A. In release and charging position the air entering from the brake pipe pushes the piston upward as far as it will go, opening the feed groove and allowing the air from the brake pipe to flow through the feed grooves, one in the piston bushing and one in the piston, into the auxiliary reservoir, until the pressure is the same on both sides of the piston. (Art. 3.)

12. Q.-When a change of pressure occurs on one side of the piston, how does it always move?

A. Toward the lower pressure. (Art. 3.)

13. Q.-Upon what principle do all automatic air brake devices operate? A. On the same principle as the triple piston; that is, the piston or diaphragm is a movable partition separating two sources of pressures. So long as these pressures are equal no movement occurs, but when the pressure on one side becomes higher than that on the other the piston or diaphragm tends to move toward the lower pressure, and when the pressures again become equal the tendency to move ceases. (Art. 3.)

14. Q.-What changes in pressure cause the triple valve to operate?

A. An increase or decrease in brake-pipe pressure, caused by a movement of the brake-valve handle, opening of a conductor's valve, a burst hose or broken pipe, or leakage, or a decrease in auxiliary reservoir pressure, caused by the flow of air from the auxiliary reservoir to the brake cylinder during an application of the brake. (Art. 3.)

15. Q.-How many positions are there that the operating parts of the triple valve may take in operation, and what are they?

A. Four positions; namely, release, service, lap, and emergency. (Art. 3.) 16. Q.-When do they go to release position?

A. When the system is first being charged and when the brakes are released after an application. (Art. 3.)

17. Q.-What connections are made in release position?

A. Connection is made between the brake pipe and auxiliary reservoir, and between the brake cylinder and the atmosphere. (Art. 3.)

18. Q.-how is the connection between brake pipe and auxiliary reservoir made?

A.-Through the two feed grooves in the piston bushing and the piston, and chamber h below the piston. (Art. 3.)

19. Q.-How long does the air flow from the brake pipe to the auxiliary reservoir?

A. Until the pressure in the auxiliary reservoir is equal to that in the brake pipe. (Art. 3.)

20. Q.-How is the connection between brake cylinder and atmosphere made?

A.-Through port r in the slide valve seat, cavity n in the face of the slide valve, and the exhaust port p in the seat opening to the atmosphere. (Art. 3.) 21. Q.-What is service position?

A. It is the first position that the operating parts assume during a service application of the brakes. (Art. 3.)

22. Q. How is service position brought about?

A. By a moderate and gradual reduction of brake-pipe pressure. (Art. 3.)

23. Q.-Why does this cause the operating parts of the triple valve to move?

A. The reduction of brake-pipe pressure causes the auxiliary reservoir pressure to be the greater. (Art. 3.)

24. Q.-When and how do the operating parts move in a service appli cation?

A. When the difference between the brake-pipe and auxiliary-reservoir pressures is enough to overcome the friction of the moving parts, the piston moves downward toward the lower pressure, first closing the feed groove, and when the knob on the end of the piston stem strikes the graduating stem it stops. (Art. 3.)

25.

Q.-How is the slide valve connected with the piston?

A. The slide valve fits into a cut-away portion of the piston stem, leaving a little play between the edges of the slide valve and the shoulders on the end of the piston stem, which allows the piston to make a slight movement without moving the slide valve. (Art. 3.)

26.

Q.-How is the graduating valve connected with the piston?

A. By means of a small pin inserted in the piston stem and the lower end of the graduating valve. (Art. 3.)

27. Q.-Does the graduating valve always move when the piston moves? A. Yes. (Art. 3.)

28. Q.-Where is the graduating-valve seat?

A. Almost in the center of the slide valve. (Art. 3.)

29. Q.-Which moves first in an application, the slide valve or the graduating valve?

A. A connection is made between the auxiliary reservoir and port Z in the slide valve through port W. (Art. 3.)

32. Q.-What connection is made in service position?

A. A connection is made between the auxiliary reservoir and the brake cylinder. (Art. 3.)

33. Q-What closes the connection between brake cylinder and atmosphere?

A. The movement of the slide valve. (Art. 3.)

34. Q.-What closes the connection between brake pipe and auxiliary reservoir?

A. The triple piston. (Art. 3.)

35. Q.-How is the connection made from auxiliary reservoir to brake cylinder?

A. When the piston is stopped by the graduating stem, port Z in the slide valve is in register with portr in the seat, thus allowing air from the auxiliary reservoir to flow through ports W, Z and r into the brake cylinder. (Art. 3.) 36. Q-What is lap position?

A. It is the second position that the operating parts assume during a service application of the brakes. (Art. 3.)

37. Q.-What causes the operating parts to go to lap position?

A. When the difference between the auxiliary reservoir and brake-pipe pressures is enough to overcome the friction of the piston and the graduating valve, the piston will move upward toward the lower pressure until the graduating valve strikes its seat in the slide valve, thus cutting off the flow of air to the brake cylinder and preventing further movement of the piston. (Art. 3.)

A. Because there is not sufficient difference between the pressures on either side of the piston to overcome the friction of the slide valve. (Art. 3.)

39. Q. What connections are made in lap position?

A.-No connections are made, as all ports are blanked. (Art. 3.)

