16. Q. How many fields in this generator?

A. Two.

17. Q. What style field is used?

A. Compound wound.

18. Q. What kind of wire is used on these fields?

A. Deltabeston wire.

19. Q. Why is Deltabeston wire used in preference to cotton-covered wire?

A. So that it cannot be injured by short circuits, for if a short circuit occurs and afterwards is removed there is no danger done to the insulation on this make of wire.

20. Q. Where are the fields located?

A. One on each side of the dynamo.

21. Q. Why?

A. So that they cannot be injured by waste oil from the ball bearing, or by water or snow.

22. Q. How should ball bearing on dynamo end be lubricated?

A. By removing oil plug in frame just back of dynamo and introducing cylinder oil.

23. Q. Is it necessary to remove the top carbon holder from the lamp to remove reflector from case?

A. No.

24. Q. Why not?

A. Because there is no top guide to the carbon, as the carbon is guided by the clutches.

25. Q. How many levers are there in the lamp?

A. Only one.

26. Q. What regulation should be given to top lever spring No. 308 on lamp?

A. Top lever spring No. 308 should be adjusted as loose as possible and not have light go out standing still.

27. Q. If this spring was tightened until the light burned steady when the locomotive was at rest, what might occur when engine was running high speed?

A. It might cause the light to dim down.

28. Q. Is there anything else that would cause the light to dim down when the engine is running fast?

A. If the clutches should be used until the sharp edge that grips the carbon have become worn smooth or round they would allow the carbon to feed too fast and the light would burn dim.

29. Q. If the light burns satisfactory while engine is in motion, but goes out when engine is stopped, where would you find the trouble?

A. This trouble is most always found to be caused by the top lever springs No. 308 being too weak; or, an imperfect carbon, though if the dash pot plunger has become corroded until it sticks in the dash pot, the light will act the same as if the tension spring was too weak.

30. Q. Is it possible to apply the bottom electrode holder wrong?

A. No

31. Q. Why not?

A. For the reason that its support is on a center line with the electrode and the holder can be turned in any direction and the electrode is held central with the top carbon.

32. Q. What would you do if you had no bottom electrode holder?

A. Place a piece of 5/8-inch carbon in the hole through the bottom bracket having top end in focal point of reflector and tighten with set-screw; as this carbon would burn away the light would be raised and it would therefore be necessary to raise the carbon about every hour, as the carbon would burn away about one-half inch per hour.

=GENERAL QUESTIONS AND ANSWERS ON ELECTRIC HEADLIGHTS=

33. Q. Describe the pa.s.sage of the current through the lamp and tell how arc light is formed?

A. It enters the lamp at the binding posts with the large hole, then to the top carbon holder, carbon, then into the electrode and holder; from there to the solenoid and back to the dynamo, leaving the lamp at the binding post with the small hole in it. The magnetism from the current while pa.s.sing through the solenoid attracts magnet in a downward motion, and it in turn, by the levers on the lamp, separate the carbon from the copper, thereby forming the arc.

34. Q. Why should sandpaper be used to smooth commutator instead of emery cloth?

A. In using emery paper a piece of emery might lodge in the grooves between the commutator segments, and being a conductor of electricity, causes short. Will also get embedded in the copper and cut the brushes.

Sand will not do this.

35. Q. State how you would go about to focus a lamp?

A. (1) Would adjust back of reflector so front edge of reflector would be parallel with front edge of case. (2) Adjust lamp to have point of copper electrode as near the center of reflector as possible with carbons as near the center of chimney hole as you can set them. (3) Have the locomotive on straight track. Now move the base of the lamp around until you get a parallel beam of white light straight down the center of the track, then tighten lamp down.

36. Q. If the light throws shadows upon the track, is it properly focused?

A. No.

37. Q. If the light is properly focused, that is, if the rays are leaving the reflector in parallel lines, but the light does not strike the center of the track, what should be done?

A. When the light rays are thrown out in parallel lines and they do not strike the center of the track, it denotes that the headlight case is not set straight with the engine, and the entire case on baseboard must be shifted until the shaft of light strikes the track as desired.

38. Q. What can you do to insure a good and unfailing light for the entire trip?

A. By carefully inspecting the entire equipment before departing on each trip and know that there are no wires with insulation chafed or worn off; that all screws and connections are tight; commutator clean; brushes set in brush holder in the proper manner; carbon in lamp of sufficient length to complete trip; copper electrode cleaned off and oil in both bearings.

39. Q. Why would you not fill the main oil cellar full of oil?