Abstract: A mine roof support has gap seals in the form of L-shaped plates on its roof cap and goaf shield. The side walls of the plates overlap at the junctures between the roof cap and the goaf shield and these walls are interconnected with pivot connections each of which is composed of complementary components fitted into openings in the walls. The components combine to form a pivot journal and and are locked to one another by a twist catch which can be released by relative rotation of the components.

Abstract: A mine roof support has gap seals in the form of L-shaped plates on its roof cap and goaf shield. The side walls of the plates overlap at the junctures between the roof cap and goaf shield and are connected with pivot connections each of which is composed of a pin inserted into apertures in the side walls of the plates. The pin has a peripheral groove at its inner end region which receives an arcuate yoke plate serving as a support. The yoke plate is itself detachably secured in place with a releasable rod permitting the pivot connection to be easily dismantled.

Abstract: A device designed to skid the chock blocks of a powered support of the type used in coal mines. The front of the skid cylinder is connected with a skid bar whose front end is jointed on an armored conveyor. The rear end of the cylinder is jointed on the rear end of an arm whose front end is jointed on the chock block pads.

Abstract: A mine roof support system includes a plurality of truss members each having first and second ends which are positioned in spaced relationships one behind another. There are vertically extensible props under each end of the truss member which include stabilizer sleeves to stabiize the truss members thereabove. The vertically extensible props can be extended and retracted to adjust a vertical height of the props for supporting the truss member and for moving it into and out of engagement with the mine roof. Each of the props is supported by a ground engaging means in the form of a selectively operable propulsion unit capable of being operated to produce horizontal movement of the respective props and ends of the truss members. Connecting elements beneath the ends of the truss members connect the props in tandem relationship to permit the horizontal movement of truss members and associated props relative to each other by the propulsion units.

Abstract: Valves regulating the supply of hydraulic fluid to hydraulic cylinders of an hydraulic walking mine-roof support are controlled by apparatus comprising an axially-movable switching shaft provided with cams which is rotatable into successive switching stations where it is immobilized by spring-loaded stop pins to that the cams bear on tappets to actuate the respective valves, there being a switching spring acting on the shaft to return the shaft to its initial position of rest after it has been axially displaced and rotated out of that position of rest.

Abstract: A mineral mining installation comprises a roof support unit and an advance mechanism. The roof support unit has a floor sill constituted by two floor girders. The advance mechanism comprises a hydraulic advance ram, the advance ram having a relatively-displaceable cylinder and a piston rod, and a device for selectively limiting the working stroke of the ram. The stroke-limiting device comprises a stop fixed to the cylinder of the advance ram, and an adjustable stop member which is mounted on the side wall of one of the floor girders.

Abstract: A shield support, suitable for use in mines, comprising a floor-engaging structure, a roof-engageable canopy, extendible and contractible prop means disposed between the floor-engaging structure and the canopy, and a shield assembly pivotally-connected to the canopy at or near its rearward end portion. The shield assembly includes a lazy tongs linkage, one element of which is pivotally-connected directly to the floor-engaging structure and another element of which is pivotally-connected to the floor-engaging structure through the intermediary of a further element.

Abstract: The invention refers to a movable supporting frame for supporting the roof in underground cavities, in particular for securing the excavating edge when recovering the pillars in coal mining, comprising a cap (5) supported against a base frame (1) by means of hydraulically extendable props (3) and a lemniscate drive means (4), the props (3) being pivotally connected with the base frame (1) and with the cap (5). The props (3) are essentially perpendicularly oriented relative to stratification and are linked to the base frame (1) and to the cap (5) in a universally pivotably manner, noting that preferably four props are arranged at the corners of a rectangle as seen in a plan view. The lemniscate drive means (4) is connected with the base frame (1) for swivelling movement in transverse direction relative to the plane defined by the lemniscate guides (8, 9) and is adjustably supported against any swivelling movement and is connected with the cap (5) for universal swivelling movement.

Abstract: A roof support, suitable for use in mines, includes a roof-engageable canopy which comprises a main portion and an extension portion having a pivotal connection to the main portion. Actuator means is carried by the main portion. A wedge member, which is operable by the actuator means, is disposed between, and is engageable with, the main portion and a part of the extension portion projecting substantially beyond the said pivotal connection towards the actuator means. The wedge member is adapted arcuately to be movable by the actuator means and such arcuate movement effects tilting of the extension portion with respect to said main portion.

