| 摘要 |
648,747. Electric selective signalling. PFEFFER, V. Sept. 27, 1946, No. 28885. Convention date, Sept. 27, 1945. [Class 40 (i)] [Also in Group XVIII] In a system of clocks including a master clock and a series of subsidiary clocks (see Group XVIII), means are provided for analysing the periodic correcting signals which are transmitted by wireless. The signal is in the form of four short impulses followed by a long one. The analysing means comprise a ratchet 45, having two toothed portions 45a and 45b and a cam portion 46 which normally abuts a stop 47. A pawl 50 carried by a toothed segment 51 is spring biassed into engagement with the teeth 45a of the ratchet wheel 45 but is normally held therefrom by a pin 52 and only engages them when the segment 51 is moved clockwise by a spring 57 when an electromagnet 63 is energized to attract its armature 61. A spring pressed pawl 53 moves into engagement with the teeth 45b when an electromagnet 56 is energized to attract its armature 54. Upon the reception of the first impulse of the time signal the electromagnets 56, 63 are energized and the ratchet wheel 45 is stepped on one tooth by the pawl 50. After each impulse the lever 61 returns the segment 51 and the pawl 50 to their initial positions. As the electromagnet 56 is of the delayed release type the pawl 53 keeps the ratchet 45 in the advanced position until the succeeding impulse and so after four impulses the ratchet 45 has advanced clockwise four teeth. When the final long impulse arrives the electromagnets 56, 63 are again energized, the lever 61 moves down, the segment 51 swings clockwise and the pawl 50 engages the last tooth. The segment 51 is stopped by the lever 61. The projection 46 closes the blade spring contacts 49 whereupon an electromagnet 70 is energized to attract its armature 67 and a second toothed segment 64 is moved clockwise. The downward movement of the lever 67 rocks a cam lever 71 to allow a spring-biassed pawl 73 to engage the periphery of the segment 64. At the end of the last impulse the pawl 73 moves into the recess 65 and the blade spring switch 74 closes whereupon an electromagnet 31 is energized to effect correction of the master clock. The ratchet 45 may be replaced by a contact carrying segment and the segment 64 moved throughout the duration of the whole signal, Fig. 2, not shown. Specification 650,611, [Group XVIII], is referred to. |
