SS Perth main engine

The main engine from SS Perth  was manufactured in 1914 by Baxter & McKie of Glasgow. It is a steam compound-reversing engine that was used continuously until 1970 when it was replaced with an English electric diesel engine. The old steam engine was left aboard until 1987 when the superstructure and engine were removed.

The term ‘compound’ refers to an engine with more than one cylinder, where the steam is expanded in successive stages to maximise the energy of the steam. The SS Perth engine has two cylinders where steam is admitted into the smaller cylinder (high pressure cylinder) and exhausted into the larger cylinder (low pressure cylinder) where further expansion takes place before the steam exhausts.

The boilers were also built in Glasgow by McKie & Baxter. Each boiler had a diameter of 6 feet 9 inches and stood 8 feet 6 inches high. Coal was burnt in the furnace of the boiler to provide the energy (heat) to turn the fresh water into steam. The steam is then directed into the cylinders where the steam provides the pressure to drive the pistons. This engine was supplied with two return-tube single furnace marine boilers.

The ferry Perth running between Perth and South Perth in February 1915. 
Credit: State Library of Western Australia, BA1271/492-493