One of the most fascinating engines to watch in action is Galloway’s non-dead centre engine pictured here running as built by P Wilson.

The engine was patented in 1838 by Elijah Galloway and was an attempt to build an engine with the advantages of self starting in any position with the simplicity of a single crank. Anthony Mount designed a model version which was serialized in Engineering In Miniature from August 2001 to June 2002. Drawings and castings are available.

There are two vertical cylinders connected by a connecting rod of triangular configuration to a single crank placed between the cylinders. As the pistons are 90 degrees out of phase to each other there is never a position where the piston of at least one cylinder cannot bear upon the crank.

During each revolution the top beam of the connecting rod goes from horizontal to an angle as the piston rods are in a fixed plane some means of extending the beam is required. This is accomplished by having sliding bearings in the crossheads.

To keep the centre of the connecting rod beam in a straight vertical line, a motion beam is connected to the centre of the connecting rod beam and goes via another sliding bearing housed in brackets to the side of one cylinder to another tie rod which goes back to the brackets. This sort of ‘parallel motion’ constrains the connecting rod into a straight vertical line.

Having a lever going up and down to the side of the engine it was a convenient place to put an air pump driven by the beam.

The engine was designed for marine use, driving paddles and for land us as a stationary engine It was reinvented by Bernay’s in 1874 and again in 1887 by Fleming and Ferguson, who used it as a marine engine driving screws. In this instance the cylinders were inverted. It was licensed by Fleming and Ferguson to Musgrave’s who built as a compound, triple and quadruple expansion mill engine. A small compound has survived and is in the care of The Northern Mill Engine Society at Bolton.

P Wilson

GALLOWAY’S NON- DEAD CENTRE ENGINE

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