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-glass, 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 classification 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.