GB421653A - Improvements in or relating to electric time switches - Google Patents

Abstract

421,653. Time switches. SANGAMO ELECTRIC CO., Springfield, Illinois, U.S.A. June 28, 1933, No. 18443. Convention date, Feb. 6. [Class 38 (v)] A time switch has a contact-operating arm 51 which is moved by hand into the position shown against the action of a spring and there retained by its pivoted end 51<e> bearing against the cut-away portion of a clock-driven shaft 65 till at a predetermined time the rotation of the shaft allows the arm 51 to snap round in a counter-clockwise direction into engagement with another cut-away shaft 66 which later releases it in a similar way, the arm 51 then moving round into engagement with a stop 67 from which it may be released by hand. In the form shown, which is adapted for closing a circuit for a predetermined time, the two shafts 65, 66 are geared together and driven by the clockwork through a friction coupling so that the shaft 65 which carries an indicating disc 101 rotates once in an hour and the shaft 66 which carries an indicating disc 102 rotates once in five minutes. To close the circuit for an interval of say 43 minutes, the shafts 65, 66 are first rotated by means of a knob 111 geared to them till the discs 101, 102 indicate something over 40 and 3 respectively, the friction coupling allowing this to be done. The arm 51 is then rotated by means of a knob 51d into the position shown in which a cam 45, which moves round with the arm 51, is free from a contact spring 34 and the contact 34 is therefore in engagement with a fixed contact 33. The clockwork then slowly revolves the shafts 65 and 66 till the shaft 65 releases the arm 51 just before the 43 minutes have elapsed and the shaft 66 releases it at the 43 minutes exactly. The cam 45 presses the contacts 33 and 34 apart during the last of these two steps. The knobs 51d may then be pressed in by hand so as to cause the arm 51 to move out of engagement with the fixed stop 67. The cam 45 is then clear of the spring 34 and the contacts are closed and remain closed unaffected by the clockwork. In a modification, Figs. 1-9 (not shown) adapted to close and open a circuit at predetermined times the shafts 65 and 66 are geared so as to move at the same speed and they are independently adjustable by separate knobs to the predetermined times. The cam 45 is also shaped so that when the arm 51 is released from the shaft 65 and moves to the shaft 66 the circuit is closed, and when the arm 51 moves from the shaft 66 to the stop 67 it is opened. Further movement of the arm 51 by means of the hand release causes the circuit to be closed.