=The Steam Chest= contains the valve, and can be on either side of
cylinder as may best suit the style of engine. Steam is admitted into
the steam chest, and passes into the cylinder by the action of the
valve.
Many engine builders cast cylinder and steam chest in one piece, while
others cast them separately and bolt them together. The only advantage
of the former over the latter is the absence of one less joint to keep
packed.
[Illustration: Steam Chest and Plain Slide Valve.]
The steam ports are the two openings through which the steam is
admitted to the cylinder.
The exhaust port is the opening through which the exhaust or waste
steam passes out of the cylinder.