Patent GB-1171454-A (GB)
Title: Improvements in or relating to Geneva Mechanisms
Inventor: MOLYNEUX JOHN
IPC: F16H27/06
Filed: 1966-11-22
Abstract: 1,171,454. Automatic circuit-breakers; actuation of switches; switchboards. ENGLISH ELECTRIC CO. Ltd. 21 Nov., 1967 [22 Nov., 1966], No. 52159/66. Heading H1N. [Also in Division F2] Mechanism for operating a three-position switch comprises a Geneva wheel 27 having only two slots 91, 92, with respective drives 41 and 42 journalled at 65, 66, for operation of rollers 53 and 54 by detachable handles to turn the Geneva wheel 27 through about 40 degrees respectively anti-clockwise and clockwise from the central position shown, the wheel 27 being locked against rotation at all times except when either drive is actuated. Wheel 27 is secured to a mainshaft 26 linked to switch blades (33, Fig. 3, not shown) which may be of three-phase type and have a central OFF position, an EARTH position (drive 41) and an ON position (drive 42). Springs (45, 46, Fig. 4, not shown) co-operate with drives 41 and 42 to provide overcentre snap action. Rollers 53 and 54 are carried between flanges 49, 50 and 51, 52, respectively, and pins 93, 95, 94, 96 on wheel 27 engage arcuate surfaces 59, 60, 62, 61, respectively, to lock the wheel 27 in the several positions of the drives 41 and 42. Fixed spacers 73 and 74 locate the drives as shown, and pins 69, 70 and 71, 72 engage cut outs 97, 98 in the operated positions of the drives. A test probe gate (not shown) is coupled to lever 76 and a pin 83 thereon engages a flange 99 on wheel 27 to prevent opening of the gate until the switch has been turned to EARTH, whereupon opening the gate rotates a three-armed lever 28, loosely pivoted on shaft 26, such that its ends 81 and 82 prevent movement of drives 41 and 42 (as in Fig. 7, not shown). When the gate is half shut (locking the probes in position) the pin 83 rises above a block 100 on wheel 27 and the end 82 permits drive 41 to move the switch to OFF for testing, but the end 81 still overlies pin 64 to prevent movement of drive 42 to ON. In this condition the pin 83 is located between flange 99 and block 100 (as in Fig. 8, not shown) and prevents full opening of the gate until the switch is again moved to EARTH. In the embodiment of Fig. 9 two threearmed levers, 128 and 228, are simultaneously operable by a key inserted to engage a shaft 106 or 107, and their ends 181, 182, 281, 282 lock the drives 41 and 42 in any combination of positions. Either a lockable handle or interlock key mechanism (16, 17, 18, Fig. 2, not shown) may be used. Automatic circuit-breaker.-In the embodiment of Fig. 10 the drive 42 and associated locking means is modified to permit the switch to be opened automatically by a spring device 342. The drive 42 is turned through 180 degrees anticlockwise to bring roller 54 against the edge 317 of a locking plate 315 and its associated overcentre spring (46) snaps it through a further 180 degrees to return it to the position shown. Roller 54 slides plate 315 to remove the end 322 of a locking lever clear of pin 323 on the Geneva wheel and then acts on slot 92 to turn the wheel to the ON position, loading spring device 342 through the linkage shown. A pin 336 on the wheel moves under the end 345 of a spring-urged latch pivoted at 328 on a lever 326 which is in turn pivoted at 327 and restrained against a compression spring 335 by a lever 330 which rests against a striker pin 344 of a fuse 343. If fuse 343 blows the latch is released and wheel 27 trips rapidly to the OFF position under action of spring device 342. The striker-pin fuse may be replaced by a shunt trip or manual push button.