Abstract: A cap shoe for connecting a mine prop to a head tree or cap in the form of a U-shaped girder whose U shanks have corrugations extending the full width thereof is engageable by complementary formations on the flanges of the cap or head tree which is received in the shoe. The latter is welded to the mine prop.

Abstract: A clamping device for connecting a number of shaped, elongated, flanged through sections of a support structure to each other includes an upper stirrup, the flanges of which are supported on the flanges of the upper through section, a lower stirrup positioned to support the flanges of the lower through section, and clamping bolts extended through the openings in the flanges of the stirrups and the through sections and tightened with nuts. The head of each bolt has supporting projections provided with convexly curved portions which are engaged in the flanges of the upper stirrup in a form-locking fashion.

Abstract: A portal-shaped installation car picks up at an assembly location remote from the face of the tunnel an upper part of a tunnel-lining arch on a pallet. It then rides along rails secured to the side of the tunnel to the face location and presses this upper part against the tunnel roof, whereupon the lower tunnel-lining arch parts are secured in place. Thereafter the car returns with the empty pallet to the rear end of the tunnel at the assembly location and deposits this empty pallet to pick up a full pallet carrying another upper arch part. The sequence is then repeated. As each upper arch part is being secured at the face of the tunnel another upper arch part is assembled on the previously deposited empty pallet with the help of a portal crane that also rides on the rails along the sides of the tunnel.