| 20090202310 | SUPPORT FOR UNDERGROUND MINING AND TUNNEL CONSTRUCTION - A hydraulic support for underground mining and tunnel construction includes an outer tube to form an upper prop and an inner tube which forms a lower prop and is received in the outer tube to define a pressure chamber. A footpiece is secured to a lower end of the inner tube. Provided on the upper end of the inner tube is a piston which is sealingly guided along the outer tube as pressure fluid is admitted into the upper prop. Disposed inside the lower prop at a location below the piston is a valve block for introducing pressure fluid into the pressure chamber, with a pressure tube connecting the valve block with the piston to thereby define a constant distance of the valve block to the footpiece. | 08-13-2009 |
