Compound engine

The several sets of blades in a single turbine are perhaps better thought of as similar in principle to the uniflow steam engine than to compounding.

[1] Three stage or triple expansion reciprocating steam engines, with three cylinders of increasing bore in line, were quite popular for steamship propulsion.

"Doctor" Alexander Carnegie Kirk, experimentally fitted his first triple expansion engine to a ship called Propontis in 1874.

In 1881, Kirk installed a refined version of his engine in SS Aberdeen on Clydeside, Scotland.

[2] This ship proved the advantages of power and economy of the new engine, in commercial service between the United Kingdom and the Far East.

Several classes of steam locomotive have existed in both simple and compound form, most commonly when locomotives originally built as compound were converted to simple in order to gain power at the expense of efficiency, for example the majority of the NZR X class.

Examples include: Deutz 1879, Forest-Gallice 1888, Connelly 1888, Diesel 1897, Bales 1897, Babled 1903, Butler 1904, Eisenhuth 1904–7, Abbot 1910.

[6] The concept was "re-invented" and patented as the five-stroke engine in 2000 by Gerhard Schmitz, which was experimented with by Ilmor.