Abstract: The present disclosure relates to a technical field of coal mining, particularly to a method of no-pillar mining with gob-entry retaining adapted for fully-mechanized top coal caving in a thick coal seam, which comprises the following steps: reinforcing support on a roof and two sides of a roadway; performing roof slitting blasting to form a pre-splitting slit; erecting a temporary support device and a gangue retaining device in the roadway along the retained entry; performing no caving within a range of a preset distance at an end of the working face near the retained entry side; and removing the temporary support device in the roadway after entry forming stabilizes, and closing the goaf to complete entry retaining.

Abstract: A pin retaining assembly for an advancing ram includes a retention plate and a retainer. The retention plate includes two oppositely facing surfaces and a channel with a notch between the two surfaces. The retainer includes a main body, a pin receiving slot, and at least two flanges. The main body is configured to slide into the notch of the channel and extend through a surface of the retention plate. The pin receiving slot has an open mouth through an end of the main body. A first flange extends from one end of the main body along a surface of retention plate and a second flange extends from another end of the main body along another surface of retention plate. The flanges retain the main body of the retainer in the first notch from moving in a direction defined by a longitudinal axis of the pin receiving slot.

Abstract: A shield support for underground mining has a slider and a roof bar between which a ram is arranged, with an inclination detector being provided with which the inclination of the roof bar can be measured.

Abstract: Corrosion resistance is provided for a power cylinder by providing a preloaded molded urethane elastomer sleeve liner within an outer cylinder of material such as a copper/nickel alloy which is subject to corrosion from long-term exposure to ambient fluids such as sea water. Preloading is preferably provided by thermal shrink fitting of the molded urethane sleeve liner to the inner bore of an outer metal cylinder. Preloading of a structure which has high structural integrity and low permeability thus effectively prevents incursion of fluids and gases at the interface between the outer cylinder and the sleeve liner as well as providing a surface which can be machined to a high degree of smoothness and against which reciprocating piston seals and wear assemblies can directly ride and which is resistant to abrasion therefrom even at high piston speeds.

Abstract: An advancing support frame is connected to the face conveyor (9) via an advancing rod (7) engaging with the advancing cylinder (5). A lifting cylinder (10) is supported on the advancing rod (7), with which the base shoes (1) are lifted during the advancing process. The lifting cylinder (10) is guided so as to be able to move in height in longitudinal guides (15) on the inner sides of the base shoes (1). A U-shaped tension stirrup (18), whose shanks (19) directed towards the ground have elongated holes (20), is supported centrally by the lifting cylinder (10) and joined to the base shoes (1) via carrying bolts (21) fastened to them.

Abstract: A method is described for protecting piston cylinder devices against corrosion by a pressure resistant thermoset or cured material coating. At least the outer and inner cylindrical surfaces, for example, of a mine prop, that cooperate with a sealing device, are coated with a three-dimensionally cross-linked, cured or thermoset material having a sufficient thickness on the one hand for providing the intended protection against corrosion and on the other hand to avoid excessive radially directed elastic deformations of the coating. An additive is included in the coating to improve the dry lubricating characteristics, and thus the cooperation between the coating and the sealing devices. The three-dimensionally interlinked thermoset material fills all surface irregularities so that gas and water pockets, for example, in a mine prop, are avoided.

Abstract: A mine roof support employs a pair of floor skids carrying hydraulic props on which a roof-engaging structure is mounted. A goaf-shield is pivotably mounted to the roof-engaging structure and is connected with a lever system to the floor skids. A shifting and guide mechanism is disposed between the floor skids and takes the form of an hydraulic ram connected at the rear to a floor rail disposed beneath the ram. The ram is supported at the front end by a bridge member connecting the front ends of the skids together. An hydraulic lifting unit is mounted on the bridge member and when extended the unit bears on the floor rail to partially lift the skids as the shifting ram is operated. The lifting unit can be mounted to the bridge member in one of several alternative height positions.

Abstract: A walking mining prop has a skid-lifting assembly in the region of the ram which braces the roof cap with respect to the skid formed by a bridge from which lifting cylinders are articulated and suspended. The pistons of these lifting cylinders are articulated to a pressure plate which at least partly surrounds the guide rods of a guide-rod assembly on which the skid is guided, a mechanism being provided to advance the skid relative to the guide-rod assembly.

