Abstract: A bracing device for a self-advancing shield tunnelling machine for tunnel construction comprising a control shield within which is mounted a cutting unit, and at least two bracing shields each having a closed circumferential wall construction which are connected together by feed cylinders, the bracing shields being able to be radially braced with the tunnel wall independently of each other by bracing elements fixed thereon. The bracing elements are composed of elastic pressure hoses positioned around the closed circumferential bracing shield walls. The circumferences of the bracing elements can be continually enlarged by expansion, particularly by inflation. The invention furthermore relates to the use of such bracing elements for a self-advancing shield tunnelling machine in which the control shield and the first bracing shield arranged behind it as well as the first and second bracing shield engage in each other and overlap telescopically.

Abstract: A drum cutter mining machine translatable along a longwall conveyor includes an auxiliary cutting drum for breaking up pieces of mineral carried by the longwall conveyor system. The auxiliary cutting drum is supported by a jib and an arm extension affixed in a fixed relationship with a support arm. The auxiliary cutting drum is positioned by the same actuator which pivotally positions the drum-cutter cutting drum at a desired cutting height at the mine roof and other times at the floor. Positioning of the cutting drum at the desired cutting height automatically positioned the auxiliary cutting drum.