Patent GB-668747-A (GB)
Abstract: 668,747. Date indicators. NEDERLANDSCHE UURWERKFABRIEKEN NUFA N. V. Nov. 18, 1949 [Nov. 27, 1948], No. 29626/49. Class 106 (iv). A clock-actuated date indicator with day-, date- and month-rings set to indicate the date in windows in a dial plate by a transmission device driven by the clockwork is characterized in that the month - ring and the date - ring are arranged one behind the other, the month-ring having a window between each month name wherein the dates on the date-ring disposed behind are successively brought into view. A clock dial 1, Figs. 1, 3, 8 has windows 40, 41 through which a day name, month name and date disposed on rings 8, 6, 7 may be viewed the month names having adjacent windows 25 exposing the date therethrough. The rings are disposed in spaces 3, 4 formed between the plate 1 and a member 2 attached to its rear which is formed with a central cylindrical part 12 around which is mounted a member 13 carrying pawls 14, 15 interlinked by a spring 50, the member 13 having a slot 16 co-operating with a pin 17 on a 24-hour clock driven wheel to reciprocate the pawls daily with a stroke covering four of the 31 teeth round the periphery of the date ring 7. Parts 32, 30, 31 of the member 2 are cut away to allow the pawls 14, 15 to co-operate with the rings 7, 6 and the ring 8 respectively and to allow one end of each of two two-armed levers 9, 10 mounted on the rear of the member 2 to cooperate with the inner circumference of the ring 7 and the rings 7, 6 respectively. At the end of every day from the 1st to the 29th of every 30 and 31 day month the inner circumferences of the rings 6, 7 hold the levers 9, 10 so that their outer arms cover three of the four teeth of the ring 7 covered by the stroke of the pawl 14 which therefore engages only one tooth in each return stroke and so advances the date by one. When the date 30 is exposed one arm of the lever 9 enters a shallow recess 27 in the ring 7 and if the month has only 30 days one of five straight faced teeth 23 on the outer circumference of the ring 6 lies within the stroke of the pawl 14 and is exposed by the other arm of the lever 9 as it rocks which also exposes two of the teeth of the ring 7 so that on its next stroke the pawl 14 changes the month name and advances the date through the 31st to the 1st. However, if the month has 31 days one of seven stepped-faced teeth 24 of the ring 6 lies within the stroke of the pawl 14 but is still covered by the outer arm of the lever 9 and itself covers one of the teeth of the ring 7 so that only one is exposed to be advanced by the pawl 14 which changes the date to 31 and causes the inner arm of the lever 9 to enter a deeper recess 28 in the ring 7 so that its outer arm exposes the stepped tooth 24 which covers a shallow tooth of the ring 7 and whose step limits the inward movement of the pawl 14 which on its next stroke changes the month name and advances the date by one of the 1st. When the date. changes to the 28th February, the inner arm of the lever 10 is aligned with a recess 26 in the ring 6 and the recess 27 in the ring 7 so that a straight part of the outer arm of lever 10 exposes a tooth of the ring 7 which is picked up by the pawl 14 at the end of the 28th, advancing the ring 7 one tooth to bring the deeper recess 28 in time with the recess 26 and inner arm of lever 10 which rocks so that the whole of its outer arm moves out of the path of the teeth of the ring 7 while the inner arm of lever 9 enters the shallow recess 27 to rock its outer arm to expose the tooth 23 of the ring 6 and allow the pawl 14 in the remainder of its stroke to change the month name and advance the date to the first. A 4-toothed wheel 37 pivoted behind the plate 1 is advanced once a year by a pin 39 on the ring 6 and in leap years a cam 38 on one tooth lies.alongside the straight part of the outer arm of lever 10 so that when that part rocks on the 28th February, the cam 38 remains to cover the first tooth of ring 7 the levers 10, 9 covering the next two, so that the pawl 14 engages the last of the four and advances the date to 29 after which the month and date changes as at the end of an ordinary February but still missing the first tooth so as to advance the necessary 3 days. The day name is advanced daily by the pawl 15.