| 摘要 |
The invention relates to a self-advancing roof supporting apparatus for providing temporary support of a portion of the roof of a tunnel, for example in an underground mine such as a coal mine. When tunnels are being extended, temporary roof supports need to be erected while the newly excavated material is removed and permanent roof supports installed. The apparatus of the invention has means engageable upon the permanent roof-supports to suspend the apparatus therefrom, and preferably has two relatively slidable gripping devices (5) or sets of devices to enable the apparatus to be advanced or withdrawn along the tunnel. |
