carbon and pivot pins, and removing any friction in the
(2) The main advantage of the system is its
pins or supports. Carbon is cleaned by releasing the
economy of operation and maintenance, since it
pressure on the carbons and then blowing the dirt out
employes only one generator for the train rather than
with an air hose, or moving the carbons up and down on
separate generators for each car.
their support rods by hand The pins may be cleaned by
polishing them with very fine emery paper; the pinholes
should be reamed to remove any foreign matter. Upon
disadvantages. In making up trains, it is necessary
reassembly, check all connections for tightness and
(unless the generator is on the locomotive) to have a car
with a generator at the head end. All cars must be
equipped with sufficient batteries to provide satisfactory
c. Pole Changer. To maintain the polarity of an
the power source.
axle generator, an automatic device called a pole
changer is used. This unit is provided in one of three
(4) Power is delivered to the cars by a three-
types: rotating, mechanical, or electrical.
wire trainline which serves to compensate for voltage
devices generally are a part of the commutator end
drop and to keep the same voltage at all lamp sockets
head and may be removed from the head for cleaning.
throughout the train. The line runs the length of the train
and has flexible connections between cars. Indicating
(1) Rotating type. This type shifts the
and control devices normally are located near the
brushes of the generator when the direction of axle
generator to facilitate control of the system.
rotation changes. On a two-pole generator, brushes
shift 180or through an angle equal to the pole pitch, on
c. Storage System. The power supply of the
a four-pole unit, they shift 90 The advantages of a
storage system consists of storage batteries carried with
rotating type of pole changer are that the continuity of
the individual cars, usually in a box ,under the car. The
box has a hinged door for access. The bottom of the
occur in the use of switches and contacts, and the
box generally is grated rather than solid to keep the
brushes can take a "lead." This is not possible in fixed
batteries cool A charging connection is provided for
charging the batteries at terminals during layover
periods As the battery voltage is reasonably constant
(2) Mechanical type. The mechanical type
during the normal discharge period of the battery, no
of pole changer consists of a reversing switch which is
auxiliary equipment or controls are employed. The size
mechanically operated by rotation of the armature shaft
of the batteries in the storage system is necessarily
and which opens and closes by rotation of the shaft In
larger than the batteries required with head-end or axle-
one direction or the other.
generator systems for the same load. The principal
advantages of the system are its simplicity and small
(3) Electrical type.
The electrical pole
investment cost. In older types of passenger cars where
changer employs a reversing switch, generally operated
lighting standards are low and no air conditioning is
by solenoids. This device is placed inside the car with
provided, the storage system may be used satisfactorily.
other electrical apparatus. The switch is thrown one way
However, the system is impractical for modern cars
or the other automatically, depending upon the direction
because of their increased loads and longer runs As the
of rotation of the generator armature.
batteries of a storage system cannot be charged while
the car is underway, it is necessary to have adequate
d. Storage Battery. The storage battery used in
capacity for the longest period of use and to schedule
electrical lighting in railway cars in an electrochemical
enough recharging time during layover periods.
device consisting of a number of cells connected in
series. It receives and stores electrical energy and
10-2. Electrical Equipment
delivers it to the circuits as needed. There are three
types of storage batteries in common use: the nickel-
iron alkaline, the lead acid, and the nickel-cadmium
a. General. The principal parts of electric lighting
types. Proper maintenance of storage batteries require
equipment for railway cars are the generator, generator
the carman to understand the factors that influence
regulator, lamp regulator, pole changer, storage
battery condition and life. Some of the conditions
batteries, and electrical fixtures.
The care and
encountered in servicing railway car battery installations
maintenance of this equipment is essentially a matter of
regular inspections and keeping it meticulously clean.
b. Regulators. Regulators should be checked
periodically. This inspection consists of cleaning the