GB692893A - Improvements in electrical switch control mechanisms - Google Patents

Abstract

692,893. Thermal switches. GENERAL MOTORS CORPORATION. March 8, 1951 [April 6, 1950], No. 5663/51. Addition to 580,287. Class 38 (v) The invention of the parent Specification is modified by providing a screw by which the initial position of the bellows is made adjustable. In one form, Fig. 1, the switch is similar to that of the parent, the bellows 38 being secured to a member 40 which is received within a split nut 44 which is adjustable in a flange 46 in the base of the frame 20. Opening movement of the bellows is limited by the engagement of a lug (not shown) on the follower 34 with a flange on an adjustable screw 82. Excessive increase of temperature causes a lug 84 to raise a plunger 86 to close contacts 92, 125 to short out a signal lamp 129. The tension of spring bar 56 and the centre line of the toggle 52, 54 are adjustable, the former by screwing a sleeve 60 into or out of the side of the frame 20, and the latter by a cam 72 secured to a shaft 62 and co-operating with a lug 74 on the bar 56. The adjustments may be independent of each other or, if the sleeve 60 and shaft 62 are secured together, simultaneous. In a modification, Fig. 5, the cam 72 is replaced by a pinion 272 co-operating with a pinion 271 having an eccentric bore in which is located a pin 253, the head of which serves as a pivot for toggle link 54. The shaft 62, carrying the pinion 272, and the sleeve 60, are separately adjustable. The contacts 92, 125 may be omitted and the screw 82 may have two flanges limiting opening and closing movement of the bellows, as shown. In a further modification, Fig. 9 (not shown), the cam 72 (or its equivalent) is omitted and the shaft 62 serves only to support the knob 64.