Rail Roading's BIG POWER!

Locomotives are railroading’s most potent and popular sym-
bols. The major types that have been used in North America are
steam (now confined to museums, tourist lines, and the occasional
mainline excursion), diesel-electric (the standard of the industry),
and straight electric (always a tiny minority).

Steam locomotives burn coal, oil, or (in early days) wood in a
firebox attached to the boiler. Hot gases from the fire pass forward
through tubes called flues inside the boiler, which contains
water. The gases heat the water, turning it to steam. By
opening the throttle, the engineer admits steam to the
dry pipe, which takes it to the two valve chests (one
on each side). Moving back and forth according to the
engineer’s setting of the valve gear with the “reverse le-
ver,” the valves admit steam to the cylinders so the steam
can push the pistons as it expands. The piston rods are
linked to main rods, which are connected to side rods,
which are attached to the driving wheels. After the steam
has done its work, it exhausts through the smokebox and
out the smokestack, pulling the hot, smoky gases from
the flues with it in the familiar chuff-chuff cadence.

The major locomotive builders were Baldwin, Amer-
ican (Alco), Lima, and several railroads themselves.
Diesel-electric locomotives have a large diesel en-
gine, or prime mover, which turns an alternator or gen-
erator, which ultimately produces a D.C. electric output.
On a D.C. locomotive, that power is regulated and sent
to axle-mounted electric traction motors. On an A.C.
locomotive, a further step is required. An inverter takes
the D.C. output from the alternator and inverts it to
three-phase A.C., which in turn feeds the electric trac-
tion motors directly. A.C. has advantages because the
traction motors can be of simpler design and main-
tenance, as well as of lighter weight. Much of the
space inside a diesel locomotive’s long hood is oc-
cupied by auxiliary items such as radiators, blowers,
and dynamic brake equipment, as well as an air
compressor, and associated equipment.

http://fossie09.hobbyshop.hop.clickbank.net/

Diesel (and electric) wheel arrangements are
expressed in terms of axles, not wheels. “A” indi-
cates a single powered axle, “B” means two togeth-
er, “C” is three, etc. Non-powered axles are indi-
cated as numbers. A handful of old A1A-A1A units
remain, but virtually every locomotive today has all
axles powered and is either a B-B (two 2-axle trucks)
or C-C (two 3-axle trucks, as in the diagram).
Today’s major builders are Electro-Motive Diesel
and General Electric. Formerly, General Motors, Alco,
Baldwin, Fairbanks-Morse, and Lima also built them.
Electric locomotives generally draw current from a
third rail or overhead wires via roof-mounted panto-
graphs, modify it, and use it in their traction motors. They
share many advantages with diesels, but are not as flexible because
they can’t operate bey­ond their power supply.
Typical of modern power roaming the rails, a new Electro-Motive
Diesel 4,300-hp BNSF Railway SD70ACe leads a westbound coal
train at Buda, Ill., on June 29, 2008. Tr ains : Tom Danneman

http://fossie09.hobbyshop.hop.clickbank.net/