Patent GB-451506-A (GB)
Title: Improvements in or relating to date indicators
IPC: G04B19/243
Filed: 1935-02-06
Abstract: 451,506. Date indicators. PREEN, A., Two Trees, Little Moss Lane, Pinner, and PREEN, G., 3, Queen's Close, Edgware, both in Middlesex. Feb. 6, 1935, No. 3833. [Class 106 (iv)] A clock-actuated date indicator comprises a lever oscillated through a constant angle every twenty-four hours and connected by a lostmotion connection to a pawl which drives a date-figure unit, the pawl having a variable movement depending on the length of the month, the movement being shortest in a thirtyone day month and longest in a twenty-eight day month, means being provided on the pawl for advancing the date-figure unit to indicate " one at the end of every month. Provision is automatically made for leap years. The device is driven from the clock, Fig. 1, by a cam 14 which rocks a lever 15 connected by a spring 17 to an arm 18 on a shaft 11. This shaft carries pawl arms 9, 10, Figs. 6 and 7, to which are pivoted pawls 7, 8 engaging ratchet wheels 5, 6 connected to the day-name unit 2 and to the datefigure unit 3 respectively. When the clock-driven cam 14 releases the lever 15 the arms 9, 10 are rocked clockwise by springs 12, 13 to advance the ratchet wheels 5, 6. When the date-figure ratchet wheel 6 passes through the " 31 " position, a pin 23 upon it rocks and releases an arm 24 connected to a pawl arm 21, Fig. 5, loosely mounted on the shaft 11, the pawl arm being rocked in opposition to a spring 22 and then released, whereby a pawl 20 advances a ratchet wheel 19 connected to the month-name unit 4. The ratchet wheel 19 rotates once in four years and has secured to it a disc 28 having notches corresponding in depth to the lengths of the forty-eight successive months, the deepest notch representing twenty-eight days and the greatest radius of the disc thirty-one days. An arm 29 having a pin 30 is secured to the shaft 11 and determines how far the shaft shall rock at each daily actuation, this variable movement being permitted by the spring 17 and being greatest in a normal February and least in a thirty-one day month. The dayname ratchet wheel 5 is advanced by one step whatever the movement of the pawl-lever 9, since the pawl is prevented from engaging more than a single tooth by an abutment 31. The pawl 8 actuating the date-figure ratchet wheel 6 is also normally controlled in a similar manner, but on the 28th day a pin 34 on the ratchet wheel comes into the range of a second pawl 33 also carried by the pawl lever 10. If this lever is performing its large (28-day) movement, the pawl 33 will engage the pin 34 and advance the date-figure ratchet wheel to its " one " position. Otherwise, this advance will occur on the 29th, the 30th or the 31st day, depending on the movement being performed by the pawl lever 10. Each indicating unit comprises a series of cards 46 pivoted between two discs. One of the two cards before the display aperture is held by a spring 48. When the unit is advanced, this card is released and turns through 180‹ about its axis, the next card being detained by the spring 48. Part of the indication can thus be on the face of one card and the other part on the back of the succeeding card. The indication can be adjusted by hand levers 39, 40, 41. In a modification, Fig. 8, the cam 14 rocks a lever 15a against the action of a spring 42, an arm 18a secured to the shaft 11 following it under the action of a spring 43 to the extent allowed by the movement permitted to the shaft 11.