Abstract: An operator carriage intended to be used at a long-walled pit face in a coal or metal mine and comprising endlessly running members arranged at both ends of a conveyor and driven by a motor, an operation table suspendedly attached to the side of a spill plate of the conveyor and supported by running supports such as guide rollers which are engaged with guide rails attached to the same side of the spill plate, and a carrying mechanism arranged at the operation table so as to hold the endlessly running members.

Abstract: Apparatus for remotely operating self-advancing supports or the like at a long-walled pit face of a coal mine comprises a receiver attached to every group of the supports which are arranged in front of and along the long-walled pit face, each of the receivers having a specific frequency, hydraulic cylinders attached to the support for causing the support to be operated, electromagnetic valves connected to the receiver to control the hydraulic cylinders, and a portable operating means including keys for specifying the groups of the supports, key switches for specifying the supports to be operated, and a transmitting circuit having operating switches, wherein operating signals are applied from the operating means via the radio system to the receivers.

Abstract: A coal mining method at a long-walled pit face of a coal mine comprises combining self-advancing supports with a conveyor which is arranged along the long-walled pit face and on which a shearer is mounted, and arranging the effective shearing depth of shearing drums of the shearer to be at least half as long as the stroke of a shifter for shifting both of the self-advancing supports and the conveyor toward the pit face, whereby each of the self-advancing supports is progressively shifted toward the pit face every time that the whole area of the pit face is sheared at least twice by the shearer.

Abstract: Apparatus for drawing shearers comprises a conveyor on which the shearers move with sledges interposed therebetween and which is arranged along a long-walled pit face of a coal mine shearers drawing cable is arranged in fixing members which are arranged on the conveyor, and a pair of means are provided for releasing and fixing the cable from and into the fixing members, the means being arranged adjacent to the sledges and the cable located between the cable releasing and fixing means being engaged with a cable driving means housed in each of the shearer bodies, wherein a drawing force is applied only to the cable located between the cable releasing and fixing means when the driving means is rendered operative.

Abstract: Apparatus employed at the long-walled pit face in the coal mine so as to shift the conveyor toward the pit face wherein the conveyor which is arranged in front of the pit face and on which the shearer travels, is divided into several individual portions, and responding to signals transmitted from a position sensor arranged in each portion of the conveyor, a position signal generator attached to the shearer and a stroke sensor attached to one of hydraulic cylinders belonging to each portion on the conveyor, a group of electromagnetic valves for rendering operative the hydraulic cylinders which belong to that portion of the conveyor to be shifted are controlled so as to shift automatically when required only the corresponding portion of the conveyor.

Abstract: A coal mining machine intended to be used in a pit having a long-walled pit face and having a mechanism in which two cutting drums are attached to the main ranging arm of a ranging drum shearer through a sub-ranging arm and the position of said cutting drums is defined by the cooperation of said main- and sub-ranging arms.