Reequilibration of chromite within Kilauea Iki lava lake

A device arranged adjacent a cam ring at jack level in a circular knitting machine. The device includes a movable cam insertable in a notch in the cam ring to maintain the continuity of the upper surface of the cam ring for action upon lower jack butts. When the cam is moved out of the notch a lever is activated to selectively act on jack butts to force the lower butts of selected jacks off the cam ring.