Secondary supports for rock tunnelling machine - supports on parts fixed during boring, preferably below machine clamps

摘要

A rock tunnelling or mine heading machine has secondary supports (10, 11) intended to take the weight of the machine when boring soft rock, arranged on parts of the machine (5) which remain stationary during the boring action. Preferably the supports should be placed below the leading and/or trailing machine clamp (5) and should be fixed to this. It should be possible to extend or contract the supports at right angles to the axis of the tunnel or heading, the boring stroke being preferably greater than the thickness of one support tubbing ring. The bearing surface of the secondary support system should be recessed round the tunnel circumference by more than one tubbing ring thickness so that the supports can be used to clamp the rings to the wall when the support has been suitably extended for this purpose.