Abstract: A lightweight jack for supporting the roof of a mine until permanent supports are in place. The jack is carried by a roof bolter or similar mining equipment on the end of a support arm. A hinge box is mounted on the sidewall of the roof bolter and one end of the arm is hingedly received therein. A support plate extends from the sidewall outwardly below the arm. The support plate carries at the far end a U-shaped bracket with a spring inside the bracket. The support arm rests on the spring when the jack is not extended. A swivel arm is received inside the support arm and held from turning by a swivel pin. When the pin is removed, the swivel arm and jack may be turned sideways for easy manuevering by the roof bolter.

Abstract: In a roof-shield support system employed in mines, at least two levelling rams each acting between a shield frame unit and an associated gap-seal plate, the latter being arranged so as to be slidable relative to the associated shield frame unit. Each levelling ram comprises a cylinder, piston and piston rod, is arranged so that the piston rod has a longitudinal bore which is open at the piston end of the piston rod, and an elongated rod which is sealed relative to the piston rod being disposed within said bore. The bore is in use in communication with a hydraulic fluid system of the ram and after levelling has occurred by actuation of the ram the pressurized hydraulic fluid admitted into the bore applies a force to the associated gap-seal plate so as to ensure its continuing tight engagement with the adjacent shield frame unit.

Abstract: A roof support, suitable for use in mines, includes a floor-engaging structure, extendible and contractible prop means carried by that structure, and a roof-engageable canopy supported by the prop means. The canopy comprises a main portion and an extension portion, each of which includes a plate member the upper face of which is engageable with the roof. Fastening means, which are provided for rigidly connecting the extension portion and the main portion together, include at least one connecting member adapted to lie within the thickness of the plate members, or substantially so.

Abstract: A mine roof support has a roof engaging structure 13 and a floor engaging base 14, spaced apart by extensible hydraulic jack means 15 and 16. The roof engaging structure and the base are interconnected by a pivotal linkage device 23, 24 arranged so that, throughout its range of working movement, a pivot point of the linkage performs substantially greater movement in the vertical direction than in the horizontal direction. This reduces the effect of problems arising from the linkage device projecting substantially into the goaf area of a mine working or into the walkway area of the support. In a preferred embodiment the linkage device comprises a parallelogram type linkage.

Abstract: A mine roof support comprises a base formed of two base members, a beam disposed therebetween, jacks for lifting the base members or the beam one relative to the other and a jack for advancing the base member or the beam one relative to the other. A roofing bar structure is supported from the base members by extendible props and an elevated platform is disposed between the base and the roofing bar structure. The support is advanced by lifting, advancing and lowering the beam relative to the base members and then lifting, advancing and lowering the base members relative to the beam.

Abstract: A mine excavator especially for heavy coal beds comprises a base on which the power loader and conveyor are provided and on which the roof support or shield is pivotally mounted. According to the invention, a back member connected to the roof plate and spaced above the base has a downwardly and forwardly swingable door which deposits caved material onto the conveyor at a forward portion of the main base.

Abstract: A self-advancing mine-roof-support for use in or aligned with a main roadway or gate has a floor-engaging part and a roof engaging part spaced apart by extensible load-bearing prop or jack means, and engagement means for a face-conveyor and a transversely acting transfer conveyor whereby their relative positions are constrained to facilitate discharge of mineral from one conveyor to the other. The engagement means for the face conveyor comprises sliding anchor beams that assure maintenance of the relative attitudes of the support and the face conveyor and the transfer conveyor is held fore and aft of the support.

Abstract: A self-advancing support, suitable for use in mines, includes a cantilever which is extendible and retractable with respect to a main portion of the support, and a sprag which is so mounted on said cantilever as to be extendible and retractable with respect thereto. Means are provided for advancing the support with respect to a mineral face and further means are provided for ensuring that during advance of the support the sprag is maintained in an extended, mineral-face-engaging, condition while the main portion is moved with respect to the cantilever in the direction towards the face, thereby reducing cantilever extension.

Abstract: An underground support, e.g. for the roof of a mine, has a roof engaging canopy 10 which can be raised and lowered in a controlled manner by hydraulic legs 14. Inflatable flexible membrane means, for example in the form of bags 12, are provided on the upper face of the canopy 10, which shape themselves to the mine roof and distribute loading evenly thereto. Inflatable flexible membrane means may also be used to prevent flushing of loose debris between adjacent supports, and on roadway supports.

