Coal-fired model of this unusual prototype roller by Wallis & Steevens of Basingstoke, England. The original engines were very compact, weighing only 3 tons. Of the twenty originally built, 6 survive in preservation. The distinctive diagonal boiler was intended to prevent low water level damaging the firebox when in less than skilled hands. By the time the firebox crown was exposed, there can only have been about a pint of water in the engine - as a further belt and braces measure, the full size engines had a firebox that could be unbolted from the rest of the boiler for quick replacement!
Silver-soldered copper boiler, working pressure 90psi, feed by injector and mechanical pump driven from the second shaft - an auxiliary hand pump is fitted on the footplate.
The single cylinder engine has a slide valve actuated by Stephenson's reversing gear - the flywheel is between the hornplates, along with the single speed road gear and differential. The cylinder block is fitted with drain cocks.
A well made engine, it runs well.
Length 35 inches
Height 24 inches
Weight approx 150 pounds