Patent GB-370044-A (GB)
Title: Improvements in or relating to automatic switches for use in telephone or like systems
IPC: H01H67/16
Filed: 1931-01-02
Abstract: 370,044. Automatic exchange switches. AUTOMATIC ELECTRIC CO., Ltd., (formerly AUTOMATIC TELEPHONE MANUFACTURING CO., Ltd.), Strowger Works, WOODLAND, C. R., 45, Warnerville Road, Broadgreen, and ELLIS, J. H., 71, Broad Square, West Derby, all in Liverpool. Jan. 2, 1931., No. 218. [Class 40 (iv).] In a bi-directional step-by-step switch, the rotary ratchet is coupled to the switch shaft by a pin and vertical slot arrangement so that it does not partake in the vertical movement, release being effected by continued rotary stepping of the shaft until the wipers move clear of the banks whereupon the circuit of the rotary magnet is opened, the vertical detent is mechanically released to drop the shaft, and the rotary magnet is again energized to continue the rotation of the shaft to normal. The release magnet and cup spring are thus dispensed with. Means for mounting and adjusting the magnets, operating the mechanically controlled springs, and feeding the wipers are also described. The switch may be adapted to engage twenty outlets (two levels) in a single rotation. The rotary ratchet 9 is formed on the upper end of a cylinder 14 rotatably mounted on a spindle 15 which is secured by a large cap 16 and screw 17 to the switch frame 10 and projects downwardly into a hollow vertical ratchet 19 fixed to the wiper shaft. The cylinder 14 is supported on a ring 18 sprung into a groove on spindle 15 and has a vertical slot engaging a pin 21 on the vertical ratchet. The switch frame comprises a rectangular box 10 with top and bottom flanges 11, 12, the vertical and rotary magnets being adjustably mounted in guides within the box by means of screws 50, 51 as shown for the vertical magnet 22, Fig. 5, which is adapted to be moved by an adjusting screw such as 53, Figs. 1 and 6. The vertical stepping pawl 25 is pivoted on the end of an arm 23 on the armature which, in unoperated position, rests on an adjustable stop 28, the pawl being provided with an arm 26 which abuts against an adjustable stop 27 to withdraw the pawl from the ratchet when magnet 22 is de-energized. The upper end of the pawl 25 engages a yoke 29 adjustably secured at 30 to the switch frame. The armature 55 of back stroke rotary magnet 49, Fig. 6, is pivoted on a vertical axis at 82 and its stepping pawl 57 engages an adjustable stop 58 when the magnet is de-energized. An adjustable armature stop is also provided. The armatures of both magnets are restored by adjustable connections to a two-armed single spring (not shown) mounted on box 10. The mechanically-operated spring sets are mounted on platforms 13, Fig. 5, on the sides of box 10. The off-normal set 73 is operated by a lever 33 and shaft cam 32 as described later ; the vertical interrupter springs 34 are operated by a plunger 36 engaged by a ball 35 mounted in the path of the armature of vertical magnet ; sets of post-springs 42, 43 are operated by vertically pivoted levers 45, 46 carrying studs 47, 48 corresponding to any desired level and operated by a ring 44 freely mounted on the switch shaft ; the rotary interrupter set 63 may be operated by a ball and plunger or by an arm 64, Fig. 6, on the armature of rotary magnet through a member 65 mounted with lost motion on a pin 66 so that the set is not operated in either direction until the armature has made a definite movement; the rotary offnormal set 68 is operated by a spring-lever 70 and stud 69 on the cylinder 14 ; eleventh step springs 71 are operated by stud 83 on cylinder 14 ; and springs 72 are operated by a similar stud when the switch is stepped past the eleventh position. To release the switch, the wipers are stepped on by the rotary magnet until springs 72 are operated. In this position, the circuit of rotary magnet is opened, the wipers are clear of the banks, and projection 84 on cylinder 14 engages pin 39 to move the spring-controlled vertical detent 37 out of engagement with ratchet 19. The switch drops to vertical normal in which position cam 32 engages lever 33, but as the lever is opposite the recessed portion 85 of the cam only the springs 73<1> of set 73 are operated and the circuit of rotary magnet is again closed. The switch takes two further steps to rotary normal, lever 33 rides out of recess 85, and spring set 73 is fully operated to open the circuit of the rotary magnet. The wiper feeds comprise a contact comb 86, Fig. 4, secured to a pillar 76 on the switch frame and having teeth corresponding to each level, adapted to be engaged by arcshaped brushes 75 preferably stamped integrally with the wipers 74. When the wipers are stepped out of the banks, the brushes leave the comb 86 and, since the shaft then drops, the wiper ends do not make contact with the comb when the switch steps on to normal. Double-ended wipers are shown, but singleended wipers wiping successively over different banks may be provided to give access to twenty outlets for a single rotation of the switch. A cover 78 abuts against a resilient strip 87 at the upper end of the switch-plate, and its lower end carries a U-shaped metal strip 80 insulated from the cover 78 and abutting the edge of flange 12 of the switch frame. The terminal banks and wipers may be protected by a guard preferably of coarse mesh through which minor adjustments may be made.