Abstract: A trough-shaped travelling bracket of a retracting and guiding arrangement of a mine roof support has fixing elements at its mine-face end for releasably coupling with an abutment, wherein the fixing elements are exchangeable, but fixedly connectable with a web of the travelling bracket.

Abstract: A mine roof support includes a first liquid supply means having a first control valve for connecting a source of liquid under pressure to the legs of the support. The support is also provided with a second control valve which is actuatable, when the pressure of the liquid being supplied to the legs attains a value below the setting pressure for the legs, to connect the legs to a source of liquid under pressure by way of a second liquid supply means. Time-delay means is operable on the second control valve to cause it to close when a predetermined time has elapsed after the pressure in the legs has reached the setting pressure.

Abstract: A fixing bridge for attachment to the goaf side of a channel section on a scraper-chain conveyor, is provided with connectors for the attachment of anchoring devices. A first connector is provided adjacent to one end of the fixing bridge, and a second connector is provided adjacent to the other end of the fixing bridge. The second connector is vertically off-set with respect to the first connector.

Abstract: An electro-hydraulic control system for an underground mineral mining installation employs individual control assemblies and devices on a series of support units which are interconnected to one another and to a central control station via lines conveying electrical control signals. Manually-operable selector switches on the units enable groups of the support units to be operated in sequence at will by operating the switches of adjacent units outside the group.

Abstract: A mineral mining installation includes a longwall conveyor and a plurality of roof support units positioned side-by-side on the goaf side of the conveyor. The conveyor is braced longitudinally by a block bracing system having a plurality of hydraulic bracing rams each of which is disposed at an acute angle to the conveyor. The bracing rams act between the conveyor and floor girders of the roof support units. Each bracing ram is attached to a respective floor girder by means of a bracket. Each bracket has first and second bracket parts welded together, the first bracket part comprising means for connecting the bracket to its floor girder, and the second bracket part forming an extension of the first bracket part and carrying a pivot joint member for pivotally supporting the cylinder of the associated bracing ram. The first bracket part is a standard cast member, to which second bracket parts of differing lengths can be welded.

Abstract: A mine roof support has a main roof bar which is pivotably connected to an auxiliary forwardly-extendible bar. At least one piston and cylinder unit serves to swing the auxiliary bar about the main bar to bring the auxiliary bar into a roof-contacting position aligned with the main bar or into a stowed position beneath the main bar or into some intermediate position. One or more pivotable guide levers connect the auxiliary bar to the piston and cylinder unit. A guide member is also connected to the unit and slidably locates in longitudinal guideways formed in ribs or the like at the underside of the main roof bar.

Abstract: A mine roof support unit has a floor sill, a roof cap supported above the floor sill by a pair of inclined hydraulic props, and control apparatus for controlling load-bearing capacity of the props. The inclination of the props relative to the vertical increases as the props are retracted. The control apparatus comprises a pressure-relief valve for limiting the pressure of the hydraulic fluid supplied to the hydraulic props. The pressure-relief valve has a closure member which is biased towards its closed position by a spring. The spring is backed by an abutment member which constitutes a setting device for adjusting the biasing force of the spring, thereby controlling the operating pressure of the pressure-relief valve, and hence the load-bearing capacity of the props.

Abstract: A method of mining a mineral in which a roof is supported by a plurality of mine roof supports of the kind specified, each advanceable by a force applied to a lower part thereof. During advance of the support an upper part thereof can be sufficiently retarded, by hydraulic jacks carried, by each of its adjacent supports, with respect to the advance of its lower part. This causes the support effectively to rotate and to raise the leading end of the lower part away from the ground on which it is advancing.

Abstract: A roof support suitable for use in mines includes roof-engageable means provided with a roof-engageable pad which is so mounted with respect to the remainder of the roof-engageable means as to be movable with respect thereto for exerting a thrust on the mine roof. A linkage is pivotally connected between the pad and the remainder of the roof-engageable means. Actuator means is so pivotally connected to and supported by the linkage that when operated it effects movement of the pad with respect to the remainder of the roof-engageable means, being itself constrained, simultaneously upon such movement, to move bodily with the pad.

