jockey valve

Definitions

A manually-controlled auxiliary valve on the regulator of a steam engine to control smaller amounts of steam than can be managed by the main valve.

Examples

“Jockey-valves of locomotive regulators are small auxiliary ports which can be opened by a suitable movement of the regulator-handle, when it is desired to pass⟳ no more than a limited amount of steam to the cylinders, as, for example, over level or slightly falling track with light⟳ loads. A jockey-valve enables such working to be conducted with more precision than is possible by a partial opening of the main regulator valve.”

CEFR level