GB892876A - Improvements relating to braking systems for drum winders, haulages, friction winders, and other like rotating devices - Google Patents

Abstract

892,876. Fluid-pressure brakes. ROBEY & CO. Ltd., and CROMPTON, A. May 15, 1958 [May 15, 1957], No. 15390/57. Class 103 (1). In a braking system for a rotating device (e.g. a mine winder) at least one brake is operable to brake the device and means responsive to overspeed of the device is adapted to actuate independently-operable first and second brakecontrol means at first and second predetermined values of overspeed of the device. Fig. 1 illustrates a theoretical duty cycle A with overspeed protection during constant speed and deceleration periods of a first predetermined overspeed value B and a second predetermined overspeed value C. In the braking system shown in Fig. 2 applied to a mine winder, a normal or first brakeapplying means is constituted by a piston 4 operating in a brake cylinder 5, the piston 4 being urged downwardly by pressure-fluid supplied to the upper end of cylinder 5 from an accumulator 2 via pipes 13 and 16 so that the arm 9 is moved downwardly to rotate the shaft 11 clockwise in the brake-applying direction when the pressure in the lower end of the cylinder is exhausted. A stored-energy emergency or second brake-applying means is constituted by weights 1 supported against gravity by fluidpressure in accumulator 2. If at any time overspeed exceeds the first margin allowance (represented by the vertical distance between lines A and B) a cam 6 on a speed governor (not shown) operates a first brake control means constituted by control valve 3 to exhaust the lower end of the cylinder 5 and cause application of the brakes. In the event of the valve 3 failing to operate and the overspeed exceeds the second margin allowance (represented by the vertical distance between lines B and C), the second brake control means, constituted by a valve 8 operated by a linkage 18 co-operating with a second cam 7 on the speed governor, is actuated so that the lower end of the brake cylinder and pressure accumulator 2 are both connected to exhaust through pipes 13, 14, respectively, and the shaft 11 is rotated in a clockwise direction by the link 10, the braking effort being supplied by the weights 1 falling under gravity. The latter braking effort is arranged to be greater than that applied at the first overspeed value by appropriate proportioning of the moments applied to the arm 9 by the piston 4 and the weights 1 or by arranging the cam 6 to cause less than total exhaust of the fluid in the lower end of cylinder 5 when tne first overspeed value is attained. The cams 6 and 7 may be replaced by solenoids associated with a speed governor for the winder. Specifications 540,921, 633,129, 674,330 and 846,555 are referred to.