Patent GB-413821-A (GB)
Title: Improvements in or relating to rotary electric switches
IPC: H01H19/64
Filed: 1933-03-27
Abstract: 413,821. Snap action switches. BULGIN, A. F., c/o Bulgin & Co., Ltd., A. F., Abbey Road, Barking, Essex, ANDREWS, W. G., Boundary Works, High Street, Ponders End, Middlesex, and STOTT, H. T., 17, Sylvan Avenue, Mill Hill, London. March 27, 1933, No. 9186. [Class 38 (v).] A rotary snap-action switch operable in both directions of rotation comprises a rotary member 7 adapted to operate the movable contacts of the switch and normally held against rotation by engagement with a stationary member, such as the switch casing 1, under the action of a spring, and an operating spindle 4 having means for moving the rotary member radially, while stressing a spring, until the rotary member is disengaged from the stationary member, whereupon the spring rotates the rotary member rapidly to a new position in which it is held by the stationary member. In the form shown in Figs. 3, 4 and 5, the sp ndle 4 passes through an elongated slot 8 in the rotary member 7, and carries at its end an arm 6 connected by a spring 11 to a stud 9 or. the rotary member. A tongue 10 on the latter normally engages one of a series of notches 2 inside the casing. On rotating the spindle by means of a knob 5 a cam 6<a> on the arm 6 engages the pin 9 and gradually moves the member 7 longitudinally to disengage the tongue 10, whereupon the member 7 is rapidly rotated by the spring 11 until the tongue engages the next notch. The L-shaped movable contact 13 is carried by a rotary plug 14 of insulating material provided with a tongue 14<a> which engages a notch 12<a> in a bridge-piece 12 secured to the member 7, so that, on rotation of the latter, the contacts 13 are rotated into or out of engagement with the fixed contacts 15. The lower end of the rotary plug 14 is provided with a slot 14b adapted to engage the tongue 14<a> of another plug, so that several sets of cor.tact members may be mounted one above the other and operated from the same spindle. Each set of fixed contacts 15 comprises pairs of spring blades, of the shape shown in Fig. 3, mounted between a pair of cruciform mouldings 16. In a modification, Figs. 11, 12 and 13, a separate spring 19 is provided for holding the rotary member 7 normally in engagement with the stationary member. This spring surrounds a shouldered portion of the mounting bush 3 of the switch, and its ends bear against bosses 7<b> mounted on either side of the slot 8 in the member 7. The snap-action movement is produced by a spring 11<a> coiled round a sleeve at the upper end of a member 20 connected to a spindle 25 carrying the rotary contact members of the switch. The two arms of the spring 11<a> engage studs 9, 23 secured respectively to the rotary member 7 and to the arm 6 carried by the spindle 4. Rotation of the latter causes the stud 23 to displace one arm of the spring, while the other arm is held by the stud 9 until cam 6<a> has moved the member 7 to release the tongue 10 from the notch 2, whereupon the spring rapidly rotates the member 7 to the next position. The contact-carrying spindle 25 is connected to the member 7 by means of an arm 22 which engages lugs 24 on the underside of the member 7.