Note:  Do not rely on this information. It is very old.

Link Motion

Link Motion in the steam-engine (q.v.) is an arrangement for varying the amount of motion of the slide-valve that opens and closes the steam ports leading to the cylinder. The two extremities of the link are made to oscillate backwards and forwards in opposite directions, and a block capable of sliding along the link will take up a motion compounded of these two and depending upon the position of the block. This actuates the slide-valve by means of the valve-rod; and the valve, by shifting the block along the link, may have its motion increased or diminished or entirely reversed. [Steam-Engine.]