Hydraulic lifting system for battery operated ground conveyor vehicle

摘要

A DC machine is used coupled to an hydraulic set (12), which works as electric motor lifting load and as a generator when lowering load. A changeover valve (22) controlled by a control system (26) is connected with the return flow outlet of the control valve (16). The output of the changeover valve is connectable selectively with the tank (32) across a hydraulic lowering brake (28) or with a pressure line (14) from the set (12) across a non-return valve (38).A first pressure measuring unit (48) measures the pressure (S1) between the lifting cylinder (18) and the control valve (16), and gives a corresp. signal to the control system (26). The changeover valve (22) connects the valve (16) with the line (14), if the measured pressure (S1) exceeds a preset value. A signal transmitter (46) is allocated to the auxiliary users (20), which with one operated, gives a signal to the control system. A second pressure system (52) measures the pressure between the valve (16) and the changeover valve, and the control system regulates the DC machine to an rpm, with which the pressures (S1,S2) are held approx. constant, and direction of rotation of DC machine (10) is reversed in to generator mode, if the pressure difference is lower than the specified value.