Control circuit for a hydraulic power lift operated with a variable-displacement pump

摘要

The control circuit has a stop valve releasable at least for lowering movements of the power lift, a load-signalling line carrying the load pressure, and a control arrangement opening and closing the stop valve as well as regulating the volumetric flow from a pump line into a working line leading to the power lift or from the power lift into a tank line leading to a tank. This control arrangement has a servo valve with three operating positions for regulating the volumetric flow to or from the power lift and a regulating unit for opening and closing the stop valve. The load-signalling line is connected to the working line and in the initial position of the control arrangement to the tank via the servo valve. Adjoining the initial operating position of the servo valve in which the working line is connected to the tank line is first of all the centre or stop position and then an operating position in which the working line is connected to the pump line. First regulating springs of the regulating unit and the servo valve are loaded via a common control line. In order to ensure that pressure reactions occur in the working line downstream of the stop block during the switching on and off of the control pressure in the common control line from the neutral position of the servo valve, a ... branches off from the common control line ... Original abstract incomplete.