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g Diagram No. 6 ET Equipment. Colors showing sequence of pressures at independent locomotiveafter automatic application. Independent brake-valve in release position, automatic brake-valve in Broken colors show reduced, or less than normal, pressures.

blanked by the rotary of the independent brakevalve.

Following an automatic service-application, if a graduated, or partial, release of the locomotive brake is made by the independent brake-valve the reduced braking pressure will remain constant (unless automatically increased by brake-pipe leakage), and if the release is complete the locomotive brake will stay off, under the conditions; but after an emergency application by the automatic brake-valve, any of the application-cylinder pressure that may be discharged by the independent brake-valve will be resupplied through the maintaining port in the automatic brake-valve, and the brakecylinder pressure will be built up as fast as it is released, after the independent brake-valve has been lapped; so, to independently release the locomotive brake under emergency conditions, it is necessary to hold the independent brake-valve in release position as long as the automatic brake-valve remains in emergency- application position.

Fig. 17 B shows the distributing valve in the position of Independent Release; it will be unnecessary to allude to the lower portion any further than to note that it holds the same position as is usual at service lap, which was explained in connection with Fig. 11, having no effect on the independent release, nor would it make any particular difference if the equalizing portion had

The E-T Air-Brake Pocket-Book

taken the emergency position, as shown in Fig. 12 B. The discharge of pressure from the application cylinder at the left of application piston 10 has resulted in the piston being moved to the left, as shown, by the pressure in chamber b on the right, thus opening the exhaust ports e, and d, through which the brake-cylinder pressure is exhausted to the atmosphere; if all of the applicationcylinder pressure should be discharged, the application piston will remain in the release position as shown in the plate, and the brake-cylinder pressure will be fully released; but if the former pressure should be only partially discharged and the independent brakevalve returned to lap position, as soon as the brakecylinder pressure in chamber b is exhausted to slightly less than the pressure remaining on the left of the piston, the application mechanism will be moved to the right until the exhaust ports, e, and d, are closed, and then will stop in the lap position, in which case all parts of the distributing valve will have assumed the same positions as they were shown in Fig. II-automatic service lap.




With the advent of all-air-braked trains it became necessary to supply additional functions to the plain triple-valves referred to earlier in this work; no changes were found necessary in its action in response to service reductions, but at emergency applications on long, air-braked trains, the forward brakes would apply with full force before the brakes on the rear cars had started to set, resulting in the sudden “bunching” of trains with disastrous effects; in other words, the slack between the cars would close-in more rapidly than the brakes could serially apply throughout the train from front to rear.

Then the quick-action triple valve was evolved for freight and passenger cars, in the service action of which there was no difference from that of the plain triplevalve; but, following a quick, heavy reduction, the new triple was devised to discharge a portion of the brake-pipe air, and—further—to make this discharge into the brake cylinder, before the latter could receive any appreciable amount of auxiliary-reservoir pressure, resulting in an increased braking pressure at emergency

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