Joanne Thoms’
DOUBLE TANGYE
STEAM ENGINE

The first design published for a model Double Tangye Engine was by William Ballantyne in 1933. It was adapted and popularized by Edgar T Westbury in 1954. Jo Thoms’ model was finished just in time for the 2015 Guildford Rally.

The prototype of this engine was the product of a business which played a significant part in engineering development  from the beginning of the industrial era. This particular type of engine was produced around the turn of the century and was one of the most advanced designs in its class for driving factory machinery and similar uses. It was not a very large engine as most industrial power requirements in those days were modest. This small size makes it convenient for scaling down to make an accurate model with no sacrifice of detail.

Although it had two cylinders of equal size, they are of the ‘simple’ type, as distinct from ‘compound’ or two-stage expansion type and so it was not known as a ‘twin-cylinder’ engine, but as a ‘double’ engine, because it consists virtually of two complete engines, arranged right- and left-handed as mirror counterparts of each other, each with its own valve gear.