GB466692A - Improvements in or relating to synchronous motor clocks and synchronous motor clock systems - Google Patents

Abstract

466,692. Electric clock systems. SIEMENS & HALSKE AKT.-GES. July 10, 1936, No. 19225. Convention date, July 16. 1935. [Class 139] In a clock installation, particularly for use on ships, wherein correction of the clocks is necessary for changes in longitude, the auxiliary clocks are each normally driven through a differential gear by two synchronous motors M1, M2, acting in opposite senses, so that by switching off one or other of the motors from the central station, the clock hands are driven backwards or forwards at a greatly increased speed. The motors M1, M2, fed from voltage supplies at the same frequency, run at equal speeds and drive the sun-wheels Z1, Z2 in opposite directions through identical gear trains G1, G2. The wheels Z1, Z2, have an unequal-number of teeth, for example, 99 and 100, respectively, and the planet wheel 1, through its carrier drives the minute shaft 2 directly. Alternatively, the wheels Z1, Z2, may have the same number of teeth in which case the trains G1, G2, differ from each other, or, if the wheels Z 1, Z2 and the trains are identical, the motors may be fed at different supply frequencies arranged to run at different speeds on the same frequency. In each clock, a pivotal setting lever 5, Fig. 2, normally attracted by the stator field of one of the motors, M2 for example, coacts, when the motor is deenergized, with notched discs 3, 4 on the minute and hour hand sleeves frictionally mounted on the spindle 2, the notches being in alignment at noon and midnight, for example, although further hour notches may be provided on disc 4. Operation. The auxiliary clocks are connected to single, or, as shown in Fig. 3, three phase supply, synchronized in accordance with the running of the ship's standard clock, so that in all of the clocks in which the setting lever 5 is actuated by motor M2, the motors M1, M2, are connected respectively to the same phase lines, whereby by opening switch s1 or s2 the motors M2 or M1, respectively, are stopped in all of these clocks. To adjust the clocks to a new local time the master clock is first adjusted whereupon the opening of switch s1 or s2 is effected automatically in a manner not shown, the clock hands then being driven at a far greater speed, backwards or forwards, according to the switch opened, until corrected, when the operated switch is closed automatically. To correct any differences between individual clocks, switch s1 is opened shortly before the time when the notches in discs 3, 4 should be in line, whereupon the hands of all the clocks are advanced at setting speed until arrested by a detent 6 on lever 5 entering the aligned notches in the discs 3, 4. The switch s1 is closed at the hour represented by the aligned notches when the clocks all revert to their normal drive.