Abstract: A self-advancing support apparatus for protecting mine gate crossings, and optionally for engaging the reversing/driving head of a longwall and/or gate conveyor. The support apparatus has at least two side by side desired construction but expediently of a construction identical with that of the support unit at the longwall face to which said unit is connected via a coupling element. Each unit includes a base, a canopy, and connected between them, expediently by articulation, bracing elements as well as advancing elements and holding devices mounted on the base, and if so desired, for advancing the reversing/driving head of the longwall conveyor, a guide track extending in the direction of the gate conveyor, and an actuating/controlling unit. A holding mechanism is provided for engaging the reversing/driving head of the longwall conveyor and has at least two degrees of freedom of movement.

Abstract: A mineral mining installation serves to win mineral by explosive blasting. The installation employs a shuttle conveyor arranged alongside a mineral face. Roof supports stand side-by-side at the side of the conveyor remote from the conveyor. The roof supports are connected to the conveyor through shifting rams and have roof-engageable caps or the like supported on hydraulic props. The pans of the conveyor have upstanding walls at the rear side nearest the roof supports which carry rails at their upper ends. The roof caps have wall components pivoted thereto and hydraulic piston and cylinder units serve to swing the wall components up and down. When explosive blasting takes place the wall components are swung down to engage on the walls of the conveyor pans to form a screen between the winning region and the access region of the working.

Abstract: A slidable filling dam has along the heading dam segments (4) articulated in a hinged roof-bar (7) of a mine lining. The slidable dam has near-floor beams (1) which are provided at their ends with terminal eyes (2) to connect two neighboring dam segments (4) at the point of their connection with footings (9) by means of bolts (10, 11). The near-floor beam (1) has in its central part at least one central eye (5) to fix a hydraulic ram (6) pulling up segments (4) of the filling dam.

Abstract: A mineral mining installation comprises a longwall conveyor, and a plurality of roof support units positioned side-by-side along the goaf side of the conveyor. The roof support units are positioned to define an access area between the conveyor and the roof support units. A plurality of hydraulic bracing rams act on the conveyor to brace the conveyor longitudinally. Each of the bracing rams is pivotally attached to a floor sill of a respective roof support unit. The hydraulic bracing rams are positioned at the goaf-side edge portion of the access area. The bracing forces are transmitted from the bracing rams to the conveyor via respective transverse arms attached to the bracing rams and to the conveyor.

Abstract: A mineral mining installation is provided for use in a steeply-inclined longwall working. The installation comprises a ladder-shaped support frame, and a plurality of roof support units. The support frame extends along the entire length of the longwall working, and has a pair of generally parallel longitudinal beams interconnected by a plurality of transverse beams. The roof support units are positioned between the longitudinal beams, and are supported on the transverse beam. Each of the longitudinal beams comprises a plurality of beam sections pivotably connected together end-to-end. The support frame comprises a plurality of detachably connected sub-frames, each of which comprises a respective transverse beam and a respective beam section of each of the longitudinal beams.

Abstract: A roof support assembly is constituted by a plurality of roof support units and a plurality of advance mechanisms. The units are positioned side-by-side along a longwall face of a mineral mining working. Each advance mechanism comprises a pair of generally parallel hydraulic advance rams and a guide rod system constituted by a pair of resilient generally parallel guide rods. Each guide rod system is attached, at one end, to a conveyor extending along the longwall face. The other end of each guide rod of each advance mechanism is attached to a respective slide piece which is slidably guided on a respective guide rail which is attached to a respective floor girder of a roof support unit. The slide pieces are attached to the piston rods of the hydraulic advance rams. The cylinders of the hydraulic advance rams are attached to one of the adjacent floor girders, and the slide piece attached to the piston rod of hydraulic advance ram is attached to the guide rod system.

Abstract: A mine excavator especially for heavy coal beds comprises a base on which the power loader and conveyor are provided and on which the roof support or shield is pivotally mounted. According to the invention, a back member connected to the roof plate and spaced above the base has a downwardly and forwardly swingable door which deposits caved material onto the conveyor at a forward portion of the main base.

Abstract: The roof support according to the invention is between the roof-bar (2) and the sill piece (1) with at least one system of levers (3,4) connected by articulation with each other and connected by articulation with the roof-bar (2) and the sill piece (1) so that they have the form of a lying letter V directed with its vertex towards the fall. Between the levers (3,4) it is provided with the hydraulic cylinder (5) spragging the levers (3,4) and thus the lining. That admits to achieve a high multiplication of the cylinder travel in relation to the change of the lining height, and a multiplication of forces. In shield roof supports of a lemniscate type the lever system can consist of the fall shield (6) and the outside arm (7) of the lemniscate arrangement.

