GB185871A - Improvements in selectively operable devices for selective signalling systems - Google Patents

Abstract

185,871. Western Electric Co., Ltd., (Western Electric Co., Inc.). June 22, 1921. Addition to 117,170. Selectors.-The seelctors described in the parent Specifica tion are modified so as not to be operated effectively by current impulses which follow each other sufficiently rapidly, for instance Morse signals. In the examples shown the step-by-step element on the reception of rapid impulses, is first advanced to a predetermined position and subsequently held there until the impulses cease. In one example, Fig. 1, the S-shaped member 10 rocked by the armature 9 operates by means of pins 11, 12 a lever 13 at each movement in either direction of armature 9. A stepping-pawl 15 on the lever 13 operates a ratchet 17 and sector 20 and a pawl 37 held normally out of engagement with the ratchet by a pin 39 on the lever 13 is arranged to hold it but not the sector 20 during movement of the arm 10 between its extreme positions. The ratchet 17 carries an element 26 carrying at predetermined points pins 29, 30, 31 adapted to engage the end 35 of an arm 32 which bears against an insulated roller 34 carried by lever 13. Normal operation is effected by sets of impulses spaced so as to allow complete discharge of condenser 40 through resistances 41, 36 in series. The ratchet is held in the various positions to which it is advanced by pins 29, 30, 31 and ultimately an alarm circuit is closed through contacts 27, 28 arm 32 and pin 31. Operation by morse impulses. The first prolonged impulse allows the condenser 40 to be charged and the ratchet 17 and sector 20 advanced one step. An arm 24 on the latter makes contact at 25 and short-circuits resistance 36. Subsequent morse impulses step round the ratchet 17 and sector 20 until the arm 24 passes off the contact 25. The ratchet 17 is held in this position, but the sector 20 is returned by the spring 21,. the contacts 24, 25 being so shaped, Fig. 2, that contact is made continuously during the advancement of the sector 20, but only momentarily on its return. resistances 36, 41 are then again in series, and further operation by morse impulses is impossible. In a modification, Fig. 3, the sector 20 is emitted. The resistance 45 is normally short-circuited through contacts 47, 48. After the element 26 has been advanced to a predetermined point, the holding-arm 32 engages an insulated pin 44 on the element 26, contacts 4i, 48 are opened, and further rapid impulses do not advance the ratchet.