| 摘要 |
518,395. Thermal switches. TUCKER & CO., Ltd., J. H., and FUKE, F. C. Sept. 23, 1938, Nos. 27731, and 36384. [Class 38 (v)] In a safety device for an electric wash boiler a switch lever 15, pivoted at 11 and biased by a spring- toggle arrangement to one side or the other of a vertical line through 11, normally bears against one or other arm 9 of a member 6 fixed to a vertical spindle soldered to a support. When the solder melts with overheating, the lever 15 moves fur- 'ther still from its central position into the dotted position shown under the action of the dead centre spring 21, pushing the arm 9 with, it and opening switch contacts. The solder then resets, and to reset the switch the shaft 11 is rotated by hand in a clockwise direction back into the switch-closed position, the lever 15 moving, however, beyond its original position till it engages the other arm 9 of the member and is there held. The spring 21 has during this action moved over its deadcentre and now tends to rotate the lever 15 further in a clockwise direction. The switch is still closed and further rotation to open the contacts only occurs when the solder melts again. The switch may, however, be rotated back by hand to open the circuit. In a modification, Figs. 4, 5 (not shown), the member 6 has a slot within which the lever 15 moves. Specification 496,940 is referred to. |
