How a Steam Loco Works
Here is a
picture of 35005 'Canadian
Pacific' in steam, yet if we could cut it in half -
this is what we will see...
This
is basically how a steam loco works;
- Coal
is shoveled in to the fire box
- There
is water around the firebox, so that warms up and turns
to steam
- There
is no escape for the steam so it has to stay in the
boiler.
- The
steam builds up as there is so much in there untill the
steam prressure reaches 250p.s.i (or around that
pressure) when the saftey valves blow.
- The
saftey valves let out any excess steam when it reaches a
set pressure, other wise to much pressure would lead to
explosion.
- The
regulator is given a nudge which will allow steam to the
cylinders.
- This
will push the valve in the cylinder across as far as it
will go.
- Because
of the way that the valve gear is aranged, it will stop
the steam from going into the cylinder any more (known as
cut off).
- The
wheels would have moved through 180 degrees.
- As
the wheels move, they move the gears, which will let
steam into the other side of the cylinder valve.
- The
steam will push the cylinder rod back the direction it
came and the cycle will start again.
- The
rods in the cylinders will be going backwards and
forwards.
- But
as the steam is being forced out of the cylinder at such
a speed it causes a draft.
- The
draft causes a suction which sucks air throught the grate
at the bottom of the fire.
- As
the air rushes throught the fire all the oxygen is used,
which keeps the fire alight
- So
the harder the loco forces steam out of the cylinders
(when working harder ie. up a hill, or when hauling a
heavy load) the harder the draft on the fire will be
causing it to burn hotter (couple of 100 degrees)
producing more steam for the job.
- Any
bits of burn or loose coal is suched up the chimney
because of the draft - this is why steam train smoke is
sometimes black.
- You
control the speed of the train by how much steam you
allow into the cylinders and how far you let the
cyclinder valves go every stroke.
- You
increese the steam production of a train by adding more
coal to incresse the temperature or by putting a greater
draft on the fire (with a control called the blower)
which will draw the fire harder and booting up the
temperature and steam production.
- The
Blower blasts a jets of steam up the chimney and creates
suction.
That is a
simple description of how steam locos work. The best book i've
come across that explains in detail so children or adults can
understand is 'The Railway Data File' by Blitz Editions
- ISBN 1-85605-499-3. Not only does it tell you about these
things, it explains about other railway related things.
For any further in depth info e-mail and
i'll try my best to answer.
stephen.newell@steamland.com
