GB1006905A - Mine hoisting equipment - Google Patents

Abstract

1,006,905. Lifts. ANGLO AMERICAN CORPORATION OF SOUTH AFRICA Ltd. July 13, 1962 [July 18, 1961], No. 27007/62. Heading B8L. In a mine hoisting system, the head sheave is vertically movable under the action of an hydraulic ram which is controlled automatically to make corrections for rope stretch so that the cage is brought to the correct decking level at each station. As shown, the head sheave 16 is supported by an hydraulic ram 22, 24 suspended from a load cell 38. An electric control circuit for the solenoid 46 of a two-way valve 36 for controlling fluid flow to and from the ram comprises a mixer unit 42 which receives signals corresponding to the total load on the head sheave 16 from the load cell 38 through an amplifier 40, signals corresponding to the tare weight of the cage through a rheostat 48 and signals corresponding to the varying weight of the suspended rope through a rheostat 52 which is coupled to the winding drum 14. The output of the mixer unit 42 together with signals from a rheostat 53 coupled to the winding drum 14 are fed to a proportioning unit 44, and compared therein with signals from a rheostat 57 indicating the position of the piston 22 in the cylinder 24. The output signal of the unit 44 gives a measure of the rope stretch due to the net load at any point in the shaft and is fed to the solenoid 46 to open the valve 36 so as to compensate for the rope stretch. The circuit includes a normally-open switch 56 which is closed on operation of the driver's brake lever 54. In a second embodiment, Fig. 2 (not shown), the position of the cage is detected by proximity switches or other scanning means which transmit signals through cables or at carrier frequencies on the hoisting rope to control the solenoid 46. In a modification, Fig. 4 (not shown), the control system is applied to a hoisting system wherein two cages in balance are provided in the shaft.