Control mechanism for fluid fuel burning appliances having main and pilot burners

737,830. Thermally-actuated valves. ROBERTSHAW-FULTON CONTROLS CO. Sept. 14, 1953, No. 25374/53. Class 135. A control mechanism for fluid fuel burning appliances having a main burner connected at 14, Fig. 3, and a pilot burner connected at 58, Fig. 4, comprises a main valve 78 and pilot valve 50 biased to close, manual means for opening the pilot valve, e.g. the axially movable handle . 22 of the cock 18 controlling the inlet 12 acting through the rod 30 and lever 70, a first thermal device for actuating the main valve, e.g. rod and tube 102, 104 acting through a snap-acting device 92, over-ride device 75 and lever 106 having a fulcrum adjustable at 108 for temperature setting, a lever 86 having a first portion 84 movable to hold the main valve closed in opposition to the device 102, 104 and a second portion at 71 movable to hold the pilot valve open, and a second thermal device for moving these portions, e.g. the phial 116 responsive to the pilot flame and diaphragm 118 acting through the lever 124 on the levers 86, 70 and pilot valve. On opening the cock gas flows via chamber 16 up to the closed main valve and via passage 44 and a filter to the closed pilot valve. On lighting the pilot burner after depressing handle 22, the diaphragm 118 moves the lever 86 to keep the pilot valve open and removes the spring loading 80 from the main valve which then opens or closes according to the position of the rod 102.