link motion

from the GNU version of the Collaborative International Dictionary of English.

• noun (Steam Engine) A valve gear, consisting of two eccentrics with their rods, giving motion to a slide valve by an adjustable connecting bar, called the link, in such a way that the motion of the engine can be reversed, or the cut-off varied, at will; -- used very generally in locomotives and marine engines.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun engineering, dated A valve gear consisting of two eccentrics with their rods, giving motion to a slide valve by an adjustable connecting bar (the link) in such a way that the motion of the engine can be reversed, or the cut-off varied.