ECCENTRIC STRAP.
The Eccentric Strap is that part of the engine in which the eccentric revolves, and is attached to link by the eccentric rod. It should be kept well oiled to secure a free and easy movement to the link.
On reversing engines there are two eccentrics exactly alike, one connecting with upper end of link, the other with lower end by the eccentric straps and rods. In this case the eccentric rod that is moving the valve is the one nearest to the link block. When the lever is in the center notch the link is also in the center of its travel. In this case, both of the eccentric rods move an equal distance and the link vibrates back and forth, but as the block is in the center it gives no motion to the valve, and as the valve, having sufficient lap, covers both ports when the lever is in this position prevents the ingress of steam to the cylinder, consequently no motion.