GB698763A - Improvements in and relating to chronographs - Google Patents

Abstract

698,763. Watches. JUNGHANS AKT.-GES., GEB. May 31, 1951. No. 12990/51. Class 139. A chronograph is characterized by the provision of a zero return lever which carries an intermediate wheel for the transmission of the movement of the fourth chronograph wheel to a centre chronograph wheel. The returning lever 1, Fig. 1, is pivoted at 11 and carries the intermediate wheel 2. A spring 14 urges the lever 1 to hold the end 1c thereof against the end 9b of a pivoted lever 9 in which position the wheel 2 meshes with a wheel 6 connected to the seconds hand and with the fourth chronograph wheel 3. Depression of a button 8 causes counterclockwise movement of the lever 9 and clockwise movement of the lever 1 to remove the wheel 2 from the wheel 6 and so stop the seconds hand. Depression of a second button 12 rocks the lever I fully clockwise so that its end la acts on a cam 5 connected to the seconds hand which is thereby brought to zero. The seconds hand again starts to rotate upon release of the buttons 8 and 12. The lever 1 is slotted at Id. In a modification, Fig. 2, not shown, the button 8 is replaced by a button which is movable back and forth along an arc to start and stop the seconds hand. The button having a cam surface which acts on the intermediate lever 9. In another embodiment, Fig. 3, only one radially and arcuately movable button 100 is provided. The button 100 has a cam surface which abuts a pin 105 on the returning lever 1. Upon counter-clockwise movement of the button 100 the lever 1 is moved to disengage the wheel 2 from the wheel b. Depression of the button causes the end la of the lever 1 to engage the heart shaped cam 5 and return the seconds hand to, zero. In another example, Fig. 4, the lever 9 is replaced by a lever 200 the end 200a of which engages the end 1c of the lever 1. A spring 202 normally urges the lever 200 against a stop 201 and so holds the wheel 2 away from the wheel 6. Depression of the button 8 allows the spring 14 to move the lever 1 against a stop 13 to cause engagement of the wheels 2 and 6 and the seconds hand rotates. Return to zero is again effected by depression of the button 12.