Cushioned low level railway vehicle

Claim 1

A CUSHIONED UNDERFRAME RAILWAY VEHICLE COMPRISING AN UNDERFRAME FORMED AS A BEAM STRUCTURE CAPABLE OF ASSUMING THE VERTICAL LOADS TO BE CARRIED ALONG THE LENGTH OF SAID UNDERFRAME AND BEING DEFLECTED ALONG THE LENGTH THEREOF, A SLIDING SILL EXTENDING LENGTHWISE OF SAID UNDERFRAME AND INCLUDING LATERALLY SPACED SILL MEMBERS SUBSTANTIALLY DETACHED FROM EACH OTHER ALONG THE LENGTHS THEREOF INTERMEDIATE THE ENDS, LATERALLY SPACED GUIDE MEANS FIXED TO SAID UNDERFRAME AND DEFLECTABLE THEREWITH CONFINING RESPECTIVE ONES OF SAID SLDING SILL MEMBERS AT LEAST AGAINST SUBSTANTAIL VERTICAL MOVEMENT RELATIVE TO SAID UNDERFRAME AND GUIDING SAID SLIDING SILL FOR LENGTHWISE MOVEMENT OF SAID UNDERFRAME WHEREBY SAID GUIDE MEANS ACTS ON SAID SLIDING SILL MEMBERS IN SUCH A WAY THAT SAID SLIDING SILL MEMBERS WILL ALREADILY DEFORM VERTICALLY IN ACCORDANCE WITH THE DEFORMATION OF THE UNDERFRAME BUT ARE CONSTRAINED AGAINST EXCESSIVE VERTICAL DEFORMATION DUE TO IMPACTS, COUPLERS CARRIED ON THE OPPOSITE ENDS OF SAID SLIDING SILL, MEANS MOUNTING SAID COUPLERS BETWEEN SAID SLIDING SILL MEMBERS ADJACENT THE ENDS THEREOF AND INTERCONNECTING SAID SLIDING SILL MEMBERS FOR SIMULTANEOUS MOVEMENT LENGTWISE OF SAID UNDERFRAME, SAID SLIDING SILL MEMBERS EACH BEING OF A LENGTH AND HAVING A CROSS SECTION INCLUDING A DEPTH DIMENSION OF SUBSTANTIALLY LESSER DEPTH THAN SAID BEAM STRUCTURE SO THAT SAID SILL MEMBERS CONFORM TO THE DEFLECTIONS OF THE SAID UNDERFRAME AND SAID GUIDE MEANS, SAID SLIDING SILL MEMBERS HAVING A TOTAL SOLID CROSS SECTIONAL AREA CAPABLE OF ASSUMING THE TENSIOSN AND COMPRESSION LOADING LONGITUDINALLY APPLIED TO SAID SLIDING SILL AT SAID COUPLERS, SAID CUSHION MEANS INTERPOSED FOR INTERACTION BETWEEN SAID UNDERFRAME AND SLIDING SILL.