Зображення сторінки
PDF
ePub

Possible leakage of Braking Pressure

Q. 29. To preserve this feature of locomotive braking-pressure maintenance, is it not essential that certain other parts of the locomotive air-brake equipment shall be absolutely free from leakage to the atmosphere?

A. Yes; the two little copper pipes that connect to the left side of the distributing valve must be perfectly free from leakage clear to their further terminals; also the head of the upper portion of the distributing valve (application-piston cylinder cover) must be tight.

Q. 30.-If, after an application by either brake-valve, when a release is attempted the locomotive brake-cylinder pressure will be exhausted until only a few pounds remains when its escape ceases, and the brake remains lightly "stuck"-this at a release by either brake valve and the only way found to completely release it is to move the independent brake-valve handle to the full Application Position for a second, and then throw it quickly to Release Position,-what could be the cause of the trouble?

A. The packing of Application Piston 10, in the upper portion of the distributing valve, is in bad condition and the Application and Exhaust Slide Valves lack lubrication, and are gummy. Experience has proven that the maintenance of proper condition of this piston is at once the most important feature, and the

hardest thing to secure, of anything relative to the distributing valve.

Q. 31. Where is the Double-Heading Cock, and in what way does it differ, constructively, as between the No. 5 and No. 6 equipments?

A.—The double-heading cock is placed in the automatic brake-valve branch of the brake pipe, and is located directly beneath the brake-valve. In the No. 5 equipment it is double ported, one port through it conveying brake-pipe pressure, and at an angle of 90 degrees to it is the port to connect with the double-heading pipe when the cock is in the "closed" position— turned 90 degrees, and closed to brake-pipe pressure. In the No. 6 equipment there is no "double-heading pipe," and the Double-Heading Cock is a common, 1-inch cut-out cock.

Q. 32. In case of Double Heading, if the engineer of the leading engine operates the train and locomotive brakes, what shall he do specially under the circumstances if his engine has E-T equipment?

A. He shall make no changes in the equipment in any way, and shall operate the brakes just the same as if there was no other engine in the train.

Q. 33. Under the same circumstances what should the engineer of the following engine do, if he has the E-T equipment?

A. He shall permit his air pump to run as usual;

Double Heading

shall close the double-heading cock. If he has the No. 5 equipment, he shall place his automatic brake-valve handle on Lap, as the regular carrying position for it under the circumstances. With the No. 6 equipment, the double-heading cock must be closed, but the automatic brake-valve handle should be left in the Running Position.

Q. 34. Suppose the air pump on the second engine should be broken down; or a "dead" engine is being towed; in either case, with E-T equipment, would the locomotive brake on such engine be operative?

A. Not unless that locomotive was equipped with the parts supplementary to the regular E-T equipment called the "Dead-Engine Feature."

Q. 35. Explain the Dead-Engine Feature, and the principle of its use.

A. It comprises a branch pipe connecting the main brake pipe, or train line, with a conveniently located pipe containing main-reservoir pressure; this branch pipe contains a cut-out cock which is normally closed, a small cylinder filled with curled hair that acts as an air strainer, a check-valve, and a choke fitting with a small hole (about 1-inch diameter) through it which limits the flow of air through the device (generally termed the "Combined Air Strainer and Check-Valve"). When a locomotive whose air pump is inoperative is coupled into a train the brakes of which are to be oper

ated from another engine, the engineman on the “dead” locomotive (in addition to closing the double-heading cock and placing his automatic brake-valve handle as prescribed in answer to question 33) should open the cutout cock in his dead-engine feature; this will charge his main reservoir to a pressure nearly equal to that of the brake pipe, and higher than is really necessary. The check-valve prevents back flow of main-reservoir pressure to the brake pipe when the operating engineer makes an automatic application, and the choke fitting limits the drain from the brake pipe to about the time flow through the feed groove of a triple valve in charging an auxiliary reservoir. The brakes of the "dead" engine will then be automatically operative, and its independent brake could be applied, if necessary.

Q. 36. Is the same set of fixtures comprised in the dead-engine feature used in another connection, in the E-T locomotive equipment?

A. Yes; if the Train Air Signal is used, the Westinghouse furnishings for the dead-engine feature are used to connect the Reducing-Valve Pipe (of 45 pounds pressure) with the main Signal Pipe.

Q. 37. What differences, if any, are found in the Combined Air Strainer and Check-Valve as between its use in the Signal Line, and as the Dead-Engine Feature?

A. In connection with the Signal Line, a light spring

Inspection of E-T-equipment

is used over the check-valve, while in the Dead-Engine Feature the check-valve spring is much stiffer.

Q. 38. At what Pressure should the Safety Valve be adjusted?

A. The safety valve on the No. 5 equipment distributing-valve should be adjusted at 53 pounds; on the No. 6 distributing valve, it should be set at 68 pounds.

Q. 39. When it is desired to inspect one of the brake-valves, to remove the feed valve, reducing valve, or distributing valve, or to make any other disconnection of parts in the E-T equipment, will it be necessary to shut down the air pump and blow off the mainreservoir pressure?

A. No. This would only be necessary in case the high-pressure governor top, or the air pipe leading to it, had to be disconnected. Before making any disconnection in all other parts of the E-T equipment, place the automatic brake-valve handle in Release Position and close the Main-Reservoir Cut-out Cock; this is a sort of 3-way cock, and, in addition to cutting off the supply of main-reservoir pressure from the general equipment, the latter is drained of pressure through a small port in the cock. The direct air-passageway through the automatic brake-valve, made by placing the handle in Release Position, is to prevent the lifting of its rotary valve and of the slide valve in the feed valve, with the chances

« НазадПродовжити »