Abstract: A course measuring device for measuring a course of a longwall mining installation along a longwall face is disclosed. The course measuring device may have a first segment extending along a first axis. The course measuring device may also have a second segment extending along a second axis. The second segment may be movably connected to the first segment. The course measuring device may have a course measuring unit for measuring a spacial relationship between the first axis and the second axis. The course measuring device may also be adapted to move along the longwall mining installation.

Abstract: An extraction device, particularly for mining, having two drive stations and a drive chain which extends between the sprockets thereof. So that hanging chain or chain wear to a conveyor chain, in the case of a conveyor device, or to a plow chain, in the case of a plow device, can be detected, magnetic sensor units for detecting at least one chain condition of the drive chain are provided, wherein each sensor unit includes a transmitter, which is formed by a static or dynamic magnetic field generator, and a detector field, which is provided with a plurality of magnetic field detectors, as a detector, the detector and the transmitter being arranged to the side of a passage for the run of the drive chain that is to be scanned. The invention also relates to a method for controlling an extraction device for preventing hanging chain.

Abstract: An extraction device, particularly for mining, having two drive stations and a drive chain which extends between the sprockets thereof. So that hanging chain or chain wear to a conveyor chain, in the case of a conveyor device, or to a plow chain, in the case of a plow device, can be detected, magnetic sensor units for detecting at least one chain condition of the drive chain are provided, wherein each sensor unit includes a transmitter, which is formed by a static or dynamic magnetic field generator, and a detector field, which is provided with a plurality of magnetic field detectors, as a detector, the detector and the transmitter being arranged to the side of a passage for the run of the drive chain that is to be scanned. The invention also relates to a method for controlling an extraction device for preventing hanging chain.