Hydraulic powered roof supports are self advancing structures which are interconnected along the length of the longwall face. Each unit along the line is also connected to each pan of the AFC.
The function of the powered supports are to:
- To control strata deformation, fracture and movement around the coal face,
- To maintain a safe and coal producing working environment,
- To limit the amount of roof to floor convergence,
- To prevent broken rock from entering the work area, and
- To secure and advance all plant on the coal face including the roof supports.
Each support structure consist of a roof canopy connected to a base via a shield and leminscate linkages. Side shields mounted to the canopy prevents excessive debris falling into the work space during support advancement. The hydraulic legs of a each type of support are inclined or splayed at an angle. This is to prevent the legs from buckling under the immense loads that they support. In Australia, the most comon types of supports used are :
Further topics related to powered supports that are covered in this module are :