HYDRAULIC DRIVE OF EXCAVATOR BOOM Russian patent published in 1997 - IPC

FIELD: hydraulic drive technology. SUBSTANCE: excavator boom hydraulic drive has hydraulic pump unit, hydraulic tank, reversible hydraulic control unit, hydraulic cylinders, hydraulic accumulator, safety and non-return valves, three-way two-position hydraulic control valve with automatic switching. Three-way control valve is connected by its first inlet with hydraulic pump, with lifting space of first boom hydraulic cylinder and with control space, and by its second inlet it is connected with inlet of hydraulic accumulator and with second control space, and by its outlet it is connected with boom lifting space of second hydraulic cylinder. In interval from maximal to minimal permissible charging rate of hydraulic accumulator, priority for shifting two-position control valve is afforded to control space which is connected with outlet of hydraulic accumulator. Gas space of hydraulic accumulator is connected with pressure relay having contacts of minimal and maximal pressure and can combine spaces of hydraulic cylinders for raising boom at closing of minimal pressure contacts, and at closing of maximal pressure contacts it can function as safety valve. Three-way two-position hydraulic control valve with automatic shifting and non-return hydraulically controlled valve can be made in the form of non-return valve with control directly through pressure relay contacts. EFFECT: high efficiency. 3 cl, 3 dwg