GB398387A - Improvements in clock-operated electric switches - Google Patents

Abstract

398,387. Time switches. CHARSLEY, E. H., Bridge House, Bexley, Kent. Jan. 18, 1933, No. 1667. [Class 38 (v).] A time switch comprises a contact arm 16 pivoted at 24 and connected by a link 15 to a link 14 pivoted at 23. A tension spring 20 biases the contact arm 16 towards the on position in which contact studs C<1>, C<2> engage studs D<1>, D<2> carried on springs 17, 18. In the off position shown in Fig. 1, the contact arm is held by the engagement of a pin 25 with the end 7A of a hooked trip lever 7 pivoted at 10 and biased by a tension spring 12. Switching on is performed by a tappet 4 carried by a 24-hour dial 2, which first moves an auxiliary lever 8 pivoted at 9 against the action of a spring 11, out of engagement with the pin 25. The lower end 8A engages a lug 19 on the contact spring 18 to depress it. The tappet 4 then engages the lever 7 to move it out of engagement with the pin 25, allowing the contact arm 16 to move under the action of its spring 20. The contacts C<1>, D<1> then engage. Finally the tappet 4 releases the auxiliary lever 8 which allows contact spring 18 to snap upwards and allow contacts C<2>, D<2> to engage and complete the circuit. Lever 7 is also released and the hooked end 7A engages round the pin 25 to hold the contact lever positively in the on position. To open the switch, an off tappet 3 engages only the lever 7 to disengage the hooked end 7A from the pin 25 and the switch is opened by the lever 8 moving the pin 25 under the action of spring 11. The hooked end 7A of the lever 7 is so formed that just before the opening movement the contact pressure is increased. Modifications are described in which mercury contacts and dippers are employed and in one form a changeover switch is shown having an additional lever for holding the contact arm in a central zero position.