GB405441A - Improved regulating means for pressure-operated electric switches - Google Patents

Abstract

405,441. Snap-action switches; actuation of switches. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Leonard, V. W.; 81, Vine Street, Saugus, Massachusetts, U.S.A.) Dec. 13, 1932, No. 35342. Convention date, Dec. 16, 1931. [Class 38 (v).] In a pressureoperated snap-action switch for maintaining pressure between two limits, the range of allowable pressure as well as the limits of pressure are varied by adjustments of the spring which opposes the action of the pressure. As shown, the pressure acts through a member 13 upon a diaphragm 12 which is acted upon by a return spring 16. Movement of the diaphragm to the right causes the clockwise rotation about its lower end of a lever 28 connected by a spring 27 to a contact member 25 pivoted at 26, causing the spring to move past the pivot 26 and open the contacts 24, 22. Closure of the contacts is similarly effected by movement of the diaphragm to the left under the action of the spring 16. The pressures at which the switch opens and closes are varied by increasing or decreasing the tension of the spring 16 which is done by rotating a screw 19 which engates a nut 17 which engages the right hand end of the spring. The nut 17, which engages at its periphery the actual turns of the spring, may also be rotated so as to move along the spring and thus vary the number of turns of the coil which are effective. This will vary the extent of the range of allowable pressure.