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Figure 11 shows the bridge in Figure 10 in a fully deployed position to the right as viewed; Figure 12 shows the bridge in Figures 10 and 11 in a deployed position to the left as viewed; and Figure 13 shows a detail of a part of the bridge in Figures 10 to 12. Refening to Figure 1, a train carriage 10 is illustrated connected to a train carriage 12, only the adjacent end section of each carriage 10,12 being visible. With particular reference to carriage 12, the carriage 12 includes a pair of doorways 14,16 in transverse alignment with one another, with respect to the longitudinal axis ofthe carriage 12. The doorways 14,16 are each of a width which is compatible for wheelchair access. The carriage 12 also includes a floor panel 18. A bridge in accordance with the invention, generally indicated at 20, is located in the floor panel 18. The bridge 20 consists of a retractable stage 22 which is positioned in general alignment with the doorways 14,16. The stage 22 includes a springloaded pivotably connected end section24, at each end ofthe stage 22 (only one of which is visible). The purpose of each end section 24 is to support the stage 22 as it is extended or retracted from the carriage. The stage 22 also includes an upstand 26 positioned substantially along the length of each longitudinal edge of the stage 22, for inhibiting movement of awheeled vehicle, such as a wheelchair, over a longitudinal edge ofthe stage 22. The stage 22 is movable between an extended position in which the stage 22 extends outside of the train carriage 12 (as illustrated in Figure 1), and a stowed position in which the stage 22 is contained within the floor panel 18 and does not project from the train carriage 12. As indicated by the arrows in Figure 1, the stage 22 is reciprocable between extended positions on either side of the carriage 12. Referring now to Figure 2, the bridge 20 is shown in a fully extended position on the right hand side of the carriage 12, as viewed. The dotted outline, designated 28, indicates the fully extended position of the bridge 20 on the opposite side of the carriage 12. As can be seen, the stage 22 consists of a central leaf 30 having apivotally connected end section 24 provided at each end of the leaf 30. In the fully extended position, one ofthe end sections 24 remains substantially within the floor panel 18, as will be described in more detail with reference to the preferred embodiment below. The stage 22 can be manually deployed, for example byholding an end of the stage 22 and pulling the stage 22 outwardly from the train carriage. Alternatively, the stage 22 can be power operated, for example using any suitable hydraulic, pneumatic or electlical means. When the bridge is power operated, an associated control circuit and control panel is also be provided. A typical control arrangement is shown in Figure 3. The control panel A including a"deploy"control button B and a"retract"control button C will be installed adj acent a carriage doorway at a height compatible for a wheel chair user, in accordance with the Rail Vehicle Accessibility Regulations 199 8. To deploy the stage 22 from the stowed position, the deploy button B is pressed and the stage 22 begins to extend progressively from the train carriage to the fully extended position. To retract the stage 22 from an extended position, the retract button C is pressed, to initiate movement ofthe stage 22 back to the stowed position. A trip switch maybe provided to prevent the carriage doors being closed when the stage 22 is in a deployed position. The bridge 20 can also be operated automatically, for example as the carriage doors are opened or closed. Referring now to Figures 4A to 4D, a preferred embodiment of the bridge 20 is shown schematically in usebetweenatrain carriage 12 and a station platform 32. Common reference numerals are used to designate similar components of the previous embodiment. As shown in the above embodiment, the bridge consists of a stage 22 including a central leaf 30 having a springloaded pivotally connected end section 24 at each end of the leaf 30. The bridge 20 includes ahousing 34 contained within the floor panel 18 ofthe carriage 12. The housing34has of apluralityofguidemembers, onlytheupperandlowermembers 36,38 being visible. The guide members are vertically and laterally spaced, in alignment with a doorwayin the carriage 12, the stage 22 being slidably supported between the guide members. In this respect, the housing 34 forms a"cassette"in which the stage 22 is reciprocable between the guide members. A stop 40 is provided at each end of the housing 34, to prevent the stage 22 from being removed from the housing 34, in use. In this embodiment, the stop 40 consists of a stop formation provided on each end of the guide members 36. A Rap in the form of cover plate 42 is hingably connected along atop edge of each end ofthe housing34, theplate 42 beinghingablymovable as the stage 22 is extended from the carriage 12. Movement of the stage 22 from a stowed position on the carriage 12 to a fully extended position onto the station