Schaufelradmaschine der Great Eastern

1858 · Oscillating Paddle Engine · Work 178 of 1,871

Schaufelradmaschine der Great Eastern, 1858, Oscillating Paddle Engine

The oscillating paddle engine of the Great Eastern inside her engine room, four enormous cylinders rocking on trunnions, connecting rods reaching a single crankshaft, gratings and ladders around the machinery.

What it was used for
The Great Eastern had two independent propulsion plants with separate boilers. John Scott Russell & Co.'s oscillating paddle engines drove wheels 56 feet in diameter: four cylinders of 6 feet 2 inches bore and 14 feet stroke. Quite separately, the screw engine by James Watt & Co., built at the Soho Foundry in Smethwick in 1857, worked four cylinders of 84 inches bore and 4 feet stroke on a four-bladed screw 24 feet across. Ten boilers served both plants; Shipping Wonders of the World gives 551 tons of coal a day. Lloyd's Register Foundation explains the double installation by Brunel's doubt that screw propulsion, still new, could move a ship of this size alone.
What was new
The scale was new, not the principle: oscillating engines and screws both already existed. The Science Museum Group states that the paddle engines produced double the power of any previous marine engine. How much that was, the sources tell differently: 3,150 horsepower from the Science Museum Group (indicated) and Lloyd's Register Foundation alike, 3,411 from Shipping Wonders of the World, 2,600 from the contemporary Ocean Steamships of 1891. The weight is unclear too — 836 tons for the whole installation in Shipping Wonders of the World against 90 tons per pair of engines at the Science Museum Group. The barb: the explosion of 9 September 1859 struck precisely this plant, whose boilers lacked safety valves; the screw engine, meant as the insurance, had boilers of its own; six firemen died.

Further reading