Continual quick service valve device for fluid pressure brake apparatus

Claim 1

A QUICK SERVICE VALVE DEVICE FOR EFFECTING REPEATED QUICK SERVICE REDUCTIONS OF PRESSURE IN THE BRAKE PIPE OF A RAILWAY VEHICLE BRAKE SYSTEM IN RESPONSE TO SUCCESSIVE REDUCTIONS FROM THE NORMAL CHARGE PRESSURE IN THE BRAKE PIPE, SAID QUICK SERVICE VALVE DEVICE COMPRISING: (A) A QUICK SERVICE CHAMBER, (B) A MOVABLE ABUTMENT HAVING A NORMAL POSITION WHEN SUBJECT TO SUBSTANTIALLY EQUAL PRESSURES IN THE BRAKE PIPE ACTING ON ONE SIDE AND IN THE QUICK SERVICE CHAMBER ACTING ON THE OPPOSITE SIDE, (C) TWO COAXIALLY ARRANGED CAGED SPRINGS SO DISPOSED THAT THE FIRST YIELDINGLY RESISTS MOVEMENT OF SAID MOVABLE ABUTMENT IN ONE DIRECTION OUT OF SAID NORMAL POSITION A CHOSEN AMOUNT AND THAT THE SECOND YIELDINGLY RESISTS MOVEMENT IN SAID ONE DIRECTION BEYOND SAID CHOSEN AMOUNT IN RESPONSE TO REDUCTIONS IN THE BRAKE PIPE WITH RESPECT TO THAT IN SAID QUICK SERVICE CHAMBER, (D) FIRST VALVE MEANS OPERATIVE UPON MOVEMENT OF SAID MOVABLE ABUTMENT IN SAID ONE DIRECTION SAID CHOSEN AMOUNT TO EFFECT VENTING OF FLUID UNDER PRESSURE ACTIVE ON SAID ONE SIDE OF SAID MOVABLE ABUTMENT AND FROM THE BRAKE PIPE TO ATMOSPHERE, AND (E) SECOND VALVE MEANS OPERATIVE SEQUENTIALLY TO SAID FIRST VALVE MEANS UPON MOVEMENT OF SAID MOVABLE ABUTMENT IN SAID ONE DIRECTION MORE THAN SAID CHOSEN AMOUNT TO EFFECT VENTING OF FLUID UNDER PRESSURE ACTIVE ON SAID OPPOSITE SIDE OF SAID MOVABLE ABUTMENT AND FROM THE QUICK SERVICE CHAMBER TO ATMOSPHERE TO CAUSE SAID MOVABLE ABUTMENT TO THEREAFTER SHIFT IN THE OPPOSITE DIRECTION TO OPERATE SAID FIRST VALVE MEANS TO TERMINATE SAID VENTING OF FLUID UNDER PRESSURE ACTIVE ON SAID ONE SIDE OF SAID MOVABLE ABUTMENT AND FROM THE BRAKE PIPE TO ATMOSPHERE, WHEREBY SAID MOVABLE ABUTMENT IS RENDERED EFFECTIVE TO SUBSEQUENTLY OPERATE SAID SECOND VALVE MEANS TO TERMINATE SAID VENTING OF FLUID UNDER PRESSURE ACTIVE ON SAID OPPOSITE SIDE OF SAID MOVABLE ABUTMENT AND FROM THE QUICK SERVICE CHAMBER TO ATMOSPHERE.