Central-valve high speed steam engine, working model, scale 1:4, sectioned through one cylinder and crank case, Willans and Robinson Limited, Rugby, Warwickshire, England, 1901

This is a working model, built in 1891, of a compound engine developed by Peter Willans in 1884. Willans' design employed two pairs of high and low pressure single-acting cylinders mounted on the same vertical shaft, with a shared central valve spindle for each pair to control the flow of steam. It also came as a triple-expansion design, with three cylinders (high, intermediate, and low pressure) each sharing a single valve spindle. THe advantages of this design were that it could run quietly and at high speeds. Connected to a Crompton dynamo, it was widely used to generate electricity.