GB226547A - Improvements in or relating to automatic braking mechanism for winding gear, elevators, railway vehicles, swing bridges and like apparatus actuated by a prime mover - Google Patents

Abstract

226,547. Siemens - Schuckertwerke Ges. Dec. 18, 1923, [Convention date]. Fluid-pressure. - In apparatus for braking large moving masses such as winding-engines for mines, in which the brakes are operated in the event of any departure from the normal working of the system, for example in the cases of overwinding, failure of compressed air in the braking system, exceeding of the maximum electric current in any circuit, failure or dropping of the current in the field system of the motors or failure of the steam supply to the engine, a joint or common member is actuated by the various features enumerated above to release manoeuvring and safety brakemechanism simultaneously the manoeuvring brake mechanism being of a kind that can fail, for example, actuated by a compressed-air system, while the safety brake is of the non-failing type, applied by weights. Fig. 1 shows one construction in which the. brake rod 12 is carried by a lever 1 mounted on two pistons 3, 7. Ordinary braking is obtained by raising the piston 3 to move the lever 1 about the point 5 as a fulcrum, this movement being initiated by the hand lever M operating the control valve 14 while safety braking is produced by the weight 8 depressing the piston 7 and swinging the lever 1 about the fulcrum 2, this movement being initiated by the hand lever S or by any of the automatic mechanisms hereinafter described. If failure of pressure in the compressed air pipe 16 occurs when the manoeuvring brake lever M is in the " off " position, which corresponds to the cylinder 3 being open to exhaust through pipe 115, the cylinder 9 is affected, and the piston 7 drops under the action of the weight 8, and moves the lever 1 about its fulcrum 2 to apply the brake. At the same, time the weighted lever 47 drops to rotate the shaft 20 to actuate triggermenhanism by raising levers 22, 22<1>, thus releasing weighted levers 37, 39. The lever 39 actuates valve-mechanism 18 to cut off the air supply and open the cylinder 9 to exhaust, and also through the levers 41 breaks an electric circuit at the switch 42 or operates a. throttle or stop valve while the lever 37 re-sets the regulator 14 to re-establish communication between the cylinder 4 and the compressed air supply so that the piston is raised to take up the braking force when the supply is resumed. If the failure occurs when the manoeuvring brake is " on," the air from both cylinders runs back into the supply pipe, and both pistons sink to. a corresponding extent, leaving the brake blocks unaffected. The lever 39 drops as before to open the cylinder 9 to exhaust and thus apply the brakes with full force, but the lever 37 cannot drop owing to the position of the hand lever M which correspondingly positions the lever 28. Restoration of the lever M to the " off " position at this stage gradually lowers the lever 37 and opens the cylinder 4 to exhaust. The subse.- quent forward movement of the lever M in the brake-applying direction resets the trigger mechanism provided the pressure is available to raise the piston 7 again. The levers 37, 39 also are released by the hand-lever S or by the electromagnet 53 in the event of an overwind, or if the maximum current allowable in the various circuits has been exceeded. The magnet 53 may be replaced by a steam-cylinder when a steam engine is employed whereby the levers are operated by failure of the steam supply. Mechanism 67 geared to the depth indicator also can be used as operating means in case of an overwind. The lever M also may operate mechanism 71 for cutting-out the Leonard circuit temporarily during winding. In a modified construction the two levers 37, 39 can be released independently. In other modifications the apparatus is designed more especially for direct-current and threephase current drives respectively. In another modification the lever 28 is replaced by a pair of pistons working in parallel cylinders.