Editing Compound steam engine (section)

===Multiple-expansion engines {{anchor|Multiple expansion engines|Triple-expansion steam engine}}===
[[File:Triple expansion engine animation.gif|thumb|Double-acting triple-expansion marine engine.<br/><small>High-pressure steam (red) passes through three stages, exhausting as low-pressure steam (blue) to the condenser</small>]]
It is a logical extension of the compound engine (described above) to split the expansion into yet more stages to increase efficiency. The result is the '''multiple-expansion engine'''. Such engines use either three or four expansion stages and are known as ''triple-'' and ''quadruple-expansion engines'' respectively. These engines use a series of [[Single- and double-acting cylinders|double-acting]] cylinders of progressively increasing diameter and/or stroke and hence volume. These cylinders are designed to divide the work into three or four equal portions, one for each expansion stage. The adjacent image shows an animation of a triple-expansion engine. The steam travels through the engine from left to right. The valve chest for each of the cylinders is to the left of the corresponding cylinder.