MINE ROOF SUPPORTS

专利名称：MINE ROOF SUPPORTS发明人：STEVENSON J,GB申请号：US3732699D申请日：19711123公开号：US3732699A公开日：19730515

摘要：The invention is for a mine roof support comprising a roof engaging structureor canopy mounted on hydraulic prop means and having an extension bar which can beadvanced and set to the roof, following the passage of a mineral mining machine alongthe mineral face, so as to provide immediate roof support over the face conveyor and/oradjacent the coal face. A hydraulic ram for advancing the extension bar is connected tosaid bar by a lever device having a part which engages an abutment on the roof engagingmember or canopy, at a predetermined amount of extension of the extension bar, so asautomatically to cause the extension bar to tilt or move upwardly and be set against theroof by said advancing ram.

申请人：GULLICK DOBSON LTD,GB

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