Abstract: A mine roof support structure includes a floor skid, a supporting shield pivotally connected thereto by a pair of rocker arms forming a lemniscate guide, a roof cap pivotally connected at a roof cap joint to the shield, and hydraulic props supporting the roof cap. A hydraulic actuator is pivotally connected at opposite ends to the skid and to one of the arms, and the other of the rocker arms is disposed nearer the coal-face end of the support than the one arm. Such other arm is longitudinally adjustable and is pivotally connected at opposite ends to the skid and to the shield. This other arm is so constructed that its opposite ends may be adjusted relative to one another to enable the cap and the roof cap joint to follow a lemniscate path during settling of the roof and to follow a circular arc during a lowering of the cap toward the skid upon actuation of the hydraulic actuator.