GB249261A - Improvements in or relating to overspeed and overwinding gears for winding engines - Google Patents

Abstract

249,261. General Electric Co., Ltd., and Whitmore, F. L. Jan. 22. 1925. Overwinding, preventing.-Relates to a safety device applicable to the type of gear for preventing over-winding described, for example, in Specifications 29424/04 and 7664/08. In this gear nuts D, E<1> travel on a revolving screwed shaft A so as to follow the movements of the cage, the nut D acting at the limit of its upward movement to release trip-gear, part of which is shown at J<1>, K<1> to cut off the power and apply the brakes, and the nut E<1> co-operating with governor-actuated mechanism O to check excessive speed as the cage approaches the pit-bank. The safety device comprises a sleeve B which can slide upon a feather on the shaft A, and is connected to a lever E so as to move upwards by gravity at a speed determined by a cataract piston in the chamber H, this speed decreasing as the sleeve is raised towards the top of its stroke. The sleeve B is normally held in its lowest position by a spring L acting through a lever J provided with an eye which slides over the link K. As the nut D approaches the top of the shaft A, it engages and raises the lever J. The sleeve B is then free to rise under the control of the cataract until it abuts against the collar C, when the gear will act in the normal way to stop the cage if it passes beyond the bank level. If, however, the speed of the cage exceeds a predetermined value, the nut D overtakes the sleeve B and then turns with the shaft A and stops the cage. When the cage is next lowered, the safety device returns automatically to the original position.