TM 55-203
roded terminals which prevent the delivery of sufficient
coated When this active material ,is used up, the lamp
current under heavy load; cracked or broken cases with
will blink on and off. At the end of life, the lamps usually
resultant loss of electrolyte, short circuits within the
show a dense -blackening at the ends Blinking of the
cells; worn out plates, chipping of active material;
lamps, failure to start, etc., are symptoms of some
freezing, sulphation; growth of positive plates; shrinkage
defect requiring attention, not necessarily the lamp tube
of negatives; and electrolyte below the tops of the plates
itself The fault may be in the starter or the ballast or
Terminals and cable connections must be kept clean of
other parts of the system.
corrosion and electrolyte maintained at level adequate
to cover the plates. Defective batteries will be replaced
c. Maintenance Procedures.
with new or rebuilt ones.
(1) If a fluorescent lamp fails to light. Check
(1) Alkaline type. The alkaline cells (fig 10-
to see that it is properly seated in the sockets. If it is,
4) consist of nickel-plated steel grids containing tubes or
check the starter If defective, replace the starter. If the
pockets to hold the active materials of nickel and iron
lamp still falls to light, test the tube in another circuit; if
oxides. The electrolyte for the nickel-iron cells is a
defective, put in a new lamp tube.
solution of potassium hydroxide, more familiarly called
caustic potash.
(2) If a lamp is slow at starting. Check the
starter switch and replace if defective. Low line voltage
(2) Lead type. In this type, the plates are
and an improper ballast may also cause sluggish
lead and lead oxide immersed in an electrolyte of dilute
starting.
sulphuric acid (fig 10-5).
(3) If only the ends of a lamp light. This
(3) Nickel cadmium type.
The nickel
indicates a short circuit in the starter, which should be
cadmium battery (fig 10-6 and 10-7) consists of 10 cells,
replaced. Starters long in service frequently fail in this
with intertray connectors and terminal adapters for SAE
manner. This trouble should be promptly corrected or
positive and negative cables, contained in two five-cell
the circuit inactivated by removal of the lamp or starter,
crates. This is a 12-volt battery, and lS used in the
since a lamp tube glowing only at the ends will shortly
mechanically activated refrigerator cars discussed in
burn out.
(4) If a lamp blinks on and off. This usually
10-3. Lighting Fixtures
indicates failure of the lamp. The starter should be
replaced as a test, if blinking continues, then renew the
a. General. Railway passenger cars are lighted
temperatures, and cold drafts may also cause difficulties
with fluorescent and/or incandescent lamps.
The
of this nature. Blinking lamps should be corrected
maintenance problems of fluorescent lights are
promptly, as this condition will ruin both the lamps and
somewhat more complicated than those of incandescent
the starter.
lamps.
Regular cleaning of fixtures, glassware
reflecting surfaces, and lamp tubes is necessary. Lamp
d.
Incandescent Lamps.
The principal
replacement is an important service function.
maintenance required for these lamps is regular
cleaning and the replacement of blackened or burned
b. Fluorescent Lamps. These do not screw into
out lamp bulbs. Regular inspection of circuits should be
sockets like incandescent lamps. There is a lamp
made for cracked or broken reflectors, damaged
holder at each end of the unit specially designed to hold
sockets,
frayed
insulation,
faulty switches, etc.
the lamp in contact. Lamp tubes are removed or
Preventive maintenance includes replacement of
inserted by a quarter turn in these holders. The tube
damaged parts or adequate repairs and cleanliness.
should be inserted gently to avoid twisting the lamp
Insulation in particular is affected by dirt, oil, and
base, but firmly enough to lock it into contact so it will
moisture, which cause failures.
not be jarred loose by vibration. The average life varies
with the size. The 14-watt lamp most commonly used
on trains is rated at 1,500 hours Normal failure of
fluorescent lamps is caused by the gradual dissipation of
the material with which the electrodes at either end are
10-5
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