Abstract: According to the invention, monitoring the load on hydraulic powered shield supports in underground use is performed by using the controller (13) serving for extraction control, which is equipped with microelectronics for load monitoring and load control, the components of the powered shield support being assigned sensors (14 to 18) whose electric measured values are used by the controller (13) for evaluating the measured signals and for driving the hydraulic rams (6, 7) and/or the angle cylinder (11) assigned to the powered shield support. The load control is preferably designed here in such a way that the critical load situations "one-sided loading" and/or "tip-toeing" are detected as early as during the setting operation, with the aid of appropriate sensors, and are rendered non-damaging in their effect by appropriately driving the hydraulic rams and/or the angle cylinder.

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: A roof cap assembly of a roof support mechanism includes a main cap having extension bearing portions at its front end, a forward cap which is pivotally attached at its rear end to the extension bearing portions of the main cap, and two supporting cylinders connected between the main cap and the forward cap at spaced apart locations across their widths and so as not to extend therebelow. The supporting cylinders include a housing containing twin pistons and an adjustable pressure transmitter is provided for each supporting cylinder and is constructed to increase the pressure in the pressure chambers therein when the pressure of the pressure medium supplied thereto exceeds a minimum set value.

Abstract: A foot element of an adjustable roof support mechanism includes side walls that have aligned guide grooves in their facing surfaces and a spherical bearing surface in a floor portion therebetween. The guide grooves include inclined entry portions and enlarged terminal portions. A cooperable, extendable strut element includes a tubular body having a spherical lower end and two cams extending away from opposite sides near its lower end. The cams are shaped so as to fit within the guide grooves of the foot element. When attaching the strut element to the foot element the cams thereof are moved along the entry portions of the aligned guide grooves and into the terminal portions thereof. Thereafter, the strut is rotated into a use position. When in its use position, the cams cannot be removed from the terminal portions of the guide grooves, thus preventing unintentional separation of the strut element and the foot element.

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 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: In a mine roof support in which a roof shield, pressed by hydraulically operated, collapsable and extensible props, arranged between the roof shield and a sole plate, against the roof of a mine gallery, is connected at its rear end to a rear shield, which in turn is connected by links to the rear end of the sole plate and in which a hydraulically operated cylinder-and-piston unit is interconnected between the roof shield and the rear shield for controlling the included angle between these shields, an arrangement for stopping further feeding of pressure fluid into the props when the inclined angle between the shield reaches a predetermined minimum or maximum angle.

Abstract: A mine roof support for an underground mine gallery comprises a sole plate adapted to rest on the floor of the mine gallery, a front shield having a front end directed toward the mine face, a rear shield pivotedly connected at one end to the other end of the front shield and projecting rearwardly therefrom, a rocker arm connected at opposite ends respectively to the front and to the rear shield intermediate opposite ends of the shields, an expandable and contractable prop connected at one end to said rocker arm intermediate the ends of the latter and at the other end to said sole plate, and a pair of arms each pivotally connected at one end to the region of the rear shield distant from the front shield and at the other end to the sole plate.

Abstract: A pit prop has a floor-engaging foot, at least one arm pivoted at the rear of this foot and extending forwardly, a roof-engaging shield carried at the front end of this arm, and at least one ram extending vertically between the arm and the foot for pressing the shield against the roof and the foot against the floor. A hydraulic ram has its rear end pivoted at the rear end of the foot and its front end pivoted on the rear end of a rigid link whose front end in turn is pivoted on the face conveyor. The rear end of this link is slidable in and pivoted on the foot. A second link has its front end pivoted on the rear end of the main link and its rear end bearing vertically down against the foot but slidable therealong. A short lifting ram has its rear end pivoted on the rear end of the second link and its front end pivoted on the rear end of the main link above the pivot for the other displacement ram pivoted on this link.

Abstract: An advancing excavation roof support has a base and a shield assembly above the base. The base has two base portions which are spaced from one another at its end which faces toward the face of the excavation, and a lifting member is mounted between the two base portions for pivoting about an axis. A hydraulic cylinder-and-piston unit extends between the base and the lifting member and pivots the latter about its pivoting axis between a retracted position in which the lifting member is out of contact with the excavation floor, and an extended position in which an engaging portion of the lifting member engages the excavation floor and is downwardly spaced from the base so that the one end of the base which faces the excavation face is elevated and digging thereof into the excavation floor is prevented.