Patent GB-413315-A (GB)
Title: Improvements in or relating to electrically-driven clocks
IPC: G04C13/04
Filed: 1933-01-11
Abstract: 413,315. Electric clocks. SMITH, S. J., and TELEPHONE MANUFACTURING CO., Ltd., Hollingsworth Works, Martell Road, West Dulwich, London. Jan. 11, 1933, No. 996. [Class 139.] Timing-mechanism for sending periodical impulses to one or more clock mechanisms (80) has a reciprocating impulse-controlling member 26 (contacts 18, 19) of which the reciprocating speed is governed by a ratchet 11 and a synchronous motor 9. This motor 9 drives ratchets 11 and 12, of which ratchet 12 rotates the faster. Electromagnet 17 is in series with contacts 18, 19 and is connectible at 23, 24 with a battery and with the secondary clocks which are to receive an impulse each halfminute over this circuit. Contact 19 is on armature 20 and contact 18 is on an arm 25 rigid with a lever 26 which is pivoted at 27, counterweighted at 34 and has fixed to it plates 31, 32 ; pivoted between the latter is a member 29 with an abutment 28 which coacts with ratchet 11. Lever 26 tends to rock clockwise under its own weight, but this rotation is governed by ratchet 11 which regulates the rate of fall of abutment 28. When the latter reaches its lowest position, contact 18 meets contact 19, the energized magnet 17 attracts its armature and throws lever 26 counterclockwise, its momentum breaking contacts 18, 19 ; abutment 28 moves on to the next tooth of ratchet 11. The periodicity of the circuit closure thus depends upon the rotation of ratchet 11. Stop 33 limits the rise of lever 26. A setting arm 36 pivoted to the plate 31 has an abutment arm 38 which is connected to member 29 by a spring 39. A stud 40 on arm 36 coacts with three recesses 41 in plate 31, and arm 36 is used to adjust member 29 to one of three positions. In the position shown, abutment 28 and ratchet 11 control the fall of lever 26. If the stud 40 be moved to the central recess 41, then member 29 coacts with neither ratchet 11 or 12, but abutment 38 meets a fixed stop 74 and prevents lever 26 falling, thereby stopping the secondary clocks. If stud 40 be in the right hand recess 41 then a second abutment 35 on member 29 coacts with ratchet 12 which rotates much more rapidly than ratchet 11 so that lever 26 gives rapid impulses to step-on the secondaries. In the position shown in Fig. 1, the weight of the parts is so designed that if the current for motor 9 fail, then lever 26 and its associated parts rotate ratchet 11 and motor 9 slightly faster than when motor 9 is energized. This permits the motor to fall back into synchronism when its supply recommences. A roller 71 on lever 70 permits ratchet 11 to raise this arm about pivot 73. A second roller 72 on arm 70 meets arm 26 to help raise the latter from its lowest position. If the battery for magnet 17 is run down and the raising of arm 26 is slow, then the longer closure of contacts 18, 19 may be used to actuate a lamp or bell in circuit with these contacts. In a modification, Fig. 5, the motor 9 drives a cam 42 which raises a lever 43 to close contacts 44, 45 once each second, each impulse lasting for half a second. Two magnets 46, 47 are in series with one another, with these contacts and with a battery 79 ; this circuit also includes the secondary clocks at 80. A high resistance 78 is connected to contact 76 as shown. When contact 45 is lowered to break the circuit, contacts 76, 44 close to prevent sparking, before 44, 45 open. The motor also directly drives a pilot dial 77. The magnet 47 is used to close contacts in leads 50, 51, impulses occurring every 6 seconds in one pair of leads and every 30 seconds in the other pair. Magnet 46 reciprocates an armature lever 60 against spring 62 and about pivot 61 so that pawl 64, Fig. 8, on lever 60 drives a ratchet 67 which is freely mounted on a spindle of the train 10 driven by motor 9. The ratchet is connected to the spindle by a spring 69 and the number of teeth on ratchet 11 is such that the ratchet 11 rotates faster than the spindle so that spring 69 is stressed until it balances spring 62. During current failure in the motor circuit, therefore, spring 69 drives the motor.