Railroad passenger walk-over seat

A railroad passenger walk-over seat having a seat back capable of being rotated into opposed positions. A locking mechanism having engaging locking elements and a lock member to arrest movement of the seat back during forces created by abrupt deceleration. The deceleration force is dissipated by a shaft section that undergoes plastic deformation.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates in general to railroad cars and, more particularly,
 to a railroad passenger walk-over seat having energy dissipation means
 during abrupt deceleration causing seat back impact by a passenger.
 2. Summary of the Prior Art
 It is common in railroad passenger cars to provide seat backs capable of
 being walked over or moved to face in opposite directions. There exists
 significant problems in the past when a passenger impacted the
 unrestrained seat back in front of him during rapid deceleration
 situations, causing catastrophic emergencies. As a result, seat backs were
 provided in the prior art with locking mechanisms by which the seat back
 was restrained when a passenger collided with the seat back in front of
 him. A restrained seat back, however, creates an unyielding wall-like
 object against which the individual would be subjected to severe
 deceleration during emergency situations. A one hundred and fifty pound
 individual, for example, could be subject to in excess of 7 g's
 deceleration under such situations.
 In the prior art, attempts were made to install energy absorbing devices in
 the seat back to lessen impact by increasing the distance and/or time in
 which an individual is subjected to deceleration forces. One technique of
 energy absorption is disclosed in U.S. Pat. No. 5,149,171 to Gilevich, et
 al. in which a latching mechanism restrains walkover movement of the seat
 back in a progressive manner when impacted under deceleration forces. The
 technique in Gilevich, et al., however, relies on a complex and cumbersome
 system using a pendulum and a series of gears. The latching system of
 Gilevich, et al. is expensive to manufacture, difficult to service,
 inspect and maintain, and does not demonstrate optimum impact absorption:
 Another seat locking mechanism for walk-over seats is disclosed in U.S.
 Pat. No. 5,362,124 to Schlidt. During rapid deceleration through impact in
 Schlidt, a wear surface contacts a braking surface in conjunction with an
 energy absorption means in the form of spring blocks and Belleville
 washers. Like the Gilevich, et al. system, the Schlidt locking mechanism
 is complex, difficult to service and is not optimally capable of
 alleviating serious injury to the impacting passenger. Moreover, the prior
 systems, such as disclosed in the foregoing Gilevich, et al. and Schlidt
 patents, are particularly designed for the presence of two passengers on
 the seat rather than a single passenger. In the case of a single
 passenger, the impact absorption capability of prior art walk-over seats
 is generally ineffective and is not sufficiently responsive to
 deceleration forces on a single individual. Accordingly, it is desirable
 in the transportation industry to provide a safer, a more economical and
 less complex walk-over passenger seat system.
 SUMMARY OF THE INVENTION
 It is, therefore, an object of the invention to provide an improved
 walk-over seat having a locking device and torsion means capable of
 dissipating significant energy during impact by one or more passengers
 from the rear during abrupt deceleration. The torsion means of the
 invention includes energy dissipation sections which undergo plastic
 deformation and are permanently twisted by an amount dependent on the
 magnitude of deceleration. The torsion means herein disclosed provides a
 light weight and less complex system than the prior art while being
 capable of superior energy dissipation under extreme conditions of abrupt
 deceleration. The torsion means is capable of attaining plastic
 deformation of up to 90.degree. and reacts in an effective, linear
 function. The walk-over seat of the invention is less expensive to
 manufacture than prior walk-over designs, demonstrates long durability,
 and can easily be inspected and maintained. The locking mechanism of the
 walk-over seat of the invention is highly effective in restraining the
 seat back during rapid deceleration and operates effectively with or
 without the torsion means herein disclosed. In one embodiment of the
 invention, the torsion means and locking mechanism are used with separated
 side by side seats and seat backs to protect the passenger under single
 occupancy situations in which the prior art systems are ineffective and
 offer little protection. Overall, the invention provides an improved
 walk-over seat greatly improving the safety of the passenger as well as