platform 32 will now be described. With the carriage 12 stationary at the platform 32, the doors of the carriage 12 are opened. In this embodiment, the stage 22 is power operated and, in use, is extended gradually from a stowed position, after a button is depressed on an associated control panel, for example. The cover plate 42 is hingably displaced as the stage 22 first protrudes from the housing 34, and provides a smooth transition between the housing 34 and the upper surface of the stage 22, e. g. for smooth passage of wheel chairs thereover. As shown in Figure 4a, as the end section 24 is extended from the housing 34, the springloaded pivotal connection to the central leaf 30 urges the leading edge end section 24 to fall in contact with the platform 32. The pivotal connection is springloaded to act against the cantilever effect of the central leaf 30, as it extends progressively from the housing 34. Hence, the end section 24 is designed to provide support for the progressively extending central leaf 30 (as illustrated in Figure 4b). In this embodiment, the upstands 26 consist of apluralityofspringloadedpanels which"pop up" progressively as the stage is extended from the housing 34. As the stage 22 is extended further, the central leaf 3 0 begins to incline to the platform 32 (Figure 4c), as the spring loaded connection of the end section is gradually overcome. From this point, the end of the stage 22 within the housing 34 (i. e. at the left hand side, as viewed) is biased into contact with the upper guide member 38. The stage 22 is extended until the pivotal connection at the left hand end of the stage 22 comes into contact with the stop 40 (the fully extended position, as illustrated in Figure 4d). In this fully extended position, the spring loaded connection of the end section 24 is fully overcome, and the stage 22 provides a planar inclined gangway between the carriage 12 and the platform 32. After use, the stage 22 is retractable within the housing 34, to return to a stowed position within the carriage 12, for example, by depressing a button on the associated control panel. Although not illustrated, rollers or wheels maybe fitted to the leading edge of the end section 24, to reduce frictional contact between the stage and the platform surface, as the stage is extended/retracted. Whereas the above embodiment ofthe invention has been described with reference to a spring loaded, pivotally connected end section, in a further preferred embodiment of the invention (not illustrated) the end section may be pivotally connected to the stage to act under gravity. Referring now to Figure 5, the bridge 20 of Figures 1 and 2 is shown in use in an alternative application, that is, bridging between two trains stopped sidebyside on adjacent tracks. As canbe seen, the bridge is shown in an extendedpositionbetween two parallel train carriages 12,44. Inthe eventofabreakdownofone ofthe traincarriages, for example, the bridge 20 can be used across the gap between the two carriages 12, 44, to provide a gangway for passengers between the trains 12,44. Connection means (not shown), for example a releasable clamp or lock mechanism, can be provided to secure the stage 22 on to the opposing carriage. In use, the bridge 20 is deployed across the gap and received on the doorstep of the adjacent <BR> <BR> caniage44, forexample. Packermeans (notshown) areprovided, whichcanbepositionedunder the leading end of the stage 22, in cases where the level ofthe"receiving"caniage 44 is sufficiently <BR> <BR> lowertlhantlle"bridging"caniage 12. Thepaclcermeans maytake theform ofblocks, for example. Alternatively, if the opposing train is also fitted with a bridge in accordance with the invention, the end of the stage 22 is receivable in a correspondingly formed housing 34 on the opposing train 44. If the stage 22 is not of a length sufficient to bridge the gap between the two trains 12,44, an extension (not shown) can be fitted manually to the stage 22 to be receivable on the train 44. Alternatively, the stage maybe attachable to a similar stage extended from aparallel train 44, for example halfway between the two carriages 12,44. A modified embodiment of a bridge in accordance with the invention is shown in Figures 6 and 7, indicated at 50. Only the right hand end of the bridge 50 is illustrated, located between the floor panel 52 and under'amie 54 of a train carriage, intransverse alignmentwith apair of opposing doorways (not shown). The bridge 50 consists of a one piece stage 56, which is located within a housing 58. The housing 58 includes a pair of guide members, upper guide member 60 and lower guide member 62, on either side of the housing 58, between which the stage 56 is moveably supported. The stage 56 is moveable between an inoperative position in which the stage 56 is contained within me housing 58, as shown in Figure 6, and an operative position in which the stage 56 extends from the housing 58, as shown in Figure 7, by way of example. The stage is reciprocable between an operative position on either side of the housing 5 8, as described with reference to the previously described