GB472983A - Improvements in or relating to electric clock movements - Google Patents

Abstract

472,983. Electric clocks. BRITISH SANGAMO CO., Ltd., and BUTHERUS, F. R. April 2, 1936, No. 9783. [Class 139] An electric clock having a self-starting synchronous motor 1 which normally drives the hands and having a spring movement in reserve to drive the hands when the motor fails, has means which, when the synchronous motor is in operation, mechanically locks the escapement of the reserve movement, under control of the motor's field, in a position of maximum potential energy and has also a differential 33 between the motor 1 and the hands in which one sun-wheel 40 drives the hands from the motor and when the latter fails, this sun-wheel is immobilized and a second sun-wheel 32 is released and drives the hands under control of the spring movement and its escapement 8, the mainspring 37 of which is wound up by the motor when the latter is running. The motor drives the sun-wheel 40 through gears 2 ; sun-wheel 32 is connected through gears 12 to the escapement 8 which is locked whilst the motor is running by the pin 13 on the balance 9 held by the lever 17 controlled by the soft iron member 14 attracted by the field of the motor 1, as described in Specification 469,029. Integral with wheel 32 is a wheel 34 which is driven by a wheel 35 integral with the barrel 36, when the motor 1 fails. One end of spring 37 is in frictional engagement with the barrel and the other end is connected to shaft 38 which has a gear 39 meshing with the sun-wheel 40, which is loose on the time shaft 4 leading to the hands. Gears 40 and 39 wind spring 37 whilst the motor is running. Normally, wheel 32 is locked and the motor drives the shaft 4 through sun-wheel 40 and a planet carrier 41 which is fast on shaft 4. When the motor fails, sunwheel 40 is immobilized and spring 37 drives shaft 4 through the train 35, 34, 32, 12 under the control of the escapement 8. In a modification, the planet carrier is connected to the time shaft and to one end of the mainspring, the other end of the spring being connected, through a slipping. clutch, to the sun-wheel which is driven by the electric motor.