Patent GB-948077-A (GB)
Title: Improvements in or relating to winding gear for colliery and like winding equipment
IPC: B66D5/00
Filed: 1959-12-21
Abstract: 948,077. External shoe drum brakes; fluid pressure control of brakes. G. A. BLACK. Dec. 16, 1960 [Dec. 21, 1959], No. 43374/59. Headings F2E and F2F. An external shoe drum brake for winding apparatus is applied by springs and released by fluid-pressure, and comprises two separate spring units for applying the same brake in a winding mechanism, means opposing the force exerted by one of the units being provided whereby this unit may be held out of operation while the other is being actuated, and means whereby both units may be operated together to produce a braking force equal to the sum of the braking forces derivable from each unit. In one embodiment, the brake comprises two spring units 6, 7, Fig. 2, carried respectively by shoes 1, 2 pivoted at 3, 4 for movement into and out of engagement with a drum 5. Each of the units 6, 7 acts on both shoes through levers 8, 9 pivoted on the respective shoes and linking rods 10, 11 each independently adjustable for wear by nuts engaging threaded portions of the rods adjacent their connecting points. One rod, i.e. the rod 11, is connected at the end remote from the corresponding spring unit 6, via a lost-motion connection 12, 13 to the opposite shoe 2. Each spring unit comprises a set of springs for applying the brake and a pair of cylinders which act against the springs to release the brake. Oil is supplied by pumps 21, Fig. 5, via non-return valves 29 and by-pass 22 to a control valve 23 which acts to pass oil either directly to and from the pairs of cylinders in both units 6, 7 associated with each of two winding drums, in one position, or in the other position to pass oil directly to and from the cylinders in units 6 but via non-return valves 23b to the cylinders in units 7 so that these units are held off. Either both units 6 and 7 or just the units 7, according to the position of valve 23, are further controlled by a driver's regulator valve 24 for varying the oil pressure between the maximum and zero, at which latter maximum braking is obtained. A trip valve 25 can be opened in an emergency to give maximum braking instantly. The valve 23 is operated by a solenoid or automatically according to the direction of movement of the winch drums so that, e.g. where the position of one cage in a mine shaft is adjusted relative to another, so that the cages are temporarily unbalanced requiring greater braking force to hold the respective winding drums, the valve 23 is moved to a position in which both units 6 and 7 are operative. In normal use the two cages are balanced and are moved together in opposite directions so that lighter braking, provided by moving the valve 23 into its other position in which units 7 only are operative, is all that is required. In order to cope with failure of the units 7 should e.g. a link rod break, the cylinders of the normally inoperative units 6 are arranged to be automatically connected to the oil feed to the cylinders of the units 7 via an annular port way 26 in each cylinder of unit 7, and a port way 27 in the associated piston which communicates by a passage 28 with the pressure side of the piston, the arrangement being such that the port ways 26 and 27 are aligned should the piston overstroke. The corresponding unit 6 is then placed under control of the driver's valve so that braking is restored. In a modification, Fig. 6, separate control valves 32 are used for the pairs of units 6, 7 associated with the respective winding drums, each movable between the position shown, in which oil is supplied direct to the associated units 7 and via non-return valves 35 to the associated units 6 so that the latter are held off, and another position in which d, e and c are interconnected for exhausting the cylinders of the associated units 6, 7, and a, f are connected in place of a, b, so that each valve supplies oil direct to both pairs of units 6, 7 of the other winding drum so that maximum braking on either drum can be doubled while still under control of driver's valve 33, the brake being held by both units 6 and 7 on the other drum independently of driver's valve 33. Solenoid valves 39 may be added if desired so that double braking can be used on both winding drums while retaining driver control. The cylinders of units 7 again have provision for coupling units 6 to the driver's valve should their pistons overstroke, so that, in the normal condition with only units 7 operative, braking is automatically restored by units 6 should a link rod associated with units 7 break. In a modification of the brake itself, Fig. 7, the units 6 and 7 are mounted side by side on one of the two brake shoes and coupled through levers 40, 41 on that shoe and link rods 42, 43 to the other shoe. Operation of the brake is identical with that shown in Fig. 2 since each spring unit operates both shoes as before. In a further modification however, Fig. 10, the units 7 are replaced by units 44 acting separately on the shoes 1, 2 so that they may be controlled independently to provide further control of maximum braking, while a unit 45 is mounted on shoe 2 and is connected by lever 46 and link rod 47 to the shoe 1 to provide emergency or additional braking as did the units 6 in the previous embodiments. The shoes 1, 2 in this embodiment are pivoted at 3, 4 on sliding blocks adjustable by screw-and-nut mechanism. Specifications 691,941 and 782,023 are referred to.