embodiments. A threshold plate 64 is provided on the upper surface of the housing 5 8, in the area adjacent the carriage doorways (not illustrated) one on either side of the housing 5 8. The threshold plate 64 is substantially flush with the floor panel 52. A cover flap 66 is hingeably connected to the end ofthe threshold plate 64, to the right as viewed in Figures 6 and 7, for movement about an axis 68. The cover flap 66 is moveable between a closure position, in which the end of the housing 5 8 is concealed behind the cover flap 66, as shown in Figure 6, and a transition position, in which the cover flap 66 forms a transition between the threshold plate 64 and the stage 56, as the stage 56 is extended from the housing 58, as can be seen in Figure 7, by way of example. The purpose of the cover flap 66 in the closure position is to inhibit the ingress of moisture and particles into the housing, which may comprise the integrity of the stage 56. In the transition position, the cover flap 66 provides a relatively smooth means of access between the threshold plate 64 and the stage 56, which is of particular advantage for wheelchair users, for example. As can be seen from Figures 6 and 7, the ends of the stage 56 are of a reduced depth and each include a roller 70. Each roller 70 has a diameter greater than the reduced depth of the stage 5 6, to enable the roller to come into contact with the surface to which the stage 5 6 is deployed, to facilitate ease of deployment or retraction of the stage 56 once in contact with the surface. A seal (not illustrated) maybe provided on the rear face of the cover flap 66, for complimentary engagement with a seal provided on the train underframe 54 or on the housing 56, to seal the housing 56 from one end in the closure position. Figure 8 shows a bridge in accordance with the invention, indicated at 72, consisting of a stage 74 which is reciprocable, in the manner described above, within a housing 76. The housing 76 consists of apair of channels 78 of substantiallyushaped cross section, eachpositioned on one side in an opposing relationship to one another, which are secured at a predetermined spacing from one another on a base plate 80. A nylon block 81 is provided on either side ofthe housing 76, connected to the lower arm of each channel 78 and extending substantiallyalongthe lengthofthehousing76, as a guide on which the stage 74 is slidably supported. In use, the upper arm of each channel 78 serves as an upper guide member for the stage 74, for sliding cooperation with a roller (not shown) provided at either end of the stage 74, substantially as described above. The stage 74 consists of a central panel 82 having a pair of side members 84, each extending longitudinally along the length of the central panel 82. Each side panel 84 includes a recess 86 in which the end ofaplurality of substantially Jshaped upstands 88 are received, only two of which are visible in Figure 8. Each upstand 88 consists of a substantially curved endportion 90 and a straight arm portion 92, which is movable between an operative position in which the arm portion 92 extends substantially perpendicular to the longitudinal axis of me bridge 72, as shown on the right hand side of Figure 8, and aninoperativepositionin whichthe armportion 92 is substantially parallel with the upper surface of the stage 74, as shown on the left hand side of Figure 8. For the purpose of description, the recess 86 in each side panel 84 will now be described in detail, with respect to the side panel 84 as shown enlarged in Figure 9. From the right as viewed, the recess 86 includes a substantially downwardly depending knuckle formation 94 having an arcuate profile, and an undercut surface 96 which terminates at a rectangular return surface 98. Recess 86 further includes a straight bottom surface 100 and a curved transition surface 102, the recess 86 ending at a vertical straight portion, to the left as viewed. The upstands 88 are introduced into arespective recess 86, from one end of the stage 74. Movement of an upstand 88 from the inoperative position on the left of Figure 8 as viewed to the operative position on the right as viewed in Figure 8 is as follows: The free end of the arm portion 92 is lifted away from the upper surface of the stage 74, causing rotation ofthe curved end portion 90 about the arcuate surface of the knuckle formation 94. As the free end of the arm portion is continued to be lifted, the free end of the curved end portion 90 comes into contact with the undercut surface 96. At this point, the upstand 88 falls within the recess 86, the curved endportion 90 contacting the curved transition surface 102 ofthe recess 86. The curved end portion 90 then moves along the transition surface 102 in the direction of the rectangular return surface 98. The junction between the curved end portion 90 and the armponion 92 on the internal side ofthe upstand 88 levers against the arcuate surface of the knuckle formation 94, with continued movement of the free end of the arm portion 92 away from the upper surface of the stage 74. The leverage of the junction between the arm