Abstract: A roof support unit has a pair of spaced floor girders and an advance mechanism comprising a hydraulic advance ram and a pair of relay rods connected, at one end, to a head-piece which is attached to a longwall conveyor. The other ends of the relay rods are attached to a guide element which is slidably guided by a pair of guide rails attached to the mutually-facing sides of the floor girders. The hydraulic advance ram is pivotally attached to the guide element and to the floor girders. Means are provided for aligning the ends of the floor girders remote from the head-piece when the hydraulic advance ram is pressurized.

Abstract: A gantry support for supporting a roof of a passage includes two parallel supporting units each having a lower frame provided with articulated tracks and an upper frame carried by props and two cross-members. The two cross-members carry an intermediate upper frame in the form of a beam which is slidable on guide elements and adapted to be clamped to the roof by small jacks. As the support advances the beam remains clamped against the roof of the passage until the beam reaches an end stop. The small jack is then released and the beam slidably advanced along the guide elements by means of a further jack.

Abstract: A roof support for a mine gallery which extends at a relatively large angle to the horizontal comprises an upper, a middle and a lower roof support unit arranged adjacent each other and having each a pair of elongated transversely spaced skids rigidly connected by bridges to each other and engaging the sole of the inclined mine gallery. An abutment beam likewise engaging the sole is arranged inclined to the elongation of the skids adjacent to the face of the gallery to be mined and connected to the skids of the middle roof support unit by a pair of flat sole plates rigid with the beam and tiltable about horizontal axes with respect to the skids, whereas the upper and the lower roof support unit are connected to the beam by flat elongated sole engaging end members connected to the beam pivotable about vertical pivot axes. In this way ample space is provided beneath the roof of the mine gallery between the beam and the roof support units to permit mining of coal seams of small height.

Abstract: A mine roof support has a main roof bar which is pivotably connected to an auxiliary forwardly-extendible bar. A piston and cylinder unit serves to swing the auxiliary bar about the main bar to bring the auxiliary bar into a roof-contacting position aligned with the main bar or into a stowed position beneath the main bar or into some intermediate position. Pivotable guide members connect between the main and auxiliary bars respectively and a pivot joint linked to the piston and cylinder unit. The guide members can take the form of simple straps or levers but an additional piston and cylinder unit can also be used as one of the guide members.

Abstract: The invention is concerned with apparatus for maintaining a set "between-centers" distance between the elements of self-advancing mine-roof supporting means for long-wall mining, the support means having at least two elements connected via connecting means so that they can pivot to a limited extent with respect to an abutment which, in use, extends substantially parallel to the long-wall face, the connecting means of at least one element being constructed as a drive means, in which the portions of the abutment connected to the respective connecting means are interconnected so that their length can be varied, and a guide lever is pivoted to the connecting means of at least one element and to an abutment portion connected to an adjacent element so that the two places at which the lever is pivoted and the place at which the connecting means of the first-mentioned element are connected to the abutment lie at the corners of a triangle.

Abstract: A mechanized longwall system for mines is provided which includes face roof supporting units disposed along the longwall and connected to a face support track by hydraulic advancing cylinders, each unit including a floor and roof element, a drift transport track mounted perpendicularly to one end of the face transport track, including two drift supporting units coupled with hydraulic linkages to the face supporting units, a guide system arranged on one of the floor elements of the drift supporting units and guiding a transfer unit in the longitudinal direction of the drift transport track, the arrangement being such that shifting of a drift supporting unit is accompanied by a simultaneous shifting of the face conveyor apparatus.

Abstract: Apparatus is disclosed for supporting the lowermost roof support unit of a series of roof support units positioned side-by-side in an inclined longwall working. The support apparatus comprises a beam mounted for pivotal movement in a plane parallel to the floor of the working. The beam can be held in any given angular position. A support plate is provided for engagement with the side of the lowermost roof support unit. The support plate is movable towards, and away from, the beam by means of hydraulic rams, which also constitute means for holding the support plate and the beam at any given spacing within a predetermined range of spacings.

Abstract: A mine roof support system having sets of laterally spaced pairs of elongated support members adapted to be moved into and out of abutting relation with a mine roof. Wheel supported frames extend between and connect adjacent end portions of each pair of support members with adjacent wheel supported frames at the ends of the support members being in spaced tandem relation and connected to each other by connector members. Extensible prop members are connected to and move the wheel supported frames and the elongated support members connected thereto selectively toward and away from the mine roof.

