Mine roof support

A mine roof support having a floor-engaging part, a roof-engaging part, a shield of substantial width pivotally connected to the roof-engaging part to extend downwardly and rearwardly towards the goaf, a top link whose width is most of the width of the shield pivotally connected by coaxial pivots at its upper corners to the shield for movement about a first axis and pivotally connected by coaxial pivots at its lower corners to the floor-engaging part for movement about a second axis, a bottom link of a narrow width closer to the goaf than the top link, pivotally connected to the shield for movement about a third axis and pivotally connected to the floor-engaging part for movement about a fourth axis close to the floor-engaging surface, all pivot axes being substantially parallel to one another, and extendible strut means carried by the floor-engaging part to adjust the height of the roof-engaging part such that reduction in height of the roof-engaging part towards its lowest position causes the bottom link to extend from the fourth pivotal axis away from the floor-engaging part and close to the goaf side of the floor surface on which the support stands, the width and the connections of the top link locating the shield against any force applied to the shield in a transverse sense which will tend to apply torsion and shear forces to the top link and resisting any tendency for the roof-engaging part to move transversely relative to the floor-engaging part.