Abstract: The mobile stope support apparatus comprises a number of individual units (10) which are interconnected by hydraulic cylinders (12). Each of the units (10) has a series of upright, double-acting legs (20). The legs (20) have independent bases of rounded shape and they are pivoted to an overhead canopy (22) which can be raised and lowered by appropriate actuation of the legs. Each unit also has a fore-and-aft hydraulic cylinder (34) which is connected to a common rail (37), the cylinder (34) being pivotable, by the action of a cylinder (36) in an upright plane to raise and lower the rail. By appropriate sequential operation of the various cylinders, the units can be advanced in turn to advance the whole apparatus. In addition, by appropriate operation of the cylinder (36), the front legs (20) can be lifted off the footwall to facilitate movement of the unit over a rough or uneven footwall.

Abstract: A mine roof support includes a ground engaging base section, a roof engageable canopy, and hydraulic props for raising and lowering the canopy relative to the base section. An advancing mechanism is provided for advancing the roof support towards the mine face, and a base lifting mechanism is provided for raising one end of the roof support prior to advancing the support towards the mine face. The base lifting mechanism includes a lifting ram mounted with respect to the base section for slidable movement between an upper operative position in which the ram can be extended to lift the one end of the roof support clear of the ground and a lower position in which the canopy can assume a position relative to the base section lower than would be possible with the lifting ram in its upper operative position.

Abstract: Mine roof support comprising a base including a pair of skids, a roof engaging canopy, jacks acting between the base and the canopy, an auxiliary jack connected to the base for lifting or lowering at least part of the base when the support advances and a lost motion arrangement connected between the base and the auxiliary jack for aiding movement of the base and the roof engaging canopy toward each other. The lost motion arrangement is connected to each of the skids by a pivotal connection which permits the front end of one skid to move vertically to a limited extent with respect to the front end of the adjacent skid.

Abstract: A method and device is provided for the moving of a shield-type support trestle 1 having stamps 4, 5 arranged between a roof pressure cap 3 and a lying skid 2, a pushing ram 6 is in the lying skid 2, and control valves 11, 12, 13, 14 for controlling the desired functions of the shield-type support trestle 1. The stamps 4, 5 have an inlet valve 22 and a discharge valve 4. A pressure line 40 is provided between control valve 13 and the pushing ram 6. A valve 51 is provided which is controlled by the pressure in the pressure line 40 and by which interconnects stamp pressure chambers. A manometric switch 48 is arranged on the pressure line 40 and activates an electronic control device 42. In lines 53, 55, and 29 between the stamp pressure chambers and the return line 18, an unlockable reflux valve 54 is provided which is actuated through the electronic control device 42 and the discharge valve 24.

Abstract: The invention relates to a travelling support pillar for use in underground mines.The support pillar has a link subjected to the action of a positioning jack. The positioning jack extends between a gate and the rear of the top of the pillar. The positioning jack hydraulically locks the support pillar by means of a sliding pressure-relief valve to compensate for load changes due to the movement of the floor or the roof. The link also permits the support pillar to be collapsed for transportation, and it provides a support pillar with a shorter length and a lower height in the collapsed position, and it permits the top of the support pillar to be placed closer to the working face of the mine when the pillar is in its roof supporting extended position.

Abstract: Attachment means are provided for attaching a mine roof support to an abutment, (e.g. a flexible conveyor) the attachment means comprising a ram arrangement in the form of at least two rams 25, 26 operable to effect relative movement between the mine roof support and the abutment. The provision of two or more rams instead of the conventional single ram means that smaller bore rams may be used, for example a 60 mm bore as opposed to 41/4 inch bore and this makes it possible to cover or encase the rams in a protective shield without reducing the vertical space available to a miner underneath the mine roof support.

Abstract: A mine roof support unit includes a pair of generally parallel floor girders, and an advance mechanism positioned between the floor girders. The advance mechanism comprises a hydraulic advance ram and a guide rod system. The advance ram is pivotally connected between the guide rod system and a cross member which interconnects the floor girders. The guide rod system is attachable to a longwall conveyor positioned adjacent to a work face. The cross member is engageable with the floor girders in such a manner that the floor girders are relatively displaceable in a vertical direction. Each of the floor girders is provided with a respective hydraulic lifting ram, the arrangement being such that the lifting rams can be operated to lift one of the floor girders relative to the other floor girder.

