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 for controlling the main and auxiliary drives of conveyors, for example, in underground mining. The drives are controlled as a function of the loading of the conveyor in such a way that in a low load range of the conveyor the auxiliary drive produces a higher output (20.sub.I) than the main drives and as the load increases the output advantage of the auxiliary drive in relation to the main drives is reduced. This special load distribution to auxiliary and main drives has the advantage that sagging of the conveyor element, for example the chain of a scraper chain conveyor in the inaccessible and concealed lower strand, close to the main drive, can be prevented. The risk of damage to the machine frame or conveyor chain is thereby reduced.