GB1070448A - Improvements in hydraulic drive systems for mineral mining machines - Google Patents

Abstract

1,070,448. Hydraulic drive systems for winding. ANDERSON MAVOR Ltd. Dec. 28, 1965 [Sept. 24, 1964], No. 38892/64. Heading B8B. An hydraulic drive system for hauling a mineral mining machine 5 via a chain 4 and pulley 3 comprises a reversible hydraulic motor 1 driven by an hydraulic pump 6 through flow and return lines 9, 10, 11, 12, a changeover valve 8 in the said lines for controlling the direction or stopping of the motor 1 and a recirculation valve 21 in a recirculating line 20 between the flow and return lines 11, 12 adjacent the motor 1, the valve 21 being held closed by fluid in a line 27 except when the changeover valve 8 is selected for stopping the motor 1, The changeover valve 8 comprises a channelled rod 14 slidable in a cavity 15 of the valve block to connect the motor lines 11, 12 to either of the flow and return pump lines 9, 10 or connect line 9 to line 10 whereby the motor is no longer driven by the pump 6. When the motor is being driven the pressure in lines 9, 27 is such that valve member 28 of valve 21 is held closed blocking the recirculation line 20, but when the motor is not driven, the pressure in the flow line 11 or 12 becomes greater than that in the lines 9, 27 and valve 21 opens allowing circulation of fluid between lines 11 and 12. In the latter situation motor 1 is driven by residual stress in the haulage chain 4 until such stress is relieved, a restriction 31 in the recirculation line 20 damping the motion. An electric motor 7 drives the pump 6 and a priming pump 34 for replacing fluid which has leaked from the system. The priming pump 34 is connected to a fluid reservoir 35 and feeds the system through a non-return valve 36. In the embodiment of Fig. 1 (not shown) the return line 10 between pump and changeover valve includes the reservoir.