GB496414A - Improvements in spring mechanism - Google Patents

Abstract

496,414. Electrically-released switches. ENGLISH ELECTRIC CO., Ltd., and JOHNSON, W. L. June 30, 1937, No. 18204. [Class 38 (v)] A spring mechanism for closing switches which are too heavy to be closed sufficiently rapidly by direct manual operation, comprises a crank and a hand-lever adapted by repeated oscillatory movements to rotate the crank through ratchet and pawl or equivalent means to stress a spring more or less gradually, the ratchet or like means, while leaving the crank free to turn forwards, preventing it at all times from turning backwards, so that the crank must be moved past a dead-centre position and the spring fully stressed before the latter can be released to effect quick closure of the switch. Successive strokes of an operating handle 3, rotatable freely about crankshaft 2, cause a ratchet 1 to be rotated step-by-step by means of a pawl 4, and so turn a crank 2a from the dead-centre position shown to the opposite dead-centre, and, by means of lever 6 and a lever. 10, freely pivoted on a shaft 11 to which the switch-operating arm is connected, to stress a spring 8, whereupon the spring 8 is free to expand and close the switch by the engagement of an arm 10a pivoted on lever 10, engaging a projection 17a on a lever 17 fast on shaft 11. If desired, and as shown, the parts are retained just beyond the upper dead-centre by means of an arm 13 on the ratchet, or by the crank itself, engaging the roller 14 of a manually or automatically trippable lever. A detent 12 locks the ratchet during spring-stressing. For manual closure in an emergency, the hand-lever 19 is inserted into lever 17 and a projection 19a thereon engages an extension 10c of arm 10a to remove it from engagement with the projection 17a, so disengaging the spring 8 from the switch. Preferably the crank, spring, and lever system 6, 10 is repeated on the other side of the ratchet, and the impact of the springs is taken up by buffers 20 or dash-pots. The Specification states also that levers 6 could be pivotally or rigidly connected to the spring-mechanism, which would then reciprocate in fixed or oscillable spring- holders, and that the equivalent of the driven member 17 could be mounted on shaft 2 with the pawl 10a pivoted to the ratchet or one of the cranks.