46.  Q. What type of incandescent lamp is used in the reflector?

A. A low voltage, gas filled bulb, containing a very compact or concentrated fillament.

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-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.