Props Chocks

EFIXED CONSTRUCTIONS E21Mining E21DSHAFTS TUNNELS GALLERIES LARGE UNDERGROUND CHAMBERS

E21D15/00Props Chocks

E21D15/002Auxiliary devices in which the prop type is not essential E21D15/005characterised by the material E21D15/007spark-reducing E21D15/02Non-telescopic props E21D15/04with wooden prop parts joined by double conical connectors E21D15/06with parts joined by a lock, with or without slight axial adjustability E21D15/08with toggle joint connection E21D15/10with dog-clutch or pin-and-hole connection E21D15/12with locking devices located near head or foot E21D15/14Telescopic props E21D15/15Means counteracting entry of dirt Built-in cleaning devices E21D15/155Built-in cleaning devices E21D15/16with parts held together by positive means, with or without relative sliding movement when the prop is subject to excessive pressure E21D15/18with one part resting on a supporting medium E21D15/20with pawl, pin, cross-piece, or the like engaging with ratchet teeth, notches, holes, or the like, spaced apart at intervals E21D15/22with member, pin, cross- piece, or the like, ruptured, sheared through, or permanently deformed upon excessive pressure E21D15/24with axial screw-and-nut, rack-and-worm, or like mechanism E21D15/26with screw, worm, or the like, not self-locking but normally prevented from rotation by friction members which slip upon excessive pressure E21D15/28with parts held relatively to each other by friction or gripping E21D15/285by means of wedges or wedge combinations E21D15/30by means expanded or contracted by pressure applied through the medium of a fluid or quasi- fluid E21D15/303by means of granular material E21D15/306by means of a liquid E21D15/32by a deformable collar or clamping means applied symmetrically inside a locking ring E21D15/325by a clamping ring E21D15/34by axially- moving balls, rollers, or the like E21D15/36by a tiltable collar surrounding one or both parts E21D15/38with longitudinally-divided upper or lower prop parts E21D15/40Collar or other support gripped to one or both parts by toggle-action, cam, or other member pivoted or similarly mounted E21D15/42with special parts to influence the friction E21D15/43Details of wedges E21D15/435hydraulic E21D15/44Hydraulic, pneumatic, or hydraulic-pneumatic props E21D15/445comprising a fluid cushion E21D15/45having closed fluid system E21D15/46with load-measuring devices with alarm devices E21D15/465with essential hydraulic or pneumatic details E21D15/48Chocks or the like E21D15/483made of flexible containers E21D15/486with essential hydraulic or pneumatic details E21D15/50Component parts or details of props E21D15/502Prop bodies characterised by their shape E21D15/51specially adapted to hydraulic, pneumatic, or hydraulic-pneumatic props E21D15/512Arrangement of valves E21D15/515Particular fluids not covered by any chemical subdivision E21D15/517Extension elements E21D15/52Extensible units located above or below standard props E21D15/523with hydraulic or pneumatic control E21D15/526for step-by-step extension of the prop E21D15/54Details of the ends of props E21D15/545hydraulic or pneumatic E21D15/55of prop heads or feet E21D15/56Details of locks of telescopic props E21D15/563by which a series of similarly shaped props can obtain an almost equal load-capacity E21D15/566comprising a fluid cushion E21D15/58Devices for setting props or chocks E21D15/581in which the props are pre- loaded E21D15/5813by means of power accumulators to be pre-charged by rock pressure E21D15/5817in which the lock is also activated E21D15/584in which a series of similarly shaped props obtain an almost equal load capacity by removable devices E21D15/585by means of hydraulically operated devices for mechanical props, or hydraulic props in which the hydraulic part is not important E21D15/586the props being pre-loaded E21D15/587by means of power accumulators to be pre-charged by rock pressure E21D15/588the lock also being activated E21D15/589in which a series of similarly shaped props are given almost equal load capacity by removable devices E21D15/60Devices for withdrawing props or chocks E21D15/603by means of hydraulic devices E21D15/606the props being moved systematically