 providing benefits of reliability and economy among many advantages.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Referring now to FIGS. 1 through 13, there is illustrated a first
 embodiment of the improved railroad passenger walk-over seat of the
 invention, generally designated by reference numeral 2. Although the
 system is described herein as a walk-over seat for passenger railroad
 cars, it is within the scope of invention to use the teachings of the
 invention in any environment in which walk-over passenger seats are
 employed. As is conventional, the passenger walk-over seat 2 includes a
 horizontal seat 4 and a walk-over seat back 6 supported on a frame 8 which
 rests on suitable opposed pedestals (not shown). The walk-over 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 walk-over capability of passenger walk-over seat 2 is best shown in
 FIGS. 1 through 7. The seat walk-over mechanism 12 is provided with a pair
 of levers 14 and 16 suitably journaled at their lower ends 14a and 16a on
 the seat frame 8. The walk-over levers 14 and 16 are interconnected at
 their upper ends by a pivotally attached link 18. A seat back tube 20 is
 attached to the link 18 and seat back 6 as shown in FIGS. 4, 5, 6 and 7 to
 allow the walk-over movement on the levers 14 and 16 in conjunction with a
 pair of horizontal walk-over tubes 22 and 24. The walk-over tubes 22 and
 24 are suitably journaled at both ends on frame 8 and extend through the
 lower ends of levers 14 and 16 and under the seat 4 from the aisle side to
 the window side of passenger seat 2. The opposed position of the walk-over
 lever mechanism 12 is shown in opposite positions of the seat back 6 in
 FIGS. 4 and 6. During walk-over movement from the position of FIG. 4 to
 the position of FIG. 6, the walk-over tubes 22 and 24 rotate in the same
 directions to facilitate movement of the entire seat back 6 to the opposed
 position.
 As best seen in FIGS. 1, 4, 5, 6 and 7, the walk-over mechanism 12 is
 provided with an improved seat back retainer 26. The retainer 26 is
 affixed to the link 18 by conventional retaining means (not shown) and
 acts to form an abutment to retain the seat back 6 in normal positions in
 either of the opposed positions which are shown in FIGS. 4 and 6. The
 retainer 26 possesses a triangular cross-sectional configuration to form
 opposed abutment surfaces 26a and 26b. As seen in FIGS. 4 and 6, one or
 the other of the abutment surfaces 26a and 26b contacts the opposite
 levers 14 and 16 in the opposed seat positions of FIGS. 4 and 6 and
 prevents further movement to maintain the seat back 6 in its proper
 generally upright position.
 As illustrated in FIGS. 1, 2 and 3, the walk-over tubes 22 and 24 are each
 separated generally at their mid-point to form two walk-over tube sections
 22a, 22b and 24a, 24b. A solid energy dissipation shaft 30 is welded in
 secured relationship to the intermediate ends of sections 22a and 22b.
 Similarly, an energy dissipation shaft 32 is welded into secured
 relationship to the intermediate ends of walk-over tube sections 24a and
 24b. Each of the energy dissipation shafts 30 and 32 are respectively
 provided with opposite end sections 32a and 34a which are arranged to be
 inserted into the ends of the walk-over tube sections 22a and 22b and
 walk-over sections 24a and 24b as best shown in FIGS. 2, 3 and 12. An
 enlarged peripheral section 32b and 34b are provided on each of the energy
 dissipation shafts 30 and 32 to improve securement to the walk-over tubes
 22 and 24 to permit rotation of the walk-over tube sections under normal
 conditions of movement and twisting of the energy dissipation shafts 30
 and 32 under conditions of rapid deceleration as will be described. As
 best seen in FIG. 12 showing energy dissipation shaft 30, both energy
 dissipation shafts 30 and 32 include a pair of respective sections 38 and
 38a which have a diameter less than the diameter of the respective
 walk-over tubes 22 and 24. Each of the energy dissipation shafts 30 and 32
 is provided with a raised central locking element 40, 42 to engage a lock
 weldment 46 which are illustrated in FIGS. 2 and 8 to 13. As shown in
 FIGS. 1, 2 and 3, the locking elements 40, 42 and the lock weldment 46 are
 encased within a box 48 which is secured by suitable braces 48a to cross
 tubes 48b of the seat frame 8. The lock weldment 46 is mounted on an end
 shaft 50 journaled on opposed walls of the box 48 for limited rotation
 parallel to the axis of rotation of the energy dissipation shafts 30 and
 32 and cooperates with the locking elements 40, 42 for locking during
 abrupt deceleration. The central portion of the lock weldment 46 is
 generally in the shape of a square having an integral lower projection or
 pendulum 56. The four corners of the lock weldment 46 are cut off to form
 flat surfaces 58 to engage the central locking elements 40, 42 of the
 energy dissipation shafts 30 and 32.
