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Brake-Valve Handle Positions
heading pipe is opened to the atmosphere through a port in the rotary valve, but which ordinarily has no effect, however, as this pipe is closed at another point -at ihe double-heading cock. In this, and the following application positions, the supply of mainreservoir pressure through the rotary valve of the automatic brake-valve to the excess-pressure top of the pump governor is cut off, and the pump is then solely under the control of the high-pressure governor top.
(Lap Position is the carrying position for the automatic brake-valve on all engines that may be in a train, except the leading one, or the engine that is to operate the brakes; and on such secondary engines the doubleheading cocks should be closed--to brake-pipe air,and this completes the opening of the double-heading pipe to the atmosphere; having the effect of converting the equalizing portion of the distributing valve into an actual triple valve with open exhaust port, that can be automatically operated by the leading engineer in both application and complete-release movements.)
Service-Application Position.—The movement this position does not change the lapped condition of the rotary-valve ports, except that the terminus of the double-heading pipe is closed, and another port is now opened: the small, preliminary-exhaust port is open, discharging equalizing-reservoir pressure from chamber D, which has the already well-known effect
of initiating an equal pressure reduction of brake-pipe air through the service exhaust port. A return of the handle to Lap Position follows, when the equalizingreservoir pressure has been reduced the desired amount.
Emergency-Application Position. Like the position for service application, that of Emergency has the same effect on the train brakes as similar positions of the H-6, or any other standard Westinghouse brakevalve. In Emergency Position a large port in the rotary valve connects the brake-pipe pressure with an equally large port in the rotary-valve seat that opens to the atmosphere, causing such a quick and heavy reduction as to apply all brakes at emergency, or quick action.
And, as in the No. 6 equipment, an emergency application produces a higher application-cylinder pressure than is obtained at a full service reduction; this pressure increase was shown to be obtained in the improved, No. 6 brake, by the cutting off of the application chamber at emergency action of the distributing-valve parts, and causing the short equalizing of the pressurechamber air with the small, application cylinder; in the No. 5 equipment, the application chamber remains in permanent communication with the applicationcylinder in all phases of distributing-valve action, and its increased pressure is only obtained by placing the automatic brake-valve in Emergency-Application Position, in which position a port in the rotary valve opens
The Maintaining Pressure
communication between chamber D and the application-chamber pipe; and the addition of the volume and unreduced pressure of the equalizing reservoir to that of the pressure chamber builds up a pressure to act upon the application piston of 60 pounds; whereas a full service application can only equalize the pressure chamber, application chamber and application cylinder, at 50 pounds pressure.
Maintaining pressure, supplied at a certain time to the application cylinder of the distributing valve, and as understood in the No. 6 equipment, is also a factor in the No. 5 brake operation, but there is an important difference in its origin—an improvement in the No. 6, decidedly for the better. In the No. 5 brake, the feed of maintaining pressure is not dependent upon the placing of the automatic brake-valve in Emergency Position; it does not come through the brake-valve at all, originating in the distributing valve; when the equalizing slide valve is drawn to the limit of its application movement, a port through it connects the main-reservoir pressure (which is always present in the distributing valve) with a port in the valve seat that leads to the application cylinder via the pressure chamber and application chamber; it will be seen from this that a full service application will produce this “straight-air” supply, which is not at all desirable.
THE S-F (No. 5) INDEPENDENT BRAKE-VALVE.
The OPERATIVE POSITIONS of the S-F INDEPENDENT BRAKE-VALVE handle are the same as with the S-6 valve; the positions of Slow Application and Quick Application are closer together in the No. 5 valve, however, and the shoulder on the quadrant that catches the handle bolt in the former position is not as pronounced. The return spring only operates to move the handle from Release to Running Position; and there is no warning port to attract attention in the Release Position of the No. 5 (S-F) VALVE. The duties of these two styles of INDEPENDENT BRAKE-VALVE in their five operative positions are just the same, in each, and have been fully described in explanation of the S-6 brake-valve.
GENERAL OPERATION OF THE NO. 5 E-T EQUIPMENT.
As IT MAY DIFFER FROM THE IMPROVED, No. 6 STYLE. In general operation it may be said that there is no difference in the instructions as between the Nos. 5 and 6 styles of E-T equipment, with the single exception of double- or triple-heading, and then so far only as concerns the “cut-out" engines; on each engine in the train except the one from which the train and locomotive brakes are operated, the independent brake-valve should, as usual, be carried in Running Position and
No. 5 Independent Brake-Valve
the automatic brake-valve must be placed in the Lap Position, with the double-heading cock beneath it “closed” to brake-pipe pressure. Under such arrangement, in order to apply the independent locomotive-brake the automatic brake-valve handle must first be placed in Holding Position; to graduate the application, the independent brake-valve should then be placed in Slow Application Position and returned to Running Position. To release the locomotive brake afterward, simply return the automatic brake-valve handle to Lap Position.
After an automatic train- and locomotive-brake application from the operating engine, if it is desired to retain the driver and tender brakes on a “cut-out engine while the train brakes are being released, the automatic brake-valve should be temporarily placed in Holding Position until it is desired to release the locomotive brake, which will be done by returning the handle to Running Position.
The DEAD-ENGINE FEATURE is not included in the No. 5 E-T brake equipment, and should be specially ordered, as its application is strongly recommended.
In the earlier furnishings of the No. 5 equipment, the branch of the feed-valve pipe to the excess-pressure top of the pump governor was connected by a union to the top of the regulating-spring case, and a stop cock was placed in the pipe near the governor; in order to