portion 92 and the curved end portion 90 with the knuckle formation 94 causes the free end ofthe curved endportion 90 to pop into frictional abutment with the top corner of the rectangular return surface 98, as shown on the right in Figure 8, to lock the armportion 92 of the upstand 88 in aposition extending upwardly, substantially perpendicular to the upper surface of the stage 74. To move the upstand 88 from the operative position to the inoperative position, the reverse procedure is carried out. A bridge in accordance with the above aspect ofthe invention will have application wherever a transitional access means is required between two spaced apart surfaces, for example on all forms ofwheelchair access ramps. For instance, the invention could be used for wheelchair access to or from a building, or for wheel chair access to or from a bus. Figures 10 to 13 show still a further embodiment of a bridge in accordance with the invention, having a housing 110 in which a stage 112 is retractable, as described with reference to the previously described embodiments. Forthepurposeofillustration, onlythesidepanel 113 ofthe stage 112 is shown. The stage 112 is shown in the stowed position on the housing 110 inFigure 10, only one comer from one end of the housing 110 being illustrated. A flipper 114 is mounted on the housing 110 by apin 116 about which the flipper 114 maybe rotated. Four such flippers 114 areprovided onthehousingl 10, one at each corner, i. e. on either side ofthe housing 110 adjacentboth ends of the housing 110, for preventing removal of the stage 112 from the housing 110, in use. The flipper 114 includes a pair of arms 118, 120 disposed at right angles to one another and a rectangular formation 122 in the area of the junction of the arms 118, 120. With the stage 112 in the stowed position shown in Figure 10, the flipper is positioned with arm 118 inabutmentwithtllesidewall 124Ofthehousing 110. Theotherarm 120isperpendicularto the side wall 124, with the spacing between the two arms 118, 120 facing out of the housing 110, to the right as viewed, so that the roller 126 at the right hand end of the stage 112 is positioned between the arms 118,120. The stage 112 is deployable from either end of the housing 110. Figure 11 shows the stage 112 in an extended position from the right hand end of the housing 110. The stage 112 is restricted from being withdrawn from me housing 110 by the flipper 114. Movement of the roller 126 on the left hand end of the stage 112 is limited by arm 120 of the flipper 114. Since the ann 118 is in contact with the side wall 124 of the housing 110, the flipper 114 is unable to rotate about pin 122, anticlockwise as viewed. Figure 12 shows the stage 112 in a deployed position to the left : of me housing 110, as viewed. As can be seen, the roller 126 at the right hand end of the stage 112 is to the left of the flipper 114, and the arms 118, 120 of the flipper 114 are in an orientation at 90 degrees rotation clockwise to the position of the arms 118, 120 in Figure 10 and 11. As the stage 112 is moved to the left as viewed from me position in Figure 10, the roller 126 causes the flipper 114 to rotate clockwise about pin 116, to enable the roller 126 to pass beyond the flipper 114. An aperture 13 0 is provided in the side wall 124 ofthe housing 110 adjacent the flipper 114, to enable the rectangular portion 122 of the flipper to rotate about the pin 116, as shown in Figure 13. A metal plate spring 132 is mounted across the aperture 130, which is secured in place byrivets 134. As the flipper 114 rotates, the spring 132 flexes to allow movement ofthe rectangular portion 122. Progressively ; as the flipper 114 rotates passed 45 degrees clockwise from the position in Figure 10, for example, the spring 132 pushes back against the flipper 114 to'flip'the arms 118, 120 into the position shown in Figure 12. If the stage is returned to the stowed position of Figure 10, the reverse of the above procedure takes place. It will be appreciated that each ofthe four flippers 114 are arranged appropriately on the housing 110 to enable or restrict the movement of the stage 112 between the stowed position and an extended position from a respective end of the housing 110. It will be understood that the invention provides a simple alternative to knows access means for train carriages or vehicles. The invention is advantageous primarily in that it can be installed in the floor panel of a train carriage or vehicle, and does not require storage space within the passenger compartment of the carriage or vehicle. The invention can be operated simply and efficiently. The upstands referred to throughout the specification are intended to conform to the requirements of the Rail Vehicle Accessibility Regulations 1998 No. 2456. It will be appreciated that the term"train"throughout the specification is intended to encompass any vehicle capable of travel along rails, such as a tram for example. Furthermore, it will be understood that references throughout the specification to a"vehicle"is intended to encompass all forms of passenger vehicle such as a coach or a bus. |
