AIR BRAKE QUESTIONS
1. Q. Explain how an air compressor should be started.
A. A compressor should be started slowly, with the drain cocks 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 accumulated 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 cocks 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 passed, 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 cock.
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 cocks, cut-out cock, 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 cocks?
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 cocks are for the purpose of opening and closing the ends of the brake pipe.
13. Q. What is the purpose of the cut-out cock?
A. To cut out any brake that is not in operating condition.
14. Q. How is a brake cut out?
A. By closing the cut-out cock in the cross-over pipe and bleeding the auxiliary reservoir.
15. Q. How would you bleed an auxiliary reservoir?
A. By holding open the release valve on the reservoir until all air has escaped.
16. Q. How would you bleed off a stuck brake?
A. By holding open the auxiliary release valve until the brake piston starts to move toward release position.