Hydraulischer Antrieb für Aufzüge

摘要

The invention concerns a secondary-control hydraulic drive system for lifts, wherein a hydrostatic unit driven by an electric motor feeds pressure medium into an operating pressure line (8) in which an applied pressure, if possible a constant pressure, is maintained. One or a plurality of hydrostatic lift cage driving motors (1), designed as hydrostatic units with lifting displacement, is/are connected to the operating pressure network. If these driving motors operate as pumps driven from the lift cage, flow medium is drawn out of a low-pressure line (12) and conveyed into the operating pressure network. Since sufficient flow medium for the pumping operation of the driving motors is always available owing to the preloaded pressure in the low-pressure line, the assembly can be set up in the cellar of a building in order to generate and maintain the high operating pressure whilst the driving motors can be installed at a separate location. This would be impossible if the driving motors were connected in the conventional manner to a tank pipe or a reservoir, since in that case no flow medium could be drawn out of a lower lying tank line during a pumping operation.