Patent GB-440442-A (GB)
Title: Improvements in or relating to mechanical date indicators
IPC: G04C17/00
Filed: 1934-07-13
Abstract: 440,442. Date indicators. GERMUNDSON, A. K. H., 13, Svarvaregatan, Stockholm. July 13, 1934, No. 20611. Convention date, July 15, 1933. [Class 106 (iv)] A date indicator showing date numbers, day names, month names, and year numbers, and provided with automatic leap-year mechanism has differential gearing for taking account of the different lengths of the months, the gear being automatically adjusted at the commencement of any month of less than 31 days into a position corresponding to the number of days in the said month and released at the end of the month to advance the indicator as many days as the month is shorter than 31 days. An impulse received every 24 hours by an electromagnet 3 causes a shaft 2 to oscillate through <1>/7 of a revolution. The shaft 2 has an arm 33, Fig. 7, carrying a pawl 34 which, on the clockwise return movement of the shaft, actuates a ratchet wheel 10 secured to the day-name drum 9. Another pawl 35 actuates a ratchet wheel 5, on a sleeve of the date-number units drum 4. The date-number tens drum 7 has eight facets and is turned # of a revolution when the units drum 4 moves from " 9 " to " 0 " by the engagement of a pin on the tens drum 7 with a notched disc on the units drum, this movement being completed by a spring which bears on the facets of the drum 7. A wheel 8, Fig. 7a, having two projections 43, is secured on a sleeve integral with the tens drum 7. When the date number " 30 " is indicated, a pin 40 lifts the pawl 35 so that at the next actuation only the tooth 41 of the units ratchet wheel 5 is moved to change the actuation to " 31." On the following actuation, the pawl 35 engages the projection 43 to turn the tens drum only from " 3 " to a blank facet, the apparatus then indicating " 1." The units ratchet wheel 5 is not at this time moved because the projection 43 holds the pawl 35 clear of the tooth 44. The pawl 35 is then dropped and on its next movement engages the tooth 44 to change the indication to " 2." The sleeve of the units drum 4 extends to the right, Fig. 4, and has secured to it a sun pinion 6 gearing with a planet pinion 17, Fig. 12, pivoted in a sector 18, the pinion 17 also engaging an internallytoothed wheel 19. The wheel 19 is thus advanced <1>/30 revolution every 24 hours. An arm 28 is secured to the oscillating shaft 2 and carries a pawl 27 which can engage with a ratchet wheel 12 attached to an extension of the months-name drum 11. The ratchet wheel 12 has shallow notches 46 corresponding to months with 31 days, deeper notches 47 for 30-day months and one deep notch 48 for a 28-day month. At the end of a month a notch 45 in the wheel 19 comes into a position to allow a control member 22 to move so that the pawl 27 may actuate the months' ratchet wheel 12. At the end of January, the pawl 27 engages with the deep notch 48 to advance the month indication to February. On account of the depth of the notch 48, the pawl 27 also engages a notch 51 in the sector 18 and advances the sector, the pinion 6 remaining stationary and the wheel 19 being driven <3>/30 of a revolution by the pinion 17. During the rest of the month, the wheel 19 is moved by the pinions 6, 7 (the sector 18 being stationary) until the notch 45 allows the control pawl 22 to fall after 27 days. At the next impulse, the pawl 27 engages a notch 46 in the wheel 12 to advance the month drum to March. One of six pins 31 on the wheel 12 then releases the detent 29 of the sector 18, which sector is returned to its initial position by springs. During this return movement, the wheel 19 is looked by the pawl 22 and thus the planet pinion 17 drives the sun pinion 6 and turns the date number to " 31." Upon the completion of the current stroke, the number indication is changed to " 1 " by the pawl 35. At the end of March, the notch 45 again releases the control member 22 and the pawl 27 enters a notch 47 to drive the wheel 12 to its " April " position. The depth of the notch 47 is such that a notch 49 on the sector 18 is engaged by the pawl 27, the wheel 19 being moved <1>/30 of a revolution so that the month-changing mechanism will become operative again after 29 days. At the end of April a pin 31 releases the detent 29, and so on. A pinion 55<1> rigid with a pinion 57 is pivoted on the wheel 12 and is engaged once a year by a fixed stop 56 so that the pinion 57 advances the pinion 16 of the year-indicating mechanism. A cam 60 is also secured to the pinion 551 and once in four years is adjacent the notch 48 when this notch is in month-changing position. The effective depth of the notch is thus reduced to that appropriate for a 29-day month, the pawl 27 in its movement picks up the sector 18 by means of a notch 50, and leap-year is thus allowed for.