Patent GB-642108-A (GB)
Title: Improvements in or relating to electric switches of the multi-pole type
IPC: H01H23/16
Filed: 1947-01-09
Abstract: 642,108. Snap-action multi-position retractive switches. IGRANIC ELECTRIC CO., Ltd. Jan. 9, 1947, No. 781. Convention date, Jan. 10, 1946. [Class 38(v)] An electric switch suitable for motor control, shown as a double-throw switch in Figs. 1-3, comprises a moulded insulating housing 15 divided into three compartments, one for each pole, by integral barriers 18, 19, each compartment being divided into three by transverse ridges 29-34. The centre part of each compartment has a double-ended spring contact 41 riveted at 35 to its terminal 36. The outer parts of each compartment house L-shaped contacts 44 similarly secured to terminals 43. Tips 44a of a moulded silver-base compostion welded to the contacts 44 co-operate with corresponding tips 44a on the up-turned ends 42a, 42b of three contactors 42 which are controlled by springs 56 and slidable on a slidable insulating block 45 to an extent limited by enlarged portions of recesses 45c, 45d, Fig. 2. Grooves 59, 60, 61 in the block 45 minimise friction, Fig. 3. The block 45 has grooves 62, 63 receiving the barriers 18, 19. An apertured insulating plate 48 located by ledges 49, 50 on the base, engages, against the resilience of the contacts 41, ridges 46, 47 on the block. A similar metal plate 51, above the plate 48, supports a bush 52 carrying the pivot 54 of the operating lever 53, the spherical lever end of which engages a compression spring 55 in a recess in the block 45. A sheet metal retaining lever 68 bears on the plate 51, and is secured to the base 15 by depending end portions 68c, 68d having lugs 68f bent against the tops of recesses 15d. Alternative or additional fixing means for the cover consists of rivets inserted in holes 69, 70 in the base, after broaching out the hole bottoms 69a, 70a, the rivets passing through corresponding holes in the plates 48, 51 and the cover. With the latter method of fixing, the depending portions 68c, 68d of the cover may be omitted. The switch is flush-mounted by tapped holes 68h, 68i. Spring-plungers 57 in the block co-operate with locating notches 15a-15c in the base, whereby also the contacts open with a snap action. Should any of the contacts have welded they will be forcibly separated by the ends of the contactors engaging the shoulders in the recesses 45c, 45d. Four compression springs 94 located in opposing grooves, as 72, 76, Fig. 9, in the base and block respectively, return the block to the central " off " position on release of the lever, one pair of springs being omitted when only one momentary position is required, as is the case in Fig. 9. A single-throw switch, Figs. 7, 9, has a base 80 smilar to the base 15, but without the ridges 29-34. One set of contacts 44 and springs 56 are provided and resilient contacts 86 are riveted at one end of the three compartments. The switch lever may be mounted as before, or, as shown, pivoted in an externally threaded bush 92 fixed to a cover 89, the metal plate 51 being omitted. Two pairs of notches 87, 88 spaced a distance equal to that between notches 15a, 15c of the double-throw switch, give an "on" " and " off " position. The compression springs 94 positioned in two pairs of adjacent grooves 72-78 make either the '' on " or " off " position momentary accordare placed. In Fig. 10, not shown, the base ing to which end of the block the springs 80 of Figs. 7-9, accommodates the contacts of the double-throw switch of Figs. 1-4, there thus being two " on positions but no " off " position.