Telescopic concrete mine support column formwork - has folding bottom half shells, and propped spring pressure for top ones

摘要

Two axially telescoping tubular form housing units, with the top one held in contact with the roof by an adjacent pressure medium, make up a mechanism for erecting a concrete or similar pillar-type support in a mine. Each unit comprises two open-ended half shells. Those for the bottom one, at least, are foldable about a swivel axis parallel to their common longitudinal axis. The top unit is set under the influence of resilient pressure media pref. helical spring, supported on a pit prop clamped between roof and floor. This is inexpensive, and promptly effective, and readily adaptable to varying distances between roof and floor.