Abstract: In a longwall mining operation wherein a takeoff shaft provided with a takeoff conveyor and an access shaft extend crosswise from a longitudinally extending face, a material recovering and conveying system has a chain itself having a longitudinally extending rear stretch extending along the face from a turnaround in the access shaft to a turnaround in the takeoff shaft and a longitudinally extending front stretch extending along the face between the rear stretch and the face. An undriven idler wheel is provided in the takeoff-shaft turnaround over which the chain is engaged between its stretches and a conveyor trough extends between the turnarounds and has a floor formed in the takeoff shaft with a throughgoing outlet hole above the takeoff conveyor. Conveyor/cutting elements on the chain move in the front stretch along the face and in the rear stretch along the trough.

Abstract: The pressure measuring device has a housing in which a pressure chamber is located in a pin extending freely in the interior of the housing from a base. The pressure chamber wall is deformable elastically under an applied pressure. In the free end portion of the pin a magnetoresistive sensor is mounted which is moved with the chamber wall in a displacement occurring because of pressure changes in the chamber and thus is displaced relative to a permanent magnet. The magnet is mounted slightly transversely in the end portion of a compensating sleeve which surrounds the pin with wall contact. The change of the magnetic field at the sensor on displacement causes a proportional resistance change of the sensor so that an electrical signal proportional to the pressure change is generated which is a measure of the pressure. An amplifier for the signal from the magnetoresistive sensor can be mounted inside the housing adjacent the permanent magnet or the magnetoresistive sensor.