Arthur Woolf - Woolf's Compound Engine

Woolf's Compound Engine

Woolf's engine was a parallel compound engine with two cylinders in which the steam worked in succession. These were both coupled to the same end of the beam of the engine. The operation of the engine can be described as being a high-pressure cylinder of Trevithick's high-pressure simple expansion engine, followed by a condensing cylinder of Watt's design. Woolf had worked as an engine erector for Hornblower and was familiar with his earlier work on compound engines. As a Cornishman, he was also familiar with Trevithick and his newly developed high-pressure 'puffer' engines that were then entering service. He recognised that, even with the new principle of expansion, the exhaust from a Trevithick engine was still of a comparable pressure to the inlet pressure of a Watt engine. From this step, it was a relatively simple matter to couple the two together.

For most uses, the cylinders of the engine were double-acting. Opposing sides of the high- and low-pressure cylinders were cross-connected to each other. Where engines were used for pumping, Woolf engines were also built with paired single-acting cylinders.

Examples of Woolf compound rotative beam engines may be seen at Abbey Pumping Station, Blagdon Lake, Claymills Pumping Station and the Western Springs Pumphouse, now part of the Museum of Transport and Technology Auckland, New Zealand.

Also in many parts of the world are engines built to his designs. He was held in very high regard by French, German, Belgian and Dutch steam engineers, who all made liberal use of his designs.