Vehicle roof structure

Claim 1

IN A ROOF STRUCTURE FOR A RAILWAY CAR, THE COMBINATION OF: A PRIMARY ROOF COVERING SAID CAR AND INCLUDING A PLURALITY OF LONGITUDINALLY-SPACED FIRST OPENINGS LOCATED SUBSTANTIALLY ALONG THE LONGITUDINAL CENTERLINE OF SAID PRIMARY ROOF; MEANS DEFINING A FIRST PLENUM SPACE WHICH EXTENDS ALONG THE CAR ABOVE SAID PRIMARY ROOF AND COMMUNICATES WITH SAID FIRST OPENINGS AND THE EXTERIOR OF THE CAR, SAID MEANS INCLUDING A SECONDARY ROOF SPACED ABOVE SAID PRIMARY ROOF AND SUPPORT MEANS SUPPORTING SAID SECONDARY ROOF ON SAID PRIMARY ROOF; SAID SUPPORT MEANS INCLUDING A PLURALITY OF TRANSVERSE PARTITIONS EXTENDING ACROSS SAID UPPER PLENUM SPACE BETWEEN SAID FIRST OPENINGS AND DIVIDING SAID UPPER PLENUM SPACE INTO A PLURALITY OF SEPARATE COMPARTMENTS EACH COMMUNICATING WITH A DIFFERENT ONE OF SAID FIRST OPENINGS; A CEILING SUPPORTED BENEATH SAID PRIMARY ROOF MEANS AND FORMING THEREWITH A SECOND PLENUM SPACE BELOW SAID FIRST PLENUM SPACE, SAID CEILING HAVING A PLURALITY OF LONGITUDINALLY-SPACED SECOND OPENINGS COMMUNICATING WITH SAID LOWER PLENUM SPACE AND THE INTERIOR OF THE CAR; A PLURALITY OF DAMPERS OPERATIVELY CONNECTED FOR CONTROLLING THE FLOW OF AIR THROUGH SAID FIRST OPENINGS; AND A PLURALITY OF FANS MOUNTED IN CERTAIN ONES OF SAID SECOND OPENINGS FOR PUMPING AIR THERETHROUGH, SAID FANS BEING ARRANGED SO THAT WHEN SAID DAMPERS ARE OPEN, FRESH AIR AND RECIRCULATED AIR ARE PUMPED INTO THE INTERIOR OF THE CAR AND SOME AIR IS EXHAUSTED, AND, WHEN SAID DAMPERS ARE CLOSED, AIR IS MERELY RECIRCULATED WITHIN THE CAR.