GB408133A - Improvements in thermally controlled electrical switches - Google Patents

Abstract

408,133. Thermal switches. BRITISH THERMOSTAT CO., Ltd., Windmill Road, Sunbury, Middlesex, and PAYNE, M., 50, Hook Road, Surbiton, Surrey. Aug. 11, 1933, No. 22488. [Class 38 (v).] In a thermal switch having amplifying mechanism such as a system of levers arranged between the thermal element and the contact mechanism, the amplifying and contact mechanism are constructed as a unit that may be moved relatively to the thermal element to adjust the operating temperature. At the extreme limit of the adjustment, the contact arm 10 engages a cam surface on the stop on the base 1 limiting the movement, and is forced into the off position so that the switch is no longer under thermal control. In the form shown the thermal element consists of a steel rod 3 mounted within a brass tube 2 which is fixed to a base 1. The base 1 has a screwed projection 7 on which is rotatably mounted a framework carrying a lever 8 which is pivoted at 9, bears against the rod 3 and is controlled by a compression spring 17 and a lever 10 which is pivoted at 11, bears against the lever 8, and is controlled by a spring 16. The lever 10 also carries a contact 12 co-operating with a contact 15, and an armature 19 co-operating with a magnet 18 to provide a definite make and break. The framework also carries a cover 22 which serves as a knob whereby the whole may be rotated through a limited angular distance to vary by means of the action of the screw 7, the temperature setting.