Bing’s twin-cylinder engine worked with hot air

Bing’s no. 135/22 puts two horizontal cylinders beside a tall firebox and chimney. A red flywheel and the exposed connecting rods make the mechanism easy to follow in the museum photographs.

The working medium in a hot-air engine is air, heated and cooled to produce changes in pressure. Those changes move a piston, while the flywheel carries the mechanism through the rest of its cycle. Heat is supplied from outside the working cylinders.

On this example, the metal firebox is pressed to resemble brickwork. The wooden base is still visible; our museum record notes that it should have a tiled covering. It also records a related single-cylinder version, no. 135/21.

The two cylinders and their linkages are a useful detail to look for when comparing surviving Bing hot-air engines.