Brake valve structure

Claim 1

A BRAKE VALVE FOR HYDRAULIC BRAKE ACTUATING INSTALLATIONS, ESPECIALLY MOTOR VEHICLES, HAVING A SERVO-PRESSURE SYSTEM WITH A PRESSURE MEDIUM SUPPLY, COMPRISING: HOUSING MEANS PROVIDED WITH PORT MEANS FOR CONNECTION WITH THE SUPPLY LINE LEADING TO THE PRESSURE MEDIUM SUPPLY AND WITH THE PRESSURE LINE LEADING SAID PRESSURE MEDIUM TO THE WHEEL BRAKE CYLINDERS, PISTON MEANS SLIDABLE WITHIN SAID HOUSING MEANS, SAID PISTON MEANS BEING ACTED UPON ON ONE END FACE THEREOF BY THE PRESSURE OF SAID PRESSURE MEDIUM AND DEFINING WITH THE OTHER END FACE THEREOF A SPACE ADAPTED TO BE CONNECTED WITH THE PRESSURE LINE LEADING TO THE WHEEL BRAKE CYLINDERS, ACTUATING MEANS OPERATIVELY CONNECTED WITH SAID PISTON MEANS FOR DISPLACING SAID PISTON MEANS ONLY IN CASE OF FAILURE OF THE SERVO-PRESSURE TO THEREBY PRODUCE A BRAKE PRESSURE IN THE PRESSURE LINE, SAID PISTON MEANS BEING NORMALLY LOADED IN ONE DIRECTION BY THE SERVO-PRESSURE AGAINST A FIXED ABUTMENT SO AS TO REMAIN STATIONARY DURING NORMAL OPERATION OF THE BRAKE VALVE WHEN THE SERVO-PRESSURE EXISTS, AND SPRING MEANS FOR LOADING THE PISTON MEANS IN THE OPPOSITE DIRECTION UPON FAILURE OF THE SERVO-PRESSURE IN SUCH A MANNER THAT THE PISTON MEANS IS AXIALLY DISPLACED IN SAID OPPOSITE DIRECTION BY SAID SPRING MEANS INTO THE STARTING POSITION FOR THE PRODUACTION OF BRAKING PRESSURE IN CASE OF FAILURE OF THE SERVO-PRESSURE.