E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
E21D15/14—Telescopic props
E21D15/28—Telescopic props with parts held relatively to each other by friction or gripping
E21D15/32—Telescopic props with parts held relatively to each other by friction or gripping by a deformable collar or clamping means applied symmetrically inside a locking ring
E—FIXED CONSTRUCTIONS
E21—EARTH OR ROCK DRILLING; MINING
E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
E21D15/00—Props; Chocks, e.g. made of flexible containers filled with backfilling material
E21D15/50—Component parts or details of props
E21D15/56—Details of locks of telescopic props
E21D15/563—Details of locks of telescopic props by which a series of similarly shaped props can obtain an almost equal load-capacity