GB560432A - Improvements in and relating to electric thermal control devices - Google Patents

Abstract

560,432. Thermal switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 28, 1942, No. 18391. Convention date, Dec. 31, 1941. [Class 38 (v)] Thermal means, shown as fluid actuated, operates on a switch arm 15 to open.or close switch contacts 13, 14 in the circuit of a refrigeratormotor. To raise the temperature at which the contacts close, to effect defrosting, the extension 26 of the arm carrying contact 13 may be allowed, at will, to move so that the contact gap is widened,' and, in an extreme position, the arm may be held with the contacts open. The extension 26 has a depending extremity, behind the temperature adjusting screw 27, which extends through the bottom of the casing 29 to bear, in normal action, against a stop formed at the end of a wire spring 32 at the normal limit of opening of the contacts. The temperature adjusting knob 30 is provided with a cam-sided projection 37 which, by bearing against a depending loop 36 of the spring 32, towards the end of the movement of the knob, can move the stop out of the path of the projection to obtain defrosting. A further projection 38, a.t the limit of knob movement positively moves the extremity of the arm 26 to hold the contacts open. Additional spring loading to the actuating device is also applied during defrosting. Specification 559,114 is referred to.