GB787654A - Improvements in electric control devices - Google Patents

Abstract

787,654. Rotating drum driers. ROBERTSHAW-FULTON CONTROLS CO. Nov. 12, 1954 [Dec. 21, 1953], No. 32923/54. Class 34(2) [Also in Groups XXXV and XXXVII] In a control device similar to that of Specification 650,601 manually-operable means are provided for opening both the first and second switching means independently of the condition responsive means. The first and second switching means comprise springs 56, 56a, respectively carrying contacts 58, 60, and 59. When a knob 18 is rotated from an "off" position to a "start" position beyond the highest temperature setting, a cam 88 thereon engages a rod 80 which is thereby pushed to the left, Fig. 4, against the bias of a spring 82 to push a member 70, 74 to the left and close contacts 58, 59. 60. The member 74 is latched in this position by a pawl 92. When moving to the "start" position, a cam 128 on the knob releases a plunger 124 thereby allowing contacts 108, 120 to close to complete the circuits to e.g. a heater 130 and motor M of a clothes dryer. The knob can then be turned back to the desired temperature setting, and eventually when the desired temperature is attained, a diaphragm 20 moves levers 28, 38 and a tension spring 36 overcentre to close contacts 48, 50, 51 to complete a holding circuit for the motor. Further movement of lever 38 causes a part 100 thereof to release pawl 92 from member 74 so that contacts 58, 59, 60 open to de-energize the heater and break the original motor circuit. When the temperature drops sufficiently, the contacts 48, 50, 51 are snapped open to stop the motor. The knob may be turned to the "off" position at any time so that plunger 124 is moved to open contacts 108, 120 and rod 102 is moved to push part 100 of lever 28 to release pawl 92 so that contacts 58, 59, 60 open. The device may alternatively control bake and broil elements in an oven so that both elements are first energized simultaneously and then the bake element alone. Specification 711,218 [Group XXXVII] also is referred to.