Progressive tunnel lining system, in underground coal mining, has a hydraulic ram supported on the runner by a lower section, forming a box structure with the U-shaped runner for increased flexibility

摘要

The progressive tunnel lining system, e.g. for coal mining, has a base plate on U-shaped runners and at least one hydraulic ram on the runners to support the hanging cap of the lining. The runner has a fitted unit as the lower section of the hydraulic ram, to keep the ram foot at a gap from it. The lower section is a fitted plate over the runner, gripping over its side walls, to give the runner a box structure.