Load responsive pressure control system

Claim 1

IN A VEHICLE HAVING A FIXED PORTION AND A PORTION MOVABLE IN RELATION TO SAID FIXED PORTION IN RESPONSE TO VARIATION IN LOAD ON SAID MOVABLE PORTION AND IN RESPONSE TO VIBRATION, A SOURCE OF FLUID PRESSURE, A SET OF PRESSURE-ACTUATED BRAKES, AND AUTOMATIC MEANS FOR VARYING THE AMOUNT OF PRESSURE APPLIED TO SAID BRAKES FROM SAID SOURCE IN RESPONSE TO THE MOVEMENT OF SAID MOVABLE PORTION RESULTING FROM CHANGES IN LOAD THEREON WHILE PREVENTING VARIATION IN APPLIED PRESSURE IN RESPONSE TO MINUTE MOVEMENT OF SAID MOVABLE PORTION RESULTING FROM VIBRATION, SAID AUTOMATIC MEANS COMPRISING A VALVE BETWEEN SAID SOURCE AND SAID BRAKES, A ROCK BAR HAVING ONE OF ITS ENDS IN ACTUATING ENGAGEMENT WITH SAID VALVE, A PISTON RESPONSIVE TO SAID PRESSURE SOURCE AND HAVING AN ACTUATING ENGAGEMENT WITH THE OPPOSITE END OF SAID ROCK BAR, A FULCRUM MOVABLE ALONG SAID ROCK BAR AND MEANS FOR MOVING SAID FULCRUM, SAID LAST-NAMED MEANS INCLUDING A TORSION SPRING HAVING ONE OF ITS ENDS SECURED TO ONE OF SAID VEHICLE PORTIONS AND ITS OPPOSITE END CONNECTED TO SAID FULCRUM AND AUTOMATIC MEANS FOR ACTUATING SAID PISTON IN RESPONSE TO DIMINUTION OF PRESSURE IN SAID SOURCE, SAID LAST NAMED MEANS INCLUDING A CYLINDER, AN EMERGENCY PISTON MOVABLE IN SAID CYLINDER, A PRESSURE INLET ON ONE SIDE OF SAID EMERGENCY PISTON COMMUNICATING WITH SAID SOURCE, SHAFT MEANS ON SAID SIDE OF SAID PISTON AND POSTIONED FOR OPERATING CONTACT WITH SAID FIRST NAMED BAR-ACTUATING PISTON AND YIELDING MEANS ON THE OPPOSITE SIDE OF SAID PISTON EFFECTIVE TO URGE SAID SHAFT MEANS INTO ACTUATING CONTACT WITH SAID FIRST NAMED PISTON IN RESPONSE TO DIMINUTION OF SAID SOURCE PRESSURE BELOW A PREDETERMINED LEVEL.