GB1270834A - Improvements in or relating to thermally operated electric switches - Google Patents

Abstract

1,270,834. Thermal switches. DIAMOND H. CONTROLS Ltd. 11 March, 1970 [14 March, 1969], No. 13491/69. Heading H1N. A thermal switch of the kind having a capsule 18 which can be moved by a knob 3 to set the operating temperature is provided also with a fixed contact adjustment 27 for calibrating the switch; the fixed contact 29 is carried by a blade 30 attached to a member 25 deformable by the adjusting screw 27 whose head is outside the casing 2 (Fig. 4); a spring 28 prevents backlash. The temperature setting knob 3 rotates a threaded sleeve 5 which is locked against axial movement; stops 10, 11 limit the rotation and a spring-loaded ball 12 locates the knob in one position. The capsule 18, connected by tube 19 to a sensing bulb 20, has a threaded extension 21 which is screwed into sleeve 5 and an extension 22 acting upon a movable contact blade 24. The capsule is prevented from rotating by engaging the pipe 19 with the forked end of a spring clip 32 so that rotation of the knob moves the capsule axially; the clip 32 also urges the screwthreads together to prevent backlash (Fig. 2, not shown). The capsule with its adjustment and the contact assembly are separately mounted in the two halves 1, 2 of the casing.