Sight-hole closure for spiral chutes in underground mining

摘要

The invention relates to a sight-hole closure for spiral chutes in underground mining, especially for underground coal mining, in which the closure cover designed as a swinging flap consists of several segmental sections (4, 5, 6) so that a relatively large opening can be arranged in the spiral-tube section (1) and in addition, during the opening of the closure cover, the weight components of the various segmental sections (4, 5, 6) do not all come into effect immediately but come into effect one after the other (Fig. 1). <IMAGE>