LINK.
The Link is that part which holds the link block and is connected at each end to the eccentric rods; it is used only on reversing engines. The link is made on a curve, so that when the link block is at either extreme end the valve is operated to its full movement. When the block is in the center of link, the valve covers both ports and prevents the ingress of steam to the cylinder.
The Link Block is attached to the slide which connects it to the valve rod. The valve rod connects the slide and valve, and where it enters the steam chest is packed in like manner to the piston rod.