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A single uncoupled rail vehicle is not technically a train, but is usually referred to as
such for signalling reasons.
The first trains were rope-hauled or pulled by horses, but from the early 19th century,
almost all were powered by s team engines. From the 1920s onwards they began to be
replaced by diesel (and some petrol) and electric-hauled trains. Most countries had replaced
steam trains for day-to-day use, by the 1970s. A few countries , most notably the People's
Republic of China where coal is in cheap and plentiful s upply, s till use steam trains , but this
is being gradually phased out. His torical s team trains still run in many other countries, for
the leis ure and enthusiast market.
Modern locomotives and powered coaches may have a diesel engine and/or electric
motors. On the most common form of diesel train, the diesel engine drives a generator
which provides power for electric motors which turn the wheels (diesel-electric), or in some
cases the power from the diesel engine is transferred to the wheels by hydraulic means
(diesel-hydraulic). Mechanical transmission, like that in an automobile, is used on a few
trains, and shunting engines (switchers). However diesel powered trains are expensive to
run. Where a railway line has sufficient traffic to justify the expense, it may be electrified, to
allow the running of electric powered trains, which are cheap to run, and have higher
performance than diesel trains.
For straight electric trains the power to run the electric motors is generated at a power
station and supplied to the train by some form of distribution system. There are two
common means of doing this, current may be supplied to the train by overhead wires, or by
a third rail system. Funiculars do not have an engine within the vehicle, but are pulled on a
cable by a motor in the station.
Passenger trains have passenger cars. Passenger trains travel between stations; the
distance between stations may vary from under 1 km to much more.
Long-distance trains, sometimes crossing several countries, may have a dining or
restaurant car; they may also have sleeping cars, but not in the case of high-speed rail, these
arrive at their destination before the night falls and are in competition with airplanes in
speed. Very long distance trains such as those on the Trans-Siberian railway are usually not
high-speed.
Ve ry fast trains sometimes tilt.
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