 As best illustrated in FIGS. 8, 9, 10 and 13, the central locking elements
 40, 42 include a pair of notches or cut-out portions 60,62 created in
 their periphery which are situated from each other by angle of less than
 180.degree. dependent on desired operative results. The cutout portions
 60, 62 each include a flat face 64 extending parallel to the axis of
 rotation of the energy dissipation shafts. The faces 64 intersect with a
 radial surface 66 which is slightly offset from the center line of the
 axis of rotation of the energy dissipation shafts. As seen in FIGS. 8 and
 9 to illustrate normal seating conditions, the lock weldment 46 does not
 engage the periphery of the central locking elements 40, 42 and either
 face 64 or radial surface 66 of a cut-out portion 60, 62 to allow free
 movement of the seat back 6.
 In FIG. 10, the locking effect of the cooperation of the locking elements
 40, 42 and the lock weldment 46 is best shown. In FIG. 10, the direction
 of travel and the direction the passenger faces is to the right. In the
 case of rapid deceleration, the walk-over tubes 22, 24 and the energy
 dissipation shaft 32 and 34 are rotated in opposite directions for a
 limited degree until the surface 58 of a corner of the lock weldment 46
 engages a portion of the flat face 64. At the same time, the periphery of
 the locking elements 40, 42 contact a face of the lock weldment 46 with
 the projection 56 being rotated to the right in response to deceleration
 forces. After the rotation shown in FIG. 10 caused by deceleration,
 walk-over seat 2 is locked after only limited movement. The deceleration
 detected by the lower pendulum 56 to cause rotation of the lock weldment
 46 is rapid in locking rotation of the energy dissipation shafts 30 and 32
 and walk-over tubes 20, 24 to prevent any further movement of the seat
 back. In FIG. 11, the opposite movement is shown by which the direction of
 travel and the direction the passenger faces is to the left. The lock
 weldment 46 is rotated in opposite direction to the left in response to
 the movement of pendulum 56 to engage the cutout areas 60, 62 of the
 central locking elements in 40, 42 to cause prompt locking of the seat
 back 6. After the locking has occurred between weldment 46 and locking
 elements 50, 52, the energy dissipation sections 30, 32 then undergo
 conditions of plastic deformation by which permanent twisting of the
 reduced diameter sections 38, 38a occurs to the extent necessary to arrest
 and dissipate the force of the impact. The energy dissipation sections 38,
 38a can undergo up to 90.degree. 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.
 Referring now to FIGS. 13 and 14, there is illustrated a second embodiment
 of the invention generally designated by reference number 100. Seat 100
 has split horizontal seats 102 and seat backs 106. Walk-over seat 100 is
 primarily intended to provide protection when the situation arises when
 the seat back 106 is impact by a single passenger because of only one
 passenger being present. In FIGS. 12 and 13, the seat 100 is split to
 provide two separate operating seats 100a, 100b for emergency situations.
 The split walk-over seat 100 is mounted in the same manner as the
 embodiment shown in FIGS. 1-13 and achieve a normal coupled movement of
 seats 100a, 100b from one back rest position to a second back rest
 position. Such coupling of the split seats 100a with seat 100b under
 normal conditions does not interfere with locking and energy dissipation
 operation under deceleration. However, when a single passenger strikes one
 of the seat backs 100a, 100b during deceleration, only one of seats 100a,
 100b being struck will separate from the other and be subject to energy
 dissipation in accordance with the teachings of invention relating to
 permanent deformation. The structure of the walk-over mechanism, energy
 dissipation system and locking means used with split seat 100 is identical
 to the single walk-over seat 2 of FIGS. 1-13 to which reference is made
 for details.