Impact ripper for coal mining - delay device retards reversal time from active to return strokes by flow resistance

摘要

Impact ripper for coal mining is retracted by fluid pressure medium and driven forward when the fluid is bled from the chamber of the piston and cylinder unit and has a pressure chamber to release stored medium during the active stroke. When the pressure in the chamber reaches maximum it reverses the return movement to initiate the forward stroke, using the ensuing low pressure in the chamber to re-start the cycle. The control line (14a, 14b), responsible for this process includes a time delay device (15) which can delay the point at which the impact stroke reverses into the return stroke. The device should be on a flow principle, having less flow resistance in the direction from the pressure storage chamber (12) to the control valve (13). The device may be a choke valve (17) whose parallel non-return valve (16) blocks flow in the direction of the pressure chamber.