A longitudinally yieldable support for underground roof support includes an elongate outer shell filled with a solid compressible filler material. At least one air ventilation tube extends between opposite sides of the support to allow a flow of air through the support as the support yields.

A support prop which includes a cylindrical aluminium liner which is externally reinforced with a shell made from a composite material, an aluminium plunger with a seal which engages with an inner surface of the liner, a filler valve through which a volume inside the liner, adjacent the seal, in use is pressurized with a fluid, and a pressure relief valve which in use allows fluid under pressure to escape from the volume as the plunger is forced into the liner.

The invention relates to the longwall face support of an underground mine having supports (plates 1-18), which longwall face support comprises camera housings (35) each having two cameras (36), which record a monitoring area of the face having a plurality of plates in the longitudinal direction of the gallery and the most complete registration possible of the cross section of the gallery. The cameras in a monitoring area are assigned to a common power supply unit (48) for the power supply and are equipped with intrinsically safe electronics. The electronics have a radio device for high-frequency data transfer (transmission and reception) together with antenna 39 (W-LAN antenna) for the wire-free connection to the local camera network (Wireless Local Area Network). Each camera and each camera housing is assigned a camera code and an address code, which is added to the identification data. Each radio device is configured such that data marked with an extrinsic camera code and data and signals marked with an extrinsic address code is emitted to be transmitted following reception.

The invention relates to the longwall face support of an underground mine having supports (plates 1-18), which longwall face support comprises camera housings (35) each having two cameras (36), which record a monitoring area of the face having a plurality of plates in the longitudinal direction of the gallery and the most complete registration possible of the cross section of the gallery. The cameras in a monitoring area are assigned to a common power supply unit (48) for the power supply and are equipped with intrinsically safe electronics. The electronics have a radio device for high-frequency data transfer (transmission and reception) together with antenna 39 (W-LAN antenna) for the wire-free connection to the local camera network (Wireless Local Area Network). Each camera and each camera housing is assigned a camera code and an address code, which is added to the identification data. Each radio device is configured such that data marked with an extrinsic camera code and data and signals marked with an extrinsic address code is emitted to be transmitted following reception.