HYDRAULIC DRIVE Russian patent published in 1997 - IPC

FIELD: mechanical engineering, mobile machines with adjustment of speed modes of operation of working elements. SUBSTANCE: hydraulic drive includes hydraulic prime mover 1, pressure line 2 connected to actuating hydraulic prime mover via hydraulic distributor 3 with closed center, device metering flow rate of working fluid installed in pressure line ahead of hydraulic distributor, device unloading pump 5 having overflow valve 6 installed in side branch of pressure line 2 communicating with hydraulic tank with the aid of control valve 8 having throttle 10 and shut-off device installed in tank and line transmitting load signal connected with one end to control channel 8 between throttle 10 and electrohydraulic valve 11 and with other end - to section of pressure line between hydraulic distributor and device metering flow rate. Hydraulic drive is fitted with check valve installed in line transmitting load signal. Device metering flow rate of working liquid is fabricated in the form of three-line flow switch 13 with first check valve connected to its second line and installed in pressure line. Third line is connected via second check valve 19 and metering throttle. In neutral position of control valve of flow switch its first line communicates with its second line via second metering throttle. EFFECT: increased functional reliability and efficiency of hydraulic drive. 1 dwg