Locomotive Propulsion and Braking Systems

(5) GE 44 Ton Locomotive.

300 hp

27,000 lbs. starting tractive effort at 30 % adhesion

9,000 lbs. continuous tractive effort at 10 mph

Max. operating speed - 20 mph

Min. curve radius - 50 ft.

Weight - 88,000 lbs.

b. Locomotive Propulsion and Braking Systems.

(1) Power Generation System. The Navy's equipment fleet for the movement of

railcars consists of diesel-electric locomotives, along with a few car movers at select locations.

Diesel-electric locomotives use diesel engines coupled to a generator or alternator to produce dc

current that powers dc traction motors located on the locomotives' axles. Locomotives are both

one- and two-diesel engine designs. Some can only be operated independently, and others can be

operated together in multiple unit (MU) service. In MU service, the coupled units are all

controlled by only one of the units. Some units also have a road/switch capability that changes

the operating characteristics of the unit depending on the use. When locomotives are

rehabilitated, current policy is to standardize all locomotives to the 26-L series brake system, or

better, and the AAR control stand. See Figures 2-14 and 2-15 for pictures of a typical 26-L series

brake and AAR control stand.

(2) Locomotive Traction system. Diesel-electric engines are controlled by a governor

that maintains a constant engine speed and a load regulator that maintains constant power output

for each power setting selected by the operator. The actual tractive effort transferred to the rail

may be limited to less than the power setting by reduced adhesion due to such factors as

contaminated rail (grease, grass, water, etc.) and lack of sand applied to the rail. Wheel slip will

occur in these cases, and on certain locomotives power output is automatically reduced for

predefined periods of time until wheel slip is corrected.

(3) Locomotive Brake system. Each locomotive has an independent and automatic air

brake valve and a mechanically operated hand brake.

The independent brake controls only the brake cylinders on the locomotive. It is the primary way

of reducing the locomotive speed when the locomotive is being operated with no cars.

The automatic brake valve controls both the car(s) and locomotive(s) brakes and is the primary

means of reducing train speed. The locomotive brakes are bailed off, (released), by the operator

until shortly before the complete stop.

The hand brake is used to secure the locomotive any time it is left unattended or attempts to stop

the locomotive in an emergency if the air brakes fail to function.

Navy locomotives are equipped with various brake systems (6RL, 24RL, 26L series, etc.) See

Figure 2-16 for a schematic of a typical series 26-L locomotive air brake system.

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