Improvements relating to electric switches suitable for gun-firing mechanisms

摘要

570,285. Press-button switches; momentarycontact switches. C. A. V., Ltd., BEVIS, W. A., CURZON, T., and BEDGGOOD, V. Dec. 6, 1943, No. 20364. [Class 38 (v)] [Also in Group XXI] A multi-contact switch for actuating a gunfiring mechanism comprises two pairs of contacts h, m and n, o which are connected in series in the circuit containing the gun-firing electromagnet. Push-button b carries a rod g, upon which slides contact h and insulating block p carrying the two contacts m, n, the slideable members being held apart by springs j, 'q, r. The other spring blade contact o presses against insulating block p. A positioning spring w engages notches v, u when the button is uppermost and depressed, respectively. Button b when depressed firstly causes contacts h and m to engage and then contact n momentarily contacts o to complete the firing circuit until w engages notch u. The time of contact between o and n is controlled by dashpot t and piston s attached to block p. On releasing the button, contact between h, m is at once broken subsequent engagement between n, o being without effect and the switch is returned to its original position when w engages v. The circuit, Fig. 2, comprises firing electromagnet 4, push-button switch x, switch y, having an operating coil 2 of low resistance and shunt coil 3 of high resistance. On closure of switch x, coil 4 is energised and 2 opens switch y, whereupon resistance 3 reduces the current and practically de-energises 4 until switch x is opened. In Fig. 3 switch y is actuated by a bimetal strip 6 and the shunting electromagnet 2 has a high resistance winding.