Abstract: A mine roof support has a base, a supporting prop extending upwardly from the base, an elongated roof-supporting element having one portion supported by the supporting prop and another portion telescopable relative to the one portion toward a mine face and having a free end formed as a housing with a width corresponding to the width of the one portion, and a thrust prop arranged to support the free end section of the telescopable portion of the roof-supporting element and having a roof-side end section which is forcedly displaceable in the housing in direction of elongation of a mine and pivotable in a substantially vertical plane about an axle arranged in the housing.

Abstract: A mine roof support has two sole-sliding elements, a bridge element connecting the sole-sliding elements with one another at the mine face ends of the latter, a roof supporting element supported on the sole-sliding elements, props supporting the roof supporting element on the sole-sliding elements, a displacing arrangement for displacing the sole-sliding elements and connected with the bride element, a guiding arrangement located between the sole-sliding elements and including two laterally spaced guiding rods connected at their mine face ends with a support element and at their backfilling ends with the bridge element via displacing arrangement, wherein a carriage is positively incorporated between the guiding rods of the guiding arrangement. The carriage carries a cylinder-and-piston unit which connects the carriage with the guiding arrangement at the backfilling end of the latter.

Abstract: A mine roof support structure includes a floor skid, a supporting shield pivotally connected thereto by a pair of rocker arms forming a lemniscate guide, a roof cap pivotally connected at a roof cap joint to the shield, and hydraulic props supporting the roof cap. A hydraulic actuator is pivotally connected at opposite ends to the skid and to one of the arms, and the other of the rocker arms is disposed nearer the coal-face end of the support than the one arm. Such other arm is longitudinally adjustable and is pivotally connected at opposite ends to the skid and to the shield. This other arm is so constructed that its opposite ends may be adjusted relative to one another to enable the cap and the roof cap joint to follow a lemniscate path during settling of the roof and to follow a circular arc during a lowering of the cap toward the skid upon actuation of the hydraulic actuator.

Abstract: A mining vehicle has a body with a center boom extending forwardly from the body. A temporary roof support is mounted on the outer end of the center boom. The roof support has a base, a telescopic column, and a cross beam on top of the column with auxiliary beams pivotally connected to the cross beam to engage the roof. Hydraulic jacks are connected between the base and the outer ends of the beams, respectively. A pedestal is pivotally mounted on the front end of the body, on each side of the center boom, to support a drill boom. A drill head is pivotally mounted at the outer end of the drill boom and is vertically movable by the drill boom for roof drilling. Each drill boom has the end opposite the drill head received in a track on the pedestal which serves to maintain the drill head on a vertical axis in any position of the drill boom. Each pedestal, at its inner end, has a laterally extending arm, the outer end of which is pivotally connected to the body at a pivot joint.

Abstract: In a system for the supply of fluid under pressure to machinery of an underground mine working, lengths of fixed conduit are secured to parts of the conveyor assembly, prior to the assembly of said parts at the underground mine working. When the conveyor assembly has been assembled, the length of fixed conduits are interconnected, either by straight lengths of flexible conduit, or by branched lengths of flexible conduit, where take off for fluid under pressure is required for the machinery, for example a roof support unit.

Abstract: A stabilizing arrangement for mine roof support systems of the type in which a series of support units, each including a transverse beam supported at opposite ends by extensible props, are interconnected by extensible struts in a manner to be self-advancing by alternate retraction of support units from a roof supporting condition and extension of the struts to advance such retracted units relative to others of such units which are in an extended roof engaging condition. The connection of each prop to the beam in a given unit is pivotal to allow deflection of the beam and props of a supporting unit from a normal perpendicular relationship under load. The stabilizing means restores the props and beam to a normal perpendicular relationship for advancing movement of each support unit.

Abstract: A support assembly for a mine working has a floor-sill structure for engaging on the floor of the working and a roof-engaging member or members braced by one or more props against the roof of the working. The floor-sill structure employs one or more slidable skids which can be selectively extended in length at the forward end by fitting an extension component of the same width thereto. The or each skid is recessed to receive rear projections of the associated extension component and securing means, such as spindles or shaped locking elements, are used to secure the extension component to the skid. When the extension component is removed, inserts are located in the recesses of the skid to fill the latter and these inserts can be likewise secured with the same securing means.