link-lever

(lingk’lev’ér), n. In a steam-engine, a lever by which the link of a link-motion valve gear is controlled by the attending engineer; in particular, the reversing-lever of a locomotive engine. linkman (lingk’man), ».; pl. linkmen (-men). A man employed to carry a link or torch to light pa engers. See linkboy. link-motion (lingk’m6’shon),”. 1. A system of pieces pivoted together, and turning about pivots attached to a fixed base, all the rotations being in the same plane or parallel planes, so that all the points describe definite curves; a complete linkwork. Link motions have been deeply Link-motion, studied by mathematicians, especially since 1864, the date of the discovery of the Peaucellier cell. The problems involved are exceedingly difficult, as well as practically of no little importance. Any algebraic curve whatever may be drawn by a suitable link-motion. See Peaucellier cell, under cell. Specifically —2. In steam-engines, a system of gearing for controlling the valves for the purpose of starting or reversing the engine, and for controlling the cut-off, See valve-gear. The link-motion combines in itself a variable cut-off by which the expansion of the steam can be diminished or increased as the resistance to the engine increases or diminishes, and reversing mechanism whereby the engine may be caused to reverse the motion of its crank-shaft as desired in locomotives, marine engines, and some kinds of stationary engines. Starting ahead or astern is effected by link-motion. Inwe, Seamanship, p. 225,