36 and 37 and hence lifts the skids 13 and 14 in this particular embodiment the two tubes 27 and 30 provide a lost motion arrangement which increases the degree to which the base 10 and canopy 11 can be moved towards one another when it is desired to collapse the support for transportation and storage it will be appreciated that mine roof supports often have to be transported or manipulated in very confined spaces and it is important to be able to reduce as much as possible the overall dimensions of a collapsed support as the hydraulic legs of the support are fully retracted to collapse the support a point is reached where the canopy bottom plate 39 comes into contact with the retention plate 28 as shown in fig3 with prior art supports maximum collapse of the support is reached at this point however with the support according to this embodiment the skids 13 and 14 i e the base 10 can continue relative movement towards the canopy 11 by relative upward sliding movement of the outer tube 30 until the outer tube 30 comes into contact with the projecting edge 31 of the retention plate 28 thus a significant additional degree of compaction of the support is made possible.