low-pressure cylinders compress air which then passes through a cooling
system to a high-pressure cylinder that compresses it still further before
feeding the air to the main reservoir. This reservoir is kept at a pressure
of 125 to 140 pounds.
Both fuel and water tanks are carried on a diesel-electric locomotive.
The fuel tank, usually suspended beneath the underframe between trucks,
contains fuel oil for operating the diesel engine. Note the parts numbered
35 and 36 on figure 2.1.
A water-expansion tank containing water for
cooling the engine is located at the highest point in the engine-cooling
water system, the part numbered 19 on figure 2.1. This system is designed
to carry away and disperse the excess heat generated in the engine.
The main function of the trucks is to provide a connection between the
axles and wheels and the locomotive itself.
The trucks must carry the
weight of the locomotive superstructure and distribute it through the wheels
to the rails. They also absorb lateral thrusts and ride over uneven rails
without excessively tilting and swaying the locomotive.
The trucks also
Army diesel-electric locomotives have either two 6-wheel swivel 3-
motor trucks or two 4-wheel swivel 2-motor trucks. Figure 2.5 shows a 4-
wheel swivel 2-motor truck used on the 0-4-4-0 diesel-electric locomotive.
The main difference between the 4-wheel and the 6-wheel truck is that the
weight of the locomotive is distributed over a wider surface by a 6-wheel
one; therefore, it has a greater working surface on the rails, giving the
locomotive more tractive effort or pulling power.
A diesel-electric locomotive is made up of many complex parts.
internal combustion diesel engine burns diesel fuel oil ignited by the heat
of compressed air within a cylinder, a process known as compression
ignition. The main generator is connected to the engine, and its mechanical
energy output turns the generator to produce the electric current needed to
power the traction motors that turn the locomotive's wheels.