The E-T Air-Brake Pocket-Book

tainable with the No. 6 than with the No. 5 E-T equipments, makes it particularly applicable to passenger engines that operate the Type L, high-speed, passenger triple valves on the cars.

It is practically impossible for the E-T brake to leak off if there is no leakage of application-cylinder pressure; the zone of such possible leakage includes the application-cylinder head, application-cylinder pipe, distributing-valve gasket, and remotely, the rotary valves of the automatic and independent brake-valves, and under certain conditions the distributing-valve release pipe; also the application piston, 10, leakage past its packing forming one of the worst troubles incidental to the E-T equipment, being concealed; when an emergency application is made by the local automatic brakevalve, however, the bad effects of leakage at this point are usually overcome by the maintaining pressure from the main reservoir via the automatic brake-valve.

Emergency-Lap Position.

In this reacting position there is no lap of the lower portion of the distributing valve, as the brakepipe pressure is almost, or wholly, discharged; all movable parts remain as in Fig. 12 B, until the brake-cylinder pressure slightly exceeds the application-cylinder pressure, when the application piston and application valve

CALIFORNIA

PRESSURE

PRESSURE APPLICATION BRAKE
CHAMBER CHAMBER CYLINDER
AIR
PRESSURE PRESSURE

43

FIG. 13.-No. 6 Distributing Valve in Emergency Lap

Position.

Copyright, 1909, by The Norman W. Henley Publishing Co.

Emergency Lap. Automatic Release

move back to the position known as emergency lap, as shown in Fig. 13; there is no change in pressures from the conditions indicated in Fig. 12 A, and that piping diagram applies as well in connection with this chart.

Automatic Release.

When the automatic brake-valve is placed in release position following a brake-pipe reduction by any manner of application, the recharge of the brake pipe will release all car brakes in the train, except those that may be held on by the cutting-in of their retaining valves, and the equalizing portion of the distributing valve on the locomotive will be moved to release position, without, however, releasing the locomotive brake, the application portion of the distributing valve remaining in the lapped position; see Fig. 14 B.

The benefit secured by this means is the ability of the engineer to release the brakes on the cars of a long freight train when the speed has been sufficiently reduced, yet to hold the locomotive brake applied so as to prevent the violent surging ahead of the forward portion of the train as the head brakes first release, and thus prevent the otherwise certain parting of the train.

Concerning the general pressure conditions incidental to this operation as indicated in the piping diagram,

The E-T Air-Brake Pocket-Book

Fig. 14 A, the automatic brake-valve having been placed in release position main-reservoir pressure finds the "open door" through that 'valve to the brake pipe, quickly increasing the pressure in the latter, and resupplying the pipe to the diaphragm-valve section of the excess-pressure top of the pump governor. The increase of brake-pipe pressure will be registered by the black hand of the small duplex gauge, and flow to the triple valves throughout the train, releasing all car brakes, but to the distributing valve on the locomotive without releasing effect. Main-reservoir pressure is now flowing to the equalizing reservoir, and the register of the pressure in the latter by the black hand of the large duplex gauge can not be taken as a proper indication of brake-pipe pressure under present conditions (although before the advent of the No. 6 E-T brake this gauge hand was the only means of showing brake-pipe pressure). The feed-valve pipe now has no outlet, and contains its maximum charge of 70-pounds pressure. The application-cylinder pipe. and distributing-valve release pipe are now in communication with each other, filled with the pressure of the application cylinder, and retained by reason of the outlet of the release pipe being blanked at the rotary of the automatic brake-valve; the result naturally being that the locomotive brake-cylinder pressure, of equal amount, is also retained as indicated in the coloring.