Hydraulic brake pumping valve

Claim 1

IN A HYDRAULIC BRAKING SYSTEM AND THE LIKE: AT LEAST ONE BREAK STRUCTURE HAVING FIRST AND SECOND FRICTION PRODUCING MEMBERS WHICH ARE ROTATED RELATIVE TO EACH OTHER AND A BRAKE ACTUATING HYDRAULIC FLUID PRESSURE MOTOR FOR MOVING SAID FIRST AND SECOND MEMBERS TOGETHER, EACH BRAKE STRUCTURE REQUIRING A PREDETERMINED BRAKE RELEASING DISPLACEMENT OF ITS FLUID PRESSURE MOTOR TO JUST ALLOW SEPARATION OF SAID FIRST AND SECOND FRICTION PRODUCING MEMBERS, A HYDRAULIC FLUID PRESSURIZING CHAMBER INCLUDING A MOVABLE WALL, SAID MOVABLE WALL HAVING A NORMAL POSITON FROM WHICH IT IS MOVED TO FORCE FLUID FROM SAID PRESSURIZING CHAMBER, A RESERVOIR OF COMPENSATING FLUID FOR SAID PRESSURIZING CHAMBER, COMPENSATING MEANS WHICH COMMUNICATES SAID RESERVOIR TO SAID FLUID PRESSURIZING CHAMBER WHEN SAID MOVABLE WALL IS IN ITS NORMAL POSITION AND WHICH CLOSES OFF SAID FLUID PRESSURIZING CHAMBER FROM SAID RESERVOIR WHEN SAID MOVABLE WALL IS MOVED TO FORCE FLUID OUT OF SAID CHAMBER, A SECOND FLUID PRESSURE CHAMBER HAVING A SECOND MOVABLE WALL DIVIDING SAID SECOND CHAMBER INTO OPPOSING INLET AND OUTLET CHAMBERS, STOP MEANS LIMITING MOVEMENT OF SAID SECOND MOVABLE WALL FROM A COLLAPSED CONDITION OF SAID INLET CHAMBER TO A COLLAPSED CONDITION OF SAID OUTLET CHAMBER AND VICE VERSA TO PROVIDE A PREDETERMINED DISPLACEMENT IN EACH DIRECTON, SAID INLET CHAMBER BEING COMMUNICATED TO SIAD PRESSURIZING CHAMBER AND SAID OUTLET CHAMBER BEING COMMUNICATED TO SAID HYDRAULIC FLUID PRESSURE MOTORS OF EACH BRAKE STRUCTURE AND SAID PREDETERMINED DISPLACEMENT OF SAID INLET AND OUTLET CHAMBERS BEING GENERALLY EQUAL TO THE SUM OF SAID PREDETERMINED BRAKE RELEASING DISPLACEMENTS OF SAID BRAKE STRUCTURE COMMUNICATING WITH SAID OUTLET CHAMBER, SAID SECOND MOVABLE WALL BEING MOVABLE FROM A COLLAPSED CONDITION OF SAID INLET CHAMBER TO A COLAPSED CONDITION OF SAID OUTLET CHAMBER WITH A SMALL PREDETERMINED PRESSURE DIFFERENTIAL, A NORMALLY CLOSED BACK PRESSURE VALVE WHICH OPENS AT A PRESSURE ABOVE SAID PREDETERMINED PRESSURE DIFFERNETIAL TO COMMUNICATE SAID INLET CHAMBER TO SAID OUTLET CHAMBER, AND MEANS PERMITTING SMALL COMPENSATING FLOWS BETWEEN SAID OUTLET AND INLET CHAMBERS AT PRESSURE DIFFERENTIALS BELOW SAID PREDETERMINED DIFFERENTIAL, WHEREBY RETURN FLOW FROM SAID BRAKE ACTUATING MOTOR IS RESTRICTED WHEN SAID COMPENSATING MEANS IS OPENED TO PERMIT FLOW INTO SAID PRESSURIZING CHAMBER FROM SAID RESERVOIR.