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COMBINED AIR STRAINER
With the advent of the No. 6 E-T equipment, the COMBINED AIR STRAINER AND CHECK-VALVE illustrated in Fig. 46 is furnished as a part of the locomotive-brake equipment, whether specified by the purchaser or not; and, if the Train Air Signal is to be used, two of these are furnished. A z-inch cut-out cock is also supplied to be used in connection with each.
In the ordinary automatic equipment the locomotive braking power is supplied from the brake pipe (train line), and the brake on a dead engine is automatically operative the same as any car brake. In the E-T equipment, however, while it is automatically operated through the brake-pipe air, locomotive braking pressure must be taken directly from the main reservoir. One application of the COMBINED AIR STRAINER AND CHECKVALVE is as the DEAD-ENGINE FEATURE, by which air from the brake pipe is supplied to the main reservoir of a dead engine, or one whose air pump is inoperative—said engine being in tow—and this is an important adjunct to the E-T locomotive-brake equipment.
Combined Air Strainer and Check-Valve
When the Train Air-Signal System is used, the ComBINED AIR STRAINER AND CHECK-VALVE forms the connection of the reducing-valve pipe to the signal pipe. The Piping Diagrams show both applications of this attachment.
As the DEAD-ENGINE FEATURE, Fig. 46 shows that the end nearest the check-valve is connected to a pipe containing main-reservoir pressure, and the opposite end to a branch of the brake pipe, the latter connection containing the cut-out cock, which should be left closed except under the conditions mentioned in which it must be opened to supply pressure from the brake pipe to the main reservoir; when open, brake-pipe air, entering as shown in the cut, passes through the disc strainers 7 and the curled-hair stuffing between the discs, lifts check-valve
which has been held to its seat by the strong spring 5, passes through the small choke bushing, and out to the main-reservoir connection as indicated, thus providing pressure for operating the brake on this locomotive. The Independent and Automatic BrakeValves should be in running position, and the doubleheading cock under the latter valve should be closed. When the tender is light of coal and water, or the locomotive boiler empty, it is commendable practice to reduce the maximum braking power of such a locomotive lower than the standard; and this can be easily and quickly done by reducing the adjustment of the
safety valve on the distributing valve; however, if an engineman is in the cab this will be unnecessary, as excessive brake power can be thrown off at will by the Independent Brake-Valve.
The spring, 5, over the check-valve is made extra strong to insure the valve seating, and, although permitting ample pressure to operate the locomotive brake, keeps the main-reservoir pressure somewhat lower than that in the brake pipe, thereby reducing the chances of back leakage from the former. The small choke port prevents a heavy drain from the brake pipe when the uncharged main-reservoir is cut into a charged brake pipe, and operates similarly to the feed groove in a triple valve.
As the SIGNAL-LINE CONNECTION, the end nearest the check-valve connects with the branch of the main signal-pipe, and the opposite end with the reducingvalve pipe; when so used, a lighter spring is furnished for check-valve 4, and this constitutes the only difference, constructively, in the two applications of the COMBINED AIR STRAINER AND CHECK-VALVE. The check-valve is here necessary to prevent back flow of signal-line pressure when an independent-brake application is made, and the consequent blowing of the air whistle out of time. A cut-out cock should also be placed in one of the pipes connecting with this signal-system attachment, preferably in the branch pipe connecting
Signal Line Connection
with the reducing-valve pipe, the cut-out cock standing open normally, but necessary for the purpose of cutting out the signal line system if such should ever be required; and to facilitate the cleaning of the check valve, which should be done occasionally.
GENERAL OPERATION OF THE TRAIN
AND LOCOMOTIVE BRAKES.
BEFORE LEAVING THE VICINITY OF THE ROUNDHOUSE.
See that everything about the air-brake and air-signal (if used) systems is working properly. While the air pump should be started slowly, the air pressures should be pumped up to the limit, with the automatic and independent brake-valves in running position. Then note air gauges, and if either hand (or both) on the large duplex gauge does not show the desired pressure, regulate the black hand first, by adjusting the feed valve. Then if the red hand is not standing at the desired figure, correct that by adjusting the regulating spring of the excess-pressure governor top. Next, make a light service reduction by the automatic brakevalve, note its action, and watch the red hand rise; if it does not stop at the desired pressure, correct the adjustment of the high-pressure governor top. Return the brake-valve from lap to holding position and watch the red hand of the small duplex gauge to see that the brake cylinder pressure will be maintained, thus making it safe to depend upon the holding power of the locomotive brake while making a running release of the train brakes on the road. Replace the brakevalve handle in running position and see that engine