40. Q-Do the operating parts always go to lap position in any service application?

A. No, not in a full-service application. (Art. 3.)

A. Because, in this case, the auxiliary reservoir and brake cylinder pres sures become equalized, and the auxiliary reservoir pressure cannot become less than the brake-pipe pressure and allow the brake-pipe pressure to the piston to lap position. (Art. 3.)

move

42. Q. What position do the operating parts remain in during a fullservice application?

A. In service position, with the auxiliary reservoir and brake connected. (Art. 3.)

су linder

43. Q. What is the result if the reduction is carried below the point required to give a full-service application?

A.-A waste of air. (Art. 3.)

44. Q.-What is a graduated application?

A. An application of the brakes in which the brake cylinder pressure is increased by a number of reductions in brake-pipe pressure. (Art. 3.)

45. Q.-If the operating parts are in lap position, what happens when another reduction is made?

A. The pressure in the brake pipe below the piston becomes less than the auxiliary reservoir pressure above the piston, causing the piston to move down until stopped by the graduating stem, pulling the graduating valve away from its seat, and allowing air from the auxiliary reservoir to flow to the brake cylinder, until the auxiliary reservoir pressure is enough less brake-pipe pressure to force the piston and graduating valve to lap position. (Art. 3.)

46. Q-What limit is there to a graduated application?

than

A. It can be continued until the auxiliary reservoir and brake cylinder pressures become equalized. (Art. 3.)

47. Q.-What is a partial application?

A.—Any service application of the brakes less than a full-service applica tion. (Art. 3.)

48. Q-How many ways can the brakes be released after an application,

and what are they?

A. There are two ways; namely, increasing the pressure in the pipe above that in the auxiliary reservoir, or reducing the pressure auxiliary reservoir below that in the brake pipe. (Art. 3.)

brake

in the

49. Q-What do the operating parts of the triple valve do in either case,

and what connections are made?

A.—The operating parts are moved upward by the greater brake-pipe pressure below the piston, the piston seating against the lower end of the slide valve bush. Connection is then made between the brake cylinder and the atmosphere, allowing the air in the brake cylinder to escape; another

con

nection is made between the brake pipe and the auxiliary reservoir, allowing

the pressure to become equal on each side of the piston. (Art. 3.)

50. Q. When is it necessary to reduce the auxiliary reservoir pressure to release brakes?

A. Only at times when they cannot be released by the engineer. (Art. 3.) 51. Q.-What is the emergency position?

A. It is the position that the operating parts assume during an emergency application of the brakes, when it is desired to stop in the shortest possible distance, to avoid a collision or to save life. (Art. 3.)

52. Q. How is it brought about?

A.

53.

By a sudden reduction of brake-pipe pressure. (Art. 3.)

Q.-Describe the movement of the operating parts following an emergency reduction.

A. The rapidly decreasing brake-pipe pressure causes such a difference in pressure on both sides of the piston that it, together with the slide valve and graduating valve, is forced downward quickly the full distance of its travel, compressing the graduating spring and opening the emergency port in the slide valve seat, thus forming direct communication between the auxiliary reservoir and the brake cylinder, causing them to equalize quickly and to give the highest possible braking pressure. (Art. 3.)

54. Q.-How long do the operating parts remain in this position?

A. Until the brakes are released.

(Art. 3.)

55. Q.-What part has the graduating valve to do in an emergency application?

A. No part whatever. (Art. 3.)

56.

Q.-How are the brakes released after an emergency application?

A. In the same manner as after a service application; namely, by restoring the air in the brake pipe until its pressure is enough greater than the equalized auxiliary reservoir and brake cylinder pressure to move the parts to release position. (Art. 3.)

57.

Q-Does it take as long to release after an emergency as after a service application: Why?

A. It takes much longer to release the brakes after an emergency application than after a service application on account of the brake-pipe pressure having been exhausted, and therefore having to build it up from atmospheric to the pressure of equalization before the triple pistons can be moved to release position. (Art. 3.)

58. Q.-How can the operating parts be made to go to the emergency position after a full-service application?

A. By reducing the brake-pipe pressure a sufficient amount below the pressure of equalization of the auxiliary reservoir and the brake cylinder to cause the higher pressure above the piston to compress the graduating spring and move the parts to emergency position. (Art. 3.)

59. Q.-What results when this is done?

A. It results in a waste of air and a longer time to release the brakes. (Art. 3.)

60. Q.-How many sizes of plain triple valves are now in common use, and what are they called?

A.-There are two sizes, called the F-1 and F-2. (Art. 4.)

61. Q.-Why is it necessary to have different sizes of triple valves?

A. In order to accommodate the different volumes of air that have to be handled with the different sizes of brake cylinders and auxiliary reservoirs required for the different weights of locomotives. (Art. 4.)

62. Q.-How do you tell the difference between the plain triple valves? A. By the letters F-1 or F-2 on the side of the body of the triple valve, and also by the F-2 valve being the larger. (Art. 4.)

63. Q.-with what sizes of cylinders are they used?

A.-The F-1 triple valve is used with all 8- and 10-inch driver-brake cylinaers and 8- and 10-inch freight or switch engine tender-brake cylinders. The F-2 triple valve is used with all 12-, 14- and 16-inch driver-brake cylinders, and 12- and 14-inch freight and switch engine tender-brake cylinders. (Art. 4.)

The illustration shows a car which turned over in the middle of the train and rolled into the river, stopping right side up, without doing any further damage. The car was loaded with ties.