Patent GB-642598-A (GB)
Title: An improved brake assembly for rotating bodies
IPC: B66D5/00
Filed: 1947-07-10
Abstract: 642,598. Winding brakes. STANDARD OIL DEVELOPMENT CO. July 10, 1947, Nos. 18374 and 18375. Convention dates, Aug. 19, 1946, and Aug. 30, 1946. [Class 78 (v)] [Also in Group XXXIV] A braking apparatus for controlling the rate of rotation of a hoisting drum comprises a pair of axially spaced brake bands, each with its own power operating means, which are arranged to be automatically applied and released in alternating periodic sequence in order to give a sensitive control. The two brake bands are shown at C and C<1> in Fig. 1, the outline of the drum being omitted. Each brake band has a cylinder and piston, 18 and 19 or 181 and 19<1>, which applies pressure to the drum by means of the linkage 24, 27, 29 shown in Fig. 2. Also connected to the brake bands are cylinders and pistons 33, 34 or 331, 341 pivotally mounted on the base frame. The two cylinders 33 and 33<1> are connected by fluid conduit pipes 60 and 60<1> by way of check valves 62, 63, 65, 66 and needle valves 68, the arrangement being such that downward movement of piston 34 produces upward movement of piston 34<1> and vice versa, the fluid flow from one cylinder to the other being uni-directional through the valves 68 by which it may be controlled. The applying pistons and cylinders 18, 19 and 181, 191 which are of the double-acting type are supplied with pressure fluid through pipes 128, 129 and 128<1>, 129<1> and identical valve members 100, 100<1>, the operation of which by the conduit system shown in Fig. 11 is as follows. As shown, the control lever 73 of a valve box 72 is in neutral position and this allows air to pass from a main supply line 71 through a branch line 80, an open valve 79, a double-check valve 81 and line 87 to a relay valve 120, so as to open the valve and allow air from supply line 121 to pass on to the valve unit 100 and by line 129 to the piston-rod end of cylinder 18. As a result, the band assembly C is tightened on the drum and carried round thereby so that the piston 34 in the cylinder 33 is moved up, it being assumed that the drum is turning anti-clockwise as seen in Fig. 2. The upward movement of piston 34 produces a downward movement of the corresponding piston 34<1> on the brake band assembly C<1> which is at present loose. The consequent clockwise movement of the band C<1> causes member 40<1> secured thereto to contact and open a valve 39<1>, which allows air from a supply line 1341 to enter the end of valve unit 100. A movable element 102 in the unit 100 is thus moved over to the right, changing over the supply of air by pipe 122 from the piston-rod to the other end of cylinder 18. Movement of element 102 to the right, also through connecting rods 111 and 111<1>, moves a similar element 1021 in the valve unit 1001 to the right and allows air to pass from pipe 122<1> to pipe 129' and the piston-rod end of cylinder 18<1>. The band assembly C<1> is thus tightened on and carried round by the drum until the opposite movement of the assembly C causes an element 40 secured thereto to open a valve 39, corresponding to the valve 39<1>, which reverses the operation. Band assemblies C and C<1> are thus applied in alternating sequence, the period of which may be adjusted by the needle valve 68. In order that the assembly being engaged shall act more quickly than the assembly being released, check valves 135 are inserted in the lines 128, 129, 128<1>, 129<1>. If it is desired to stop the drum by applying both the bands C and C<1> together, the control lever 73 is moved to bring into action the valve member 75. This allows air to pass from airline 71 by lines 76, 78 and 89 to open a diaphragm-operated valve 88. Air from line 71 may then pass by line 91 to expand diaphragm 112 intermediate between the rods 111, 111<1>. Both valve elements 102 and 102<1> (Fig. 6, not shown) are then moved to opposite ends of valve units 100 and 100<1>, thus allowing air to pass to the piston-rod ends of both cylinders 18 and 18<1> to apply both brake bands. If it is required to release both brake bands, control lever 73 is moved to bring into action valve member 74. This allows air to pass from pipe 71 by lines 76 and 77 to operate a relay valve 124 which permits air from a supply line 125 to pass by lines 126 and 1261 through valve units 100 and 1001 to the cylinder head ends of both cylinders 18 and 18<1> to release both band brakes. In a modification, the valve units 100 and 100<1> are operated electrically by switches corresponding to the valves 39 and 40.