Abstract: A mine-roof support has a floor beam, an advancing ram and a relay bar. A bell-crank lever is pivotally-connected to the floor beam and the advancing ram is pivotally-connected to the bell-crank lever. One arm of the bell-crank lever has a member which may be in the form of a ball. The pivotal connections are such that, on extension of the ram, when the relay bar is connected to part of a conveyor, the bell-crank lever is initially urged downwardly from an inoperative position away from contact with the relay bar, into an operative position in contact with the relay bar, thereby to apply an upward thrust to the front end of the support and to maintain an upward thrust during further extension of the ram and consequential advancing movement of the mine-roof support towards the conveyor.

Abstract: A shield-type support frame for serving as a face support in underground mining operations having a bottom structure, a one-piece roof cap, at least one hydraulic plunger connecting the bottom structure and the roof cap and two shield elements arranged side by side, which can be adjusted in height separately and which are each pivotally connected to the bottom structure and the roof cap. Joint connections between each shield element and the roof cap permit tilting of the roof cap relative to the shield elements about axes extending in the forward direction.

Abstract: A mobile mine roof support assembly has three mine roof support units coupled together by a common transverse beam. Roller devices are mounted beneath the floor sills of the support units. The roller devices are spring biased away from their floor sills so that they can lift the floor sills away from the floor of a working when the assembly is to be moved. At least one roller device of each support unit is a steerable roller device so that the assembly can be steered round bends. Each steerable roller device is pivotally mounted on its floor sill about a vertical axis, and is provided with an associated steering device. The steerable roller devices are preferably coupled together by means of a common steering device.

Abstract: A support for the roof in longwall mining operations includes a gob canopy at the rear of a roof canopy. The gob canopy can move about a vertical pivot and a horizontal pivot by operation of a hydraulic actuator. To stabilize the support, the gob canopy moves into or out of contact with the roof at the rear of the roof canopy. The actuators can move the gob canopy to the left or right side of the roof canopy about a vertical pivot so that a skeg member on the upper surface of the gob canopy drags along the mine roof for steering the roof support when it is advanced toward the mine face. Gaps between the gob canopies of side-by-side roof supports function in the manner of grizzly bars to permit recovery of small pieces of gob roof rock.

Abstract: A self-advancing mine roof support has a beam-like abutment adapted to be disposed generally adjacent and parallel to a work face. Three roof support elements are spaced apart along the abutment and are pivoted to the abutment. The abutment may be angled relative to the direction of advance by arranging the three support elements in staggered formation. A beam of the central support element is pivoted to the abutment. The two outer roof support elements are connected to the abutment by a linkage, e.g., guide arms, which allows the abutment to pivot about the beam of the central element without changing the distance between the three elements as measured at right angles to the direction of advance.

Abstract: A gantry support for supporting a roof of a passage is advanceable along a floor of the passage. The support has two parallel supporting elements mutually spaced apart laterally of the support, each element including at least two pairs of frames provided with articulated tracks. One frame of each pair is an upper frame and the other is a lower frame, the tracks of which are adapted to be applied respectively against the roof and floor of the passage by loading jacks applying a spreading force between the upper and lower frames. An intermediate upper frame is carried by an upper cross-member extending from one supporting element to the other and at least one loading jack applying a spreading force connects each lower frame to the corresponding end of the upper cross-member.

Abstract: A self-advancing, hydraulically powered mine roof support comprises a base means, a double-acting hydraulic advancing ram extending in the intended direction of advance of the support in use, the cylinder of the advancing ram being located towards the forward end of the support and the piston rod of the advancing ram being located towards the rearward end of the support, a lifting ram mounted on the support at or towards the forward end thereof and being operable on the periphery of the cylinder to lift the forward end with respect to the cylinder, the end of the cylinder remote from the piston rod being connectable to a pan of an armoured conveyor, and the advancing ram being connected to the support by an inclined link means pivotally attached to the base means and to the piston rod.

Abstract: A mobile self-propelled mine roof support system employing pairs of individually self-propelled roof support units movable along opposite ribs of a mine room to follow an advancing mine face. Each support unit comprises an elongated, wheel-mounted frame positioned along the adjacent rib. Pairs of vertical jacks are connected to opposite sides of the frame, being positioned loosely, and vertically movable, within oversize openings in brackets attached to the frame. A foot plate is universally pivotally attached to the lower ends of each pair of jacks and extends across the underside of the frame. A top-supporting canopy is universally pivotally attached across the upper ends of each pair of jacks and has an overhanging portion extending cantileverly into the room toward the opposite support unit. The jacks have external flanges engagable with the brackets.

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.