GB436968A - Improvements in or relating to mechanically operated time switches, particularly forswitching electric circuits in and out - Google Patents

Abstract

436,968. Time switches. KARLSSON, A. B., 82, Gitschinerstrasse, Berlin. April 24, 1934, No. 12359. [Class 38 (v)] In a short-time switch in which a knob 11 is rotated by hand through a predetermined number of revolutions or partial revolutions to wind up a spring 37 and then returns slowly under the action of the spring and the control of escapement mechanism 44 to cause, at the end of its return movement, the " on " or " off " movement of a switch which may also be independently operated by hand, the knob 11 is mounted on a spindle carrying a pin 33 which engages the teeth of a serrated disc 30 in the manner of a Geneva stop so as to cause the disc 30 to move on step by step while the knob 11 continuously rotates ; the disc 30 carries an indicating disc 36 marked in hours and the knob 11 is also provided with an indicating flange marked in minutes. The switch itself comprises a contact lever 27 and a hand lever 9, both pivoted at 25 and connected by a deadcentre spring 21. A projection 22 on the lever 27 is adapted in certain circumstances to engage the end of a spring-biassed lever 29 but normally the lever 29 is pressed into the position shown by a pin 31 on the disc 30. The switch may then be operated on and off by hand without interference. To use the device as a time switch, the knob 11 is rotated till the desired number of hours and minutes are indicated on the dials 36 and 10 and then released. The first movement withdraws the pin 31 from the lever 29. The hand lever 9 is then moved into its other position but the contact member 27 is held latched till at the end of the slow running-down movement the pin 31 re-engages the lever 29 and releases the member 27. The action is similar whether the switch is originally " off " or " on," but in one case the nose 22 is above and in the other case below the end 29<d> of the lever 29.