Tractor-trailer braking system

Claim 1

IN A TRACTOR BRAKING SYSTEM INCLUDING A SOURCE OF SERVICE FLUID PRESSURE, A BRAKE VALVE, FLUID PRESSURE ACTUATORS, AND A TRACTOR PROTECTION VALVE INCLUDING A CONTROL PORT, AN EMERGENCY CONDUIT CONNECTING SAID SERVICE SOURCE AND SAID TRACTOR PROTECTION VALVE, A SERVICE CONDUIT INTER-CONNECTING SAID SERVICE SOURCE, BRAKE VALVE, FLUID PRESSURE ACTUATORS AND THE TRACTOR PROTECTION VALVE, OTHER CONDUIT MEANS INCLUDING A NORMALLY CLOSED VALVE INTERCONNECTING SAID SERVICE SOURCE AND THE CONTROL PORT OF SAID TRACTOR PROTECTION VALVE, NORMALLY OPEN EXHAUST VALVE MEANS IN SAID OTHER CONDUIT MEANS BETWEEN SAID NORMALLY CLOSED VALVE AND SAID CONTROL PORT, SPRING APPLIED, PRESSURE RELEASED, BRAKE LOCKING MEANS FOR LOCKING SAID ACTUATORS IN BRAKE APPLIED POSITION, AN ISOLATED FLUID PRESSURE SOURCE ON SAID TRACTOR, A FLUID PRESSURE RESPONSIVE ELEMENT OPERATIVELY CONNECTED TO SAID EXHAUSE VALVE MEANS AND SAID NORMALLY CLOSED VALVE IN SAID OTHER CONDUIT MEANS, A MANUAL CONTROL VALVE HAVING AN INLET PORT CONNECTED TO SAID ISOLATED SOURCE OF FLUID PRESSURE, AN OUTLET PORT AND AN EXHAUST PORT, SAID CONTROL VALVE BEING ALTERNATIVELY OPERABLE TO CONNECT SAID OUTLET PORT TO EITHER SAID INLET OR SAID EXHAUST PORT WHILE DISCONNECTING IT FROM THE OTHER PORT, AND FOURTH CONDUIT MEANS INTER-CONNECTING THE OUTLET PORT OF SAID MANUAL CONTROL VALVE WITH SAID FLUID PRESSURE RESPONSIVE ELEMENT AND SAID BRAKE LOCKING MEANS WHEREBY PRESSURE ADMITTED TO THE BRAKE LOCKING MEANS TO RELEASE THE SAME IS SIMULTANEOUSLY ADMITTED TO THE FLUID PRESSURE RESPONSIVE ELEMENT TO CLOSE THE EXHAUST VALVE MEANS IN SAID OTHER CONDUIT AND OPEN SAID NORMALLY CLOSED VALVE TO ADMIT FLUID FROM SAID SERVICE PRESSURE SOURCE TO THE CONTROL PORT OF THE TRACTOR PROTECTION VALVE.