GB381738A - Improvements in safety devices of motor-wound spring movements - Google Patents

Abstract

381,738. Spring mechanism. AKT.- GES. FœR SCHALTAPPARATE, 23, Gerbergasse, Berne, Switzerland. Oct. 29, 1931, No. 29989. Convention date, Nov. 5, 1930. [Class 10.] In a safety device for preventing overwinding of motor-wound clock movements, in particular for electric time switches, a coupling between the motor and the movement is thrown in and out by means of a friction coupling concentrically disposed in relation to, and operated by, a nut or other control element which moves along the arbor of the spring in accordance with the relative movement between the arbor and spring barrel. The spring movement shown, which is intended to operate a time switch, is wound by a motor (not shown) which rotates a wheel 28 which drives, through a helical spring clutch 29, a pinion 31 gearing with a wheel 3 on the arbor 4 of the spring 6. The arbor 4 is screwed, and carries a nut 8 on which is mounted a lever 9 having a turned-up end 91 which engages a stop 10 on the spring barrel, so that as the spring is wound the nut travels downwards and finally causes the face of the lever 9 to force down a ball bearing 12 which in turn presses a loose friction disc 11 into frictional engagement with the wheel 3. The disc 11 is thus turned, and by means of a forked extension 11<1> engaging a pin 13 on a lever 14 it moves the lever towards the left. An arm 16 secured to the same shaft 15 as the lever 14 is thus rocked and caused to arrest the movement of a star wheel 26 which is mounted loosely on the hub 27 of the wheel 28 and is provided with a pin 26<1> engaging the end of the spring 29, with which spring it normally turns. The spring 29 is thus prevented from turning and so ceases to tighten itself round the hub 27, thus allowing the wheel 28 to turn idly and arresting the winding movement. At the same time a tumbler switch 19 controlling the motor circuit is opened by means of the long arm of the lever 16, on which are pins 18<1>, 18<11> which engage a flexible extension 19<1> of the tumbler 19. When during unwinding the spring barrel has made a complete turn, the stop 10 engages the lever 9 and rotates it, causing the friction disc 11 to be raised and so allowing the lever 16 to be returned by a spring 17, thus releasing the star wheel 26 and closing the switch 19, so that rewinding commences.