47. Q. Why cannot a standard or house type of lamp be successfully used in the reflector?

A. Because the fillament or light-giving wire inside the bulb is not sufficiently compact or concentrated to reflect the light in the form of a beam. The voltage of the house lamp is also too high to be used on a locomotive installation.

48. Q. How is the lamp held in place in the reflector?

A. By the usual socket, into which the lamp screws. The socket is a part of the focusing device, one type of which holds the lamp in a horizontal position, while in the other the lamp is held vertically or upright.

49. Q. Before turning the steam into the turbine, what precautions should be observed?

A. The turbo-generator should be lubricated by a small amount of black or engine oil, placed in the cup on the turbine or steam end. On the generator end, the oil should be maintained within one-half inch of the top of the hinge-cover cup; using black oil. The drainage of the steam end is cared for automatically by a three-eighth inch drain pipe without a valve. The pipe should be kept open.

50. Q. How do you proceed when you wish to use the light?

A. Open the globe valve in the steam pipe to the turbo-generator, at least two turns. The water-gla.s.s, steam and air gauge lamps in the cab, and the number indicator lamp in the headlight case should light up as soon as the turbo-generator reaches full speed. A double-throw knife switch in the cab controls the headlight. In one position the switch gives the full brilliancy of the headlight. The opposite or "dimmer"

position reduces the brilliancy about one-half. When the switch bar is in neither position the headlight is entirely out, and only the number lamp is burning. The cla.s.sification lamp, lubricator and order or reading lamp, are controlled by a small switch on the socket of each lamp.

51. Q. For what purpose is the dimmer, and how does it operate?

A. It is to reduce the intensity of the headlight when locomotive is in yards or around stations. It consists of a small resistance tube in the wiring circuit, and with the cab switch in dimmer position, a portion of the current is converted into heat instead of light.

52. Q. How is an incandescent headlight focussed?

A. By moving the lamp in its position in the reflector until the most brilliant and compact beam of light is obtained. If the beam does not strike the track centrally, or as high or low, the headlight case must be moved on its platform until the beam is properly directed. It is often necessary to raise the front or back of the case by shimming between the case and its platform in order to direct the beam of light the proper distance ahead of the locomotive.

53. Q. What provision is made for moving or focussing the lamp in the reflector?

A. When the lamp is mounted horizontally there are thumb screws by which the lamp may be moved sidewise, up and down, and forward and backward.

This mounting is called the "micrometer" device, because of the accuracy of adjustment. With the vertical mounting, a flat head thumb screw at the base of the lamp support releases the ball joint so that the lamp may be easily moved sidewise or forward and backward. To raise or lower the lamp, the thumb screw higher on the lamp stand must be loosened.

54. Q. What causes a "black spot" in the illumination ahead of the locomotive?

A. The lamp is out of focus, being too far ahead or back of the proper position in the reflector.

55. Q. How would you remedy the following possible defects?

A. (a) =All lamps fail to burn.= If turbine is not running the wrong steam valve in the cab may have been opened, or there may be a second valve, closed, in the steam pipe. The screen on the governor valve in the turbine may be clogged. Remove bra.s.s cap at top of turbine and unscrew screen or strainer-cap.

(b) =Turbo-generator runs, but no lights.= Wires may be "short-circuited" (crossed) which will cause brushes to spark badly, and turbo-generator to pull hard. The "short" can usually be found by an occasional sparking or smoke at the point of trouble. Separate and protect wires when short is found. The brushes may be "c.o.c.ked up" as left by some repair man. Open the dynamo door and see that the brushes bear on the copper commutator. A wire may be loose at the dynamo binding posts (which may be seen when the dynamo door is open), or at the main switch in the cab. A main wire may have broken. (All locomotives are not equipped with fuse plugs.) A fuse plug may have become loose or burnt out. Replace with new fuse plugs or break an incandescent lamp and twist the leads in the base together, when the base may be screwed into the fuse plug socket, answering the purpose of a fuse plug, temporarily.

(c) =Headlight fails to burn.= Examine the wires between cab switch and head lamp for breaks or disconnections. Examine fuse plugs (which are sometimes in head lamp circuit only) and proceed as in (b) if trouble is found there. Headlight bulb may not be screwed in far enough to make contact in the socket, as the lock-sockets provided to prevent lamps loosening cause lamp to screw in hard. Lamp may have broken fillament.

Replace with proper type of lamp or use a cab lamp.

(d) =Lamps burn dim.= Steam valve not open wide enough. Boiler pressure too low. Brushes sparking badly on commutator of dynamo--due to poor contact. Governor or steam-valve of turbine improperly adjusted.

(e) =Lamps burn too brightly.= Improper turbine regulation. Throttle the steam valve in cab until lamps are reduced to proper brilliancy. Report all irregularities on arriving at terminal.

=SCHROEDER HEADLIGHT=

1. Q. What is the speed of a Schroeder headlight dynamo?

A. About 2,800 revolutions per minute.

2. Q. How is the speed altered?

A. By a governor in the turbine.

3. Q. How would you proceed to change the speed of the governor?

A. Remove cover No. 3 and loosen lock nut No. 14 and turn nut No. 13 to the right to increase the speed and to the left to decrease it.

4. Q. What is a short circuit?

A. A connection between the positive and negative wires of the dynamo without any resistance between.

5. Q. How does the dynamo act when short-circuited?

A. It will run very slowly as it is under a heavy strain.

6. Q. What would be the result if left to run under that strain?

A. The armature or fields would burn out.

7. Q. What would you do if a short circuit developed while on the road?

A. Shut the steam off and remove the positive or right-hand wire of the cab circuit from the dynamo, start up and see if the headlight went to work properly; if not, replace the cab wire and remove the positive or left-hand wire and see if the cab lights burned properly. If such was the case, let it run, using the small incandescent light in the case for a headlight and report it at the roundhouse.

8. Q. What is a volt?

A. The unit of pressure of electricity.

9. Q. What is an ampere?

A. The unit of quant.i.ty of electricity.

10. Q. What is the proper voltage of a Schroeder headlight?

A. About 28 volts.

11. Q. Can a person be injured by that voltage?

A. No.

12. Q. What is the proper amperage of a Schroeder headlight?