Device for controlling the slide-bar cylinders of hydraulic self-advancing powered support units

摘要

The invention relates to an improvement and further refinement of the synchronous control system according to the main patent P 3318641.3. The improvement and further refinement consists in the synchronous control system being designed as a reversing control system which, during pressurising of the shifting cylinder for shifting the support, controls the shifting operation as a function of the retraction of the slide bar so that the support is only drawn up when the slide bar also actually retracts.