GB325008A - Improvements in and relating to timing devices - Google Patents

Abstract

325,008. Marks, Sir G. C., (Horn, J. A. L.). Nov. 10, 1928. Sand glasses; timelimit devices. - A device for timing cooking operations or for actuating an electric switch comprises a sand glass device which rocks, after the sand has flowed from one division to another, to actuate a visible or audible signal or to operate a switch. The sand may be replaced by a liquid or by a, weight falling through a liquid. The sand glass 1 is contained in a case 2 the ends of which are extended at 4 to support a threaded rod 5 upon which is a counterweight nut 6. The case is pivoted at 9 to brackets 10 on the base 11 and is adjustable as to its initial position by a screw 15. A frame 14 also pivoted at 9 carries a hammer 13 for the bell 12. When the sand passes to the lower half of the glass 1 the centre of gravity shifts to the left of the axis 9 and the device rocks counterclockwise to move frame 14 which comes back against pin 16 to strike the bell sharply. The timing is adjusted by the nut 6. In modifications (1) the sand is replaced by liquid such as oil, kerosene or diluted spirit of wine, and a cap to the container forms the counterweight, (2) in place of the central narrow orifice, the liquid passes through a small tube to the lower half of the container and is returned to the upper half .through a large tube, (3) a ball falls slowly through liquid to cause the overbalancing, (4) this ball is replaced by a cylindrical weight fitting the cylindrical container closely and having a central passage with a one-way valve, and (5) the weight or ball is adapted when it overbalances the device to cause the latter to open a switch'35, 36, Fig. 11, the device being returned to the set position shown by a disc 37.