TELESCOPIC NON-YIELDING HYDRAULIC PROP Russian patent published in 1994 - IPC

FIELD: mining. SUBSTANCE: telescopic non-yielding hydraulic prop includes cylinder with piston and rod having axial hole accommodating second stage piston with hollow rod accommodating additional check valve and tube communicated with head end of second stage and above-valve space of additional check valve whose under-valve space is communicated with return hydraulic line. Additional check valve is located in head of rod of hydraulic prop second stage. Above-valve space of additional check valve is communicated with additional inlet accommodating emergency safety device, and under-valve space is communicated with pressure-return hydraulic line of head end. EFFECT: higher efficiency. 2 dwg