Model showing operation of Stephenson Valve Gear.

This picture shows a model of the machinery known as "Stevenson". A valve gear is a part of a steam engine. It is the mechanism that operates the inlet and exhaust valves to let steam in and out of the cylinder at the correct points of the cycle. It is also known as the "motion".<br /> <br /> The Stevenson Valve Gear was first invented in 1841 by William Howe and William Williams, employees in the Stevenson Locomotive Works. This was more efficient than previous valve gears and made reversing easier. <br /> <br /> This was used in steam locomotives, steam lorries and steam cars. <br /> <br /> <br /> This image may be available to purchase.<br /> For further information about purchasing and prices please email<br /> <a href="mailto: photographic.archive@highlifehighland.com">Highland Photographic Archive</a><br />