Hydraulic screw press drive

A drive of a hydraulic screw press comprising:

• a source of pressure;
• a low-pressure hydraulic line;
• a pneumatic line;
• a power cylinder whose movable member is connected with a press slide of the screw press;
• a pneudraulic accumulator comprising a hydraulic chamber communicating with said pressure source and a pneumatic chamber;
• an inlet valve;
• the power cylinder having a chamber communicating with the hydraulic chamber of said pneudraulic accumulator through said inlet valve;
• a discharge valve through which said chamber of the power cylinder communicates with said low-pressure hydraulic line;
• means for charging the pneumatic chamber of said pneudraulic accumulator comprising a pneudraulic cylinder with a piston, a distributor, and nonreturn valves;
• the pneudraulic cylinder of said means for charging the pneumatic chamber of said pneudraulic accumulator comprises a hydraulic under-piston chamber communicated alternately through the distributor with said pressure source and said low-pressure hydraulic line, and an above-piston pneumatic chamber communicated alternately through the nonreturn valves respectively with said pneumatic line and the pneumatic chamber of the pneudraulic accumulator.