559,437. Snap-action switches; linkwork. FOSTER TRANSFORMERS & SWITCHGEAR Ltd., and MORRIS, F. Oct. 30, 1942, No. 15237. [Class 38 (v)] [Also in Group XXIV] A dead-centre spring toggle comprises a cylinder c pivoted on a crank pin 3 on the primary, or operating, shaft P and a plunger b engaging over a crank pin 4 on a cam lever L on the secondary, or operated, shaft S. To close, shaft P is rotated clockwise and as pin'3 nears the line of centres P, 3, 4, a pin 1 driven by shaft P engages cam surface lSP1/SP and moves pin 4 clockwise across the line of centres S, 3, 4, the pin 1 engaging a recess lSP2/SP in the cam lever L to prevent opening of the switch by moving shaft S, Fig. 4. In opening, reverse movement of P produces a similar operation, the pin 2 engaging the under-surface of the cam. The pins 1, 2 provide positive actuation if the spring breaks. The Provisional Specification refers to Specification 530,586.
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