Fluid pressure brake control apparatus with empty and load change-over

Claim 1

A CHANGE-OVER VALVE DEVICE HAVING: (A) A CASING, (B) AN INPUT CONNECTION, (C) SELECTOR VALVE MEANS OPERATIVE BETWEEN A FIRST AND SECOND POSITION, (D) MEANS FOR MOVING SAID SELECTOR VALVE MEANS INTO SAID FIRST AND SECOND POSITIONS, (E) RELAY VALVE MEANS HAVING A NORMALLY SEATED VALVE MEMBER OPERATIVE UPON ACTUATION TO CONNECT A PAIR OF PASSAGEWAYS, WHEREIN ONE OF SAID PASSAGEWAYS IS ADAPTED TO BE CONNECTED TO A PRESSURE SOURCE (F) SAID RELAY VALVE MEANS HAVING A PAIR OF SPACED DIAPHRAGMS OF DIFFERENT EFFECTIVE AREAS COOPERATIVE WITH SAID CASING TO DEFINE PRESSURE CHAMBERS, (G) ONE OF SAID DIAPHRAGMS BEING COMMON TO A PAIR OF ADJACENT PRESSURE CHAMBERS, (H) VALVE MEANS, (I) SAID RELAY VALVE MEANS HAVING ONE OF SAID ADJACENT PRESSURE CHAMBERS CONSTANTLY CONNECTED TO SAID INPUT CONNECTION FOR ACUTATION OF SAID RELAY VALVE MEANS AND ACTUATION OF SAID NORMALLY SEATED VALVE MEMBER UPON PRESSURIZATION OF SAID INPUT CONNECTION, (J) SAID SELECTOR VALVE MEANS IN ONE OF SAID POSITIONS CONDITIONS SAID VALVE MEANS TO MAINTAIN COMMUNICATTION BETWEEN THE OTHER OF SAID ADJACENT PRESSURE CHAMBERS THROUGH SAID VALVE MEANS TO SAID INPUT CONNECTION FOR ACTUATION OF SAID RELAY VALVE MEANS AND ACTUATION OF SAID NORMALLY SEATED VALVE MEMBER UPON PRESSURIZATION OF SAID INPUT CONNECTION, (K) SAID RELAY VALVE MEANS COOPERATIVE WITH A PORTION OF SAID CASING TO DEFINE A BALANCING CHAMBER, (L) THE OTHER OF SAID DIAPHRAGMS BEING COMMON TO SAID BALANCING AND SAID OTHER ADJACENT PRESSURE CHAMBER, (M) SAID BALANCING CHAMBER OPERATIVELY CONNECTED TO THE OTHER OF SAID PASSAGEWAYS FOR PRESSURIZATION OF SAID BALANCING CHAMBER TO BALANCE PRESSURE IN SAID PRESSURE CHAMBERS FOR SEATING OF SAID VALVE MEMBER, (N) SAID VALVE MEANS NORMALLY INTERCONNECTING SAID INPUT CONNECTION TO THE OTHER OF SAID ADJACENT PRESSURE CHAMBER, AND (O) SAID SELECTOR VALVE MEANS IN THE OTHER OF SAID POSITIONS, CONDITIONS SAID VALVE MEANS TO MAKE SUCH SAID VALVE MEANS RESPONSIVE TO A PREDETERMINED PRESSURE IN SAID INPUT CONNECTION TO BLOCK COMMUNICATION BETWEEN SAID INPUT CONNECTION AND SAID OTHER PRESSURE CHAMBER.