GB692531A - Improvements in or relating to circuits for selector switches - Google Patents

Abstract

692,531. Automatic exchange systems. PHILIPS ELECTRICAL INDUSTRIES, Ltd. July 24, 1951 [July 27, 1950], No. 17486/51. Class 40 (iv). A latch - controlled wiper - switch driven through a clutch which is automatically released on overload following the stopping of the switch by the engagement of the latch, the wiper-carriage remaining subject to a force in the original direction of movement, e.g. through a spring coupling to part of the clutch, is set by means of a control device comprising testing means which cause engagement of the latch when the switch reaches a marked outlet, the circuit for the testing means being completed a definite time after the disengagement of the latch, in which time the switch has passed several outlets. This allows the switch to reach approximately its normal speed before engagement of the latch. As shown, the wiper carriage 9 of a single-motion group selector GK is rigidly secured to a ratchet-wheel 2 which is resiliently connected by a spring 20 to an auxiliary wheel 4 adapted to rotate in only one direction by means of a free-wheel device. The switch is driven by a constantly rotating ratchet wheel 3 through a pawl 21 which is pivoted to the auxiliary wheel 4 and engages a stud 22 on the wheel 2. Release of a magnet SM causes a latch 18 to engage the ratchet wheel 2 and stop the switch. The auxiliary wheel 4 continues its rotation for a short distance and the pawl 21 is then disengaged from the ratchet wheel 3. The spring 20 still exerts a torque on the wheel 2 in its direction of previous motion, and starts it rotating again when the magnet SM is re-energized to withdraw the latch 18. The pawl 21 then reengages the rotating ratchet wheel 3 to restore the driving connection. Circuit operation.-The selector GK, together with a control circuit BI common to a number of such selectors, is seized by the application of earth to line L3. Relays C and B are energized; relay A repeats incoming dialling impulses to a slow-releasing relay V, which holds during the impulse train, and to a rotary magnet D which steps a marking switch MS, operating off-normal contacts k1, k2, k3. At the end of the impulse train, relay V releases and energizes the magnet SM to start the switch GK as described above. After a delay, during which the speed of the switch GK settles down to approximately its normal value, a relay X operates to complete a circuit for test relay T which is energized when the switch GK reaches the outlet marked by marking switch MS. Magnet SM is then deenergized to stop the switch GK, relay P operates, relays C, B, T, V and X are released, and a pulse-sender KG drives the marking switch MS back to normal.