Patent GB-867721-A (GB)
Title: Improvements in or relating to switching devices
IPC: H01H67/22
Filed: 1958-09-16
Abstract: 867,721. Devices responsive to call signals. STICKEL, H. A. Sept. 16, 1958 [Sept. 23, 1957], No. 29645/58. Class 40 (1). A device adapted to respond to a predetermined signal in the form of a succession of groups of pulses (e.g. 4-2-2) consists of a solenoid with a fast-moving armature 45, Fig. 1, and a slow-releasing armature, the former responding to the individual pulses to rotate a spring-loaded toothed wheel 19 through a stepping mechanism, the latter remaining attracted between pulses of a group but dropping out at the end of a group and a latch 117 controlled by this armature to retain the wheel against its spring in the attracted position and in the fully-dropped position to allow the wheel to return to zero position, abutments being provided on the wheel which at the end of a predetermined pulse group retain the slow-releasing armature against full movement to the dropped position and thereby prevent the wheel returning to zero. The slow-to-release armature 55, Fig. 2, co-operates magnetically with end-plates 41, 49 of the solenoid and is hinged at 53. It remains in the attracted position between pulses of a group but drops out in the larger interval between groups. An arm 87 from this armature is bent so as to lie over the top plate 11 of the device as shown in Fig. 7, and carry a disabling lever 95, a lug 121 and a spring 115. The toothed wheel 19 is adapted to be stepped round by armature 45 acting through lever 64 and an operating rod 71 having an upstanding end arm 83 engaging the teeth in turn. Until armature 55 moves to the inward position the disabling lever 95 prevents the arm 83 engaging the teeth of wheel 19. During a signal pulse train the wheel 19 is held against backward motion by a pawl 117 pulled into engagement by spring 115 when the armature 55 is in the attracted inward position. At the end of a pulse train the armature 55 drops out and if not locked in the inward position, releases the tension on spring 115 and by abutment with a lug 120, Fig. 2, positively disengages the pawl so that the wheel 19 returns to its initial position. This releasing operation is prevented at the end of each predetermined groups of pulses by locking pins 130 (Fig. 4), which are clipped on to the wheel with an end 132 projecting downwardly through a hole 127, there being a hole in each tooth. When, as shown in Fig. 7, such a pin is aligned with the lug 121 on the arm 87 the armature 55 is prevented from returning to its outer position and the wheel 19 remains latched in the new position. Contact members 133, Fig. 5, are clipped to the wheel 19 to provide one or more positions of the wheel in which contact is made with a conductor 149 secured to armature 55, contact pin 139 bearing against contactpin 151, as shown in Fig. 8, when this armature is magnetically released. The engagement between the contacts prevents full dropping out and accordingly the wheel does not return to the zero position. Operation.-As shown, the wheel is fitted with two contact members 133a, 133b and two locking pins 130a, 130b. The first pulse of the first group draws armature 55 inwardly, carrying with it the disabling lever 95 so that the arm 83 of operating rod 71 can engage the teeth. The armature 45 is also energized to work the rod 71 and advance the wheel 19 by one tooth. The next pulse advances the wheel again, the armature 55 remaining in the inward position. This brings the pin 139 of contact member 133a into position to engage the contact 151 when the armature 55 drops out. The device therefore responds to the single group of two pulses, i.e. to digit " 2." If a first group of four pulses are applied, the end 132 of locking-pin 130a prevents the armature 55 from dropping out at the end of the group so that the pawl 117 continues to retain the wheel 19. A following group of two pulses brings the locking pin 130b to the retaining position and the next group of two pulses brings the contact 139 of member 133b to the contact-making position. The device accordingly responds to the signal " 4, 2, 2 ". Had the first group been " 3 " the wheel would have moved to the third notch where there is no locking pin and accordingly when the armature 55 was released it would drop out and allow the wheel to return to zero position. If five pulses had been received, the wheel would have moved five steps causing the end 132 of locking pin 130a to bear on an upstanding flange 101 of lever 95 displacing it to a position where it prevented the arm 83 of rod 71 engaging the teeth of wheel 19. Subsequent pulses would then be ineffective until the device was reset.