GB446932A - Improvements in or relating to electrically driven clocks or like isochronous devices - Google Patents

Abstract

446,932. Electric clocks. FERRANTI, Ltd., and EASTON, H., Hollinwood, Lancashire. Feb. 28, 1935, Nos. 6367 and 15738. [Class 139] In a synchronous-motor clock having in reserve a time-governed spring motor continuously operating at normal speed, the synchronous motor drives the motionwork through a one-way drive, the reserve motor drives the motionwork through a second oneway drive and means are provided for intermittently or continuously overriding or rendering ineffective the drive from the reserve motor whilst the synchronous motor is operating. Rigid with the clock shaft a are ratchet wheels band c driven by pawls d and e on wheels s and k loose on shaft a. The synchronous motor h drives the train f, g, s to operate (1) the pawl d, (2) a wheel t rigid with sun-wheel q, and (3) a wheel m for winding a spring motor n, the shaft p of which is controlled by an escapement o and drives, through wheel u, a wheel w rigid with a sun-wheel r. Sun-wheels q and r rotate oppositely and coact with a planet carrier i which drives the train j, v, k to rotate the pawl e. If motor h fails, sun-wheel q is immobilized and the auxiliary movement o, p drives pawl e and shaft a through the differential; but whilst the motor h rotates the wheel q, the effect is to slow up the planet carrier so that ratchet c overrides its pawl e continuously. In a modification, Fig. 2, the synchronous motor h drives the pawl d through gearing f, 2, 3, 4, and winds the spring motor n, and the latter drives the pawl e through a friction device consisting of members 8, 9, 10 and a toothed wheel 11 which is arrested periodically by a lug on the end of an arm 18 rigid with shaft 17 ; the latter carrying also an arm 16 which is rocked by a pin 14 on a disc 13 driven from the synchronous motor h through gearing f<1>, m, 15. The spring motor may be wound by hand. Specification 389,908 is referred to.