Patent GB-468860-A (GB)
Title: Improvements relating to the hoisting of coal by winding skips
IPC: B66B17/32
Filed: 1936-02-06
Abstract: 468,860. Skip-winding of coal with hoppers forming air - locks. INTERNATIONAL COMBUSTION, Ltd., and DAVIDSON, G. W. Feb. 6, 1936, No. 3649. [Classes 78 (i), 78 (iii), and 78 (iv)] In the skip - hoisting of coal in pit-shafts with sealed mouths, in which the skip is received in an air-lock at the top of the shaft and transfers its contents to a hopper which feeds a conveyer belt outside the shaft, the hopper is provided with two doors constituting an auxiliary air-lock and operated automatically by the movement of the skip so that as the latter approaches its discharging position the lower or delivery door is closed and the upper or receiving door subsequently opened, while the downward movement of the skip after discharge first closes the upper door and then opens the lower one. In the form shown, a pneumatic control system with differential piston valves is employed, but hydraulic or electric systems may be used. As shown, the upward movement of the skip causes a ramp 3 thereon to actuate valves 5, 5<a> in turn. Actuation of valve 5, admits air from pressure main 6 to pipe 8 through the check valve 7. This air then passes through a non- return valve 8<a> to charge a reservoir 9 and also to apply pressure to and open a differential piston valve 10, the reverse side of which is subject to reduced pressure from the main 6 supplied through pipe 11 and a reducing - valve 12. Opening of valve 10 puts the pipe 11 into communication with pipe 13. This causes valve 14 to be operated to put pipe 11 into communication with cylinder 15 to slide the bottom door 16 to the right to close the hopper 17 and also operates valve 33 to open the opposite end of the cylinder to the atmosphere through the pipe 34. At the completion of the movement of the door a projection 18 contacts a pivoted member 19 and opens valve 20 mechanically so that the pressure in pipe 13 is transmitted through pipes 21, 22 and 23 to the cylinder 24 to open the upper doors 26 by a movement to the left. During this movement the pressure in the pipes 21, 22 maintains the valve 25 in such position that the left-hand end of the cylinder 24 is open to the atmosphere. As the skip moves upwards and allows the valve 5 to close, the reservoir 9 supplies the necessary pressure to the valve 10 to allow both door-operating movements to continue until the skip opens valve 5<a> and restores the pressure in the pipe 8. In the same way the reservoir maintains the pressure in the system during the initial downward movement of the skip, but when valve 5 has re-closed after the downward passage of the skip the pressure in pipe 8 gradually falls by regulated leakage to atmosphere at the valve 8<a> until the valve 10 is re-closed by the counterpressure in the pipe 11. This closure cuts off communication between the pipes 11 and 13 and allows the pressure in pipe 11 to operate valve 25 to open pipe 23 to atmosphere and to put pipe 11 into communication with the left - hand end of cylinder 24 to close the upper door. At this stage pipes 13, 21 and 22 also are exhausted through their open connection with the pipe 23, and the valve 29 is opened mechanically on the completion of the closing movement of the upper door. The absence of pressure in pipe 13 allows the pressure in pipe 11 to set valve 14 to open left-hand end of cylinder 15 to exhaust and also allows pressure in the pipe 35 to open the valve 33 so that pressure to open the lower doors is supplied through the pipes 35, 30, 31 and valve 32. A master cut-off valve X renders the whole system inoperative when winding men. The upper door may be interlocked with a switch controlling the hoisting motor so that the skip cannot be lowered when these doors are open.