Wabco Westinghouse Gmbh

Wabco Westinghouse Equipements Ferroviaires

Wabco Westinghouse Equipements Ferroviaires S.a.

Georges Dalibout

Michel Grenier

Daniel Cieplinski

Henri Limozin

A dual-piston hydraulic brake master cylinder includes a large hydraulic piston which supplies an initial large brake fluid volume and a small hydraulic piston which continues to supply brake fluid to the brakes when the large piston stops moving forward in its cylinder at higher brake pressures. The small, central hydraulic piston is connected to the end of a piston rod extension of a pneumatic booster piston. The large piston surrounds the small piston and opens a reservoir line tilt-valve in the piston retracted position. A passageway between the large and small hydraulic chambers is open in the retracted position to allow communication of braking fluid therebetween. During brake actuation a seal arrangement interrupts this communication. The large and small hydraulic chambers supply the brake circuits through delivery passages.

Double-piston master cylinder with central booster-driven piston driving

Brake cylinder with two pistons

A brake cylinder device combining a pneumatically-applied service brake and a spring-applied parking brake in a compact unit made possible by limiting the stroke of the parking brake piston to minimize the expansion of the spring and thus the amount of force relaxation, so that a relatively small spring may be used. The service brake piston carries a threaded shaft on which a nut is rotatably carried for locking engagement with the parking brake piston. The position of this nut during service braking is maintained in a predetermined position in proximity with the parking brake piston, by reason of a back-up spring imparting rotation, as the service piston takes up slack in the brake rigging, so that when the parking brake is subsequently applied, by locking engagement with the nut following only a short stroke, the stored energy of the spring acting through the parking brake piston, the nut and screw end of the service piston, and the service piston itself, substantially full force of the constrained parking brake spring is effective.

Brake cylinder device combining a pneumatically-applied service brake

A brake cylinder fluid pressure distributor having a control valve device of the pressure proportioning type that includes a main and auxiliary reaction piston, each subject on a corresponding face to pressure delivered by the control valve device to the brake cylinders in order to provide an actuating force on the piston valve assembly in a counteracting direction to the control force thereon, thereby automatically regulating the brake cylinder pressure. The auxiliary reacting piston is arranged on the piston valve assembly so as to be either engaged therewith or disengaged therefrom according to the effective load condition, speed range, deceleration rate or other parameter of a vehicle to be braked, thereby adjusting the effective brake cylinder pressure by adjusting the point in time when the delivery of pressure to the brake cylinders is terminated by the regulating action of the control valve device. Additional improvements include a segmented differential control piston via which the control force is transmitted to the piston assembly according to the variation of brake pipe pressure acting on one side of the control piston in opposition to a constant reference pressure on the other side. When the control force differential exceeds a predetermined level, corresponding to an emergency brake application, for example, one member of the segmented control piston is withheld from engagement with the other member such that only the reference pressure acts on the control piston to provide a constant control force on the piston assembly.

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Gagny, France

Georges Dalibout