The present invention concerns automatic fluid brake devices in which the fill and discharge of the brake cylinder or cylinders of the equipment are controlled by a device functioning as a distributing valve in relation to pressure variations in the brake pipe. In the aforementioned automatic braking devices generally used for rail vehicles, and commonly known as distributors, the brake cylinder pressure obtained during the braking process is a function of the pressure in the brake pipe. The present invention concerns distributors of the graduated release type, in which brake release is not only initiated via pressure increase in the brake pipe, but it is entirely a function of the pressure increase in this brake pipe. More specifically, the present invention concerns the type of graduated release distributor in which the discharge is adjustable, and the brake is inexhaustible regardless of the manner in which the valve is manipulated by the engine driver to carry out braking or brake release.
Passenger rail vehicle brake control valve apparatus includes, a control valve device of the type limited to direct release of the brakes, having service, emergency, and continuous quick service portions secured to a pipe bracket, and a graduated release valve portion governed jointly by brake cylinder pressure, brake cylinder exhaust passage pressure from the control valve device, and brake pipe pressure to at times modify output of the control valve device to provide for graduated control of the passenger rail vehicle brakes.
A brake accelerator is operable sequentially upon each successive braking stage over the service application range of brake line pressure reductions and is employed with a single release brake control valve of an indirectly acting compressed air brake for railway vehicles. The control valve has a service brake portion and an emergency brake portion provided with a emergency brake piston one side of which is subjected to brake line pressure and the other side is subjected to auxiliary chamber pressure . The accelerator has a main piston which operates an inlet valve to connect the accelerator to the brake line. The main piston which is also subjected on one side to brake line pressure and the other side to auxiliary chamber pressure is moved to a service position upon an application of the brakes to open the inlet valve and connect a control piston with the brake line such that the control piston is subjected on both sides to brake line pressure. The control piston is repeatedly moved between two positions such that quantities of air are cyclically withdrawn from the brake line and the auxiliary chamber to maintain the pressure relationship existing on both sides of the main piston during the service application. The drawing off of air from the auxiliary chamber by the control piston is carried out separately and independently from venting of the auxiliary chamber by the emergency brake piston.
