Patent GB-305690-A (GB)
Title: Improvements in or relating to lighthouse and like lamps
IPC: F21V19/04
Filed: 1927-10-11
Abstract: 305,690. Gas Accumulator Co. (United Kingdom), Ltd., and Goodwin, G. Oct. 11, 1927. Convertible gas and electric lamps; mounting electric lamps in lanterns.-In a lighthouse or like lamp in which the illumination is restored automatically after failure, the illuminants are carried by a table capable only of uni-directional rotation. The stand-by illuminant may be of the same kind as the main illuminant, and may comprise one or more electric bulbs supplied by the same mains or by an alternative electric supply such as a petrol electric set, or it may be of a different kind, such as acetylene or other gas. In the form shown in Fig. 1, two electric bulbs 1, 2 and a gas mantle 3 are carried on a threearmed table 4 having a boss 5, the axis of which is arranged eccentrically of the lens (not shown) so that each illuminant can be brought into the focus of the lens. The boss 5 is loosely mounted on a shaft 6 to which is fixed an arm 7 carrying a vertical spindle 8, the upper end of which is engaged by a forked or slotted arm 11 on the boss 5. The lower end of the spindle 8 is fitted with a spindle 9 engaging a stationary toothed ring 10 concentric with the shaft 6. The spindle 8 is arranged to be directed radially inwards when each illuminant is at the focus of the lens, so as to lock the table automatically against inadvertent movement. The shaft 6 carries a sunwheel 16 in mesh with planet wheels 15 carried by a floating grooved ring 14 to which is connected the flexible connection 13 of a weight 12. The planet wheels 15 also mesh with the internal teeth of a floating worm wheel 17 which is engaged by, and normally held stationary by, a worm 18 on the shaft 19 of an electric motor 20. The shaft 6 also carries a toothed wheel 21 which is geared by a wheel-combination 25 to the spindle 24 of a metal disc 22, which, together with a permanent magnet 23, forms an eddycurrent brake for controlling the movement of the table. The disc 22 has a projection 26 adapted to be engaged by a twin-trigger 27, 28 having an extension 32 connected to the arm 33 of an electromagnet 34. The trigger is pivoted at 29 at the end of a lever 30 movable about a fixed axis 30a and having a roller 31 adapted to be raised and lowered by humps 32a, 33a and a depression 34a on the under surface of the wheel 21. The shaft 6 may be made hollow for the supply of gas to the mantle 3, and the supply valve may be connected at 42 to a pivoted lever 40 having a roller 39 adapted to co-operate with a hump 38 on the underside of the wheel 21. Normally, the bulb 1 is supplied from the mains - + by means of brushes 48, 57 engaging certain contacts on segmental rings 55, 61, and is connected in series with the winding 47 of the electromagnet 24. At the same time the hump 32a is in engagement with the roller 31 and the trigger 28 is engaged by the projection 26 to secure the table 4 in position. A pair of brushes 56, engaging other contacts on the ring 55, is connected up to the negative main beyond the main switch and through a resistance (not shown) to form an auxiliary circuit for the winding 47, so that the electromagnet 34 remains energized by a sustaining current when the main switch is switched off, or if the contact of a flasher is open. If the bulb 1, fails, the electromagnet 34 is de-energized, the trigger 28 releases the eddy-curent brake, and the table 4 is rotated by the falling weight 12, the planet wheels 15 travelling idly around the inner teeth of the worm wheel 17. When the second bulb is in position, the table 4 is arrested by the hump 33a engaging the roller 31, the electromagnet 34 is re-energized, and the trigger 28 again causes the eddy-current brake to lock the table in position. A similar action takes place if more than one stand-by bulb is used, and when the last bulb fails, or if the mains fail, the gas mantle 3 is brought into operation, the roller 31 then lying in the depression 34a and the trigger 28 again locking the table in position. When the drum 14 has made a complete revolution, a pin 62 engages a snap-over switch-arm 63 to operate switches 35, 36 which close the circuit of the electric motor 20 and short circuit the electromagnet 34. If the current is restored, the motor 20 re-winds the weight 12, the planet wheels 15 travelling idly round the sun-wheel 16 and the shaft 6 remaining stationary. Another pin 64 then opens the switches 35, 36 to stop the motor and to bring the electromagnet 34 into operation again. The table is then rotated, the gas is cut off, and the table once more stops with the first sound bulb in position. An alternative method of operating the eddy-current brake to lock the table during the re-wind of the weight, and a parallel-motion system for raising the bulbs into the lens one after the other, also is described and illustrated in the Specification.