A. Remove the broken valve, blocking the opening made by its removal, and as there are two upper and two lower receiving valves the compressor will now take air through the other valve.

73. Q. If an intermediate discharge valve breaks or sticks open, how may it be located?

A. No air will be taken in to that end of the compressor as the piston moves from the defective valve, and may be located by holding the hand over the strainer.

74. Q. If an intermediate discharge valve breaks, what may be done?

A. Remove the broken valve, blocking the opening made by its removal, and as there are two upper and two lower intermediate discharge valves the air will now pa.s.s from the low pressure cylinder to the high pressure cylinder through the other valve.

75. Q. If a final discharge valve breaks, what effect will it have on the compressor?

A. Will cause the compressor to stop when the main reservoir pressure is in excess of forty pounds.

76. Q. How would you test for a defective final discharge valve?

A. To test for this defect, bleed the main reservoir pressure below forty pounds, and if the compressor starts it indicates a defective discharge valve.

77. Q. If a final discharge valve breaks, what may be done?

A. As the receiving valves and final discharge valves are the same size, the defective valve may be replaced by one of the receiving valves, blocking the opening made by the removal of the receiving valve.

78. Q. Where piston rod packing is blowing bad, what may be done to stop it?

A. This generally indicates lack of lubrication, and by cleaning and oiling the swab the trouble may be overcome. However, there are times when leakage by the packing is so great that the oil is blown off the swab as fast as it is applied, therefore is of no value in lubricating the parts. Where this condition exists, a little hard grease wrapped up in an old flag and tied around the piston rod will ensure its being lubricated.

79. Q. If the compressor stops, how can you tell if the governor is responsible for the trouble?

A. By opening the drain c.o.c.k in the steam pa.s.sage between the governor and the compressor; if steam flows freely, the trouble is in the compressor; if not, it is in the governor.

80. Q. How may a compressor often be started when it stops?

A. By closing the steam throttle for a few seconds, then opening it quickly; if this does not start it, try tapping the main valve chamber.

This will usually overcome the trouble where the compressor stops on account of lack of lubrication.

81. Q. What will cause a compressor to short-stroke or dance?

A. Too much oil in the steam end; bent reversing rod; or low steam pressure, as when the governor has almost shut off the steam.

ENGINEER'S BRAKE VALVE

82. Q. Name the different positions of the G-6 and H-6 brake valves.

A. Release, running, lap, service, and emergency position, with the G-6; release, running, holding, lap, service, and emergency positions, with the H-6.

83. Q. What is the purpose of release position?

A. To provide a large and direct opening from the main reservoir to the brake pipe, for the free flow of air, when charging and recharging the brakes.

84. Q. What pressure will be had in the brake pipe if the brake valve be left in release position?

A. Main reservoir pressure.

85. Q. Can the locomotive brake be released by the automatic brake valve in release position, when using the H-6 valve?

A. No; as the port in the automatic brake valve to which the distributing valve release pipe is attached is blanked in this position of the valve.

86. Q. What is the purpose of running position, and when should it be used?

A. This is the proper position for the brake valve when the brakes are charged and not in use, also when it is desired to release the locomotive brake with this valve. In this position the brake pipe pressure is maintained at a predetermined amount by the feed valve, as all air that now enters the brake pipe must pa.s.s through the feed valve.

87. Q. What is the purpose of holding position?

A. To hold the locomotive brake applied while recharging the brakes. The charging of the brake pipe and equalizing reservoir is the same in holding as in running position.

88. Q. What is the purpose of lap position?

A. To hold both the locomotive and train brakes applied after an automatic application.

89. Q. What is the purpose of service position?

A. This position of the brake valve enables the engineer to make a gradual reduction of brake pipe pressure, thus causing a service application of the brakes.

90. Q. What is the purpose of emergency position?

A. In this position of the brake valve, the brake pipe is connected directly with the atmosphere through the large ports in the valve, causing a sudden reduction of brake pipe pressure, this in turn causing the distributing valve on the engine and all operating triple valves on cars in the train to move to emergency position, thus insuring a quick and full application of the brake.

91. Q. How should the brake valve be handled when making an emergency application of the brake?

A. The valve should be placed in full emergency position and left there until the train stops, even though the danger may have disappeared.

DEFECTS OF THE BRAKE VALVE

92. Q. What will cause a constant blow at the brake pipe exhaust port, and what may be done to overcome it?

A. This indicates that the brake pipe exhaust valve is being held off its seat, due no doubt to dirt; tapping the side of the valve will sometimes stop the blow; if not, close the brake pipe cut-out c.o.c.k and make a heavy service reduction; next, place the brake valve handle in release position. This will cause a strong blow at the exhaust port, which will invariably remove the trouble.

93. Q. If the pipe connecting the brake valve with the equalizing reservoir breaks, can both locomotive and train brakes be operated with the automatic brake valve?

A. Yes; by placing a blind gasket in the pipe connection at the brake valve and plugging the brake pipe exhaust port. To apply the brake, move the handle carefully toward emergency position, making a gradual reduction of brake pipe pressure through the direct exhaust ports of the brake valve; when the desired reduction is made, the handle should be moved gradually back to lap position.

94. Q. What would be the effect if the handle were moved to lap quickly?

A. Would cause the release of the brakes on the head end of the train.

95. Q. What will cause air to blow at the brake pipe exhaust port when the handle is moved to lap position?

A. This is caused by a leak from the equalizing reservoir or its connections, which reduces the pressure in chamber "D" above the equalizing piston, allowing brake pipe pressure under the piston to force it up, unseating the brake pipe exhaust valve, permitting brake pipe air to flow to the atmosphere.