
     2. Summary of the Invention 
     Numerous designs for railcar passenger seats have been employed over the long history of railroads. A walkover seat is commonly used in current passenger car applications because the seat back position can be moved to oppositely facing directions. Known walkover seats suffer from several problems involving economy of design and manufacture, safety, maintenance and durability. From the safety standpoint, the presence of an unrestrained or restrained seat in front of a passenger creates a hazard during rapid deceleration, such as during a catastrophic emergency. The unrestrained seat offers no protection and causes serious injuries when impacted by a passenger during deceleration. Restrained seats, such as by means of latches and the like, form a rigid obstacle, which likewise causes injury to the passenger impacting the seat back during deceleration. Attempts have been made in the prior art to absorb the energy of impact by a passenger against a seat back, but a need exists in providing effective and economical means of protecting the passenger during emergency situations. 
     In its opposing positions, the seat back of prior devices utilize latches, stops and support brackets to retain the seat back. Such retention elements are subject to unnecessary wear and require periodic adjustment. Further, the use of brackets and the like to retain the seat back upright does not provide optimum strength characteristics. The seat frames in the past have further used latches or locks to retain it in an operable position. Such latches or locks are subject to stress, which requires repair or replacement. In moving the walkover seat back, the latches can be noisy and are not passenger friendly. The design of seat cushion of prior walkover seats further do not have a frame and cushion design which maximizes the ease of installation by being easily self-positioning. In addition, prior seat cushions do not optimize protection to the cushion by preventing damage from retention clips, vandalism, and normal everyday use. Therefore, it is desirable in the prior art to provide an improved passenger seat overcoming the foregoing and other problems in the prior art. 
     SUMMARY OF THE INVENTION 
     It is, therefore, an objective of the invention to provide an improved walkover sat for passenger railcars. The invention hereto provides a seat design of superior strength with a low weight ratio and smooth operative characteristics. The walkover seat of the application is easy to install and service. The cushion frame is designed to rest directly on the seat frame in opposite positions to eliminate the need of latches or locks for retention. By resting on the seat frame, stress on the seat linkages is substantially reduced and a more lightweight linkage assembly can be employed. Such support of the seat cushion frame further provides a stable, quiet, and passenger friendly seat design and is self-positioning. 
     The seat back of the invention is mounted for movement on a pair of self-positioning levers on each side. In the opposite seat positions, the levers abut each other to retain the seat back in its upright positions. The abutting levers eliminate the need to use support brackets, stops and the like. The abutting levers further provide greater longevity of service, eliminate wear and do not require costly adjustment. The levers also provide excellent strength when stressed to provide a good strength to weight ratio. 
     The seat cushion of the invention is provided with a unique bottom pan, which protects the seat cushion against damage from installation and use. The cushion pan allows the seat cushion to be dropped onto attachment elements for easy installation and has no exterior protrusions to damage other cushions during transport and use. 
     The invention herein further is provided with dual locks at opposite ends of the shafts carrying the walkover seat back levers. The dual locks are mounted in end blocks, which also contain energy dissipation shafts. The energy dissipation shafts cooperate with the locks in the blocks to dissipate energy upon the locks restraining rotation of the walkover shafts during extraordinary deceleration conditions of the railcar. The end blocks simplify the elastic components and reduce associated costs and weight. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front perspective view of a passenger seat employing the improvements of the invention; 
     FIG. 2 is a partial side elevational view of the seat back frame and linkage assembly of the passenger seat of the invention viewing outward of the seat; 
     FIG. 3 is a partial side elevational view of seat back frame and linkage assembly of the passenger seat of FIG. 2 showing the seat back in a first seating position; 
     FIG. 4 is a partial side elevational view of the seat back frame and linkage assembly of FIG. 2 in an intermediate position; 
     FIG. 5 is a partial side elevational view of the sat back frame and linkage assembly of FIG. 2 in an opposite seating position from FIG. 3; 
     FIG. 6 is a partial end perspective side view, with parts in phantom, of the locking block of the passenger seat of the invention showing the locking element in a locked configuration; 
     FIG. 7 is a partial top perspective view of the locking block and torsion shaft of the invention showing the locking element in an unlocked seating position; and 
     FIG. 8 is a side perspective view, with parts exploded, of the cushion frame and cushion of the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 to  10 , there is illustrated the improved walkover seat of the invention, generally designated by reference numeral  2 . Although the seat  2  is described herein as a walkover seat for passenger railroad cars, it is within the scope of the invention to use the teachings of the invention in any environment in which passenger seats are employed. As is conventional, the passenger walkover seat  2  includes a horizontal seat cushion  4  and a walkover seat back  6  supported on a seat frame  8 , which rests on suitable opposed pedestals (not shown). The walkover feature of seat  2  allows the conductor or passenger to move the seat back  6  to opposed positions relative to seat  4  whereby the passengers face in opposite directions. 
