82. Q. If a sight feed gets stopped up, how could you clean it out?

A. Close the water valve and the regulating valves to the other feeds.

Open drain c.o.c.k and draw out a small quant.i.ty of water so as to bring the oil in top part of lubricator below the top end of oil pipe leading to feed arm, then open wide the regulating valve to feed that is stopped up and the pressure from the equalizing tube will force the obstruction out of the feed nozzle and up into the body of the lubricator. Next, close this regulating valve until the feed gla.s.s fills with water, then open water valve and start feeds.

83. Q. How would you clean out chokes?

A. First, shut off boiler pressure and condenser valve; next, remove feed valve bonnet, then open main throttle valve, when the steam from steam chest will blow back through the choke plug, clearing it of any obstruction.

84. Q. What is superheated steam?

A. It is the saturated steam separated from the water from which it is generated with more heat added, increasing its temperature from 100 degrees to 250 degrees Fahrenheit above the saturated steam temperature.

85. Q. What is the advantage of superheating or increasing the temperature of the steam?

A. By increasing the temperature of the steam the volume of a given weight of steam is increased and all losses due to cylinder condensation are eliminated, which result in a reduced steam consumption, a saving in coal and water and increased boiler capacity.

86. Q. How is the increased temperature obtained by the use of the superheater?

A. By admitting the saturated steam into a part.i.tioned receiver which has a number of 1-1/2-inch pipes attached to it. These are located in and extend nearly the full length of the large flues, the steam having to pa.s.s through these 1-1/2-inch pipes on its way back to the receiver, absorbs the heat from the gases pa.s.sing through the large tubes, causing its temperature to rise, or in other words, become superheated.

87. Q. How much is the volume of steam increased by superheating?

A. For each 100 degrees of superheat added to saturated steam, at temperatures ordinarily used in locomotive practice, the volume of a given weight is increased roughly from sixteen to seventeen per cent.

88. Q. Why is the superheated steam so much more economical on coal and water than the saturated steam?

A. Because for a given amount of water evaporated you can increase the volume of steam 33 per cent. by superheating. It is readily seen that the coal does not have to be burned if the steam used has 33 per cent.

more volume for filling s.p.a.ce, or in other words, only so much steam can be admitted to the cylinders for every movement of the valve, and what can not be used must remain in the boiler, so if the engine can not use all of the steam that the boiler is capable of generating, the saving must show in coal and water. If you can not use all of the steam you do not have to burn coal to make it.

89. Q. Which is the better practice, to close the feed valves or water valve while waiting on sidings, etc.?

A. Close the feed valves; the water valve may leak.

90. Q. How can you tell if equalizer tubes become stopped up or broken?

A. If they were stopped up the equalization would be destroyed, and when the steam-chest pressure was less than the boiler pressure the feed would work too fast, the oil would enter the feed gla.s.s in a stream instead of forming into drops. If they were broken, the lubricator could not be used. The auxiliary oilers would have to be used to lubricate the cylinders.

=AIR BRAKE QUESTIONS=

1. Q. Explain how an air compressor should be started.

A. A compressor should be started slowly, with the drain c.o.c.ks open to allow the water of condensation to escape; and as no provision is made in the steam end to cushion the pistons at the end of their stroke, it should be allowed to work slowly until a pressure of thirty or forty pounds has acc.u.mulated in the main reservoir; the piston, having to work against this pressure, will be cushioned at the end of each stroke.

After the compressor is warm, the drain c.o.c.ks should be closed and the throttle opened sufficiently to run the compressor at the proper speed.

The lubricator should then be started and allowed to feed freely until eight or ten drops have pa.s.sed, when the feed should be reduced to an amount sufficient for proper lubrication.

2. Q. What kind of oil should be used to lubricate both the steam and air cylinders of the compressor?

A. Valve oil.

3. Q. Where does the main reservoir pressure begin and end?

A. Begins at the discharge valves in the compressor and ends at the engineer's brake valve.

4. Q. Where does the brake pipe pressure begin and end?

A. The brake pipe pressure begins at the feed valve and ends at the brake pipe side of the triple piston, conductor's valve and at the rear angle c.o.c.k.

5. Q. What is meant by excess pressure, and where is this pressure carried?

A. Excess pressure is carried in the main reservoir and is the pressure above that in the brake pipe.

6. Q. Why is excess pressure necessary?

A. To insure the prompt release of all brakes and quick recharge of the brake pipe and auxiliary reservoirs.

7. Q. How is the amount of excess pressure regulated?

A. By the compressor governor.

8. Q. Name the different parts of the air brake as applied to a car.

A. The triple valve, auxiliary reservoir, brake cylinder, brake pipe, angle c.o.c.ks, cut-out c.o.c.k, retaining valve, centrifugal dirt collector and strainer tee.

9. Q. What is the duty of the triple valve?

A. The triple valve has three duties to perform: Charge the auxiliary reservoir; apply the brake; and release the brake.

10. Q. What is the purpose of the auxiliary reservoir?

A. It is here that the air is stored that is admitted to the brake cylinder when the brake is applied; thus, each car carries its own brake power.

11. Q. What is the purpose of the brake cylinder?

A. It is here where the power of the compressed air is converted into work by forcing the brake piston out, moving the brake levers, rods and brake beams, forcing the brake shoes against the wheels, applying the brake.

12. Q. What is the purpose of the brake pipe and angle c.o.c.ks?

A. It is through the brake pipe that all brakes in the train are placed into communication with the brake valve on the locomotive; and through the brake pipe, air from the main reservoir flows to the triple valves and auxiliary reservoirs on the different cars. The angle c.o.c.ks are for the purpose of opening and closing the ends of the brake pipe.

13. Q. What is the purpose of the cut-out c.o.c.k?

A. To cut out any brake that is not in operating condition.