1. IN A COMBINED COMPRESSED AIR AND VACUUM OPERATED BRAKE EQUIPMENT FOR A RAILWAY LOCOMOTIVE, THE COMBINATION OF: (A) A VACUUM BRAKE PIPE NORMALLY EVACUATED TO A CERTAIN DEGREE OF VACUUM IN WHICH THE BRAKES ARE RELEASED, AND SUBJECT TO A CERTAIN REDUCTION OF VACUUM THEREIN TO CAUSE A BRAKE APPLICATION, (B) A BRAKE CONTROL VALVE DEVICE COMPRISING (I) A DIAPHRAGM HAVING A CHAMBER ON EACH SIDE THEREOF, THE CHAMBER ON ONE SIDE OF SAID DIAPHRAGM BEING IN CONSTANT COMMUNICATION WITH SAID VACUUM BRAKE PIPE, (II) COMMUNICATION MEANS BETWEEN THE CHAMBER ON THE ONE SIDE AND THE CHAMBER ON THE OTHER SIDE OF SAID DIAPHRAGM INCLUDING CHOKE MEANS VIA WHICH THE EVACUATION OF THE CHAMBER ON THE THE OTHER SIDE OF SAID DIAPHRAGM IS EFFECTED WHILE THE CHAMBER ON THE ONE SIDE OF THE DIAPHRAGM IS BEING EVACUATED, AND (III) A VALVE MEANS CONTROLLED BY SAID DIAPHRAGM, UPON A PREDETERMINED REDUCTION OF THE VACUUM IN SAID ONE CHAMBER RELATIVE TO THAT IN SAID OTHER CHAMBER, TO CAUSE SAID VALVE MEANS TO OPERATE TO EFFECT A SUPPLY OF FLUID AT SUPERATMOSHPERIC PRESSURE, (C) A RELAY VALVE DEVICE COMPRISING: (I) FLUID PRESSURE OPERATED SELF-LAPPING VALVE