GB895132A - Improvements in a mine hoisting system - Google Patents

Abstract

895,132. Pit-head winding gear. SOC. DES FORGES ET ATELIERS DU CREUSOT. July 4, 1960 [July 3, 1959], No. 23266/60. Class 78 (5). A mine hoisting system comprises a pit-head pulley 1 comprising main brake shoes 3 operable to arrest the pit cage at a prescribed pit level, and auxiliary brake means 8 engageable with the pulley 1 and mounted for limited angular displacements bodily and coaxially with the pulley 1 when in the engaged condition. Senser means (not shown) are positioned at the pit level for sensing minor displacements of the cage due to rope stretch, and actuator means 15 are operated from the sensor means for imparting compensatory angular movements to the auxiliary brake means 8 to oppose the displacements. In Fig. 1, auxiliary brake shoes 8, 8 (one only can be seen in Fig. 1) are journalled on eccentric portions 7 of a shaft 6 which is carried by arms 5 journalled on the shaft 2 of the winding pulley 1. A pneumatic piston and cylinder 12 acts on an arm 9 rigid with the shaft 6. The latter is coupled by a member 14 to a fluid pressure piston and cylinder 15. In operation, when the cage engages contacts adjacent the desired pit level, conventional circuitry results in the actuation of the main brake shoes 3, 3. After a suitable delay (produced by means not shown) the brake shoes 3 are released and the cylinder 12 is actuated to apply the brake shoes 8, 8. A suitable positional senser (not shown) is provided at the pit level in question for sensing minor cage departures from the level and associated servomechanism (not shown) operates the cylinder 15 to displace the brake shoes 8, 8 and thus rotate the driving pulley 1 so as to maintain a senser signal at a predetermined reference value thereby holding the cage in its constant desired vertical position. When the brake shoes 8, 8 are in their non-braking position, a roller 18 carried by an arm rigid with the shaft 6, bears on a surface 19 which is concentric with the pivot 2. This prevents friction in the bearing of the pivot 2 during winding operations. In a modification (Fig. 3) the shaft 6 is carried by plates 20 which are mounted on rollers 21. The latter bear on the surface of a block 22 concentric with the axis of the pivot 2. The piston 15 may be replaced by a spindle which is displaced by a screw-and-nut mechanism rotated by an electric motor (Figs. 5 and 6, not shown). The drive shaft of the motor may be connected to a follow-up generator for providing the necessary feedback action for the servosystem.