     The walkover capability of passenger walkover seat  2  is best shown in FIGS. 2-4. The seat walkover mechanism  12  is provided with a pair of flat walkover levers  14  and  16 . The walkover levers  14  and  16  are interconnected at their upper ends  14   a  and  16   a  by a link  18  pivotally attached to the lever ends by pins  19 . A seat back frame member  20  is attached to the upper portion  18   a  of link  18  by a suitable technique to attain walkover movement of seat back frame member  20  on the levers  14  and  16  in conjunction with a pair of horizontal walkover tubes  22  and  24 . The walkover tubes  22  and  24  are suitably journaled at both ends on frame  8  and extend through the lower ends of levers  14  and  16  in fixed relationship and under the seat cushion  4  from the aisle side to the window side of passenger seat  2 . The opposed positions of the walkover levers  14  and  16  are shown in opposite positions of the seat back  6  in FIGS. 3 and 5. During walkover movement from the position of FIG. 3 to the position of FIG. 5, the walkover tubes  22  and  24  rotate in the same directions to facilitate movement of the entire seat back  6  to the opposed position. 
     Referring now to FIGS. 6 and 7, a locking block assembly  30  is mounted at each end of hollow walkover shafts  22  and  24  immediately inside of seat back frame levers  14  and  16 . The locking block assembly  30  includes a metal block  30   a  having rear integral anchoring plate  32  which is arranged to be secured to frame  8  at both sides by bolt assemblies (not shown) through bolt holes  32   a . A front plate  34  (FIG. 7) is also secured to block  30   a  by bolts  36  to mount the linkage assembly to be described. The block  30   a  has a cavity  38  to permit solid end extensions  40   a ,  40   b  to be secured to the ends of walkover tubes  22  and  24  and extend through levers  14  and  16  in fixed securement by a conventional technique. The inner ends  42  of the end extensions  40   a ,  40   b  have flattened faces  44  for interfitting in fixed relationship respectively within the ends of hollow walkover shafts  22 ,  24  having a hollow square cross-sectional configuration. 
     A locking element  50  is journaled between end extensions shafts  40   a ,  40   b  for pivotal movement on a shaft  50   a  carried on locking block  30   a  as seen in FIGS. 6 and 7. The locking element  50  is generally in the form of a rectangular plate having opposed cutout areas  52  disposed on opposite vertical sides of the locking element  50  and cut-off upper corners  54 . The lower portion  56  of locking element  50  extends a greater distance from the shaft  50   a  than upper portion  56   a  to create an imbalance to respond to deceleration and cause pivoting action of the locking element  50  about shaft  50   a  dependent on the direction of the deceleration forces. In a normal vertical orientation of the locking element  50  in absence of any extraordinary forces, the walkover tubes  22 ,  24  and end extensions  40   a ,  40   b  are free to rotate to change seat back positions. The end extension shafts  40   a  and  40   b  are formed with locking notches  52   a ,  52   b  in the periphery at two positions on each end extension shaft  40   a ,  40   b . The cutout areas  52   a ,  52   b  are formed by two intersecting faces  54   a ,  54   b  whereby one face  52   a  extends parallel to the axis of rotation of end extensions  40   a ,  40   b.    
     In FIG. 6, the locking effect of the locking elements  50  and the cutout areas  52   a ,  52   b  can be seen. In the case of rapid deceleration, the walkover tubes  22 ,  24  are rotated in opposite directions for a limited degree until the surface of a cutoff corner of the lock element  54   a  engages a portion of the flat face  56   a  of the end extension  40   a ,  40   b  at the same time the locking elements  50  contacts a respective cutout area  52   a ,  52   b  and the upper corner contacts the notches  52   a ,  52   b  of the opposite shaft. The deceleration detected by the locking element  50  is rapid in locking rotation of the walkover shafts  22  and  24  to prevent any further movement of the seat back. After the locking has occurred between the locking element  50  and walkover tubes  22 ,  24 , the energy dissipation sections  60   a ,  60   b  formed by the thinner diameter of the end extensions  40   a ,  40   b  then undergo conditions of plastic deformation by which permanent twisting of the reduced diameter section occurs to the extent necessary to arrest and dissipate the force of the impact. The energy dissipation sections  60   a ,  60   b  can under go up to 90° of permanent deformation under which twisting optimum energy dissipation of the impact force of the passenger with the seat back occurs because the time in dissipating the energy is significantly increased by the plastic deformation. 
     The levers  14 , 16  are fixedly retained on the lower ends  14   b ,  16   b  to end portions of walkover tube extensions  40   a ,  40   b . The pair of levers  14 ,  16  are mounted at each shaft end in a common vertical plane. In the normal opposed seating positions of the seat backs, the adjacent edges  14 ′,  16 ′ of the levers  16  directly abut each other (FIGS. 2,  3  and  5 ) to support the seat back with a high strength to strength ratio. Such direct support eliminates the stops and brackets needed in the prior art and provides good strength in the stressed direction. As seen in FIG. 4, the adjacent edges of the levers are spaced from each other in the intermediate position. As seen in FIGS. 2-5, a pair of linkage assemblies  70   a ,  70   b  are further provided in operative relationship between the walkover tubes  22  and  24  and the lower seat cushion frame  72 . The cushion frame  72  includes a horizontal pair of elongated edge cross frame members  74  interconnected by end members  76  (FIGS.  8  and  9 ). A pair of intermediate supports  78  further extend between the end members  76 . The pair of linkage assemblies  70   a ,  70   b  move the seat back frame  20  from the position shown in FIG. 3 to the position shown in FIG.  5 . In is normal opposed seating portions, the upper surface  80  of the end members  74  are slightly sloped downward from the seat front to the walkover seat back as seen in FIGS. 3 and 5. Each of the linkage assemblies  70   a,    70   b  are operatively connected to a respective walkover tube  22 ,  24  by a pair of oppositely facing pivot arms  82   a,    82   b  which are affixed at one end to tube extensions  40   a,    40   b.    
     The opposite ends of the pair of pivot arms  82   a,    82   b  include a pin  86  which extends into an elongated slot  88  formed along a straight longitudinal axis in elements  90  of each of the pair of linkage assemblies  70   a,    70   b.  The link elements  90  are flat members having a modified “L” shape with a pair of straight edge portions  92  and a curved interconnecting portion  94  (FIG.  2 ). Each link element  90  is pivotally connected to the cushion frame end members  76  at a point adjacent the intersection of the straight edge portions  92  and curved portion  94  of the link elements  90 . As the walkover seat back is moved between opposed seating positions, the pin  86  of the lever element  90  moves in the slots  88  in opposite directions of the respective link members. At the upright position during initial movement of the seat back, the respective pins  92  move to opposite ends of the slots  94 . As the seat back continues movement to opposite seat positions, the link elements  90  continue pivotal movement and alter the position of the seat cushion frame  72 . In the position of seat cushion frame  72  in FIG. 3, the frame member  74  of the seat cushion frame  72  directly rests on cross horizontal member  90   a  of the main seat frame in direct supporting contact along the width of the seat. One of the intermediate frame member  78  of the cushion frame  72  also directly contacts a second horizontal member  92   a  of the main seat frame. For better support both the cushion frame members  74  and main frame members  90   a,    92   b  advantageously possess a square configuration. Such direct contact between the cushion frame  72  and main frame cross members  90   a,    92   b  provides maximum support of the seat cushion frame and seat back without latches or locks. 
     When walkover seat  2  is moved to the seating position of FIG. 5, the opposite cushion cross frame  74  directly contacts the main seat cross frame  92   a . The second intermediate cross frame  78  rests on the opposite seat main frame  90   a  in FIG.  5 . At the seat back position of FIG. 3, the lever arms  82   a ,  82   b  are disposed along generally parallel planes with the lever arms  82   a ,  82   b  directed upward and the free end of the lever arm  82   b  is directed downward. In the seat back position of FIG. 5, the pin end of the pivot arms  82   a  is directed downward and the pin end of the pivot arm  82   b  is directed upward in generally parallel relationship. In the intermediate position of FIG. 5, the pin ends of lever arms  82   a ,  82   b  are generally directed in opposite directions along the same horizontal axis. 
     Referring to FIG. 10, there is illustrated the bottom of a seat cushion  100  prior to attachment to the seat cushion frame  72 . The bottom of seat cushion  100  includes a pan  102  in the form of a metal or plastic that covers the bottom of the seat cushion  100  for protection. The pan  102  includes a pair of rectangular openings  104  and is secured to the seat cushion by mechanical fasteners (not shown). A series of strips  106  of hooks or loops of material, such as sold under the trademark VELCRO hooks are secured along the front and rear portions of the pan  102 . Complimentary strips  108  of loops, which adhere to strips  106 , are secured by an adhesive to cushion frame members  74 , whereby the cushion  100  is simply installed by being placed on the seat cushion frame  72  with strips  106  and  108  in contact. Such a securement capability results in immediate self positioning of the cushion on the seat frame and permits ready removal of the cushion  100  for repair and replacement.